Mix C and assembly, minor modifications to print routines.

Makefile

@@ -1,7 +1,8 @@
 PROJECT := demo
 
 SRC = \
-	  src/ceda_print.c		\
+	  src/ceda_print_a.asm	\
+	  src/ceda_print_c.c	\
 	  src/main.c 			\
 	  \
 

src/ceda_print.h

@@ -1,7 +1,8 @@
 #ifndef CEDA_PRINT_H
 #define CEDA_PRINT_H
 
-void ceda_print(const char* s);
+void ceda_cls(void);
+
+void ceda_print(const char *s);
 
 #endif // CEDA_PRINT_H
-

src/ceda_print_a.asm

@@ -0,0 +1,26 @@
+SECTION code
+PUBLIC _ceda_cls
+
+_ceda_cls:
+    push    af
+    push    bc
+    push    de
+    push    hl
+
+    ld      hl,$d000
+    ld      de,2000
+    ld      c,$20
+_ceda_cls_loop:
+    ld      (hl),c
+    inc     hl
+    dec     de
+    ld      a,d
+    or      e
+    jp      nz,_ceda_cls_loop
+
+    pop     hl
+    pop     de
+    pop     bc
+    pop     af
+
+    ret

src/main.c

@@ -4,6 +4,7 @@ int globalvar = 0x7777;
 
 int main(void) {
     ceda_print("Hello world!");
+    ceda_cls();
 
     return 0;
 }