os_c_lib_func.c

arm_bootloader _flash writter &USB

#include <stdio.h>
#include <stdarg.h>

#include <ucos_ii.h>

#include "os_uart.h"

// Tailor for C standard Library
// printf() requires low-level fputc(), below is its implementation.
// However, printf() didn't place a lock to guarteen the message's integrity
// i.e. A task printing message maybe interrupted...
// So I write another stdout function OS_printf(), which uses OS_uart_putstring().
int fputc(int ch, FILE *f)
{
	char c = (char)ch;
    OS_uart_putstring(&c, 1);
    return ch;
}

void OS_printf(const char *fmt, ...)
{
    unsigned int len_str;
    char buf[1024];
    va_list ap;

    va_start(ap, fmt);
    len_str = vsnprintf(buf, sizeof(buf), fmt, ap);
    va_end(ap);
    
    OS_uart_putstring(buf, len_str);
}