syscalls.c

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/*!
 * @file
 * 
 * @brief Support files for GNU libc.
 * 
 * @author  stolen from Sheaff.  
 * 
 * @date Jan  2016
 * 
 * Some standard syscall functions are redefined here in order to 
 * make printf() calls direct output to the USART (to be accessed 
 * by the host when the development board is connected through the
 * USB connector)
 * 
 * note the changes to _write()
 */


#include <_ansi.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/fcntl.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <sys/time.h>
#include <sys/times.h>
#include <errno.h>
#include <reent.h>
#include <unistd.h>
#include <sys/wait.h>
#include <stdint.h>
#include "usart.h"

#define FreeRTOS
#define MAX_STACK_SIZE 0x2000

extern int __io_putchar(int ch) __attribute__((weak));
extern int __io_getchar(void) __attribute__((weak));

#ifndef FreeRTOS
  register char * stack_ptr asm("sp");
#endif




caddr_t _sbrk(int incr)
{
        extern char end asm("end");
        static char *heap_end;
        char *prev_heap_end,*min_stack_ptr;

        if (heap_end == 0)
                heap_end = &end;

        prev_heap_end = heap_end;

#ifdef FreeRTOS
        /* Use the NVIC offset register to locate the main stack pointer. */
        min_stack_ptr = (char*)(*(unsigned int *)*(unsigned int *)0xE000ED08);
        /* Locate the STACK bottom address */
        min_stack_ptr -= MAX_STACK_SIZE;

        if (heap_end + incr > min_stack_ptr)
#else
        if (heap_end + incr > stack_ptr)
#endif
        {
//              write(1, "Heap and stack collision\n", 25);
//              abort();
                errno = ENOMEM;
                return (caddr_t) -1;
        }

        heap_end += incr;

        return (caddr_t) prev_heap_end;
}

/*
 * _gettimeofday primitive (Stub function)
 * */
int _gettimeofday (struct timeval * tp, struct timezone * tzp)
{
  /* Return fixed data for the timezone.  */
  if (tzp)
    {
      tzp->tz_minuteswest = 0;
      tzp->tz_dsttime = 0;
    }

  return 0;
}
void initialise_monitor_handles()
{
}

int _getpid(void)
{
        return 1;
}

int _kill(int pid, int sig)
{
        errno = EINVAL;
        return -1;
}

void _exit (int status)
{
        _kill(status, -1);
        while (1) {}
}

int _write(int file, char *ptr, int len)
{
        // Transmit printf string to USART - blocking call
        HAL_UART_Transmit(&UsartHandle,(uint8_t *)ptr,len,10000);
        return len;
}

int _close(int file)
{
        return -1;
}

int _fstat(int file, struct stat *st)
{
        st->st_mode = S_IFCHR;
        return 0;
}

int _isatty(int file)
{
        return 1;
}

int _lseek(int file, int ptr, int dir)
{
        return 0;
}

int _read(int file, char *ptr, int len)
{
        int DataIdx;

        for (DataIdx = 0; DataIdx < len; DataIdx++)
        {
          *ptr++ = __io_getchar();
        }

   return len;
}

int _open(char *path, int flags, ...)
{
        /* Pretend like we always fail */
        return -1;
}

int _wait(int *status)
{
        errno = ECHILD;
        return -1;
}

int _unlink(char *name)
{
        errno = ENOENT;
        return -1;
}

int _times(struct tms *buf)
{
        return -1;
}

int _stat(char *file, struct stat *st)
{
        st->st_mode = S_IFCHR;
        return 0;
}

int _link(char *old, char *new)
{
        errno = EMLINK;
        return -1;
}

int _fork(void)
{
        errno = EAGAIN;
        return -1;
}

int _execve(char *name, char **argv, char **env)
{
        errno = ENOMEM;
        return -1;
}