/******************************************************************************
 *
 * Copyright (C) 2022-2023 Maxim Integrated Products, Inc. (now owned by 
 * Analog Devices, Inc.),
 * Copyright (C) 2023-2024 Analog Devices, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 ******************************************************************************/

/* **** Includes **** */
#include <string.h>
#include "mxc_assert.h"
#include "mxc_sys.h"
#include "owm_reva.h"

/* **** Definitions **** */
#define MXC_OWM_CLK_FREQ 1000000 //1-Wire requires 1MHz clock

/* **** Globals **** */
static int LastDiscrepancy;
static int LastDeviceFlag;

/* **** Functions **** */
static uint8_t CalculateCRC8(uint8_t *data, int len);
static uint8_t update_crc8(uint8_t crc, uint8_t value);

/* ************************************************************************* */
int MXC_OWM_RevA_Init(mxc_owm_reva_regs_t *owm, const mxc_owm_cfg_t *cfg)
{
    uint32_t ext_pu_en = 0;

    // Select the PU mode and polarity based on cfg input
    switch (cfg->ext_pu_mode) {
    case MXC_OWM_EXT_PU_ACT_HIGH:
        ext_pu_en = 1; // EXT_PULLUP_MODE_USED;
        break;

    case MXC_OWM_EXT_PU_ACT_LOW:
        ext_pu_en = 1; // EXT_PULLUP_MODE_USED;
        break;

    case MXC_OWM_EXT_PU_UNUSED:
        ext_pu_en = 0; // EXT_PULLUP_MODE_UNUSED;
        break;

    default:
        return E_BAD_PARAM;
    }

    // Set owm internal clock divider
    MXC_OWM_SystemClockUpdated();

    // Set configuration
    owm->cfg = (((cfg->int_pu_en << MXC_F_OWM_REVA_CFG_INT_PULLUP_ENABLE_POS) &
                 MXC_F_OWM_REVA_CFG_INT_PULLUP_ENABLE) |
                ((ext_pu_en << MXC_F_OWM_REVA_CFG_EXT_PULLUP_ENABLE_POS) &
                 MXC_F_OWM_REVA_CFG_EXT_PULLUP_ENABLE) |
                ((cfg->long_line_mode << MXC_F_OWM_REVA_CFG_LONG_LINE_MODE_POS) &
                 MXC_F_OWM_REVA_CFG_LONG_LINE_MODE));

    // If external pullup is enabled, set the mode
    if (ext_pu_en) {
        MXC_SETFIELD(owm->cfg, MXC_F_OWM_REVA_CFG_EXT_PULLUP_MODE,
                     cfg->ext_pu_mode << MXC_F_OWM_REVA_CFG_EXT_PULLUP_MODE_POS);
    }

    // Clear all interrupt flags
    owm->intfl = owm->intfl;

    return E_NO_ERROR;
}

/* ************************************************************************* */
void MXC_OWM_RevA_Shutdown(mxc_owm_reva_regs_t *owm)
{
    // Disable and clear interrupts
    owm->inten = 0;
    owm->intfl = owm->intfl;
}

/* ************************************************************************* */
int MXC_OWM_RevA_Reset(mxc_owm_reva_regs_t *owm)
{
    owm->intfl = MXC_F_OWM_REVA_INTFL_OW_RESET_DONE; // Clear the reset flag
    owm->ctrl_stat |= MXC_F_OWM_REVA_CTRL_STAT_START_OW_RESET; // Generate a reset pulse

    while ((owm->intfl & MXC_F_OWM_REVA_INTFL_OW_RESET_DONE) == 0) {}
    // Wait for reset time slot to complete

    return MXC_OWM_GetPresenceDetect(); // Return presence pulse detect status
}

/* ************************************************************************* */
int MXC_OWM_RevA_TouchByte(mxc_owm_reva_regs_t *owm, uint8_t data)
{
    owm->cfg &= ~MXC_F_OWM_REVA_CFG_SINGLE_BIT_MODE; // Set to 8 bit mode
    owm->intfl = (MXC_F_OWM_REVA_INTFL_TX_DATA_EMPTY | MXC_F_OWM_REVA_INTEN_LINE_SHORT |
                  MXC_F_OWM_REVA_INTFL_RX_DATA_READY); // Clear the flags
    owm->data = (data << MXC_F_OWM_REVA_DATA_TX_RX_POS) & MXC_F_OWM_REVA_DATA_TX_RX; // Write data

