#include "ds18b20_ds2480.h"
#include <string.h>

static ds2480_status write_byte(ds2480 *bus, uint8_t value)
{
    uint8_t echoed;
    ds2480_status status = ds2480_byte(bus, value, &echoed);
    if (status != DS2480_OK) return status;
    return echoed == value ? DS2480_OK : DS2480_DATA;
}

static ds2480_status select_rom(ds2480 *bus, const uint8_t *rom)
{
    uint8_t i;
    ds2480_status status;
    if (rom && (rom[0] != 0x28 || ds2480_crc8(rom, 8))) return DS2480_ARGUMENT;
    status = ds2480_reset(bus);
    if (status != DS2480_OK) return status;
    status = write_byte(bus, rom ? 0x55 : 0xCC);
    if (status != DS2480_OK || !rom) return status;
    for (i = 0; i < 8; ++i) {
        status = write_byte(bus, rom[i]);
        if (status != DS2480_OK) return status;
    }
    return DS2480_OK;
}

ds2480_status ds18b20_ds2480_next(ds2480 *bus, ds2480_search *search)
{
    ds2480_status status;
    do {
        status = ds2480_search_next(bus, search);
        if (status != DS2480_OK) return status;
    } while (search->rom[0] != 0x28);
    return DS2480_OK;
}

ds2480_status ds18b20_ds2480_convert(ds2480 *bus, const uint8_t rom[8])
{
    ds2480_status status = select_rom(bus, rom);
    if (status != DS2480_OK) return status;
    return ds2480_power_byte(bus, 0x44, 750);
}

ds2480_status ds18b20_ds2480_read(ds2480 *bus, const uint8_t rom[8], uint8_t scratchpad[9])
{
    uint8_t data[9], i;
    ds2480_status status;
    if (!rom || !scratchpad) return DS2480_ARGUMENT;
    status = select_rom(bus, rom);
    if (status != DS2480_OK) return status;
    status = write_byte(bus, 0xBE);
    if (status != DS2480_OK) return status;
    for (i = 0; i < 9; ++i) {
        status = ds2480_byte(bus, 0xFF, &data[i]);
        if (status != DS2480_OK) return status;
    }
    if (ds2480_crc8(data, 9)) return DS2480_CRC;
    /* All-zero data has valid CRC but cannot be a DS18B20 scratchpad. */
    if ((data[4] & 0x9F) != 0x1F) return DS2480_DATA;
    memcpy(scratchpad, data, sizeof data);
    return DS2480_OK;
}

ds2480_status ds18b20_ds2480_temperature(ds2480 *bus, const uint8_t rom[8], int16_t *raw)
{
    uint8_t data[9], undefined;
    uint16_t value;
    int32_t signed_value;
    ds2480_status status;
    if (!raw) return DS2480_ARGUMENT;
    status = ds18b20_ds2480_read(bus, rom, data);
    if (status != DS2480_OK) return status;
    undefined = (uint8_t)(3 - ((data[4] >> 5) & 3));
    value = (uint16_t)((uint16_t)data[0] | ((uint16_t)data[1] << 8));
    value &= (uint16_t)~((1U << undefined) - 1U);
    signed_value = value & 0x8000 ? (int32_t)value - 65536 : (int32_t)value;
    if (signed_value < -55 * 16 || signed_value > 125 * 16) return DS2480_DATA;
    *raw = (int16_t)signed_value;
    return DS2480_OK;
}

ds2480_status ds18b20_ds2480_configure(ds2480 *bus, const uint8_t rom[8],
    int8_t th, int8_t tl, uint8_t resolution, uint8_t save)
{
    uint8_t data[9], config;
    ds2480_status status;
    if (!rom || resolution < 9 || resolution > 12) return DS2480_ARGUMENT;
    config = (uint8_t)(0x1F | ((resolution - 9) << 5));
    status = select_rom(bus, rom);
    if (status != DS2480_OK) return status;
    status = write_byte(bus, 0x4E);
    if (status != DS2480_OK) return status;
    status = write_byte(bus, (uint8_t)th);
    if (status != DS2480_OK) return status;
    status = write_byte(bus, (uint8_t)tl);
    if (status != DS2480_OK) return status;
    status = write_byte(bus, config);
    if (status != DS2480_OK) return status;
    status = ds18b20_ds2480_read(bus, rom, data);
    if (status != DS2480_OK) return status;
    if (data[2] != (uint8_t)th || data[3] != (uint8_t)tl || data[4] != config)
        return DS2480_DATA;
    if (!save) return DS2480_OK;
    status = select_rom(bus, rom);
    if (status != DS2480_OK) return status;
    return ds2480_power_byte(bus, 0x48, 12);
}