SystemK/Protocols/Dynasty.c

/*
 * This program source code file is part of SystemK, a library in the KTag project.
 *
 * 🛡️ <https://ktag.clubk.club> 🃞
 *
 * Copyright © 2016-2025 Joseph P. Kearney and the KTag developers.
 *
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU Affero General Public License as published by the Free
 * Software Foundation, either version 3 of the License, or (at your option) any
 * later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more
 * details.
 *
 * There should be a copy of the GNU Affero General Public License in the LICENSE
 * file in the root of this repository.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdbool.h>
#include <stdio.h>

#include "SystemK.h"

#define DYNASTY_BLUE_TEAM 0x01
#define DYNASTY_RED_TEAM 0x02
#define DYNASTY_GREEN_TEAM 0x03
#define DYNASTY_WHITE_TEAM 0x04

#define DYNASTY_HEADER_MARK_DURATION_IN_us 1700
#define DYNASTY_ZERO_DURATION_IN_us 450
#define DYNASTY_ONE_DURATION_IN_us 800
#define DYNASTY_TOLERANCE_IN_us 150

#define MIN_ZERO_IN_us (DYNASTY_ZERO_DURATION_IN_us - DYNASTY_TOLERANCE_IN_us)
#define MAX_ZERO_IN_us (DYNASTY_ZERO_DURATION_IN_us + DYNASTY_TOLERANCE_IN_us)
#define MIN_ONE_IN_us (DYNASTY_ONE_DURATION_IN_us - DYNASTY_TOLERANCE_IN_us)
#define MAX_ONE_IN_us (DYNASTY_ONE_DURATION_IN_us + DYNASTY_TOLERANCE_IN_us)

static const TimedBit_T DYNASTY_HEADER_MARK = {.symbol = MARK, .duration = DYNASTY_HEADER_MARK_DURATION_IN_us};
static const TimedBit_T DYNASTY_ZERO_SPACE = {.symbol = SPACE, .duration = DYNASTY_ZERO_DURATION_IN_us};
static const TimedBit_T DYNASTY_ONE_SPACE = {.symbol = SPACE, .duration = DYNASTY_ONE_DURATION_IN_us};
static const TimedBit_T DYNASTY_ZERO_MARK = {.symbol = MARK, .duration = DYNASTY_ZERO_DURATION_IN_us};
static const TimedBit_T DYNASTY_ONE_MARK = {.symbol = MARK, .duration = DYNASTY_ONE_DURATION_IN_us};
static const TimedBit_T DYNASTY_END = {.symbol = SPACE, .duration = LAST_PULSE};

static TimedPulseTrain_T Tag_Send_Buffer;
static DecodedPacket_T Dynasty_Tag_Received_Buffers[3] =
    {
        {.Tag.type = DECODED_PACKET_TYPE_BUFFER_FREE},
        {.Tag.type = DECODED_PACKET_TYPE_BUFFER_FREE},
        {.Tag.type = DECODED_PACKET_TYPE_BUFFER_FREE}};

static inline DecodedPacket_T *Get_Tag_Packet_Buffer(void)
{
    if (Dynasty_Tag_Received_Buffers[0].Tag.type == DECODED_PACKET_TYPE_BUFFER_FREE)
    {
        return &Dynasty_Tag_Received_Buffers[0];
    }
    else if (Dynasty_Tag_Received_Buffers[1].Tag.type == DECODED_PACKET_TYPE_BUFFER_FREE)
    {
        return &Dynasty_Tag_Received_Buffers[1];
    }
    else
    {
        // Just use it.
        return &Dynasty_Tag_Received_Buffers[2];
    }
}

static inline uint8_t Calculate_Checksum(uint32_t data)
{
    uint8_t result = 0;

    // uint8_t byte_1 = (uint8_t)((data >> 8) & 0xFF);
    // uint8_t byte_0 = (uint8_t)(data & 0xFF);

    // TODO: Finish implementing the Dynasty checksum.

