#include <stdbool.h>
#include <stdint.h>
#include <assert.h>

#include <stm32f407xx.h>

#include "sr_global.h"
#include "adc.h"
#include "spi_flash.h"
#include "freq_meas.h"
#include "dsss_demod.h"

static struct spi_flash_if spif;


void __libc_init_array(void) { /* we don't need this. */ }
void __assert_func (unused_a const char *file, unused_a int line, unused_a const char *function, unused_a const char *expr) {
    asm volatile ("bkpt");
    while(1) {}
}

static void clock_setup(void)
{
    /* 8MHz HSE clock as PLL source.
     * 
     * Divide by 8 -> 1 MHz */
#define PLL_M 8
    /* Multiply by 336 -> 336 MHz VCO frequency */
#define PLL_N 336
    /* Divide by 2 -> 168 MHz (max freq for our chip) */
#define PLL_P 2
    /* Aux clock for USB OTG, SDIO, RNG: divide VCO frequency (336 MHz) by 7 -> 48 MHz (required by USB OTG) */
#define PLL_Q 7

    RCC->CR |= RCC_CR_HSEON;
    while(!(RCC->CR & RCC_CR_HSERDY));

    RCC->APB1ENR |= RCC_APB1ENR_PWREN;

    /* set voltage scale to 1 for max frequency
     * (0b0) scale 2 for fCLK <= 144 Mhz
     * (0b1) scale 1 for 144 Mhz < fCLK <= 168 Mhz
     */
    PWR->CR |= PWR_CR_VOS;

    /* set AHB prescaler to /1 (CFGR:bits 7:4) */
    RCC->CFGR |= (0 << RCC_CFGR_HPRE_Pos);
    /* set ABP1 prescaler to 4 */
    RCC->CFGR |= (5 << RCC_CFGR_PPRE1_Pos);
    /* set ABP2 prescaler to 2 */
    RCC->CFGR |= (0x4 << RCC_CFGR_PPRE2_Pos);

    /* Configure PLL */
    static_assert(PLL_P % 2 == 0);
    static_assert(PLL_P >= 2 && PLL_P <= 8);
    static_assert(PLL_N >= 50 && PLL_N <= 432);
    static_assert(PLL_M >= 2 && PLL_M <= 63);
    static_assert(PLL_Q >= 2 && PLL_Q <= 15);
    RCC->PLLCFGR = (PLL_M<<RCC_PLLCFGR_PLLM_Pos)
        | (PLL_N << RCC_PLLCFGR_PLLM_Pos)
        | ((PLL_P/2 - 1) << RCC_PLLCFGR_PLLP_Pos)
        | (PLL_Q << RCC_PLLCFGR_PLLQ_Pos)
        | RCC_PLLCFGR_PLLSRC; /* select HSE as PLL source */
    RCC->CR |= RCC_CR_PLLON;

    /* Wait for main PLL */
    while(!(RCC->CR & RCC_CR_PLLRDY))
        ;

    /* Configure Flash: enable prefetch, insn cache, data cache; set latency = 5 wait states
     * See reference manual (RM0090), Section 3.5.1, Table 10 (p. 80)
     */
    FLASH->ACR = FLASH_ACR_PRFTEN | FLASH_ACR_ICEN | FLASH_ACR_DCEN | (5<<FLASH_ACR_LATENCY);

    /* Select PLL as system clock source */
    RCC->CFGR &= ~RCC_CFGR_SW_Msk;
    RCC->CFGR |= 2 << RCC_CFGR_SW_Pos;

    /* Wait for clock to switch over */
    while ((RCC->CFGR & RCC_CFGR_SWS_Msk)>>RCC_CFGR_SWS_Pos != 2)
        ;
}

static void led_setup(void)
{
    GPIOA->MODER |= (1<<GPIO_MODER_MODER6_Pos) | (1<<GPIO_MODER_MODER7_Pos);
}

static void spi_flash_if_set_cs(bool val) {
    if (val)
        GPIOB->BSRR = 1<<0;
    else
        GPIOB->BSRR = 1<<16;
}

static void spi_flash_setup(void)
{
    GPIOB->MODER &= ~GPIO_MODER_MODER3_Msk & ~GPIO_MODER_MODER4_Msk & ~GPIO_MODER_MODER5_Msk & ~GPIO_MODER_MODER0_Msk;
    GPIOB->MODER |= (2<<GPIO_MODER_MODER3_Pos) /* SCK */
        | (2<<GPIO_MODER_MODER4_Pos) /* MISO */
        | (2<<GPIO_MODER_MODER5_Pos) /* MOSI */
        | (1<<GPIO_MODER_MODER0_Pos); /* CS */

    GPIOB->OSPEEDR &= ~GPIO_OSPEEDR_OSPEED3_Msk & ~GPIO_OSPEEDR_OSPEED4_Msk
        & ~GPIO_OSPEEDR_OSPEED5_Msk & ~GPIO_OSPEEDR_OSPEED0_Msk;
    GPIOB->OSPEEDR |= (2<<GPIO_OSPEEDR_OSPEED3_Pos) /* SCK */
        | (2<<GPIO_OSPEEDR_OSPEED4_Pos) /* MISO */
        | (2<<GPIO_OSPEEDR_OSPEED5_Pos) /* MOSI */
        | (2<<GPIO_OSPEEDR_OSPEED0_Pos); /* CS */

    GPIOB->AFR[0] &= ~GPIO_AFRL_AFSEL3_Msk & ~GPIO_AFRL_AFSEL4_Msk & ~GPIO_AFRL_AFSEL5_Msk;
    GPIOB->AFR[0] |= (5<<GPIO_AFRL_AFSEL3_Pos) | (5<<GPIO_AFRL_AFSEL4_Pos) | (5<<GPIO_AFRL_AFSEL5_Pos);

    RCC->APB2ENR |= RCC_APB2ENR_SPI1EN;
    RCC->APB2RSTR |= RCC_APB2RSTR_SPI1RST;
    RCC->APB2RSTR &= RCC_APB2RSTR_SPI1RST;

    spif_init(&spif, 256, SPI1, &spi_flash_if_set_cs);
}

/* SPI flash test routine to be called from gdb */
#ifdef SPI_FLASH_TEST
void spi_flash_test(void) {
    spif_clear_mem(&spif);

    uint32_t buf[1024];
    for (size_t addr=0; addr<0x10000; addr += sizeof(buf)) {
        for (size_t i=0; i<sizeof(buf); i+= sizeof(buf[0]))
            buf[i/sizeof(buf[0])] = addr + i;

        spif_write(&spif, addr, sizeof(buf), (char *)buf);
    }

    for (size_t i=0; i<sizeof(buf)/sizeof(buf[0]); i++)
        buf[i] = 0;
    spif_read(&spif, 0x1030, sizeof(buf), (char *)buf);
    asm volatile ("bkpt");
}
#endif

static unsigned int measurement_errors = 0;
static struct dsss_demod_state demod_state;
static uint32_t freq_sample_ts = 0;

int main(void)
{
    clock_setup();
    led_setup();
    spi_flash_setup();
    adc_init();

    while (23) {
        if (adc_fft_buf_ready_idx != -1) {
            float out;
            if (adc_buf_measure_freq(adc_fft_buf[adc_fft_buf_ready_idx], &out)) {
                measurement_errors++;
                continue;
            }

            dsss_demod_init(&demod_state);
            dsss_demod_step(&demod_state, out, freq_sample_ts);

            freq_sample_ts++; /* TODO: also increase in case of freq measurement error? */
            adc_fft_buf_ready_idx = -1;
        }
    }

    return 0;
}