diff --git a/arch/cpu/arm/arm-def.h b/arch/cpu/arm/arm-def.h
index 2cd31604c..92b19048d 100644
--- a/arch/cpu/arm/arm-def.h
+++ b/arch/cpu/arm/arm-def.h
@@ -60,6 +60,25 @@ typedef uint32_t uip_stats_t;
 typedef uint32_t rtimer_clock_t;
 #define RTIMER_CLOCK_DIFF(a, b)     ((int32_t)((a) - (b)))
 /** @} */
+
+/*
+ * The stdio.h that ships with the arm-gcc toolchain does this:
+ *
+ * int  _EXFUN(putchar, (int));
+ * [...]
+ * #define  putchar(x)  putc(x, stdout)
+ *
+ * This causes us a lot of trouble: For platforms using this toolchain, every
+ * time we use putchar we need to first #undef putchar. What we do here is to
+ * #undef putchar across the board. The resulting code will cause the linker
+ * to search for a symbol named putchar and this allows us to use the
+ * implementation under os/lib/dbg-io.
+ *
+ * This will fail if stdio.h is included before contiki.h, but it is common
+ * practice to include contiki.h first
+ */
+#include <stdio.h>
+#undef putchar
 /*---------------------------------------------------------------------------*/
 #endif /* ARM_DEF_ */
 /*---------------------------------------------------------------------------*/
diff --git a/arch/cpu/arm/common/SD-card/cfs-sdcard.c b/arch/cpu/arm/common/SD-card/cfs-sdcard.c
index 9be29fd2e..4c44e3e6b 100644
--- a/arch/cpu/arm/common/SD-card/cfs-sdcard.c
+++ b/arch/cpu/arm/common/SD-card/cfs-sdcard.c
@@ -1,7 +1,6 @@
 #include <efs-sdcard.h>
 #include <sys/process.h>
 #include <cfs/cfs.h>
-#include <debug-uart.h>
 