    while ((owm->intfl & MXC_F_OWM_REVA_INTFL_TX_DATA_EMPTY) == 0) {}
    // Wait for data to be sent

    while ((owm->intfl & MXC_F_OWM_REVA_INTFL_RX_DATA_READY) == 0) {}
    // Wait for data to be read

    // Check error flag
    if (owm->intfl & MXC_F_OWM_REVA_INTEN_LINE_SHORT) {
        return E_COMM_ERR; // Wire was low before transaction
    }

    return (owm->data >> MXC_F_OWM_REVA_DATA_TX_RX_POS) & 0xFF; // Return the data read
}

/* ************************************************************************* */
int MXC_OWM_RevA_WriteByte(uint8_t data)
{
    // Send one byte of data and verify the data sent = data parameter
    return (MXC_OWM_TouchByte(data) == data) ? E_NO_ERROR : E_COMM_ERR;
}

/* ************************************************************************* */
int MXC_OWM_RevA_ReadByte(void)
{
    // Read one byte of data
    return MXC_OWM_TouchByte(0xFF);
}

/* ************************************************************************* */
int MXC_OWM_RevA_TouchBit(mxc_owm_reva_regs_t *owm, uint8_t bit)
{
    owm->cfg |= MXC_F_OWM_REVA_CFG_SINGLE_BIT_MODE; // Set to 1 bit mode
    owm->intfl = (MXC_F_OWM_REVA_INTFL_TX_DATA_EMPTY | MXC_F_OWM_REVA_INTEN_LINE_SHORT |
                  MXC_F_OWM_REVA_INTFL_RX_DATA_READY); // Clear the flags
    owm->data = (bit << MXC_F_OWM_REVA_DATA_TX_RX_POS) & MXC_F_OWM_REVA_DATA_TX_RX; // Write data

    while ((owm->intfl & MXC_F_OWM_REVA_INTFL_TX_DATA_EMPTY) == 0) {}
    // Wait for data to be sent

    while ((owm->intfl & MXC_F_OWM_REVA_INTFL_RX_DATA_READY) == 0) {}
    // Wait for data to be read

    // Check error flag
    if (owm->intfl & MXC_F_OWM_REVA_INTEN_LINE_SHORT) {
        return E_COMM_ERR; // Wire was low before transaction
    }

    return (owm->data >> MXC_F_OWM_REVA_DATA_TX_RX_POS) & 0x1; // Return the bit read
}

/* ************************************************************************* */
int MXC_OWM_RevA_WriteBit(uint8_t bit)
{
    // Send a bit and verify the bit sent = bit parameter
    return (MXC_OWM_TouchBit(bit) == bit) ? E_NO_ERROR : E_COMM_ERR;
}

/* ************************************************************************* */
int MXC_OWM_RevA_ReadBit(void)
{
    // Read a bit
    return MXC_OWM_TouchBit(1);
}

/* ************************************************************************* */
int MXC_OWM_RevA_Write(mxc_owm_reva_regs_t *owm, uint8_t *data, int len)
{
    int num = 0;

    owm->cfg &= ~MXC_F_OWM_REVA_CFG_SINGLE_BIT_MODE; // Set to 8 bit mode

    while (num < len) { // Loop for number of bytes to write
        if (MXC_OWM_WriteByte(data[num]) != E_NO_ERROR) {
            return E_COMM_ERR;
        }

        num++; // Keep track of how many bytes written
    }

    return num; // Return number of bytes written
}

/* ************************************************************************* */
int MXC_OWM_RevA_Read(mxc_owm_reva_regs_t *owm, uint8_t *data, int len)
{
    int num = 0;

    owm->cfg &= ~MXC_F_OWM_REVA_CFG_SINGLE_BIT_MODE; // Set to 8 bit mode

    while (num < len) { // Loop for number of bytes to read
        // Store read data into buffer
        data[num] = MXC_OWM_ReadByte();

        num++; // Keep track of how many bytes read
    }

    return num; // Return number of bytes read
}

/* ************************************************************************* */
int MXC_OWM_RevA_ReadROM(uint8_t *ROMCode)
{
    int num_read;

