#include "system.h"
#include "spiclass.h"
typedef __SIZE_TYPE__ size_t;

enum SPICLK : uint32_t {
  FPCLK_2 = 0u, // 72 MHz
  FPCLK_4,      // 72 MHz
  FPCLK_8,      // 36 MHz
  FPCLK_16,     // 18 MHz
  FPCLK_32,     // 9     MHz
  FPCLK_64,     // 4.5   MHz
  FPCLK_128,    // 2.25  MHz
  FPCLK_256,    // 1.125 MHz
};

static SpiClass * pSpiInstance = nullptr;
extern "C" {
  [[gnu::interrupt]] extern void SPI1_IRQHandler ();
  extern void * memcpy (void * dest, const void * src, size_t n);
};
void SPI1_IRQHandler () {
  if (pSpiInstance) pSpiInstance->irq();
}
static void InitPins () noexcept {
  // PA4 - NSS (software), PA5 - SCK, PA6 - MISO, PA7 - MOSI
  GPIOA.CFGLR.modify([](GPIOA_Type::CFGLR_DEF & r) -> uint32_t {
    r.B.MODE4 = 3u; // 50 MHz
    r.B.CNF4  = 0u; // gen push - pull
    r.B.MODE5 = 3u; // 50 MHz
    r.B.CNF5  = 3u; // alt push - pull
    
    r.B.MODE6 = 0u; // input mode
    r.B.CNF6  = 1u; // floating
    r.B.MODE7 = 3u; // 50 MHz
    r.B.CNF7  = 3u; // alt push - pull
    return r.R;
  });
  // AFIO - default
}
void SpiClass::irq() {
  if (SPI1.STATR.B.RXNE) {
    buffer [index++] = SPI1.DATAR.R;
    if (index == total) {
      complete = true;
      index    = 0u;
      select (true);
      return;
    }
    // tady by mělo být už odesláno
    SPI1.DATAR.R = buffer [index];
  }
}

SpiClass::SpiClass() noexcept : index(0u), total(0u), complete (false) {
  pSpiInstance = this;
  RCC.APB2PCENR.modify([](RCC_Type::APB2PCENR_DEF & r) -> uint32_t {
    r.B.SPI1EN = SET;
    r.B.IOPAEN = SET;
    r.B.AFIOEN = SET;
    return r.R;
  });
  InitPins();
  select  (true);
  SPI1.CTLR1.modify([](SPI1_Type::CTLR1_DEF & r) -> uint32_t {
    r.B.CPHA     = SET;
    r.B.CPOL     = SET;
    r.B.MSTR     = SET;
    r.B.DFF      = RESET;     // 8 bit
    r.B.SSM      = SET;
    r.B.SSI      = SET;
    r.B.LSBFIRST = RESET;
    r.B.BR       = FPCLK_64;  // 4.5 MHz
    return r.R;
  });
  SPI1.CTLR2.modify([](SPI1_Type::CTLR2_DEF & r) -> uint32_t {
    r.B.SSOE   = SET;
    r.B.RXNEIE = SET;
    return r.R;
  });
  NVIC.EnableIRQ(SPI1_IRQn);
  SPI1.CTLR1.B.SPE = SET;
}
void SpiClass::select (const bool set) const noexcept {
  if (set) GPIOA.BSHR.B.BS4 = SET;
  else     GPIOA.BSHR.B.BR4 = SET;
}

bool SpiClass::send (const char * data, const unsigned int len) {
  if (!complete) return false;
  select (false);
  complete = false;
  index    = 0u;
  total    = len > SPIBUFLEN ? SPIBUFLEN : len;
  memcpy (buffer, data, total);
  SPI1.DATAR.R = buffer [index];
  
  return true;
}
char * SpiClass::received (unsigned int & count) {
  if (complete) count = total;
  else          count = 0;
  return buffer;
}