 #include <stdio.h>
 
diff --git a/arch/cpu/arm/common/dbg-io/dbg-printf.c b/arch/cpu/arm/common/dbg-io/dbg-printf.c
deleted file mode 100644
index 9bd09c1ac..000000000
--- a/arch/cpu/arm/common/dbg-io/dbg-printf.c
+++ /dev/null
@@ -1,30 +0,0 @@
-#include <stdio.h>
-#include <debug-uart.h>
-#include <string.h>
-#include <strformat.h>
-
-static StrFormatResult
-write_str(void *user_data, const char *data, unsigned int len)
-{
-  if (len > 0) dbg_send_bytes((unsigned char*)data, len);
-  return STRFORMAT_OK;
-}
-
-
-static StrFormatContext ctxt =
-  {
-    write_str,
-    NULL
-  };
-int
-printf(const char *fmt, ...)
-{
-  int res;
-  va_list ap;
-  va_start(ap, fmt);
-  res = format_str_v(&ctxt, fmt, ap);
-  va_end(ap);
-  return res;
-}
-
-
diff --git a/arch/cpu/arm/common/dbg-io/dbg-putchar.c b/arch/cpu/arm/common/dbg-io/dbg-putchar.c
deleted file mode 100644
index 54f3db53f..000000000
--- a/arch/cpu/arm/common/dbg-io/dbg-putchar.c
+++ /dev/null
@@ -1,26 +0,0 @@
-#include <stdio.h>
-#include <debug-uart.h>
-#include <string.h>
-
-#undef putchar
-#undef putc
-
-int
-putchar(int c)
-{
-  dbg_putchar(c);
-  return c;
-}
-
-int
-putc(int c, FILE *f)
-{
-  dbg_putchar(c);
-  return c;
-}
-
-int
-__sp(struct _reent *_ptr, int c, FILE *_p) {
-  dbg_putchar(c);
-  return c;
-}
diff --git a/arch/cpu/arm/common/dbg-io/dbg-puts.c b/arch/cpu/arm/common/dbg-io/dbg-puts.c
deleted file mode 100644
index fa90d1022..000000000
--- a/arch/cpu/arm/common/dbg-io/dbg-puts.c
+++ /dev/null
@@ -1,11 +0,0 @@
-#include <stdio.h>
-#include <debug-uart.h>
-#include <string.h>
-
-int
-puts(const char *str)
-{
-  dbg_send_bytes((unsigned char*)str, strlen(str));
-  dbg_putchar('\n');
-  return 0;
-}
diff --git a/arch/cpu/arm/common/dbg-io/dbg-snprintf.c b/arch/cpu/arm/common/dbg-io/dbg-snprintf.c
deleted file mode 100644
index 230d6891a..000000000
--- a/arch/cpu/arm/common/dbg-io/dbg-snprintf.c
+++ /dev/null
@@ -1,48 +0,0 @@
-#include <stdio.h>
-#include <strformat.h>
-#include <string.h>
-
-struct FmtBuffer
-{
-  char *pos;
-  size_t left;
-};
-
-static StrFormatResult
-buffer_str(void *user_data, const char *data, unsigned int len)
-{
-  struct FmtBuffer *buffer = (struct FmtBuffer*)user_data;
-  if (len >= buffer->left) {
-    len = buffer->left;
-    len--;
-  }
-    
-  memcpy(buffer->pos, data, len);
-  buffer->pos += len;
-  buffer->left -= len;
-  return STRFORMAT_OK;
-}
-
-int snprintf(char *str, size_t size, const char *format, ...)
-{
-  int res;
-  va_list ap;
-  va_start(ap, format);
-  res = vsnprintf(str, size, format, ap);
-  va_end(ap);
-  return res;
-}
-
-int vsnprintf(char *str, size_t size, const char *format, va_list ap)
-{
-  struct FmtBuffer buffer;
-  StrFormatContext ctxt;
-  int res;
-  ctxt.write_str = buffer_str;
-  ctxt.user_data = &buffer;
-  buffer.pos = str;
-  buffer.left = size;
-  res = format_str_v(&ctxt, format, ap);
-  *buffer.pos = '\0';
-  return res;
-}
diff --git a/arch/cpu/arm/common/dbg-io/dbg-sprintf.c b/arch/cpu/arm/common/dbg-io/dbg-sprintf.c
deleted file mode 100644
index 8124fc363..000000000
--- a/arch/cpu/arm/common/dbg-io/dbg-sprintf.c
+++ /dev/null
@@ -1,26 +0,0 @@
-#include <stdio.h>
-#include <strformat.h>
-#include <string.h>
-
-static StrFormatResult
-buffer_str(void *user_data, const char *data, unsigned int len)
-{
-  memcpy(*(char**)user_data, data, len);
-  (*(char**)user_data) += len;
-  return STRFORMAT_OK;
-}
-
-int
-sprintf(char *str, const char *format, ...)
-{
-  StrFormatContext ctxt;
-  int res;
-  va_list ap;
-  va_start(ap, format);
-  ctxt.write_str = buffer_str;
-  ctxt.user_data = &str;
-  res = format_str_v(&ctxt, format, ap);
-  *str = '\0';
-  va_end(ap);
-  return res;
-}
diff --git a/arch/cpu/arm/common/dbg-io/strformat.c b/arch/cpu/arm/common/dbg-io/strformat.c
deleted file mode 100644
index 13b91a563..000000000
--- a/arch/cpu/arm/common/dbg-io/strformat.c
+++ /dev/null
@@ -1,617 +0,0 @@
-#include <strformat.h>
-
-#define HAVE_DOUBLE
-
-#define HAVE_LONGLONG
-#ifndef LARGEST_SIGNED
-#ifdef HAVE_LONGLONG
-#define LARGEST_SIGNED long long int
-#else
-#define LARGEST_UNSIGNED long int
-#endif
-#endif
-
-#ifndef LARGEST_UNSIGNED
-#ifdef HAVE_LONGLONG
-#define LARGEST_UNSIGNED unsigned long long int
-#else
-#define LARGEST_UNSIGNED unsigned long int
-#endif
-#endif
-
-#ifndef POINTER_INT
-#define POINTER_INT unsigned long
-#endif
-
-typedef unsigned int FormatFlags;
-
-#define MAKE_MASK(shift,size) (((1 << size) - 1) << (shift))
-
-#define JUSTIFY_SHIFT	0
-#define JUSTIFY_SIZE	1
-#define JUSTIFY_RIGHT	0x0000
-#define JUSTIFY_LEFT	0x0001
-#define JUSTIFY_MASK	MAKE_MASK(JUSTIFY_SHIFT,JUSTIFY_SIZE)
-
-
-/* How a positive number is prefixed */
-#define POSITIVE_SHIFT	(JUSTIFY_SHIFT + JUSTIFY_SIZE)
-#define POSITIVE_NONE	(0x0000 << POSITIVE_SHIFT)
-#define POSITIVE_SPACE	(0x0001 << POSITIVE_SHIFT)
-#define POSITIVE_PLUS	(0x0003 << POSITIVE_SHIFT)
-#define POSITIVE_MASK	MAKE_MASK(POSITIVE_SHIFT, POSITIVE_SIZE)
-
-#define POSITIVE_SIZE	2
-
-#define ALTERNATE_FORM_SHIFT (POSITIVE_SHIFT + POSITIVE_SIZE)
-#define ALTERNATE_FORM_SIZE 1
-#define ALTERNATE_FORM  (0x0001 << ALTERNATE_FORM_SHIFT)
-
-
-#define PAD_SHIFT	(ALTERNATE_FORM_SHIFT + ALTERNATE_FORM_SIZE)
-#define PAD_SIZE	1
-#define PAD_SPACE	(0x0000 << PAD_SHIFT)
-#define PAD_ZERO	(0x0001 << PAD_SHIFT)
-
-#define SIZE_SHIFT	(PAD_SHIFT + PAD_SIZE)
-#define SIZE_SIZE	3
-#define SIZE_CHAR	(0x0001 << SIZE_SHIFT)
-#define SIZE_SHORT	(0x0002 << SIZE_SHIFT)
-#define SIZE_INT	(0x0000 << SIZE_SHIFT)
-#define SIZE_LONG	(0x0003 << SIZE_SHIFT)
-#define SIZE_LONGLONG	(0x0004 << SIZE_SHIFT)
-#define SIZE_MASK	MAKE_MASK(SIZE_SHIFT,SIZE_SIZE)
-
-#define CONV_SHIFT	(SIZE_SHIFT + SIZE_SIZE)
-#define CONV_SIZE	3
-#define CONV_INTEGER	(0x0001 << CONV_SHIFT)
-#define CONV_FLOAT	(0x0002 << CONV_SHIFT)
-#define CONV_POINTER	(0x0003 << CONV_SHIFT)
-#define CONV_STRING	(0x0004 << CONV_SHIFT)
-#define CONV_CHAR	(0x0005 << CONV_SHIFT)
-#define CONV_PERCENT	(0x0006 << CONV_SHIFT)
-#define CONV_WRITTEN	(0x0007 << CONV_SHIFT)
-#define CONV_MASK	MAKE_MASK(CONV_SHIFT, CONV_SIZE)
-
-#define RADIX_SHIFT	(CONV_SHIFT + CONV_SIZE)
-#define RADIX_SIZE	2
-#define RADIX_DECIMAL	(0x0001 << RADIX_SHIFT)
-#define RADIX_OCTAL	(0x0002 << RADIX_SHIFT)
-#define RADIX_HEX	(0x0003 << RADIX_SHIFT)
-#define RADIX_MASK	MAKE_MASK(RADIX_SHIFT,RADIX_SIZE)
-
-#define SIGNED_SHIFT	(RADIX_SHIFT + RADIX_SIZE)
-#define SIGNED_SIZE	1
-#define SIGNED_NO	(0x0000 << SIGNED_SHIFT)
-#define SIGNED_YES	(0x0001 << SIGNED_SHIFT)
-#define SIGNED_MASK	MAKE_MASK(SIGNED_SHIFT,SIGNED_SIZE)
-
-#define CAPS_SHIFT	(SIGNED_SHIFT + SIGNED_SIZE)
-#define CAPS_SIZE	1
-#define CAPS_NO		(0x0000 << CAPS_SHIFT)
-#define CAPS_YES	(0x0001 << CAPS_SHIFT)
-#define CAPS_MASK	MAKE_MASK(CAPS_SHIFT,CAPS_SIZE)