    return result;
}

static inline void PackPulseTrain(TimedPulseTrain_T *pulsetrain, uint32_t data)
{
    pulsetrain->bitstream[0] = DYNASTY_HEADER_MARK;

    for (uint8_t n = 0; n < 16; n++)
    {
        if ((data & 0x0001) == 0x0001)
        {
            pulsetrain->bitstream[1 + (n * 2)] = DYNASTY_ONE_SPACE;
        }
        else
        {
            pulsetrain->bitstream[1 + (n * 2)] = DYNASTY_ZERO_SPACE;
        }
        data = data >> 1;
        if ((data & 0x0001) == 0x0001)
        {
            pulsetrain->bitstream[1 + (n * 2)] = DYNASTY_ONE_MARK;
        }
        else
        {
            pulsetrain->bitstream[1 + (n * 2)] = DYNASTY_ZERO_MARK;
        }
        data = data >> 1;
    }

    // TODO: Append the Dynasty checksum.

    pulsetrain->bitstream[(2 * 20) - 1] = DYNASTY_END;
}

TimedPulseTrain_T *DYNASTY_EncodePacket(TagPacket_T *packet)
{
    uint16_t packed_data = 0;

    PackPulseTrain(&Tag_Send_Buffer, packed_data);

    return &Tag_Send_Buffer;
}

DecodedPacket_T *DYNASTY_MaybeDecodePacket(TimedPulseTrain_T *packet)
{
    // Some implementations (ESP32) do not report odd numbers of pulses.
    if ((packet->count != 41) && (packet->count != 42))
    {
        // Fail fast!
        return NULL;
    }
    else
    {
        // Convert pulse durations to bits.
        // packet->bitstream[0] is the header mark--ignore it.

        uint32_t data = 0;
        for (uint8_t n = 0; n < 32; n++)
        {
            if ((packet->bitstream[n + 1].duration > MIN_ONE_IN_us) && (packet->bitstream[n + 1].duration < MAX_ONE_IN_us))
            {
                // One
                data |= ((uint32_t)1 << (31 - n));
            }
            else if ((packet->bitstream[n + 1].duration > MIN_ZERO_IN_us) && (packet->bitstream[n + 1].duration < MAX_ZERO_IN_us))
            {
                // Zero--nothing to do.
            }
            else
            {
                // This mark is neither a zero or a one; abort.
                return NULL;
            }
        }

        uint8_t checksum = 0;
        for (uint8_t n = 0; n < 8; n++)
        {
            if ((packet->bitstream[n + 33].duration > MIN_ONE_IN_us) && (packet->bitstream[n + 33].duration < MAX_ONE_IN_us))
            {
                // One
                checksum |= ((uint8_t)1 << (7 - n));
            }
            else if ((packet->bitstream[n + 33].duration > MIN_ZERO_IN_us) && (packet->bitstream[n + 33].duration < MAX_ZERO_IN_us))
            {
                // Zero--nothing to do.
            }
            else
            {
                // This mark is neither a zero or a one; abort.
                return NULL;
            }
        }

        DecodedPacket_T *Tag_Rx_Buffer = Get_Tag_Packet_Buffer();
        Tag_Rx_Buffer->Tag.type = DECODED_PACKET_TYPE_TAG_RECEIVED;
        Tag_Rx_Buffer->Tag.protocol = DYNASTY_PROTOCOL;
        Tag_Rx_Buffer->Tag.player_ID = 0;
        Tag_Rx_Buffer->Tag.team_ID = DYNASTY_RED_TEAM;
        Tag_Rx_Buffer->Tag.damage = 10;
        Tag_Rx_Buffer->Tag.color = COLOR_RED;
        return Tag_Rx_Buffer;
    }
}

color_t DYNASTY_GetTeamColor(uint8_t team_ID)
{
    color_t result = COLOR_RED;

    if (team_ID == DYNASTY_RED_TEAM)
    {
        result = COLOR_RED;
    }
    else if (team_ID == DYNASTY_BLUE_TEAM)
    {
        result = COLOR_BLUE;
    }
    else if (team_ID == DYNASTY_GREEN_TEAM)
    {
        result = COLOR_GREEN;
    }
    else if (team_ID == DYNASTY_WHITE_TEAM)
    {
        result = COLOR_WHITE;
    }
    else
    {
        // Nothing to do.
    }

    return result;
}