#include <assert.h>
#include <stddef.h>

#include "nrf.h"

#include "driver.h"
#include "spi.h"

static inline int spi_transfer(uint32_t t);


int spi_open(const struct driver *drv)
{
    assert(NULL != drv);

    struct spi *this = (struct spi *)drv->dev;

    NRF_SPI0->ENABLE = 0;
    NRF_SPI0->PSELSCK = this->sck_pin;
    NRF_SPI0->PSELMOSI = this->mosi_pin;
    NRF_SPI0->PSELMISO = this->miso_pin;
    NRF_SPI0->FREQUENCY = SPI_FREQUENCY_FREQUENCY_M8;

    NRF_SPI0->CONFIG = (0x03 << 1); //Sample on trailing edge of clock, shift serial data on leading edge, SCK polarity Active low
    NRF_SPI0->EVENTS_READY = 0;
    NRF_SPI0->ENABLE = (SPI_ENABLE_ENABLE_Enabled << SPI_ENABLE_ENABLE_Pos);

    return 0;
}

int spi_close(const struct driver *drv)
{
    NRF_SPI0->ENABLE = 0;

    return 0;
}

int spi_write(const struct driver *drv, const char *buffer, unsigned int len)
{
    assert(NULL != buffer);

    //FIXME: missing CS handling

    for(unsigned int i = 0; i < len; i++) {
        spi_transfer(buffer[i]);
    }

    //FIXME: missing CS handling

    return len;
}

static inline int spi_transfer(uint32_t t)
{
    volatile uint32_t r;
    NRF_SPI0->EVENTS_READY = 0;           // ready
    NRF_SPI0->TXD = t;          // out
    while(NRF_SPI0->EVENTS_READY == 0) {
    }
    r = NRF_SPI0->RXD;                    // in
    return (int)r;
}