-
-#define FLOAT_SHIFT	(CAPS_SHIFT + CAPS_SIZE)
-#define FLOAT_SIZE	2
-#define FLOAT_NORMAL	(0x0000 << FLOAT_SHIFT)
-#define FLOAT_EXPONENT	(0x0001 << FLOAT_SHIFT)
-#define FLOAT_DEPENDANT	(0x0002 << FLOAT_SHIFT)
-#define FLOAT_HEX	(0x0003 << FLOAT_SHIFT)
-#define FLOAT_MASK	MAKE_MASK(FLOAT_SHIFT, FLOAT_SIZE)
-
-static FormatFlags
-parse_flags(const char **posp)
-{
-  FormatFlags flags = 0;
-  const char *pos = *posp;
-  while (1) {
-    switch(*pos) {
-    case '-':
-      flags |= JUSTIFY_LEFT;
-      break;
-    case '+':
-      flags |= POSITIVE_PLUS;
-      break;
-    case ' ':
-      flags |= POSITIVE_SPACE;
-      break;
-    case '#':
-      flags |= ALTERNATE_FORM;
-      break;
-    case '0':
-      flags |= PAD_ZERO;
-      break;
-    default:
-      *posp = pos;
-      return flags;
-    }
-    pos++;
-  }
-      
-}
-
-static unsigned int
-parse_uint(const char **posp)
-{
-  unsigned v = 0;
-  const char *pos = *posp;
-  char ch;
-  while((ch = *pos) >= '0' && ch <= '9') {
-    v = v * 10 + (ch - '0');
-    pos++;
-  }
-  *posp = pos;
-  return v;
-}
-
-#define MAXCHARS_HEX ((sizeof(LARGEST_UNSIGNED) * 8) / 4 )
-
-/* Largest number of characters needed for converting an unsigned integer.
- */
-#define MAXCHARS ((sizeof(LARGEST_UNSIGNED) * 8  + 2) / 3 )
-
-static unsigned int
-output_uint_decimal(char **posp, LARGEST_UNSIGNED v)
-{
-  unsigned int len;
-  char *pos = *posp;
-  while (v > 0) {
-    *--pos = (v % 10) + '0';
-    v /= 10;
-  }
-  len = *posp - pos;
-  *posp = pos;
-  return len;
-}
-
-static unsigned int
-output_uint_hex(char **posp, LARGEST_UNSIGNED v, unsigned int flags)
-{
-  unsigned int len;
-  const char *hex = (flags & CAPS_YES) ?"0123456789ABCDEF":"0123456789abcdef";
-  char *pos = *posp;
-  while (v > 0) {
-    *--pos = hex[(v % 16)];
-    v /= 16;
-  }
-  len = *posp - pos;
-  *posp = pos;
-  return len;
-}
-
-static unsigned int
-output_uint_octal(char **posp, LARGEST_UNSIGNED v)
-{
-  unsigned int len;
-  char *pos = *posp;
-  while (v > 0) {
-    *--pos = (v % 8) + '0';
-    v /= 8;
-  }
-  len = *posp - pos;
-  *posp = pos;
-  return len;
-}
-
-static StrFormatResult
-fill_space(const StrFormatContext *ctxt, unsigned int len)
-{
-  StrFormatResult res;
-  static const char buffer[16] = "                ";
-  while(len > 16) {
-    res = ctxt->write_str(ctxt->user_data, buffer, 16);
-    if (res != STRFORMAT_OK) return res;
-    len -= 16;
-  }
-  if (len == 0) return STRFORMAT_OK;
-  return ctxt->write_str(ctxt->user_data, buffer, len);
-}
-
-static StrFormatResult
-fill_zero(const StrFormatContext *ctxt, unsigned int len)
-{
-  StrFormatResult res;
-  static const char buffer[16] = "0000000000000000";
-  while(len > 16) {
-    res = ctxt->write_str(ctxt->user_data, buffer, 16);
-    if (res != STRFORMAT_OK) return res;
-    len -= 16;
-  }
-  if (len == 0) return STRFORMAT_OK;
-  return ctxt->write_str(ctxt->user_data, buffer, len);
-}
-
-#define CHECKCB(res) {if ((res) != STRFORMAT_OK) {va_end(ap); return -1;}}
-
-int
-format_str(const StrFormatContext *ctxt, const char *format, ...)
-{
-  int ret;
-  va_list ap;
-  va_start(ap, format);
-  ret = format_str_v(ctxt, format, ap);
-  va_end(ap);
-  return ret;
-}
-
-int
-format_str_v(const StrFormatContext *ctxt, const char *format, va_list ap)
-{
-  unsigned int written = 0;
-  const char *pos = format;
-  while(*pos != '\0') {
-    FormatFlags flags;
-    unsigned int minwidth = 0;
-    int precision = -1; /* Negative means no precision */
-    char ch;
-    const char *start = pos;
-    while( (ch = *pos) != '\0' && ch != '%') pos++;
-    if (pos != start) {
-      CHECKCB(ctxt->write_str(ctxt->user_data, start, pos - start));
-      written += pos - start;
-    }
-    if (*pos == '\0') {
-      va_end(ap);
-      return written;
-    }
-    pos++;
-    if (*pos == '\0') {
-      va_end(ap);
-      return written;
-    }
-    flags = parse_flags(&pos);
-
-    /* parse width */
-    if (*pos >= '1' && *pos <= '9') {
-      minwidth = parse_uint(&pos);
-    } else if (*pos == '*') {
-      int w = va_arg(ap,int);
-      if (w < 0) {
-	flags |= JUSTIFY_LEFT;
-	minwidth = w;
-      } else {
-	minwidth = w;
-      }
-      pos ++;
-    }
-
-    /* parse precision */
-    if (*pos == '.') {
-      pos++;
-      if (*pos >= '0' && *pos <= '9') {
-	precision = parse_uint(&pos);
-      } else if (*pos == '*') {
-	pos++;
-	precision = va_arg(ap,int);
-      }
-    }
-    if (*pos == 'l') {
-      pos++;
-      if (*pos == 'l') {
-	flags |= SIZE_LONGLONG;
-	pos++;
-      } else {
-	flags |= SIZE_LONG;
-      }
-    } else if (*pos == 'h') {
-      pos++;
-      if (*pos == 'h') {
-	flags |= SIZE_CHAR;
-	pos++;
-      } else {
-	flags |= SIZE_SHORT;
-      }
-    }
-
-    /* parse conversion specifier */
-    switch(*pos) {
-    case 'd':
-    case 'i':
-      flags |= CONV_INTEGER | RADIX_DECIMAL | SIGNED_YES;
-      break;
-    case 'u':
-      flags |= CONV_INTEGER | RADIX_DECIMAL | SIGNED_NO;
-      break;
-    case 'o':
-      flags |= CONV_INTEGER | RADIX_OCTAL | SIGNED_NO;
-      break;
-    case 'x':
-      flags |= CONV_INTEGER | RADIX_HEX | SIGNED_NO;
-      break;
-    case 'X':
-      flags |= CONV_INTEGER | RADIX_HEX | SIGNED_NO | CAPS_YES;
-      break;
-#ifdef HAVE_DOUBLE
-    case 'f':
-      flags |= CONV_FLOAT | FLOAT_NORMAL;
-      break;
-    case 'F':
-      flags |= CONV_FLOAT | FLOAT_NORMAL | CAPS_YES;
-      break;
-    case 'e':
-      flags |= CONV_FLOAT | FLOAT_EXPONENT;
-      break;
-    case 'E':
-      flags |= CONV_FLOAT | FLOAT_EXPONENT | CAPS_YES;
-      break;
-    case 'g':
-      flags |= CONV_FLOAT | FLOAT_DEPENDANT;
-      break;
-    case 'G':
-      flags |= CONV_FLOAT | FLOAT_DEPENDANT | CAPS_YES;
-      break;
-    case 'a':
-      flags |= CONV_FLOAT | FLOAT_HEX;
-      break;
-    case 'A':
-      flags |= CONV_FLOAT | FLOAT_HEX | CAPS_YES;
-      break;
-#endif
-    case 'c':
-      flags |= CONV_CHAR;
-      break;
-    case 's':
-      flags |= CONV_STRING;
-      break;
-    case 'p':
-      flags |= CONV_POINTER;
-      break;
-    case 'n':
-      flags |= CONV_WRITTEN;
-      break;
-    case '%':
-      flags |= CONV_PERCENT;
-      break;
-    case '\0':
-      va_end(ap);
-      return written;
-    }
-    pos++;
-    switch(flags & CONV_MASK) {
-    case CONV_PERCENT:
-      CHECKCB(ctxt->write_str(ctxt->user_data, "%", 1));
-      written++;
-      break;
-    case CONV_INTEGER:
-      {
-	/* unsigned integers */
-	char *prefix = 0; /* sign, "0x" or "0X" */
-	unsigned int prefix_len = 0;
-	char buffer[MAXCHARS];
-	char *conv_pos = buffer + MAXCHARS;
-	unsigned int conv_len = 0;
-	unsigned int width = 0;
-	unsigned int precision_fill;