    // Send reset and wait for presence pulse
    if (MXC_OWM_Reset()) {
        // Send Read ROM command code
        if (MXC_OWM_WriteByte(READ_ROM_COMMAND) == E_NO_ERROR) {
            // Read 8 bytes and store in buffer
            num_read = MXC_OWM_Read(ROMCode, 8);

            // Check the number of bytes read
            if (num_read != 8) {
                return E_COMM_ERR;
            }
        } else {
            // Write failed
            return E_COMM_ERR;
        }
    } else {
        // No presence pulse
        return E_COMM_ERR;
    }

    return E_NO_ERROR;
}

/* ************************************************************************* */
int MXC_OWM_RevA_MatchROM(uint8_t *ROMCode)
{
    int num_wrote;

    // Send reset and wait for presence pulse
    if (MXC_OWM_Reset()) {
        // Send match ROM command code
        if (MXC_OWM_WriteByte(MATCH_ROM_COMMAND) == E_NO_ERROR) {
            // Write 8 bytes in ROMCode buffer
            num_wrote = MXC_OWM_Write(ROMCode, 8);

            // Check the number of bytes written
            if (num_wrote != 8) {
                return E_COMM_ERR;
            }
        } else {
            // Write failed
            return E_COMM_ERR;
        }
    } else {
        // No presence pulse
        return E_COMM_ERR;
    }

    return E_NO_ERROR;
}

/* ************************************************************************* */
int MXC_OWM_RevA_ODMatchROM(mxc_owm_reva_regs_t *owm, uint8_t *ROMCode)
{
    int num_wrote;

    // Set to standard speed
    owm->cfg &= ~(MXC_F_OWM_REVA_CFG_OVERDRIVE);

    // Send reset and wait for presence pulse
    if (MXC_OWM_Reset()) {
        // Send Overdrive match ROM command code
        if (MXC_OWM_WriteByte(OD_MATCH_ROM_COMMAND) == E_NO_ERROR) {
            // Set overdrive
            owm->cfg |= MXC_F_OWM_REVA_CFG_OVERDRIVE;

            // Write 8 bytes in ROMCode buffer
            num_wrote = MXC_OWM_Write(ROMCode, 8);

            // Check the number of bytes written
            if (num_wrote != 8) {
                return E_COMM_ERR;
            }
        } else {
            // Write failed
            return E_COMM_ERR;
        }
    } else {
        // No presence pulse
        return E_COMM_ERR;
    }

    return E_NO_ERROR;
}

/* ************************************************************************* */
int MXC_OWM_RevA_SkipROM(void)
{
    // Send reset and wait for presence pulse
    if (MXC_OWM_Reset()) {
        // Send skip ROM command code
        return MXC_OWM_WriteByte(SKIP_ROM_COMMAND);
    } else {
        // No presence pulse
        return E_COMM_ERR;
    }
}

/* ************************************************************************* */
int MXC_OWM_RevA_ODSkipROM(mxc_owm_reva_regs_t *owm)
{
    // Set to standard speed
    owm->cfg &= ~(MXC_F_OWM_REVA_CFG_OVERDRIVE);

    // Send reset and wait for presence pulse
    if (MXC_OWM_Reset()) {
        // Send Overdrive skip ROM command code
        if (MXC_OWM_WriteByte(OD_SKIP_ROM_COMMAND) == E_NO_ERROR) {
            // Set overdrive speed
            owm->cfg |= MXC_F_OWM_REVA_CFG_OVERDRIVE;

            return E_NO_ERROR;
        } else {
            // Write failed
            return E_COMM_ERR;
        }
    } else {
        // No presence pulse
        return E_COMM_ERR;
    }
}

