STDIN, STDOUT, STDERR

These three file pointers are automatically defined when a program executes and provide access to the keyboard and screen.

stdin

• gets
• getchar

• fgets
• fgetc
• fscanf

stdout

• printf
• puts
• putchar

stderr

• fprintf
• fputs

//Replace the gcc default connectors for stdin and stdout  
int _write(int file, char *ptr, int len) {  
    int i;  
    file = file;  
    for (i = 0; i < len; i++) {  
        UART_UartPutChar(*ptr++);  
        }  
    return len;  
    }  
  
  
int _read (int fd, const void *buf, size_t count) {  
  size_t CharCnt = 0x00;  
  (void)fd;                            /* Parameter is not used, suppress unused argument warning */  
  for (;count > 0x00; --count) {  
    /* Save character received by UARTx device into the receive buffer */  
    while(!(*(uint8_t*)buf = (unsigned char)UART_UartGetChar()));  
    CharCnt++;                         /* Increase char counter */  
    /* Stop reading if CR (Ox0D) character is received */  
    if (*(uint8_t*)buf == 0x0DU) {     /* New line character (CR) received ? */  
      *(uint8_t*)buf = '\n';           /* Yes, convert LF to '\n' char. */  
      break;                           /* Stop loop and return received char(s) */  
    }  
    buf++;                   /* Increase buffer pointer */  
  }  
  //return 1; /* WRONG! */  
  return CharCnt;  
}