-	unsigned int field_fill;
-	LARGEST_UNSIGNED uvalue = 0;
-	int negative = 0;
-      
-	if (precision < 0) precision = 1;
-	else flags &= ~PAD_ZERO;
-      
-	if (flags & SIGNED_YES) {
-	  /* signed integers */
-	  LARGEST_SIGNED value = 0;
-	  switch(flags & SIZE_MASK) {
-	  case SIZE_CHAR:
-	    value = (signed char)va_arg(ap, int);
-	    break;
-	  case SIZE_SHORT:
-	    value = (short)va_arg(ap, int);
-	    break;
-	  case SIZE_INT:
-	    value = va_arg(ap, int);
-	    break;
-#ifndef HAVE_LONGLONG
-	  case SIZE_LONGLONG:	/* Treat long long the same as long */
-#endif
-	  case SIZE_LONG:
-	    value = va_arg(ap, long);
-	    break;
-#ifdef HAVE_LONGLONG
-	  case SIZE_LONGLONG:
-	    value = va_arg(ap, long long);
-	    break;
-#endif
-	  }
-	  if (value < 0) {
-	    uvalue = -value;
-	    negative = 1;
-	  } else {
-	    uvalue = value;
-	  }
-	} else {
-	
-	  switch(flags & SIZE_MASK) {
-	  case SIZE_CHAR:
-	    uvalue = (unsigned char)va_arg(ap,unsigned int);
-	    break;
-	  case SIZE_SHORT:
-	    uvalue = (unsigned short)va_arg(ap,unsigned int);
-	    break;
-	  case SIZE_INT:
-	    uvalue = va_arg(ap,unsigned int);
-	    break;
-#ifndef HAVE_LONGLONG
-	  case SIZE_LONGLONG:	/* Treat long long the same as long */
-#endif
-	  case SIZE_LONG:
-	    uvalue = va_arg(ap,unsigned long);
-	    break;
-#ifdef HAVE_LONGLONG
-	  case SIZE_LONGLONG:
-	    uvalue = va_arg(ap,unsigned long long);
-	    break;
-#endif
-	  }
-	}
-	
-	switch(flags & (RADIX_MASK)) {
-	case RADIX_DECIMAL:
-	  conv_len = output_uint_decimal(&conv_pos,uvalue);
-	  break;
-	case RADIX_OCTAL:
-	  conv_len = output_uint_octal(&conv_pos,uvalue);
-	  break;
-	case RADIX_HEX:
-	  conv_len = output_uint_hex(&conv_pos,uvalue, flags);
-	  break;
-	}
-
-	width += conv_len;
-	precision_fill = (precision > conv_len) ? precision - conv_len : 0;
-	if ((flags & (RADIX_MASK | ALTERNATE_FORM))
-	    == (RADIX_OCTAL | ALTERNATE_FORM)) {
-	  if (precision_fill < 1) precision_fill = 1;
-	}
-
-	width += precision_fill;
-	
-	if ((flags & (RADIX_MASK | ALTERNATE_FORM))
-	    == (RADIX_HEX | ALTERNATE_FORM) && uvalue != 0) {
-	  prefix_len = 2;
-	  if (flags & CAPS_YES) {
-	    prefix = "0X";
-	  } else {
-	    prefix = "0x";
-	  }
-	}
-
-	if (flags & SIGNED_YES) {
-	  if (negative) {
-	    prefix = "-";
-	    prefix_len = 1;
-	  } else {
-	    switch(flags & POSITIVE_MASK) {
-	    case POSITIVE_SPACE:
-	      prefix = " ";
-	      prefix_len = 1;
-	      break;
-	    case POSITIVE_PLUS:
-	      prefix = "+";
-	      prefix_len = 1;
-	      break;
-	    }
-	  }
-	}
-
-	width += prefix_len;
-
-	field_fill = (minwidth > width) ? minwidth - width : 0;
-
-	if ((flags & JUSTIFY_MASK) == JUSTIFY_RIGHT) {
-	  if (flags & PAD_ZERO) {
-	    precision_fill += field_fill;
-        field_fill = 0;  /* Do not double count padding */
-	  } else {
-	    CHECKCB(fill_space(ctxt,field_fill));
-	  }
-	}
-
-	if (prefix_len > 0)
-	  CHECKCB(ctxt->write_str(ctxt->user_data, prefix, prefix_len));
-	written += prefix_len;
-	
-	CHECKCB(fill_zero(ctxt,precision_fill));
-	written += precision_fill;
-	
-	CHECKCB(ctxt->write_str(ctxt->user_data, conv_pos,conv_len));
-	written += conv_len;
-	
-	if ((flags & JUSTIFY_MASK) == JUSTIFY_LEFT) {
-	  CHECKCB(fill_space(ctxt,field_fill));
-	}
-	written += field_fill;
-      }
-      break;
-    case CONV_STRING:
-      {
-	unsigned int field_fill;
-	unsigned int len;
-	char *str = va_arg(ap,char *);
-	if (str) {
-	  char *pos = str;
-	  while(*pos != '\0') pos++;
-	  len = pos - str;
-	} else {
-	  str = "(null)";
-	  len = 6;
-	}
-	if (precision >= 0 && precision < len) len = precision;
-	field_fill = (minwidth > len) ? minwidth - len : 0;
-	if ((flags & JUSTIFY_MASK) == JUSTIFY_RIGHT) {
-	  CHECKCB(fill_space(ctxt,field_fill));
-	}
-	CHECKCB(ctxt->write_str(ctxt->user_data, str,len));
-	written += len;
-	if ((flags & JUSTIFY_MASK) == JUSTIFY_LEFT) {
-	  CHECKCB(fill_space(ctxt,field_fill));
-	}
-	written += field_fill;
-      }
-      break;
-    case CONV_POINTER:
-      {
-	LARGEST_UNSIGNED uvalue =
-	  (LARGEST_UNSIGNED)(POINTER_INT)va_arg(ap,void *);
-	char buffer[MAXCHARS_HEX + 3];
-	char *conv_pos = buffer + MAXCHARS_HEX+3;
-	unsigned int conv_len;
-	unsigned int field_fill;
-	
-	conv_len = output_uint_hex(&conv_pos,uvalue,flags);
-	if (conv_len == 0) {
-	  *--conv_pos = '0';
-	  conv_len++;
-	}
-	*--conv_pos = 'x';
-	*--conv_pos = '0';
-	*--conv_pos = '#';
-	conv_len += 3;
-
-	field_fill = (minwidth > conv_len) ? minwidth - conv_len : 0;
-	
-	if ((flags & JUSTIFY_MASK) == JUSTIFY_RIGHT) {
-	  CHECKCB(fill_space(ctxt,field_fill));
-	}
-	
-	CHECKCB(ctxt->write_str(ctxt->user_data, conv_pos,conv_len));
-	written += conv_len;
-	
-	if ((flags & JUSTIFY_MASK) == JUSTIFY_LEFT) {
-	  CHECKCB(fill_space(ctxt,field_fill));
-	}
-	written += field_fill;
-      }
-      break;
-    case CONV_CHAR:
-      {
-	char ch = va_arg(ap,int);
-	unsigned int field_fill = (minwidth > 1) ? minwidth - 1 : 0;
-	if ((flags & JUSTIFY_MASK) == JUSTIFY_RIGHT) {
-	  CHECKCB(fill_space(ctxt,field_fill));
-	  written += field_fill;
-	}
-	
-	CHECKCB(ctxt->write_str(ctxt->user_data, &ch, 1));
-	written++;
-	
-	if ((flags & JUSTIFY_MASK) == JUSTIFY_LEFT) {
-	  CHECKCB(fill_space(ctxt,field_fill));
-	}
-	written+= field_fill;
-      }
-      break;
-    case CONV_WRITTEN:
-      {
-	int *p = va_arg(ap,int*);
-	*p = written;
-      }
-      break;
-
-    }
-  }
-  
-  return written;
-}
diff --git a/arch/cpu/arm/common/dbg-io/strformat.h b/arch/cpu/arm/common/dbg-io/strformat.h
deleted file mode 100644
index c32eed670..000000000
--- a/arch/cpu/arm/common/dbg-io/strformat.h
+++ /dev/null
@@ -1,25 +0,0 @@
-#ifndef STRFORMAT_H_
-#define STRFORMAT_H_
-
-#include <stdarg.h>
-
-#define STRFORMAT_OK 0
-#define STRFORMAT_FAILED 1
-typedef unsigned int StrFormatResult;
-
-/* The data argument may only be considered valid during the function call */
-typedef StrFormatResult (*StrFormatWrite)(void *user_data, const char *data, unsigned int len);
-
-typedef struct _StrFormatContext
-{
-  StrFormatWrite write_str;
-  void *user_data;
-} StrFormatContext;
-
-int format_str(const StrFormatContext *ctxt, const char *format, ...)
-     __attribute__ ((__format__ (__printf__, 2,3)));
-     
-int
-format_str_v(const StrFormatContext *ctxt, const char *format, va_list ap);
-
-#endif /* STRFORMAT_H_ */
diff --git a/arch/cpu/cc2538/Makefile.cc2538 b/arch/cpu/cc2538/Makefile.cc2538
index f6e76f571..03758aa9b 100644
--- a/arch/cpu/cc2538/Makefile.cc2538
+++ b/arch/cpu/cc2538/Makefile.cc2538
@@ -27,14 +27,13 @@ CONTIKI_CPU_SOURCEFILES += slip-arch.c slip.c
 CONTIKI_CPU_SOURCEFILES += i2c.c cc2538-temp-sensor.c vdd3-sensor.c
 CONTIKI_CPU_SOURCEFILES += cfs-coffee.c cfs-coffee-arch.c pwm.c
 
