// Copyright (c) 2013 Matthias Blankertz <matthias@blankertz.org>

#include <stdbool.h>

#include "uart.h"

static volatile unsigned char *_uart_sreg = (unsigned char *)0x08010021;
static volatile unsigned char *_uart_dreg = (unsigned char *)0x08010020;

static bool _uart_writefull() {
  return ((*_uart_sreg&0x2)==0x2);
}

static bool _uart_readempty() {
  return ((*_uart_sreg&0x4)==0x4);
}

void uart_writeb(unsigned char b) {
  while(_uart_writefull()) {}
  *_uart_dreg = b;
}

void uart_writes(const char *str) {
  while(*str)
    uart_writeb(*str++);
}

unsigned char uart_readb() {
  while(_uart_readempty()) {}
  return *_uart_dreg;
}

// Read from uart until a newline is recvd. The recvd line is written into buf
// as a 0-terminated string. If more than max bytes are read, the bytes already
// read are returned in buf and the function returns false.
bool uart_readline(char *buf, int max) {
  int i = 0;
  while(i < max-1) {
    buf[i] = uart_readb();
    if(buf[i] == '\n') {
      buf[i] = '\0';
      return true;
    }
    ++i;
  }
  buf[i] = '\0';
  return false;
}