// ch32x035 and ch32v203

#include "ch32fun_i2c.h"

#define I2C_TIMEOUT_MAX 100000
#define WAIT_FOR_FLAG(reg, flag) { \
    uint32_t timeout = I2C_TIMEOUT_MAX; \
    while (!((reg) & (flag))) { \
        if (--timeout == 0) return -1; \
    } \
}

extern uint8_t * make_output_buffer(mrb_vm *vm, mrb_value v[], int argc,
                             int start_idx, int *ret_bufsiz);
#if !MRBC_USE_STRING
extern mrbc_value mrbc_array_new_alloc(mrbc_vm *vm, const uint8_t *c_array, int size);
#endif

void i2c_init(){
  RCC->APB1PCENR |= RCC_APB1Periph_I2C1;
#if defined( CH32X03x )
  AFIO->PCFR1 &= ~AFIO_PCFR1_SWJ_CFG;
  AFIO->PCFR1 |= AFIO_PCFR1_SWJ_CFG_DISABLE;
  GPIOC->CFGXR &= ~(0xF << 8 | 0xF << 12); //PC18 DIO, PC19 DCK
  GPIOC->CFGXR |= GPIO_CFGLR_OUT_50Mhz_AF_PP << 8 | GPIO_CFGLR_OUT_50Mhz_AF_PP << 12;
  AFIO->PCFR1 &= ~AFIO_PCFR1_I2C1_REMAP;
  AFIO->PCFR1 |= AFIO_PCFR1_I2C1_REMAP_1 | AFIO_PCFR1_I2C1_REMAP_0; //011
#elif defined( CH32V20x )
  funPinMode(26,GPIO_CFGLR_OUT_50Mhz_AF_PP); //PB10
  funPinMode(27,GPIO_CFGLR_OUT_50Mhz_AF_PP); //PB11
#endif
  I2C1->CTLR1 &= ~I2C_CTLR1_PE;
  I2C1->CTLR2 = (FUNCONF_SYSTEM_CORE_CLOCK / 1000000);
  I2C1->CKCFGR = FUNCONF_SYSTEM_CORE_CLOCK / (100000 << 1); //100kHz
  I2C1->CTLR1 |= I2C_CTLR1_PE;
  I2C1->CTLR1 |= I2C_CTLR1_ACK;
}

int i2c_start(uint8_t adrs, uint8_t rw){ // rw=1 if read
  uint32_t timeout = I2C_TIMEOUT_MAX;
  while (I2C1->STAR2 & I2C_STAR2_BUSY) {
    if (--timeout == 0) return -1;
  }
  I2C1->CTLR1 |= I2C_CTLR1_START;
  WAIT_FOR_FLAG(I2C1->STAR1, I2C_STAR1_SB);
  I2C1->DATAR = (adrs << 1) | rw;
  WAIT_FOR_FLAG(I2C1->STAR1, I2C_STAR1_ADDR);
  (void)I2C1->STAR1;
  (void)I2C1->STAR2;
  return 0;
}
int i2c_write(const uint8_t *buf, uint16_t len){
  for (uint16_t i = 0; i < len; i++) {
    WAIT_FOR_FLAG(I2C1->STAR1, I2C_STAR1_TXE);
    I2C1->DATAR = buf[i];
  }
  WAIT_FOR_FLAG(I2C1->STAR1, I2C_STAR1_BTF);
  return 0;
}
int i2c_read(uint8_t *buf, uint16_t len){
  I2C1->CTLR1 |= I2C_CTLR1_ACK;
  for (uint16_t i = 0; i < len; i++) {
    if(i==len-1) I2C1->CTLR1 &= ~I2C_CTLR1_ACK;
    WAIT_FOR_FLAG(I2C1->STAR1, I2C_STAR1_RXNE);
    buf[i] = I2C1->DATAR;
  }
  I2C1->CTLR1 |= I2C_CTLR1_STOP;
  return 0;
}

void c_i2c_new(mrb_vm *vm, mrb_value *v, int argc){
  i2c_init();
}

void c_i2c_write(mrb_vm *vm, mrb_value *v, int argc){
  uint8_t *buf = 0;
  int bufsiz = 0;
  if( argc>0 ){
    uint8_t adrs = GET_INT_ARG(1);
    i2c_start(adrs,0);
    if(argc>1){
      buf = make_output_buffer( vm, v, argc, 2, &bufsiz );
      i2c_write(buf, bufsiz);
      mrbc_free( vm, buf );
    }
    I2C1->CTLR1 |= I2C_CTLR1_STOP;
  }
  SET_RETURN( mrbc_integer_value(bufsiz) );
}

void c_i2c_read(mrb_vm *vm, mrb_value *v, int argc){
  uint8_t *buf = 0;
  int bufsiz = 0;
  mrbc_value ret = mrbc_nil_value();
  if( argc>1 ){
    int adrs = GET_INT_ARG(1);
    int size = GET_INT_ARG(2);
    if( argc > 2 ) {
      i2c_start(adrs,0);
      buf = make_output_buffer( vm, v, argc, 3, &bufsiz );
      i2c_write(buf, bufsiz);
      mrbc_free( vm, buf );
    }
    buf = mrbc_alloc(vm, size);
    i2c_start(adrs,1);
    i2c_read(buf,size);
#if MRBC_USE_STRING
    ret = mrbc_string_new_alloc(vm, buf, size);
#else
    ret = mrbc_array_new_alloc( vm, buf, size);
    mrbc_free( vm, buf );
#endif
  }
  SET_RETURN(ret);
}

void mrbc_init_class_i2c(void){
  mrb_class *i2c = mrbc_define_class(0, "I2C",  mrbc_class_object);
  mrbc_define_method(0, i2c, "new", c_i2c_new);
  mrbc_define_method(0, i2c, "read", c_i2c_read);
  mrbc_define_method(0, i2c, "write", c_i2c_write);
}