-DEBUG_IO_SOURCEFILES += dbg-printf.c dbg-snprintf.c dbg-sprintf.c strformat.c
+MODULES += os/lib/dbg-io
 
 USB_SOURCEFILES += usb-core.c cdc-acm.c usb-arch.c usb-serial.c cdc-acm-descriptors.c
 
 CPU_START_SOURCEFILES = startup-gcc.c
 
-CONTIKI_SOURCEFILES += $(CONTIKI_CPU_SOURCEFILES) $(DEBUG_IO_SOURCEFILES)
-CONTIKI_SOURCEFILES += $(USB_SOURCEFILES)
+CONTIKI_SOURCEFILES += $(CONTIKI_CPU_SOURCEFILES) $(USB_SOURCEFILES)
 
 ### Always re-build ieee-addr.o in case the command line passes a new NODEID
 FORCE:
diff --git a/arch/cpu/cc2538/dbg.c b/arch/cpu/cc2538/dbg.c
index b97936feb..7b33bc471 100644
--- a/arch/cpu/cc2538/dbg.c
+++ b/arch/cpu/cc2538/dbg.c
@@ -28,16 +28,9 @@
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  * OF THE POSSIBILITY OF SUCH DAMAGE.
  */
-/** \addtogroup cc2538-char-io
- * @{ */
-/**
- * \file
- *     Implementation of arch-specific functions required by the dbg_io API in
- *     cpu/arm/common/dbg-io
- */
+/*---------------------------------------------------------------------------*/
 #include "contiki.h"
 
-#include "dbg.h"
 #include "dev/uart.h"
 #include "usb/usb-serial.h"
 
@@ -55,13 +48,10 @@
 #define flush()
 #endif
 /*---------------------------------------------------------------------------*/
-#undef putchar
-#undef puts
-
 #define SLIP_END     0300
 /*---------------------------------------------------------------------------*/
 int
-putchar(int c)
+dbg_putchar(int c)
 {
 #if DBG_CONF_SLIP_MUX
   static char debug_frame = 0;
@@ -80,7 +70,7 @@ putchar(int c)
     write_byte(SLIP_END);
     debug_frame = 0;
 #endif
-    dbg_flush();
+    flush();
   }
   return c;
 }
@@ -100,18 +90,3 @@ dbg_send_bytes(const unsigned char *s, unsigned int len)
   return i;
 }
 /*---------------------------------------------------------------------------*/
-int
-puts(const char *s)
-{
-  unsigned int i = 0;
-
-  while(s && *s != 0) {
-    putchar(*s++);
-    i++;
-  }
-  putchar('\n');
-  return i;
-}
-/*---------------------------------------------------------------------------*/
-
-/** @} */
diff --git a/arch/cpu/cc2538/dbg.h b/arch/cpu/cc2538/dbg.h
deleted file mode 100644
index d5ab51f9d..000000000
--- a/arch/cpu/cc2538/dbg.h
+++ /dev/null
@@ -1,89 +0,0 @@
-/*
- * Copyright (c) 2012, Texas Instruments Incorporated - http://www.ti.com/
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- *
- * 3. Neither the name of the copyright holder nor the names of its
- *    contributors may be used to endorse or promote products derived
- *    from this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
- * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
- * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
- * OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-/**
- * \addtogroup cc2538
- * @{
- *
- * \defgroup cc2538-char-io cc2538 Character I/O
- *
- * CPU-specific functions for debugging and SLIP I/O
- *
- * On the cc2538, character I/O can be directed over USB or UART. This is
- * controlled by a series of configuration directives:
- * - SLIP_ARCH_CONF_USB: Controls the operation of slip-arch.
- * - DBG_CONF_USB: Controls all debugging output
- *
- * Defaults for those defines are set in contiki-conf.h
- * @{
- *
- * \file
- * Header file for the cc2538 Debug I/O module
- */
-#ifndef DBG_H_
-#define DBG_H_
-
-#include "contiki.h"
-
-#include "usb/usb-serial.h"
-/**
- * \brief Print a stream of bytes
- * \param seq A pointer to the stream
- * \param len The number of bytes to print
- * \return The number of printed bytes
- *
- * This function is an arch-specific implementation required by the dbg-io
- * API in cpu/arm/common/dbg-io. It prints a stream of bytes over the
- * peripheral used by the platform.
- */
-unsigned int dbg_send_bytes(const unsigned char *seq, unsigned int len);
-
-/**
- * \brief Flushes character output
- *
- *        When debugging is sent over USB, this functions causes the USB
- *        driver to immediately TX the content of output buffers. When
- *        debugging is over UART, this function does nothing.
- *
- *        There is nothing stopping you from using this macro in your code but
- *        normally, you won't have to.
- */
-#if DBG_CONF_USB
-#define dbg_flush() usb_serial_flush()
-#else
-#define dbg_flush()
-#endif
-
-#endif /* DBG_H_ */
-
-/**
- * @}
- * @}
- */
diff --git a/arch/cpu/cc2538/slip-arch.c b/arch/cpu/cc2538/slip-arch.c
index 58aec9f84..dee023a4f 100644
--- a/arch/cpu/cc2538/slip-arch.c
+++ b/arch/cpu/cc2538/slip-arch.c
@@ -28,21 +28,12 @@
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  * OF THE POSSIBILITY OF SUCH DAMAGE.
  */
-/**
- * \addtogroup cc2538-char-io
- * @{
- *
- * \file
- * Arch-specific SLIP functions for the cc2538
- *
- * SLIP can be configured to operate over UART or over USB-Serial, depending
- * on the value of SLIP_ARCH_CONF_USB
- */
+/*---------------------------------------------------------------------------*/
 #include "contiki.h"
 #include "dev/slip.h"
 #include "dev/uart.h"
 #include "usb/usb-serial.h"
-
+/*---------------------------------------------------------------------------*/
 #ifndef SLIP_ARCH_CONF_USB
 #define SLIP_ARCH_CONF_USB 0
 #endif
@@ -59,10 +50,6 @@
 
 #define SLIP_END     0300
 /*---------------------------------------------------------------------------*/
-/**
- * \brief Write a byte over SLIP
- * \param c the byte
- */
 void
 slip_arch_writeb(unsigned char c)
 {
@@ -72,14 +59,9 @@ slip_arch_writeb(unsigned char c)
   }
 }
 /*---------------------------------------------------------------------------*/
-/**
- * \brief Initialise the arch-specific SLIP driver
- */
 void
 slip_arch_init()
 {
   set_input(slip_input_byte);
 }
 /*---------------------------------------------------------------------------*/
-
-/** @} */
diff --git a/arch/cpu/cc26xx-cc13xx/Makefile.cc26xx-cc13xx b/arch/cpu/cc26xx-cc13xx/Makefile.cc26xx-cc13xx
index 979d7f5e4..75dbad7ad 100644
--- a/arch/cpu/cc26xx-cc13xx/Makefile.cc26xx-cc13xx
+++ b/arch/cpu/cc26xx-cc13xx/Makefile.cc26xx-cc13xx
@@ -30,16 +30,16 @@ CONTIKI_CPU_DIRS += . dev rf-core rf-core/api rf-core/ble-hal $(TI_XXWARE_STARTU
 ### CPU-dependent source files
 CONTIKI_CPU_SOURCEFILES += clock.c rtimer-arch.c soc-rtc.c uart.c
 CONTIKI_CPU_SOURCEFILES += contiki-watchdog.c aux-ctrl.c
-CONTIKI_CPU_SOURCEFILES += putchar.c ieee-addr.c batmon-sensor.c adc-sensor.c
+CONTIKI_CPU_SOURCEFILES += dbg.c ieee-addr.c batmon-sensor.c adc-sensor.c
 CONTIKI_CPU_SOURCEFILES += slip-arch.c slip.c cc26xx-uart.c lpm.c
 CONTIKI_CPU_SOURCEFILES += gpio-interrupt.c gpio-hal-arch.c oscillators.c
 CONTIKI_CPU_SOURCEFILES += rf-core.c rf-ble.c ieee-mode.c
 CONTIKI_CPU_SOURCEFILES += ble-cc2650.c ble-hal-cc26xx.c ble-addr.c rf-ble-cmd.c
 CONTIKI_CPU_SOURCEFILES += random.c soc-trng.c int-master.c
 
-DEBUG_IO_SOURCEFILES += dbg-printf.c dbg-snprintf.c dbg-sprintf.c strformat.c
+MODULES += os/lib/dbg-io
 
-CONTIKI_SOURCEFILES += $(CONTIKI_CPU_SOURCEFILES) $(DEBUG_IO_SOURCEFILES)
+CONTIKI_SOURCEFILES += $(CONTIKI_CPU_SOURCEFILES)
 
 CPU_START_SOURCEFILES += fault-handlers.c $(TI_XXWARE_STARTUP_SRCS)
 
diff --git a/arch/cpu/cc26xx-cc13xx/putchar.c b/arch/cpu/cc26xx-cc13xx/dbg.c
similarity index 84%
rename from arch/cpu/cc26xx-cc13xx/putchar.c
rename to arch/cpu/cc26xx-cc13xx/dbg.c
index 7cbd1901a..bf03aade4 100644
--- a/arch/cpu/cc26xx-cc13xx/putchar.c
+++ b/arch/cpu/cc26xx-cc13xx/dbg.c
@@ -34,33 +34,12 @@
 #include <string.h>
 /*---------------------------------------------------------------------------*/
 int
-putchar(int c)
+dbg_putchar(int c)
 {
   cc26xx_uart_write_byte(c);
   return c;
 }
 /*---------------------------------------------------------------------------*/
-int
-puts(const char *str)
-{
-  int i;
-  if(str == NULL) {
-    return 0;
-  }
-  for(i = 0; i < strlen(str); i++) {
-    cc26xx_uart_write_byte(str[i]);
-  }
-  cc26xx_uart_write_byte('\n');
-
-  /*
-   * Wait for the line to go out. This is to prevent garbage when used between
-   * UART on/off cycles
-   */
-  while(cc26xx_uart_busy() == UART_BUSY);
-
-  return i;
-}
-/*---------------------------------------------------------------------------*/
 unsigned int
 dbg_send_bytes(const unsigned char *s, unsigned int len)
 {
diff --git a/arch/cpu/cc26xx-cc13xx/slip-arch.c b/arch/cpu/cc26xx-cc13xx/slip-arch.c
index 6c6914363..f4141e11d 100644
--- a/arch/cpu/cc26xx-cc13xx/slip-arch.c
+++ b/arch/cpu/cc26xx-cc13xx/slip-arch.c
@@ -29,31 +29,16 @@
  * OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 /*---------------------------------------------------------------------------*/
-/**
- * \addtogroup cc26xx-char-io
- * @{
- *
- * \file
- * Arch-specific SLIP functions for the CC13xx/CC26xx
- */
-/*---------------------------------------------------------------------------*/
 #include "contiki.h"
 #include "dev/cc26xx-uart.h"
 #include "dev/slip.h"
 /*---------------------------------------------------------------------------*/
-/**
- * \brief Write a byte over SLIP
- * \param c the byte
- */
 void
 slip_arch_writeb(unsigned char c)
 {
   cc26xx_uart_write_byte(c);
 }
 /*---------------------------------------------------------------------------*/
-/**
- * \brief Initialise the arch-specific SLIP driver
- */
 void
 slip_arch_init()
 {
@@ -64,5 +49,3 @@ slip_arch_init()
   cc26xx_uart_set_input(slip_input_byte);
 }
 /*---------------------------------------------------------------------------*/
-
-/** @} */
diff --git a/arch/cpu/nrf52832/Makefile.nrf52832 b/arch/cpu/nrf52832/Makefile.nrf52832
index c2bdbbf81..5e0db414d 100644
--- a/arch/cpu/nrf52832/Makefile.nrf52832
+++ b/arch/cpu/nrf52832/Makefile.nrf52832
@@ -54,7 +54,7 @@ remduplicates = $(strip $(if $1,$(firstword $1) $(call remduplicates,$(filter-ou
 CONTIKI_CPU_DIRS += . dev ble #compat
 
