ARMSX1/psx/dev/mcd.c

#include "mcd.h"
#include "../log.h"

psx_mcd_t* psx_mcd_create(void) {
    return (psx_mcd_t*)malloc(sizeof(psx_mcd_t));
}

int psx_mcd_init(psx_mcd_t* mcd, const char* path) {
    memset(mcd, 0, sizeof(psx_mcd_t));

    mcd->state = MCD_STATE_TX_HIZ;
    mcd->flag = 0x08;
    mcd->path = path;
    mcd->buf = malloc(MCD_MEMORY_SIZE);
    mcd->tx_data_ready = 0;

    memset(mcd->buf, 0, MCD_MEMORY_SIZE);

    if (!path)
        return 0;

    FILE* file = fopen(path, "rb");

    if (!file)
        return 1;

    if (!fread(mcd->buf, 1, MCD_MEMORY_SIZE, file))
        return 2;

    fclose(file);

    return 0;
}

uint8_t psx_mcd_read(psx_mcd_t* mcd) {
    switch (mcd->state) {
        case MCD_STATE_TX_HIZ: mcd->tx_data = 0xff; break;
        case MCD_STATE_TX_FLG: mcd->tx_data = mcd->flag; mcd->flag = 0x00; break;
        case MCD_STATE_TX_ID1: mcd->tx_data = 0x5a; break;
        case MCD_STATE_TX_ID2: {
            mcd->tx_data_ready = 1;
            mcd->tx_data = 0x5d;

            switch (mcd->mode) {
                case 'R': mcd->state = MCD_R_STATE_RX_MSB; break;
                case 'W': mcd->state = MCD_W_STATE_RX_MSB; break;
                case 'S': mcd->state = MCD_S_STATE_TX_ACK1; break;
            }

            // printf("mcd read %02x\n", mcd->tx_data);

            // log_set_quiet(0);
            // log_fatal("mcd read %02x", mcd->tx_data);
            // log_set_quiet(1);

            return mcd->tx_data;
        } break;

        // Read states
        case MCD_R_STATE_RX_MSB: mcd->tx_data = 0x00; break;
        case MCD_R_STATE_RX_LSB: mcd->tx_data = mcd->msb; break;
        case MCD_R_STATE_TX_ACK1: mcd->tx_data = 0x5c; break;
        case MCD_R_STATE_TX_ACK2: mcd->tx_data = 0x5d; break;
        case MCD_R_STATE_TX_MSB: mcd->tx_data = mcd->msb; mcd->checksum  = mcd->msb; break;
        case MCD_R_STATE_TX_LSB: mcd->tx_data = mcd->lsb; mcd->checksum ^= mcd->lsb;
                                 mcd->pending_bytes = 128; break;
        case MCD_R_STATE_TX_DATA: {
            --mcd->pending_bytes;

            uint8_t data = mcd->buf[mcd->addr++];

            mcd->checksum ^= data;

            if (!mcd->pending_bytes) {
                mcd->tx_data = data;

                break;
            }

            // printf("mcd read %02x\n", data);

            // log_set_quiet(0);
            // log_fatal("mcd read %02x", data);
            // log_set_quiet(1);

            return data;
        } break;
        case MCD_R_STATE_TX_CHK: mcd->tx_data = mcd->checksum; break;
        case MCD_R_STATE_TX_MEB: {
            mcd->tx_data_ready = 0;
            mcd->state = MCD_STATE_TX_HIZ;

            // log_set_quiet(0);
            // log_fatal("mcd read %02x", 'G');
            // log_set_quiet(1);

            // printf("mcd read %02x\n", 'G');

            return 'G';
        } break;

        /* Write states */
        case MCD_W_STATE_RX_MSB: mcd->tx_data = 0x00; break;
        case MCD_W_STATE_RX_LSB: mcd->tx_data = mcd->msb;
                                 mcd->pending_bytes = 127; break;
        case MCD_W_STATE_RX_DATA: {
             --mcd->pending_bytes;

            mcd->buf[mcd->addr++] = mcd->rx_data;

            if (!mcd->pending_bytes) {
                mcd->tx_data = mcd->rx_data;

                break;
            }

            // printf("mcd read %02x\n", mcd->rx_data);

            // log_set_quiet(0);
            // log_fatal("mcd read %02x", mcd->rx_data);
            // log_set_quiet(1);

            return mcd->rx_data;
        } break;
        case MCD_W_STATE_RX_CHK: mcd->tx_data = mcd->rx_data; break;
        case MCD_W_STATE_TX_ACK1: mcd->tx_data = 0x5c; break;
        case MCD_W_STATE_TX_ACK2: mcd->tx_data = 0x5d; break;
        case MCD_W_STATE_TX_MEB: {
            mcd->tx_data_ready = 0;
            mcd->state = MCD_STATE_TX_HIZ;

            // log_set_quiet(0);
            // log_fatal("mcd read %02x", 'G');
            // log_set_quiet(1);

            // printf("mcd read %02x\n", 'G');

            return 'G';
        } break;
    }

    mcd->tx_data_ready = 1;
    mcd->state++;

    // log_set_quiet(0);
    // log_fatal("mcd read %02x", mcd->tx_data);
    // log_set_quiet(1);

    // printf("mcd read %02x\n", mcd->tx_data);

    return mcd->tx_data;
}

void psx_mcd_write(psx_mcd_t* mcd, uint8_t data) {
    // log_set_quiet(0);
    // log_fatal("mcd write %02x", data);
    // log_set_quiet(1);

    printf("mcd write %02x\n", data);

    switch (mcd->state) {
        case MCD_STATE_TX_FLG: mcd->mode = data; break;
        case MCD_R_STATE_RX_MSB: mcd->msb = data; break;
        case MCD_R_STATE_RX_LSB: {
            mcd->lsb = data;
            mcd->addr = ((mcd->msb << 8) | mcd->lsb) << 7;
        } break;
        case MCD_W_STATE_RX_MSB: mcd->msb = data; break;
        case MCD_W_STATE_RX_LSB: {
            mcd->lsb = data;
            mcd->addr = ((mcd->msb << 8) | mcd->lsb) << 7;
        } break;
        case MCD_W_STATE_RX_DATA: mcd->rx_data = data; break;
        case MCD_W_STATE_RX_CHK: /* Don't care */ break;
    }
}

int psx_mcd_query(psx_mcd_t* mcd) {
    return mcd->tx_data_ready;
}

void psx_mcd_reset(psx_mcd_t* mcd) {
    mcd->state = MCD_STATE_TX_HIZ;
}

void psx_mcd_destroy(psx_mcd_t* mcd) {
    FILE* file = fopen(mcd->path, "wb");

    fwrite(mcd->buf, 1, MCD_MEMORY_SIZE, file);
    fclose(file);

    free(mcd->buf);
    free(mcd);
}