// Lots of the info came from: https://teslabs.com/openplayer/docs/docs/other/ds18b20_pre1.pdf and https://www.circuitbread.com/tutorials/embedded-c-programming-with-the-pic18f14k50-12-digital-thermometer
// Also needed to use a scope to check the timings were reasonably accurate

#include <libopencm3/stm32/gpio.h>
#include <libopencm3/stm32/rcc.h>
#include <libopencm3/cm3/systick.h>
#include <stdint.h>
#include <string.h>
#include "ds18b20.h"
#include "misc.h"

// Delay function
void ds18b20_delay_us(uint32_t us) {
	for (uint32_t i = 0; i < (us * 3); i++) {
		__asm__("nop");
	}
}

void ds18b20_delay_us_nop() {
	__asm__("nop");

}

// OneWire low-level functions
static void ds18b20_pin_mode_output(uint32_t ds18b20_port, uint32_t ds18b20_pin) {
	gpio_mode_setup(ds18b20_port, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, ds18b20_pin);
}

static void ds18b20_pin_mode_input(uint32_t ds18b20_port, uint32_t ds18b20_pin) {
	gpio_mode_setup(ds18b20_port, GPIO_MODE_INPUT, GPIO_PUPD_NONE, ds18b20_pin);
}

static void ds18b20_write_bit(uint32_t ds18b20_port, uint32_t ds18b20_pin, uint8_t bit) {
	ds18b20_pin_mode_output(ds18b20_port, ds18b20_pin);
	gpio_clear(ds18b20_port, ds18b20_pin);

	if (bit) {
		delay_us(1); // Short low pulse for '1'
		gpio_set(ds18b20_port, ds18b20_pin);
		ds18b20_pin_mode_input(ds18b20_port, ds18b20_pin);
	}

	delay_us(60);
	ds18b20_pin_mode_input(ds18b20_port, ds18b20_pin);
	delay_us(10);
}

static uint8_t ds18b20_read_bit(uint32_t ds18b20_port, uint32_t ds18b20_pin) {
	uint8_t bit;
	ds18b20_pin_mode_output(ds18b20_port, ds18b20_pin);
	gpio_clear(ds18b20_port, ds18b20_pin);
//	ds18b20_delay_us(1);
//	gpio_set(ds18b20_port, ds18b20_pin);

	ds18b20_pin_mode_input(ds18b20_port, ds18b20_pin);
	ds18b20_delay_us(10);
	bit = gpio_get(ds18b20_port, ds18b20_pin);
	ds18b20_delay_us(50);
	return bit;
}

uint8_t ds18b20_reset(uint32_t ds18b20_port, uint32_t ds18b20_pin) {
	uint8_t presence;
	ds18b20_pin_mode_output(ds18b20_port, ds18b20_pin);
	gpio_clear(ds18b20_port, ds18b20_pin);

        ds18b20_delay_us(960);

	ds18b20_pin_mode_input(ds18b20_port, ds18b20_pin);
        ds18b20_delay_us(120);

	presence = gpio_get(ds18b20_port, ds18b20_pin);

        ds18b20_delay_us(840);

	return presence == 0; // If presence is detected, return 1
}

void ds18b20_write_byte(uint32_t ds18b20_port, uint32_t ds18b20_pin, uint8_t byte) {
	for (uint8_t i = 0; i < 8; i++) {
		ds18b20_write_bit(ds18b20_port, ds18b20_pin, byte & 0x01);
		byte >>= 1;
	}
	ds18b20_pin_mode_input(ds18b20_port, ds18b20_pin);
}

uint8_t ds18b20_read_byte(uint32_t ds18b20_port, uint32_t ds18b20_pin)
{
     uint8_t byte = 0;   	//Value to be returned
     for (uint8_t i = 0; i< 8; i++)//Loop to read the whole byte
     {
    	byte >>= 1;     	//Shift the byte at one bit to the right
    	if (ds18b20_read_bit(ds18b20_port, ds18b20_pin))  //If 1 has been read
        	byte |= 0x80; 	 //Then add it to the byte
     }
     return (byte);
}


// DS18B20 high-level functions
void ds18b20_start_conversion(uint32_t ds18b20_port, uint32_t ds18b20_pin) {
	ds18b20_reset(ds18b20_port, ds18b20_pin);
	delay_ms(1);
	ds18b20_write_byte(ds18b20_port, ds18b20_pin, 0xCC); // Skip ROM
	delay_ms(1);
	ds18b20_write_byte(ds18b20_port, ds18b20_pin, 0x44); // Start conversion
	delay_ms(1);
}

int16_t ds18b20_read_raw_temperature(uint32_t ds18b20_port, uint32_t ds18b20_pin) {
        uint8_t scratchpad[10];

        int16_t temp_raw;
        ds18b20_reset(ds18b20_port, ds18b20_pin);
        delay_ms(1);
        ds18b20_write_byte(ds18b20_port, ds18b20_pin, 0xCC);  // Skip ROM
        delay_ms(1);
        ds18b20_write_byte(ds18b20_port, ds18b20_pin, 0xBE);  // Read Scratchpad
        delay_ms(1);


        // Read all 9 bytes of the scratchpad
        for (int i = 0; i <= 9; i++) {
                scratchpad[i] = ds18b20_read_byte(ds18b20_port, ds18b20_pin);
        }

        // Raw temperature is stored in the first two bytes
        uint8_t temp_lsb = scratchpad[0];
        uint8_t temp_msb = scratchpad[1];
        temp_raw = (temp_msb << 8) | temp_lsb;

        return (temp_raw * 625) / 10;  // Scale to Celsius * 1000
}