 ### CPU-dependent source files
-CONTIKI_CPU_SOURCEFILES += clock.c rtimer-arch.c uart0.c putchar.c watchdog.c
+CONTIKI_CPU_SOURCEFILES += clock.c rtimer-arch.c uart0.c dbg.c watchdog.c
 CONTIKI_CPU_SOURCEFILES += int-master.c
 
 ifneq ($(NRF52_WITHOUT_SOFTDEVICE),1)
diff --git a/arch/platform/nrf52dk/dbg-io/dbg.c b/arch/cpu/nrf52832/dbg.c
similarity index 94%
rename from arch/platform/nrf52dk/dbg-io/dbg.c
rename to arch/cpu/nrf52832/dbg.c
index db9bb63c0..8f7be5cfc 100644
--- a/arch/platform/nrf52dk/dbg-io/dbg.c
+++ b/arch/cpu/nrf52832/dbg.c
@@ -27,16 +27,12 @@
  * SUCH DAMAGE.
  *
  */
-
 /**
- * \addtogroup nrf52dk
- * @{
- *
- * \addtogroup nrf52dk-dbg-io Debug IO over UART
+ * \addtogroup nrf52832
  * @{
  *
  * \file
- *         Function implementations for debug io module.
+ *         Hardware specific implementation of putchar() and puts() functions.
  * \author
  *         Wojciech Bober <wojciech.bober@nordicsemi.no>
  *
diff --git a/arch/cpu/nrf52832/putchar.c b/arch/cpu/nrf52832/putchar.c
deleted file mode 100644
index c4163ba3d..000000000
--- a/arch/cpu/nrf52832/putchar.c
+++ /dev/null
@@ -1,70 +0,0 @@
-/*
- * Copyright (c) 2015, Nordic Semiconductor
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the Institute nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- */
-/**
- * \addtogroup nrf52832
- * @{
- *
- * \file
- *         Hardware specific implementation of putchar() and puts() functions.
- * \author
- *         Wojciech Bober <wojciech.bober@nordicsemi.no>
- *
- */
-/*---------------------------------------------------------------------------*/
-#include <string.h>
-#include "dev/uart0.h"
-/*---------------------------------------------------------------------------*/
-int
-putchar(int c)
-{
-  uart0_writeb(c);
-  return c;
-}
-/*---------------------------------------------------------------------------*/
-int
-puts(const char *str)
-{
-  int i;
-
-  if (str == NULL) {
-    return 0;
-  }
-
-  for (i = 0; i < strlen(str); i++) {
-    uart0_writeb(str[i]);
-  }
-
-  uart0_writeb('\n');
-  return i;
-}
-/*---------------------------------------------------------------------------*/
-/**
- * @}
- */
diff --git a/arch/platform/nrf52dk/Makefile.nrf52dk b/arch/platform/nrf52dk/Makefile.nrf52dk
index 6187fc532..6561de980 100644
--- a/arch/platform/nrf52dk/Makefile.nrf52dk
+++ b/arch/platform/nrf52dk/Makefile.nrf52dk
@@ -13,10 +13,8 @@ ifeq ($(NRF52_USE_RTT),1)
 CONTIKI_TARGET_DIRS += rtt
 CONTIKI_SOURCEFILES += rtt-printf.c segger-rtt.c segger-rtt-printf.c
 else
-CONTIKI_TARGET_DIRS += dbg-io
 CONTIKI_SOURCEFILES += dbg.c
-CONTIKI_CPU_DIRS += ../arm/common/dbg-io
-CONTIKI_CPU_SOURCEFILES += dbg-printf.c dbg-putchar.c dbg-snprintf.c dbg-sprintf.c strformat.c
+MODULES += os/lib/dbg-io
 endif
 
 CLEAN += *.nrf52dk
diff --git a/arch/platform/nrf52dk/dbg-io/dbg.h b/arch/platform/nrf52dk/dbg-io/dbg.h
deleted file mode 100644
index 5d9568270..000000000
--- a/arch/platform/nrf52dk/dbg-io/dbg.h
+++ /dev/null
@@ -1,67 +0,0 @@
-/*
- * Copyright (c) 2015, Nordic Semiconductor
- * All rights reserved.
- *
-3 * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the Institute nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- */
-/**
- * \addtogroup nrf52dk
- * @{
- *
- * \addtogroup nrf52dk-dbg-io Debug IO over UART
- * @{
- *
- * \file
- *         Header file for the debug module.
- * \author
- *         Wojciech Bober <wojciech.bober@nordicsemi.no>
- *
- */
-#ifndef DBG_H_
-#define DBG_H_
-/*---------------------------------------------------------------------------*/
-#include "contiki.h"
-/*---------------------------------------------------------------------------*/
-/**
- * \brief Print a stream of bytes
- * \param seq A pointer to the stream
- * \param len The number of bytes to print
- * \return The number of printed bytes
- */
-unsigned int dbg_send_bytes(const unsigned char *seq, unsigned int len);
-/**
- * \brief Print a character to debug output
- * \param c Character to print
- * \return Printed character
- */
-int dbg_putchar(int c);
-/*---------------------------------------------------------------------------*/
-#endif /* DBG_H_ */
-/*---------------------------------------------------------------------------*/
-/**
- * @}
- * @}
- */
diff --git a/arch/platform/nrf52dk/dbg-io/debug-uart.h b/arch/platform/nrf52dk/dbg-io/debug-uart.h
deleted file mode 100644
index b52d2fb50..000000000
--- a/arch/platform/nrf52dk/dbg-io/debug-uart.h
+++ /dev/null
@@ -1,54 +0,0 @@
-/*
- * Copyright (c) 2015, Nordic Semiconductor
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the Institute nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- */
-/**
- * \addtogroup nrf52dk
- * @{
- *
- * \addtogroup nrf52dk-dbg-io Debug IO over UART
- * @{
- *
- * \file
- *      A header file to maintain compatibility with DBG I/O.
- * \author
- *      Wojciech Bober <wojciech.bober@nordicsemi.no>
- *
- */
-/*---------------------------------------------------------------------------*/
-#ifndef DEBUG_UART_H_
-#define DEBUG_UART_H_
-/*---------------------------------------------------------------------------*/
-#include "dbg.h"
-/*---------------------------------------------------------------------------*/
-#endif /* DEBUG_UART_H_ */
-/*---------------------------------------------------------------------------*/
-/**
- * @}
- * @}
- */
diff --git a/arch/cpu/cc26xx-cc13xx/dbg.h b/os/lib/dbg-io/dbg.h
similarity index 83%
rename from arch/cpu/cc26xx-cc13xx/dbg.h
rename to os/lib/dbg-io/dbg.h
index 4460b6eb4..6440b5eca 100644
--- a/arch/cpu/cc26xx-cc13xx/dbg.h
+++ b/os/lib/dbg-io/dbg.h
@@ -1,10 +1,11 @@
 /*
- * Copyright (c) 2014, Texas Instruments Incorporated - http://www.ti.com/
+ * Copyright (c) 2015, Nordic Semiconductor
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
+ *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ -29,16 +30,17 @@
  */
 /*---------------------------------------------------------------------------*/
 /**
- * \addtogroup cc26xx
+ * \addtogroup lib
  * @{
  *
- * \defgroup cc26xx-char-io CC13xx/CC26xx Character I/O
- *
- * CC13xx/CC26xx CPU-specific functions for debugging and SLIP I/O
+ * \addtogroup dbg-io Portable debugging output functons
  * @{
  *
  * \file
- * Header file for the CC13xx/CC26xx Debug I/O module
+ *         Header file for the dbg-io module.
+ * \author
+ *         Wojciech Bober <wojciech.bober@nordicsemi.no>
+ *
  */
 #ifndef DBG_H_
 #define DBG_H_
@@ -50,12 +52,14 @@
  * \param seq A pointer to the stream
  * \param len The number of bytes to print
  * \return The number of printed bytes
- *
- * This function is an arch-specific implementation required by the dbg-io
- * API in cpu/arm/common/dbg-io. It prints a stream of bytes over the
- * peripheral used by the platform.
  */
 unsigned int dbg_send_bytes(const unsigned char *seq, unsigned int len);
+/**
+ * \brief Print a character to debug output
+ * \param c Character to print
+ * \return Printed character
+ */
+int dbg_putchar(int c);
 /*---------------------------------------------------------------------------*/
 #endif /* DBG_H_ */
 /*---------------------------------------------------------------------------*/
diff --git a/arch/cpu/cc26xx-cc13xx/debug-uart.h b/os/lib/dbg-io/printf.c
similarity index 78%
rename from arch/cpu/cc26xx-cc13xx/debug-uart.h
rename to os/lib/dbg-io/printf.c
index c2d9b0ffb..9749f1f7d 100644
--- a/arch/cpu/cc26xx-cc13xx/debug-uart.h
+++ b/os/lib/dbg-io/printf.c
@@ -1,16 +1,16 @@
 /*
- * Copyright (c) 2012, Texas Instruments Incorporated - http://www.ti.com/
+ * Copyright (c) 2009, Simon Berg
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
+ *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
- *
  * 3. Neither the name of the copyright holder nor the names of its
  *    contributors may be used to endorse or promote products derived
  *    from this software without specific prior written permission.
@@ -29,21 +29,36 @@
  * OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 /*---------------------------------------------------------------------------*/
-/**
- * \addtogroup cc26xx-char-io
- * @{
- *
- * \file
- * This file is here because DBG I/O expects it to be. It just includes
- * our own dbg.h which has a non-misleading name and which also adheres
- * to Contiki's naming convention
- */
+#include "contiki.h"
+#include "lib/dbg-io/dbg.h"
+
+#include <stdio.h>
+#include <string.h>
+#include <strformat.h>
 /*---------------------------------------------------------------------------*/
-#ifndef DEBUG_UART_H_
-#define DEBUG_UART_H_
+static strformat_result
+write_str(void *user_data, const char *data, unsigned int len)
+{
+  if(len > 0) {
+    dbg_send_bytes((unsigned char *)data, len);
+  }
+  return STRFORMAT_OK;
+}
 /*---------------------------------------------------------------------------*/
-#include "dbg.h"
+static strformat_context_t ctxt =
+{
+  write_str,
+  NULL
+};
 /*---------------------------------------------------------------------------*/
-#endif /* DEBUG_UART_H_ */
+int
+printf(const char *fmt, ...)
+{
+  int res;
+  va_list ap;
+  va_start(ap, fmt);
+  res = format_str_v(&ctxt, fmt, ap);
+  va_end(ap);
+  return res;
+}
 /*---------------------------------------------------------------------------*/
-/** @} */
diff --git a/arch/cpu/cc2538/debug-uart.h b/os/lib/dbg-io/putchar.c
similarity index 78%
rename from arch/cpu/cc2538/debug-uart.h
rename to os/lib/dbg-io/putchar.c
index 88a2fc3e0..26a35446d 100644
--- a/arch/cpu/cc2538/debug-uart.h
+++ b/os/lib/dbg-io/putchar.c
@@ -1,16 +1,16 @@
 /*
- * Copyright (c) 2012, Texas Instruments Incorporated - http://www.ti.com/
+ * Copyright (c) 2009, Simon Berg
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
+ *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
- *
  * 3. Neither the name of the copyright holder nor the names of its
  *    contributors may be used to endorse or promote products derived
  *    from this software without specific prior written permission.
@@ -28,20 +28,17 @@
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  * OF THE POSSIBILITY OF SUCH DAMAGE.
  */
-/**
- * \addtogroup cc2538-char-io
- * @{
- *
- * \file
- * This file is here because DBG I/O expects it to be. It just includes
- * our own dbg.h which has a non-misleading name and which also adheres
- * to Contiki's naming convention
- */
-#ifndef DEBUG_UART_H_
-#define DEBUG_UART_H_
+/*---------------------------------------------------------------------------*/
+#include "contiki.h"
+#include "lib/dbg-io/dbg.h"
 
