syscalls.c.svn-base

本驱动是 s3c2410 声卡驱动,实现了 mp3,wav格式的音频文件的播放

/***********************************************************************/
/*                                                                     */
/*  SYSCALLS.C:  System Calls Remapping                                */
/*                                                                     */
/***********************************************************************/

#include <stdlib.h>
#include <reent.h>
#include <sys/stat.h>

#include "lib.h"

_ssize_t _read_r(struct _reent *r, int file, void *ptr, size_t len)
{
  char c;
  int  i;
  unsigned char *p;

  p = (unsigned char*)ptr;

  for (i = 0; i < len; i++)
  {
    c = sio_getc();

    *p++ = c;
    sio_putc(c);

    if (c == 0x0D && i <= (len - 2))
    {
      *p = 0x0A;
      sio_putc(0x0A);
      return i + 2;
    }
  }
  return i;
}

_ssize_t _write_r (
    struct _reent *r, 
    int file, 
    const void *ptr, 
    size_t len)
{
	int i;
	const unsigned char *p;
	
	p = (const unsigned char*) ptr;
	
	for (i = 0; i < len; i++) {
		if (*p == '\n' ) sio_putc('\r');
		sio_putc(*p++);
	}
	
	return len;
}

int _close_r(
    struct _reent *r, 
    int file)
{
	return 0;
}

_off_t _lseek_r(
    struct _reent *r, 
    int file, 
    _off_t ptr, 
    int dir)
{
	return (_off_t)0;	/*  Always indicate we are at file beginning.	*/
}


int _fstat_r(
    struct _reent *r, 
    int file, 
    struct stat *st)
{
	/*  Always set as character device.				*/
	st->st_mode = S_IFCHR;	
		/* assigned to strong type with implicit 	*/
		/* signed/unsigned conversion.  Required by 	*/
		/* newlib.					*/

	return 0;
}

int isatty(int file); /* avoid warning */

int isatty(int file)
{
	return 1;
}


extern char end[];
static char *heap_ptr;		/* Points to current end of the heap.	*/

void * _sbrk_r(
    struct _reent *_s_r, 
    ptrdiff_t nbytes)
{
	char  *base;

	if (!heap_ptr) {
		heap_ptr = end;
	}
	base = heap_ptr;
	heap_ptr += nbytes;
	
	return base;
}