/* ************************************************************************* */
int MXC_OWM_RevA_Resume(void)
{
    // Send reset and wait for presence pulse
    if (MXC_OWM_Reset()) {
        // Send resume command code
        return MXC_OWM_WriteByte(RESUME_COMMAND);
    } else {
        // No presence pulse
        return E_COMM_ERR;
    }
}

/* ************************************************************************* */
int MXC_OWM_RevA_SearchROM(mxc_owm_reva_regs_t *owm, int newSearch, uint8_t *ROMCode)
{
    int nibble_start_bit = 1;
    int rom_byte_number = 0;
    uint8_t rom_nibble_mask = 0x0F;
    uint8_t search_direction;
    int readValue;
    int sentBits;
    int discrepancy;
    int bit_position;
    int discrepancy_mask;
    int last_zero = 0;
    uint8_t crc8;
    int search_result = 0;

    // Clear ROM array
    memset(ROMCode, 0x0, 8);

    if (newSearch) {
        // Reset all global variables to start search from beginning
        LastDiscrepancy = 0;
        LastDeviceFlag = 0;
    }

    // Check if the last call was the last device
    if (LastDeviceFlag) {
        // Reset the search
        LastDiscrepancy = 0;
        LastDeviceFlag = 0;
        return search_result;
    }

    // Send reset and wait for presence pulse
    if (MXC_OWM_Reset()) {
        // Send the search command
        MXC_OWM_WriteByte(SEARCH_ROM_COMMAND);

        // Set search ROM accelerator bit
        owm->ctrl_stat |= MXC_F_OWM_REVA_CTRL_STAT_SRA_MODE;

        // Loop through all ROM bytes 0-7(this loops 2 times per byte)
        while (rom_byte_number < 8) {
            // Each loop finds the discrepancy bits and finds 4 bits(nibble) of the ROM

            // Set the search direction the same as last time for the nibble masked
            search_direction = ROMCode[rom_byte_number] & rom_nibble_mask;

            // If the upper nibble is the mask then shift bits to lower nibble
            if (rom_nibble_mask > 0x0F) {
                search_direction = search_direction >> 4;
            }

            // Get the last discrepancy bit position relative to the nibble start bit
            bit_position = LastDiscrepancy - nibble_start_bit;

            // Check if last discrepancy is within this nibble
            if ((bit_position >= 0) && (bit_position < 4)) {
                // Last discrepancy is within this nibble
                // Set the bit of the last discrepancy bit
                search_direction |= (1 << (bit_position));
            }

            // Performs two read bits and a write bit for 4 bits of the ROM
            readValue = MXC_OWM_TouchByte(search_direction);
            // Get discrepancy flags
            discrepancy = readValue & 0xF;
            // Get the 4 bits sent to select the ROM
            sentBits = (readValue >> 4) & 0xF;

            // Store the bit location of the MSB discrepancy with sentbit = 0
            if (discrepancy) {
                // Initialize bit_position to MSB of nibble
                bit_position = 3;

                while (bit_position >= 0) {
                    // Get discrepancy flag of the current bit position
                    discrepancy_mask = discrepancy & (1 << bit_position);

                    // If there is a discrepancy and the sent bit is 0 save this bit position
                    if ((discrepancy_mask) && !(sentBits & discrepancy_mask)) {
                        last_zero = nibble_start_bit + bit_position;
                        break;
                    }

                    bit_position--;
                }
            }

            // Clear the nibble
            ROMCode[rom_byte_number] &= ~rom_nibble_mask;

            // Store the sentBits in the ROMCode
            if (rom_nibble_mask > 0x0F) {
                ROMCode[rom_byte_number] |= (sentBits << 4);
            } else {
                ROMCode[rom_byte_number] |= sentBits;
            }

            // Increment the nibble start bit and shift mask
            nibble_start_bit += 4;
            rom_nibble_mask <<= 4;

            // If the mask is 0 then go to new ROM byte rom_byte_number and reset mask
            if (rom_nibble_mask == 0) {
                rom_byte_number++;
                rom_nibble_mask = 0x0F;
            }
        } // End while(rom_byte_number < 8)

        // Clear search ROM accelerator
        owm->ctrl_stat &= ~(MXC_F_OWM_REVA_CTRL_STAT_SRA_MODE);