-#include "dbg.h"
-
-#endif /* DEBUG_UART_H_ */
-
-/** @} */
+#include <stdio.h>
+#include <string.h>
+/*---------------------------------------------------------------------------*/
+int
+putchar(int c)
+{
+  dbg_putchar(c);
+  return c;
+}
+/*---------------------------------------------------------------------------*/
diff --git a/os/lib/dbg-io/puts.c b/os/lib/dbg-io/puts.c
new file mode 100644
index 000000000..93d73d3a5
--- /dev/null
+++ b/os/lib/dbg-io/puts.c
@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2009, Simon Berg
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+/*---------------------------------------------------------------------------*/
+#include "contiki.h"
+#include "lib/dbg-io/dbg.h"
+
+#include <stdio.h>
+#include <string.h>
+/*---------------------------------------------------------------------------*/
+int
+puts(const char *str)
+{
+  dbg_send_bytes((unsigned char *)str, strlen(str));
+  dbg_putchar('\n');
+  return 0;
+}
+/*---------------------------------------------------------------------------*/
diff --git a/os/lib/dbg-io/snprintf.c b/os/lib/dbg-io/snprintf.c
new file mode 100644
index 000000000..96f99e568
--- /dev/null
+++ b/os/lib/dbg-io/snprintf.c
@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2009, Simon Berg
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+/*---------------------------------------------------------------------------*/
+#include "contiki.h"
+
+#include <stdio.h>
+#include <strformat.h>
+#include <string.h>
+/*---------------------------------------------------------------------------*/
+struct fmt_buffer {
+  char *pos;
+  size_t left;
+};
+/*---------------------------------------------------------------------------*/
+static strformat_result
+buffer_str(void *user_data, const char *data, unsigned int len)
+{
+  struct fmt_buffer *buffer = (struct fmt_buffer *)user_data;
+  if(len >= buffer->left) {
+    len = buffer->left;
+    len--;
+  }
+
+  memcpy(buffer->pos, data, len);
+  buffer->pos += len;
+  buffer->left -= len;
+  return STRFORMAT_OK;
+}
+/*---------------------------------------------------------------------------*/
+int
+snprintf(char *str, size_t size, const char *format, ...)
+{
+  int res;
+  va_list ap;
+  va_start(ap, format);
+  res = vsnprintf(str, size, format, ap);
+  va_end(ap);
+  return res;
+}
+/*---------------------------------------------------------------------------*/
+int
+vsnprintf(char *str, size_t size, const char *format, va_list ap)
+{
+  struct fmt_buffer buffer;
+  strformat_context_t ctxt;
+  int res;
+  ctxt.write_str = buffer_str;
+  ctxt.user_data = &buffer;
+  buffer.pos = str;
+  buffer.left = size;
+  res = format_str_v(&ctxt, format, ap);
+  *buffer.pos = '\0';
+  return res;
+}
+/*---------------------------------------------------------------------------*/
diff --git a/os/lib/dbg-io/sprintf.c b/os/lib/dbg-io/sprintf.c
new file mode 100644
index 000000000..4ecf5b540
--- /dev/null
+++ b/os/lib/dbg-io/sprintf.c
@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2009, Simon Berg
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+/*---------------------------------------------------------------------------*/
+#include "contiki.h"
+
+#include <stdio.h>
+#include <strformat.h>
+#include <string.h>
+/*---------------------------------------------------------------------------*/
+static strformat_result
+buffer_str(void *user_data, const char *data, unsigned int len)
+{
+  memcpy(*(char **)user_data, data, len);
+  (*(char **)user_data) += len;
+  return STRFORMAT_OK;
+}
+/*---------------------------------------------------------------------------*/
+int
+sprintf(char *str, const char *format, ...)
+{
+  strformat_context_t ctxt;
+  int res;
+  va_list ap;
+  va_start(ap, format);
+  ctxt.write_str = buffer_str;
+  ctxt.user_data = &str;
+  res = format_str_v(&ctxt, format, ap);
+  *str = '\0';
+  va_end(ap);
+  return res;
+}
+/*---------------------------------------------------------------------------*/
diff --git a/os/lib/dbg-io/strformat.c b/os/lib/dbg-io/strformat.c
new file mode 100644
index 000000000..b5ad18f89
--- /dev/null
+++ b/os/lib/dbg-io/strformat.c
@@ -0,0 +1,707 @@
+/*
+ * Copyright (c) 2009, Simon Berg
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+/*---------------------------------------------------------------------------*/
+#include "contiki.h"
+
+#include <strformat.h>
+/*---------------------------------------------------------------------------*/
+#define HAVE_DOUBLE
+#define HAVE_LONGLONG
+
+#ifndef LARGEST_SIGNED
+#ifdef HAVE_LONGLONG
+#define LARGEST_SIGNED long long int
+#else
+#define LARGEST_UNSIGNED long int
+#endif /* HAVE_LONGLONG */
+#endif /* LARGEST_SIGNED */
+
+#ifndef LARGEST_UNSIGNED
+#ifdef HAVE_LONGLONG
+#define LARGEST_UNSIGNED unsigned long long int
+#else
+#define LARGEST_UNSIGNED unsigned long int
+#endif /* HAVE_LONGLONG */
+#endif /* LARGEST_UNSIGNED */
+
+#ifndef POINTER_INT
+#define POINTER_INT unsigned long
+#endif
+/*---------------------------------------------------------------------------*/
+typedef unsigned int FormatFlags;
+/*---------------------------------------------------------------------------*/
+#define MAKE_MASK(shift, size) (((1 << size) - 1) << (shift))
+/*---------------------------------------------------------------------------*/
+#define JUSTIFY_SHIFT   0
+#define JUSTIFY_SIZE    1
+#define JUSTIFY_RIGHT   0x0000
+#define JUSTIFY_LEFT    0x0001
+#define JUSTIFY_MASK    MAKE_MASK(JUSTIFY_SHIFT, JUSTIFY_SIZE)
+/*---------------------------------------------------------------------------*/
+/* How a positive number is prefixed */
+#define POSITIVE_SHIFT  (JUSTIFY_SHIFT + JUSTIFY_SIZE)
+#define POSITIVE_NONE   (0x0000 << POSITIVE_SHIFT)
+#define POSITIVE_SPACE  (0x0001 << POSITIVE_SHIFT)
+#define POSITIVE_PLUS   (0x0003 << POSITIVE_SHIFT)
+#define POSITIVE_MASK   MAKE_MASK(POSITIVE_SHIFT, POSITIVE_SIZE)
+
+#define POSITIVE_SIZE   2
+/*---------------------------------------------------------------------------*/
+#define ALTERNATE_FORM_SHIFT (POSITIVE_SHIFT + POSITIVE_SIZE)
+#define ALTERNATE_FORM_SIZE  1
+#define ALTERNATE_FORM       (0x0001 << ALTERNATE_FORM_SHIFT)
+/*---------------------------------------------------------------------------*/
+#define PAD_SHIFT (ALTERNATE_FORM_SHIFT + ALTERNATE_FORM_SIZE)
+#define PAD_SIZE  1
+#define PAD_SPACE (0x0000 << PAD_SHIFT)
+#define PAD_ZERO  (0x0001 << PAD_SHIFT)
+/*---------------------------------------------------------------------------*/
+#define SIZE_SHIFT    (PAD_SHIFT + PAD_SIZE)
+#define SIZE_SIZE     3
+#define SIZE_CHAR     (0x0001 << SIZE_SHIFT)
+#define SIZE_SHORT    (0x0002 << SIZE_SHIFT)
+#define SIZE_INT      (0x0000 << SIZE_SHIFT)
+#define SIZE_LONG     (0x0003 << SIZE_SHIFT)
+#define SIZE_LONGLONG (0x0004 << SIZE_SHIFT)
+#define SIZE_MASK     MAKE_MASK(SIZE_SHIFT, SIZE_SIZE)
+/*---------------------------------------------------------------------------*/
+#define CONV_SHIFT    (SIZE_SHIFT + SIZE_SIZE)
+#define CONV_SIZE     3
+#define CONV_INTEGER  (0x0001 << CONV_SHIFT)
+#define CONV_FLOAT    (0x0002 << CONV_SHIFT)
+#define CONV_POINTER  (0x0003 << CONV_SHIFT)
+#define CONV_STRING   (0x0004 << CONV_SHIFT)
+#define CONV_CHAR     (0x0005 << CONV_SHIFT)
+#define CONV_PERCENT  (0x0006 << CONV_SHIFT)
+#define CONV_WRITTEN  (0x0007 << CONV_SHIFT)
+#define CONV_MASK     MAKE_MASK(CONV_SHIFT, CONV_SIZE)
+/*---------------------------------------------------------------------------*/
+#define RADIX_SHIFT   (CONV_SHIFT + CONV_SIZE)
+#define RADIX_SIZE    2
+#define RADIX_DECIMAL (0x0001 << RADIX_SHIFT)
+#define RADIX_OCTAL   (0x0002 << RADIX_SHIFT)
+#define RADIX_HEX     (0x0003 << RADIX_SHIFT)
+#define RADIX_MASK    MAKE_MASK(RADIX_SHIFT, RADIX_SIZE)
+/*---------------------------------------------------------------------------*/
+#define SIGNED_SHIFT  (RADIX_SHIFT + RADIX_SIZE)
+#define SIGNED_SIZE   1
+#define SIGNED_NO     (0x0000 << SIGNED_SHIFT)
+#define SIGNED_YES    (0x0001 << SIGNED_SHIFT)
+#define SIGNED_MASK   MAKE_MASK(SIGNED_SHIFT, SIGNED_SIZE)
+/*---------------------------------------------------------------------------*/
+#define CAPS_SHIFT  (SIGNED_SHIFT + SIGNED_SIZE)
+#define CAPS_SIZE 1
+#define CAPS_NO     (0x0000 << CAPS_SHIFT)
+#define CAPS_YES    (0x0001 << CAPS_SHIFT)
+#define CAPS_MASK   MAKE_MASK(CAPS_SHIFT, CAPS_SIZE)
+/*---------------------------------------------------------------------------*/
+#define FLOAT_SHIFT     (CAPS_SHIFT + CAPS_SIZE)
+#define FLOAT_SIZE      2
+#define FLOAT_NORMAL    (0x0000 << FLOAT_SHIFT)
+#define FLOAT_EXPONENT  (0x0001 << FLOAT_SHIFT)
+#define FLOAT_DEPENDANT (0x0002 << FLOAT_SHIFT)
+#define FLOAT_HEX       (0x0003 << FLOAT_SHIFT)
+#define FLOAT_MASK      MAKE_MASK(FLOAT_SHIFT, FLOAT_SIZE)
+/*---------------------------------------------------------------------------*/
+#define CHECKCB(res) { if((res) != STRFORMAT_OK) { va_end(ap); return -1; } }
+/*---------------------------------------------------------------------------*/
+#define MAXCHARS_HEX ((sizeof(LARGEST_UNSIGNED) * 8) / 4)
+
+/* Largest number of characters needed for converting an unsigned integer. */
+#define MAXCHARS ((sizeof(LARGEST_UNSIGNED) * 8 + 2) / 3)
+/*---------------------------------------------------------------------------*/
+static FormatFlags
+parse_flags(const char **posp)
+{
+  FormatFlags flags = 0;
+  const char *pos = *posp;
+
+  while(1) {
+    switch(*pos) {
+    case '-':
+      flags |= JUSTIFY_LEFT;
+      break;
+    case '+':
+      flags |= POSITIVE_PLUS;
+      break;
+    case ' ':
+      flags |= POSITIVE_SPACE;
+      break;
+    case '#':
+      flags |= ALTERNATE_FORM;
+      break;
+    case '0':
+      flags |= PAD_ZERO;
+      break;
+    default:
+      *posp = pos;
+      return flags;
+    }
+
+    pos++;
+  }
+}
+/*---------------------------------------------------------------------------*/
+static unsigned int
+parse_uint(const char **posp)
+{
+  unsigned v = 0;
+  const char *pos = *posp;
+  char ch;
+
+  while((ch = *pos) >= '0' && ch <= '9') {
+    v = v * 10 + (ch - '0');
+    pos++;
+  }
+
+  *posp = pos;
+
+  return v;
+}
+/*---------------------------------------------------------------------------*/
+static unsigned int
+output_uint_decimal(char **posp, LARGEST_UNSIGNED v)
+{
+  unsigned int len;
+  char *pos = *posp;
+
+  while(v > 0) {
+    *--pos = (v % 10) + '0';
+    v /= 10;
+  }
+
+  len = *posp - pos;
+  *posp = pos;
+
+  return len;
+}
+/*---------------------------------------------------------------------------*/
+static unsigned int
+output_uint_hex(char **posp, LARGEST_UNSIGNED v, unsigned int flags)
+{
+  unsigned int len;
+  const char *hex = (flags & CAPS_YES) ? "0123456789ABCDEF" : "0123456789abcdef";
+  char *pos = *posp;
+
+  while(v > 0) {
+    *--pos = hex[(v % 16)];
+    v /= 16;
+  }
+
+  len = *posp - pos;
+  *posp = pos;
+
+  return len;
+}
+/*---------------------------------------------------------------------------*/
+static unsigned int
+output_uint_octal(char **posp, LARGEST_UNSIGNED v)
+{
+  unsigned int len;
+  char *pos = *posp;
+
+  while(v > 0) {
+    *--pos = (v % 8) + '0';
+    v /= 8;
+  }
+
+  len = *posp - pos;
+  *posp = pos;
+
+  return len;
+}
+/*---------------------------------------------------------------------------*/
+static strformat_result
+fill_space(const strformat_context_t *ctxt, unsigned int len)
+{
+  strformat_result res;
+  static const char buffer[16] = "                ";
+
+  while(len > 16) {
+    res = ctxt->write_str(ctxt->user_data, buffer, 16);
+    if(res != STRFORMAT_OK) {
+      return res;
+    }
+    len -= 16;
+  }
+
+  if(len == 0) {
+    return STRFORMAT_OK;
+  }
+
+  return ctxt->write_str(ctxt->user_data, buffer, len);
+}
+/*---------------------------------------------------------------------------*/
+static strformat_result
+fill_zero(const strformat_context_t *ctxt, unsigned int len)
+{
+  strformat_result res;
+  static const char buffer[16] = "0000000000000000";
+
+  while(len > 16) {
+    res = ctxt->write_str(ctxt->user_data, buffer, 16);
+    if(res != STRFORMAT_OK) {
+      return res;
+    }
+    len -= 16;
+  }
+
+  if(len == 0) {
+    return STRFORMAT_OK;
+  }
