/*
 * sht30_driver.c
 *
 *  Created on: 30. apr. 2025
 *      Author: Christian L. V. Madsen (OZ1CM)
 */
 #include "sht30_driver.h"
 
#define REV16_A(X) (((X) << 8) | ((X)>>8))
#define REV8_A(X) (((X) << 4) | ((X)>>4))

static int isStructOk(SHT30_Struct_Type *inst){
	
	if(inst == NULL)return 0;
	if(inst->i2c_transfer_inst == NULL)return 0;
	if(inst->i2c_transfer_evt == NULL)return 0;
	
	return 1;
}

uint8_t crc8_i2c_u16(uint16_t input) {
    uint8_t crc = 0xFF;
    uint8_t poly = 0x31;

    // Process MSB first (big endian)
    for (int i = 1; i >= 0; i--) {
        uint8_t byte = (input >> (8 * i)) & 0xFF;
        crc ^= byte;

        for (uint8_t j = 0; j < 8; j++) {
            if (crc & 0x80)
                crc = (crc << 1) ^ poly;
            else
                crc <<= 1;
        }
    }

    return crc;  // Final XOR is 0x00, so this is the final CRC
    
}
static int readRegister(SHT30_Struct_Type *inst, uint8_t *data_addr, uint8_t *data, uint32_t len){

	// Write what kind of addr we would like to read from:
	int ret = inst->i2c_transfer_evt(inst->i2c_transfer_inst,data_addr,2, SHT30_I2C_SET);

	// Read data:
	ret += inst->i2c_transfer_evt(inst->i2c_transfer_inst,data,len, SHT30_I2C_GET);

	return ret;
}

static int writeRegister(SHT30_Struct_Type *inst, uint16_t data_addr, uint8_t *data, uint32_t len){

	// Write what kind of addr we would like to read from:
	inst->i2c_transfer_evt(inst->i2c_transfer_inst,(uint8_t *)&data_addr,2, SHT30_I2C_SET);

	// Write data:
	inst->i2c_transfer_evt(inst->i2c_transfer_inst,data,len, SHT30_I2C_SET);

	return 0;
}

int sht30_writeCmd(SHT30_Struct_Type *inst, uint16_t command){
	
	if(!isStructOk(inst))return 1;
	
	int ret;
	uint8_t buffer[2] = {0};
	buffer[0] = (command >> 8) & 0xff;
	buffer[1] = (command & 0xff);
	ret = inst->i2c_transfer_evt(inst->i2c_transfer_inst,buffer,sizeof(buffer), SHT30_I2C_SET);
	
	
	return ret;
	
}
 
static int SHT30_resetConnection(SHT30_Struct_Type *inst){
	
	if(!isStructOk(inst))return 1;

	for(int i = 0; i< 3; i++){
		int ret = 0;

		ret = sht30_writeCmd(inst,0x30A2); // Soft reset device
		ret = sht30_writeCmd(inst,0x272A); // Measurement Command for Periodic Data Acquisition Mode
		if(ret == 0){
			return 0;
		}
		
	}
	
	return 1;

}

void SHT30_calcRawData(SHT30_Struct_Type *p){


	p->Message.RawTemp = REV16_A(p->Message.RawTemp);
	p->Message.RawHumidity = REV16_A(p->Message.RawHumidity);
	
	if(crc8_i2c_u16(p->Message.RawTemp) != p->Message.CRC_Temp) return;
	if(crc8_i2c_u16(p->Message.RawHumidity) != p->Message.CRC_Humidity) return;

	// Calc Temperature
	p->Temperature_mC = p->Message.RawTemp * 17500;
	p->Temperature_mC = p->Temperature_mC >> 16;
	p->Temperature_mC -= 4500;

	// Calc Humidity
	p->Humidity = p->Message.RawHumidity * 100;
	p->Humidity = p->Humidity >> 16;

}
 
int sht30_ReadData(SHT30_Struct_Type *inst){
		int ret;
		uint8_t reg[2] = {0xe0,0x00};
		ret = readRegister(inst, reg, (void*)&inst->Message, sizeof(SHT30_Message_Type));

		if(ret != 0){
			SHT30_resetConnection(inst);
			return 1;

		}else{
			SHT30_calcRawData(inst);
			return 0;
		}



}

int sht30_init(SHT30_Struct_Type *inst, void *i2c_transfer_inst, setGet_I2C_Event_fpt i2c_transfer_evt){
	if(inst == NULL)return -1;
	if(i2c_transfer_inst == NULL)return -1;
	if(i2c_transfer_evt == NULL)return -1;
	
	inst->i2c_transfer_inst = i2c_transfer_inst;
	inst->i2c_transfer_evt = i2c_transfer_evt;
	
	SHT30_resetConnection(inst);
	
	return 0;

}