        // Calculate CRC to verify ROM code is correct
        crc8 = CalculateCRC8(ROMCode, 7);

        // If the search was successful then
        if ((nibble_start_bit >= 65) && (crc8 == ROMCode[7])) {
            // Search successful so set LastDiscrepancy,LastDeviceFlag,search_result
            LastDiscrepancy = last_zero;

            // Check for last device
            if (LastDiscrepancy == 0) {
                LastDeviceFlag = 1;
            }

            search_result = 1;
        }
    } // End if(MXC_OWM_Reset)

    // If no device found then reset counters so next 'search' will be like a first
    if (!search_result || !ROMCode[0]) {
        LastDiscrepancy = 0;
        LastDeviceFlag = 0;
        search_result = 0;
    }

    return search_result;
}

/* ************************************************************************* */
void MXC_OWM_RevA_ClearFlags(mxc_owm_reva_regs_t *owm, uint32_t mask)
{
    owm->intfl = mask;
}

/* ************************************************************************* */
unsigned MXC_OWM_RevA_GetFlags(mxc_owm_reva_regs_t *owm)
{
    return (owm->intfl);
}

/* ************************************************************************* */
void MXC_OWM_RevA_SetExtPullup(mxc_owm_reva_regs_t *owm, int enable)
{
    if (enable) {
        owm->cfg |= MXC_F_OWM_REVA_CFG_EXT_PULLUP_ENABLE;
    } else {
        owm->cfg &= ~(MXC_F_OWM_REVA_CFG_EXT_PULLUP_ENABLE);
    }
}

/* ************************************************************************* */
void MXC_OWM_RevA_SetOverdrive(mxc_owm_reva_regs_t *owm, int enable)
{
    if (enable) {
        owm->cfg |= MXC_F_OWM_REVA_CFG_OVERDRIVE;
    } else {
        owm->cfg &= ~(MXC_F_OWM_REVA_CFG_OVERDRIVE);
    }
}

/* ************************************************************************* */
void MXC_OWM_RevA_EnableInt(mxc_owm_reva_regs_t *owm, int flags)
{
    owm->inten |= flags;
}

/* ************************************************************************* */
void MXC_OWM_RevA_DisableInt(mxc_owm_reva_regs_t *owm, int flags)
{
    owm->inten &= ~flags;
}

/* ************************************************************************* */
int MXC_OWM_RevA_SetForcePresenceDetect(mxc_owm_reva_regs_t *owm, int enable)
{
    MXC_SETFIELD(owm->cfg, MXC_F_OWM_REVA_CFG_FORCE_PRES_DET,
                 enable << MXC_F_OWM_REVA_CFG_FORCE_PRES_DET_POS);
    return E_NO_ERROR;
}

/* ************************************************************************* */
int MXC_OWM_RevA_SetInternalPullup(mxc_owm_reva_regs_t *owm, int enable)
{
    MXC_SETFIELD(owm->cfg, MXC_F_OWM_REVA_CFG_INT_PULLUP_ENABLE,
                 enable << MXC_F_OWM_REVA_CFG_INT_PULLUP_ENABLE_POS);
    return E_NO_ERROR;
}

/* ************************************************************************* */
int MXC_OWM_RevA_SetExternalPullup(mxc_owm_reva_regs_t *owm, mxc_owm_ext_pu_t ext_pu_mode)
{
    switch (ext_pu_mode) {
    case MXC_OWM_EXT_PU_ACT_HIGH:
        owm->cfg |= MXC_F_OWM_REVA_CFG_EXT_PULLUP_ENABLE;
        owm->cfg &= ~MXC_F_OWM_REVA_CFG_EXT_PULLUP_MODE;
        break;

    case MXC_OWM_EXT_PU_ACT_LOW:
        owm->cfg &= ~MXC_F_OWM_REVA_CFG_EXT_PULLUP_ENABLE;
        owm->cfg &= ~MXC_F_OWM_REVA_CFG_EXT_PULLUP_MODE;
        break;

    case MXC_OWM_EXT_PU_UNUSED:
        owm->cfg &= ~MXC_F_OWM_REVA_CFG_EXT_PULLUP_ENABLE;
        owm->cfg |= MXC_F_OWM_REVA_CFG_EXT_PULLUP_MODE;
        break;
    }

    return E_NO_ERROR;
}

/* ************************************************************************* */
int MXC_OWM_RevA_SystemClockUpdated(mxc_owm_reva_regs_t *owm)
{
    uint32_t mxc_owm_clk, clk_div = 0;

