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

#include <stdbool.h>

#include "spi.h"

static volatile unsigned char * const spi_data = (unsigned char *)0x08010030;
static volatile unsigned char * const spi_status = (unsigned char *)0x08010031;
static volatile unsigned char * const spi_config = (unsigned char *)0x08010032;
static volatile unsigned char * const spi_ss = (unsigned char *)0x08010033;

static bool _spi_rxempty() {
  return ((*spi_status&0x4)==0x4);
}

static bool _spi_txfull() {
  return ((*spi_status&0x2)==0x2);
}

static bool _spi_idle() {
  return ((*spi_status&0x1)==0x1);
}

void spi_write(unsigned char data) {
  while(_spi_txfull()) {}
  *spi_data = data;
}

unsigned char spi_read() {
  while(_spi_rxempty()) {}
  return *spi_data;
}

unsigned char spi_xmit(unsigned char data) {
  spi_write(data);
  return spi_read();
}

void spi_set_ss(bool active) {
  while(!_spi_idle()) {}
  if(active)
    *spi_ss = 0x0;
  else
    *spi_ss = 0x1;
}

void spi_setclk(unsigned char div) {
  while(!_spi_idle()) {}
  *spi_config = div;
}