nes-proj/cpu/mc1322x/lib/uart2.c

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/*
* Copyright (c) 2010, Mariano Alvira <mar@devl.org> and other contributors
* to the MC1322x project (http://mc1322x.devl.org)
* 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.
*
* This file is part of libmc1322x: see http://mc1322x.devl.org
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* for details.
*
*
*/
#include <mc1322x.h>
#include <stdint.h>
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volatile char u2_tx_buf[UART2_TX_BUFFERSIZE];
volatile uint32_t u2_tx_head, u2_tx_tail;
#if UART2_RX_BUFFERSIZE > 32
volatile char u2_rx_buf[UART2_RX_BUFFERSIZE-32];
volatile uint32_t u2_rx_head, u2_rx_tail;
#endif
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void uart2_isr(void) {
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#if UART2_RX_BUFFERSIZE > 32
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if (*UART2_USTAT & ( 1 << 6)) { //receive interrupt
while( *UART2_URXCON != 0 ) { //flush the hardware fifo into the software buffer
uint32_t u2_rx_tail_next;
u2_rx_tail_next = u2_rx_tail+1;
if (u2_rx_tail_next >= sizeof(u2_rx_buf))
u2_rx_tail_next = 0;
if (u2_rx_head != u2_rx_tail_next) {
u2_rx_buf[u2_rx_tail]= *UART2_UDATA;
u2_rx_tail = u2_rx_tail_next;
} else { //buffer is full, flush the fifo
while (*UART2_URXCON !=0) if (*UART2_UDATA);
}
}
return;
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}
#endif
while( *UART2_UTXCON != 0 ) {
if (u2_tx_head == u2_tx_tail) {
#if UART2_RX_BUFFERSIZE > 32
*UART2_UCON |= (1 << 13); /*disable tx interrupt */
#else
disable_irq(UART2);
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#endif
return;
}
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*UART2_UDATA = u2_tx_buf[u2_tx_tail];
u2_tx_tail++;
if (u2_tx_tail >= sizeof(u2_tx_buf))
u2_tx_tail = 0;
}
}
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void uart2_putc(char c) {
/* disable UART2 since */
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/* UART2 isr modifies u2_tx_head and u2_tx_tail */
#if UART2_RX_BUFFERSIZE > 32
*UART2_UCON |= (1 << 13); /*disable tx interrupt */
#else
disable_irq(UART2);
#endif
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if( (u2_tx_head == u2_tx_tail) &&
(*UART2_UTXCON != 0)) {
*UART2_UDATA = c;
} else {
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u2_tx_buf[u2_tx_head] = c;
u2_tx_head += 1;
if (u2_tx_head >= sizeof(u2_tx_buf))
u2_tx_head = 0;
if (u2_tx_head == u2_tx_tail) { /* drop chars when no room */
#if UART2_DROP_CHARS
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if (u2_tx_head) { u2_tx_head -=1; } else { u2_tx_head = sizeof(u2_tx_buf); }
#else
{
uint32_t u2_tx_tail_save=u2_tx_tail;
/* Back up head to show buffer not empty, and enable tx interrupt */
u2_tx_head--;
#if UART2_RX_BUFFERSIZE > 32
*UART2_UCON &= ~(1 << 13); /*enable tx interrupt */
#else
enable_irq(UART2);
#endif
/* Tail will change after one character goes out */
while (u2_tx_tail_save == u2_tx_tail) ;
/* Restore head to character we just stuffed */
u2_tx_head++;
return;
}
#endif /* UART2_DROP_CHARS */
}
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#if UART2_RX_BUFFERSIZE > 32
*UART2_UCON &= ~(1 << 13); /*enable tx interrupt */
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#else
enable_irq(UART2);
#endif
}
}
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uint8_t uart2_getc(void) {
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#if UART2_RX_BUFFERSIZE > 32
/* First pull from the ram buffer */
uint8_t c=0;
if (u2_rx_head != u2_rx_tail) {
c = u2_rx_buf[u2_rx_head++];
if (u2_rx_head >= sizeof(u2_rx_buf))
u2_rx_head=0;
return c;
}
#endif
/* Then pull from the hardware fifo */
while(uart2_can_get() == 0) { continue; }
return *UART2_UDATA;
}