    // Configure clk divisor to get 1MHz OWM clk
    mxc_owm_clk = PeripheralClock;

    if (mxc_owm_clk == 0) {
        return E_UNINITIALIZED;
    }

    // Return error if clk doesn't divide evenly to 1MHz
    if (mxc_owm_clk % MXC_OWM_CLK_FREQ) {
        return E_NOT_SUPPORTED;
    }

    clk_div = (mxc_owm_clk / (MXC_OWM_CLK_FREQ));

    // Can not support lower frequencies
    if (clk_div == 0) {
        return E_NOT_SUPPORTED;
    }

    // Set clk divisor
    owm->clk_div_1us = (clk_div << MXC_F_OWM_REVA_CLK_DIV_1US_DIVISOR_POS) &
                       MXC_F_OWM_REVA_CLK_DIV_1US_DIVISOR;

    return E_NO_ERROR;
}

/* ************************************************************************ */
int MXC_OWM_RevA_SetSearchROMAccelerator(mxc_owm_reva_regs_t *owm, int enable)
{
    MXC_SETFIELD(owm->ctrl_stat, MXC_F_OWM_REVA_CTRL_STAT_SRA_MODE,
                 enable << MXC_F_OWM_REVA_CTRL_STAT_SRA_MODE_POS);
    return E_NO_ERROR;
}

/* ************************************************************************* */
int MXC_OWM_RevA_BitBang_Init(mxc_owm_reva_regs_t *owm, int initialState)
{
    owm->cfg |= MXC_F_OWM_REVA_CFG_BIT_BANG_EN;

    MXC_SETFIELD(owm->ctrl_stat, MXC_F_OWM_REVA_CTRL_STAT_BIT_BANG_OE,
                 initialState << MXC_F_OWM_REVA_CTRL_STAT_BIT_BANG_OE_POS);

    return E_NO_ERROR;
}

/* ************************************************************************* */
int MXC_OWM_RevA_BitBang_Read(mxc_owm_reva_regs_t *owm)
{
    return !!(owm->ctrl_stat & MXC_F_OWM_REVA_CTRL_STAT_BIT_BANG_OE);
}

/* ************************************************************************* */
int MXC_OWM_RevA_BitBang_Write(mxc_owm_reva_regs_t *owm, int state)
{
    MXC_SETFIELD(owm->ctrl_stat, MXC_F_OWM_REVA_CTRL_STAT_BIT_BANG_OE,
                 state << MXC_F_OWM_REVA_CTRL_STAT_BIT_BANG_OE_POS);
    return E_NO_ERROR;
}

/* ************************************************************************* */
int MXC_OWM_RevA_BitBang_Disable(mxc_owm_reva_regs_t *owm)
{
    owm->cfg &= ~MXC_F_OWM_REVA_CFG_BIT_BANG_EN;
    return E_NO_ERROR;
}

/* ************************************************************************* */
static uint8_t CalculateCRC8(uint8_t *data, int len)
{
    int i;
    uint8_t crc = 0;

    for (i = 0; i < len; i++) {
        crc = update_crc8(crc, data[i]);
    }

    return crc;
}

/* ************************************************************************* */
static uint8_t update_crc8(uint8_t crc, uint8_t val)
{
    uint8_t inc, tmp;

    for (inc = 0; inc < 8; inc++) {
        tmp = (uint8_t)(crc << 7); // Save X7 bit value
        crc >>= 1; // Shift crc

        if (((tmp >> 7) ^ (val & 0x01)) == 1) { // If X7 xor X8(input data)
            crc ^= 0x8c; // XOR crc with X4 and X5, X1 = X7^X8
            crc |= 0x80; // Carry
        }

        val >>= 1;
    }

    return crc;
}