syscalls.c

UART I/O and Memory Allocation Example for GNU The project GNU_IODemo shows how to use memory alloc

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

#include <stdlib.h>


extern int putchar (int ch);
extern int getchar (void);

int read (int file, char * ptr, int len) {
  char c;
  int  i;

  for (i = 0; i < len; i++) {
    c = getchar();
    if (c == 0x0D) break;
    *ptr++ = c;
    putchar(c);
  }
  return len - i;
}

/*	Write a buffer using putchar function in serial.c 	*/

int write (int file, char * ptr, int len) {
  int i;

  for (i = 0; i < len; i++) putchar (*ptr++);
  return len;
}

int isatty (int fd) {
  return 1;
}


void _exit (int n) {
label:  goto label; /* endless loop */
}

// Note that the external RAM is not available on the real device
#define HEAP_START 0x10000000
#define HEAP_LIMIT 0x10010000

caddr_t sbrk (int incr) {
//extern char   end asm ("end");	/* Defined by the linker */
  static char * heap_end;
         char * prev_heap_end;

  if (heap_end == NULL) heap_end = (char *)HEAP_START;//&end;
  prev_heap_end = heap_end;

  if (heap_end + incr >= (char *)HEAP_LIMIT) {
    abort ();	   /* Out of Memory */
  }
  heap_end += incr;

  return (caddr_t) prev_heap_end;
}