+  return ctxt->write_str(ctxt->user_data, buffer, len);
+}
+/*---------------------------------------------------------------------------*/
+int
+format_str(const strformat_context_t *ctxt, const char *format, ...)
+{
+  int ret;
+  va_list ap;
+  va_start(ap, format);
+  ret = format_str_v(ctxt, format, ap);
+  va_end(ap);
+  return ret;
+}
+/*---------------------------------------------------------------------------*/
+int
+format_str_v(const strformat_context_t *ctxt, const char *format, va_list ap)
+{
+  unsigned int written = 0;
+  const char *pos = format;
+
+  while(*pos != '\0') {
+    FormatFlags flags;
+    unsigned int minwidth = 0;
+    int precision = -1; /* Negative means no precision */
+    char ch;
+    const char *start = pos;
+
+    while((ch = *pos) != '\0' && ch != '%') {
+      pos++;
+    }
+
+    if(pos != start) {
+      CHECKCB(ctxt->write_str(ctxt->user_data, start, pos - start));
+      written += pos - start;
+    }
+
+    if(*pos == '\0') {
+      va_end(ap);
+      return written;
+    }
+
+    pos++;
+
+    if(*pos == '\0') {
+      va_end(ap);
+      return written;
+    }
+
+    flags = parse_flags(&pos);
+
+    /* parse width */
+    if(*pos >= '1' && *pos <= '9') {
+      minwidth = parse_uint(&pos);
+    } else if(*pos == '*') {
+      int w = va_arg(ap, int);
+
+      if(w < 0) {
+        flags |= JUSTIFY_LEFT;
+        minwidth = w;
+      } else {
+        minwidth = w;
+      }
+
+      pos++;
+    }
+
+    /* parse precision */
+    if(*pos == '.') {
+      pos++;
+
+      if(*pos >= '0' && *pos <= '9') {
+        precision = parse_uint(&pos);
+      } else if(*pos == '*') {
+        pos++;
+        precision = va_arg(ap, int);
+      }
+    }
+
+    if(*pos == 'l') {
+      pos++;
+
+      if(*pos == 'l') {
+        flags |= SIZE_LONGLONG;
+        pos++;
+      } else {
+        flags |= SIZE_LONG;
+      }
+    } else if(*pos == 'h') {
+      pos++;
+
+      if(*pos == 'h') {
+        flags |= SIZE_CHAR;
+        pos++;
+      } else {
+        flags |= SIZE_SHORT;
+      }
+    }
+
+    /* parse conversion specifier */
+    switch(*pos) {
+    case 'd':
+    case 'i':
+      flags |= CONV_INTEGER | RADIX_DECIMAL | SIGNED_YES;
+      break;
+    case 'u':
+      flags |= CONV_INTEGER | RADIX_DECIMAL | SIGNED_NO;
+      break;
+    case 'o':
+      flags |= CONV_INTEGER | RADIX_OCTAL | SIGNED_NO;
+      break;
+    case 'x':
+      flags |= CONV_INTEGER | RADIX_HEX | SIGNED_NO;
+      break;
+    case 'X':
+      flags |= CONV_INTEGER | RADIX_HEX | SIGNED_NO | CAPS_YES;
+      break;
+#ifdef HAVE_DOUBLE
+    case 'f':
+      flags |= CONV_FLOAT | FLOAT_NORMAL;
+      break;
+    case 'F':
+      flags |= CONV_FLOAT | FLOAT_NORMAL | CAPS_YES;
+      break;
+    case 'e':
+      flags |= CONV_FLOAT | FLOAT_EXPONENT;
+      break;
+    case 'E':
+      flags |= CONV_FLOAT | FLOAT_EXPONENT | CAPS_YES;
+      break;
+    case 'g':
+      flags |= CONV_FLOAT | FLOAT_DEPENDANT;
+      break;
+    case 'G':
+      flags |= CONV_FLOAT | FLOAT_DEPENDANT | CAPS_YES;
+      break;
+    case 'a':
+      flags |= CONV_FLOAT | FLOAT_HEX;
+      break;
+    case 'A':
+      flags |= CONV_FLOAT | FLOAT_HEX | CAPS_YES;
+      break;
+#endif
+    case 'c':
+      flags |= CONV_CHAR;
+      break;
+    case 's':
+      flags |= CONV_STRING;
+      break;
+    case 'p':
+      flags |= CONV_POINTER;
+      break;
+    case 'n':
+      flags |= CONV_WRITTEN;
+      break;
+    case '%':
+      flags |= CONV_PERCENT;
+      break;
+    case '\0':
+      va_end(ap);
+      return written;
+    }
+    pos++;
+
+    switch(flags & CONV_MASK) {
+    case CONV_PERCENT:
+      CHECKCB(ctxt->write_str(ctxt->user_data, "%", 1));
+      written++;
+      break;
+    case CONV_INTEGER:
+    {
+      /* unsigned integers */
+      char *prefix = 0; /* sign, "0x" or "0X" */
+      unsigned int prefix_len = 0;
+      char buffer[MAXCHARS];
+      char *conv_pos = buffer + MAXCHARS;
+      unsigned int conv_len = 0;
+      unsigned int width = 0;
+      unsigned int precision_fill;
+      unsigned int field_fill;
+      LARGEST_UNSIGNED uvalue = 0;
+      int negative = 0;
+
+      if(precision < 0) {
+        precision = 1;
+      } else {
+        flags &= ~PAD_ZERO;
+      }
+
+      if(flags & SIGNED_YES) {
+        /* signed integers */
+        LARGEST_SIGNED value = 0;
+        switch(flags & SIZE_MASK) {
+        case SIZE_CHAR:
+          value = (signed char)va_arg(ap, int);
+          break;
+        case SIZE_SHORT:
+          value = (short)va_arg(ap, int);
+          break;
+        case SIZE_INT:
+          value = va_arg(ap, int);
+          break;
+#ifndef HAVE_LONGLONG
+        case SIZE_LONGLONG: /* Treat long long the same as long */
+#endif
+        case SIZE_LONG:
+          value = va_arg(ap, long);
+          break;
+#ifdef HAVE_LONGLONG
+        case SIZE_LONGLONG:
+          value = va_arg(ap, long long);
+          break;
+#endif
+        }
+        if(value < 0) {
+          uvalue = -value;
+          negative = 1;
+        } else {
+          uvalue = value;
+        }
+      } else {
+
+        switch(flags & SIZE_MASK) {
+        case SIZE_CHAR:
+          uvalue = (unsigned char)va_arg(ap, unsigned int);
+          break;
+        case SIZE_SHORT:
+          uvalue = (unsigned short)va_arg(ap, unsigned int);
+          break;
+        case SIZE_INT:
+          uvalue = va_arg(ap, unsigned int);
+          break;
+#ifndef HAVE_LONGLONG
+        case SIZE_LONGLONG: /* Treat long long the same as long */
+#endif
+        case SIZE_LONG:
+          uvalue = va_arg(ap, unsigned long);
+          break;
+#ifdef HAVE_LONGLONG
+        case SIZE_LONGLONG:
+          uvalue = va_arg(ap, unsigned long long);
+          break;
+#endif
+        }
+      }
+
+      switch(flags & (RADIX_MASK)) {
+      case RADIX_DECIMAL:
+        conv_len = output_uint_decimal(&conv_pos, uvalue);
+        break;
+      case RADIX_OCTAL:
+        conv_len = output_uint_octal(&conv_pos, uvalue);
+        break;
+      case RADIX_HEX:
+        conv_len = output_uint_hex(&conv_pos, uvalue, flags);
+        break;
+      }
+
+      width += conv_len;
+      precision_fill = (precision > conv_len) ? precision - conv_len : 0;
+      if((flags & (RADIX_MASK | ALTERNATE_FORM))
+         == (RADIX_OCTAL | ALTERNATE_FORM)) {
+        if(precision_fill < 1) {
+          precision_fill = 1;
+        }
+      }
+
+      width += precision_fill;
+
+      if((flags & (RADIX_MASK | ALTERNATE_FORM))
+         == (RADIX_HEX | ALTERNATE_FORM) && uvalue != 0) {
+        prefix_len = 2;
+        if(flags & CAPS_YES) {
+          prefix = "0X";
+        } else {
+          prefix = "0x";
+        }
+      }
+
+      if(flags & SIGNED_YES) {
+        if(negative) {
+          prefix = "-";
+          prefix_len = 1;
+        } else {
+          switch(flags & POSITIVE_MASK) {
+          case POSITIVE_SPACE:
+            prefix = " ";
+            prefix_len = 1;
+            break;
+          case POSITIVE_PLUS:
+            prefix = "+";
+            prefix_len = 1;
+            break;
+          }
+        }
+      }
+
+      width += prefix_len;
+
+      field_fill = (minwidth > width) ? minwidth - width : 0;
+
+      if((flags & JUSTIFY_MASK) == JUSTIFY_RIGHT) {
+        if(flags & PAD_ZERO) {
+          precision_fill += field_fill;
+          field_fill = 0; /* Do not double count padding */
+        } else {
+          CHECKCB(fill_space(ctxt, field_fill));
+        }
+      }
+
+      if(prefix_len > 0) {
+        CHECKCB(ctxt->write_str(ctxt->user_data, prefix, prefix_len));
+      }
+      written += prefix_len;
+
+      CHECKCB(fill_zero(ctxt, precision_fill));
+      written += precision_fill;
+
+      CHECKCB(ctxt->write_str(ctxt->user_data, conv_pos, conv_len));
+      written += conv_len;
+
+      if((flags & JUSTIFY_MASK) == JUSTIFY_LEFT) {
+        CHECKCB(fill_space(ctxt, field_fill));
+      }
+      written += field_fill;
+    }
+    break;
+    case CONV_STRING:
+    {
+      unsigned int field_fill;
+      unsigned int len;
+      char *str = va_arg(ap, char *);
+
+      if(str) {
+        char *pos = str;
+        while(*pos != '\0') pos++;
+        len = pos - str;
+      } else {
+        str = "(null)";
+        len = 6;
+      }
+
+      if(precision >= 0 && precision < len) {
+        len = precision;
+      }
+
+      field_fill = (minwidth > len) ? minwidth - len : 0;
+
+      if((flags & JUSTIFY_MASK) == JUSTIFY_RIGHT) {
+        CHECKCB(fill_space(ctxt, field_fill));
+      }
+
+      CHECKCB(ctxt->write_str(ctxt->user_data, str, len));
+      written += len;
+
+      if((flags & JUSTIFY_MASK) == JUSTIFY_LEFT) {
+        CHECKCB(fill_space(ctxt, field_fill));
+      }
+      written += field_fill;
+    }
+    break;
+    case CONV_POINTER:
+    {
+      LARGEST_UNSIGNED uvalue =
+        (LARGEST_UNSIGNED)(POINTER_INT)va_arg(ap, void *);
+      char buffer[MAXCHARS_HEX + 3];
+      char *conv_pos = buffer + MAXCHARS_HEX + 3;
+      unsigned int conv_len;
+      unsigned int field_fill;
+
+      conv_len = output_uint_hex(&conv_pos, uvalue, flags);
+
+      if(conv_len == 0) {
+        *--conv_pos = '0';
+        conv_len++;
+      }
+
+      *--conv_pos = 'x';
+      *--conv_pos = '0';
+      *--conv_pos = '#';
+      conv_len += 3;
+
+      field_fill = (minwidth > conv_len) ? minwidth - conv_len : 0;
+
+      if((flags & JUSTIFY_MASK) == JUSTIFY_RIGHT) {
+        CHECKCB(fill_space(ctxt, field_fill));
+      }
+
+      CHECKCB(ctxt->write_str(ctxt->user_data, conv_pos, conv_len));
+      written += conv_len;
+
+      if((flags & JUSTIFY_MASK) == JUSTIFY_LEFT) {
+        CHECKCB(fill_space(ctxt, field_fill));
+      }
+
+      written += field_fill;
+    }
+    break;
+    case CONV_CHAR:
+    {
+      char ch = va_arg(ap, int);
+      unsigned int field_fill = (minwidth > 1) ? minwidth - 1 : 0;
+
+      if((flags & JUSTIFY_MASK) == JUSTIFY_RIGHT) {
+        CHECKCB(fill_space(ctxt, field_fill));
+        written += field_fill;
+      }
+
+      CHECKCB(ctxt->write_str(ctxt->user_data, &ch, 1));
+      written++;
+
+      if((flags & JUSTIFY_MASK) == JUSTIFY_LEFT) {
+        CHECKCB(fill_space(ctxt, field_fill));
+      }
+      written += field_fill;
+    }
+    break;
+    case CONV_WRITTEN:
+    {
+      int *p = va_arg(ap, int *);
+      *p = written;
+    }
+    break;
+    }
+  }
+
+  return written;
+}
+/*---------------------------------------------------------------------------*/
diff --git a/os/lib/dbg-io/strformat.h b/os/lib/dbg-io/strformat.h
new file mode 100644
index 000000000..62d99b303
--- /dev/null
+++ b/os/lib/dbg-io/strformat.h
@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2009, Simon Berg
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+/*---------------------------------------------------------------------------*/
+#ifndef STRFORMAT_H_
+#define STRFORMAT_H_
+/*---------------------------------------------------------------------------*/
+#include "contiki.h"
+
+#include <stdarg.h>
+/*---------------------------------------------------------------------------*/
+#define STRFORMAT_OK 0
+#define STRFORMAT_FAILED 1
+/*---------------------------------------------------------------------------*/
+typedef unsigned int strformat_result;
+/*---------------------------------------------------------------------------*/
+/* The data argument may only be considered valid during the function call */
+typedef strformat_result (*strformat_write)(void *user_data,
+                                            const char *data,
+                                            unsigned int len);
+
+typedef struct strformat_context_s {
+  strformat_write write_str;
+  void *user_data;
+} strformat_context_t;
+/*---------------------------------------------------------------------------*/
+int format_str(const strformat_context_t *ctxt, const char *format, ...)
+     __attribute__ ((__format__ (__printf__, 2,3)));
+     
+int
+format_str_v(const strformat_context_t *ctxt, const char *format, va_list ap);
+/*---------------------------------------------------------------------------*/
+#endif /* STRFORMAT_H_ */
+/*---------------------------------------------------------------------------*/