shithub: psxe

ref: ccc90b4d065c3e2287161bc679109f7aa7816c10
dir: /psx/dev/cdrom/cdrom.c/

#include <string.h>
#include <assert.h>
#include <stdlib.h>
#include <stdio.h>

#include "cdrom.h"

typedef void (*cdrom_cmd_func)(psx_cdrom_t* cdrom);

void cdrom_cmd_getstat(psx_cdrom_t* cdrom);
void cdrom_cmd_setloc(psx_cdrom_t* cdrom);
void cdrom_cmd_play(psx_cdrom_t* cdrom);
void cdrom_cmd_forward(psx_cdrom_t* cdrom);
void cdrom_cmd_backward(psx_cdrom_t* cdrom);
void cdrom_cmd_readn(psx_cdrom_t* cdrom);
void cdrom_cmd_motoron(psx_cdrom_t* cdrom);
void cdrom_cmd_stop(psx_cdrom_t* cdrom);
void cdrom_cmd_pause(psx_cdrom_t* cdrom);
void cdrom_cmd_init(psx_cdrom_t* cdrom);
void cdrom_cmd_mute(psx_cdrom_t* cdrom);
void cdrom_cmd_demute(psx_cdrom_t* cdrom);
void cdrom_cmd_setfilter(psx_cdrom_t* cdrom);
void cdrom_cmd_setmode(psx_cdrom_t* cdrom);
void cdrom_cmd_getparam(psx_cdrom_t* cdrom);
void cdrom_cmd_getlocl(psx_cdrom_t* cdrom);
void cdrom_cmd_getlocp(psx_cdrom_t* cdrom);
void cdrom_cmd_setsession(psx_cdrom_t* cdrom);
void cdrom_cmd_gettn(psx_cdrom_t* cdrom);
void cdrom_cmd_gettd(psx_cdrom_t* cdrom);
void cdrom_cmd_seekl(psx_cdrom_t* cdrom);
void cdrom_cmd_seekp(psx_cdrom_t* cdrom);
void cdrom_cmd_test(psx_cdrom_t* cdrom);
void cdrom_cmd_getid(psx_cdrom_t* cdrom);
void cdrom_cmd_reads(psx_cdrom_t* cdrom);
void cdrom_cmd_reset(psx_cdrom_t* cdrom);
void cdrom_cmd_getq(psx_cdrom_t* cdrom);
void cdrom_cmd_readtoc(psx_cdrom_t* cdrom);
void cdrom_cmd_videocd(psx_cdrom_t* cdrom);

cdrom_cmd_func cdrom_cmd_table[] = {
    (cdrom_cmd_func)0,
    cdrom_cmd_getstat,
    cdrom_cmd_setloc,
    cdrom_cmd_play,
    cdrom_cmd_forward,
    cdrom_cmd_backward,
    cdrom_cmd_readn,
    cdrom_cmd_motoron,
    cdrom_cmd_stop,
    cdrom_cmd_pause,
    cdrom_cmd_init,
    cdrom_cmd_mute,
    cdrom_cmd_demute,
    cdrom_cmd_setfilter,
    cdrom_cmd_setmode,
    cdrom_cmd_getparam,
    cdrom_cmd_getlocl,
    cdrom_cmd_getlocp,
    cdrom_cmd_setsession,
    cdrom_cmd_gettn,
    cdrom_cmd_gettd,
    cdrom_cmd_seekl,
    cdrom_cmd_seekp,
    (cdrom_cmd_func)0,
    (cdrom_cmd_func)0,
    cdrom_cmd_test,
    cdrom_cmd_getid,
    cdrom_cmd_reads,
    cdrom_cmd_reset,
    cdrom_cmd_getq,
    cdrom_cmd_readtoc,
    cdrom_cmd_videocd
};

static const char* cdrom_cmd_names[] = {
    "<unimplemented>",
    "CdlGetstat",
    "CdlSetloc",
    "CdlPlay",
    "CdlForward",
    "CdlBackward",
    "CdlReadn",
    "CdlMotoron",
    "CdlStop",
    "CdlPause",
    "CdlInit",
    "CdlMute",
    "CdlDemute",
    "CdlSetfilter",
    "CdlSetmode",
    "CdlGetparam",
    "CdlGetlocl",
    "CdlGetlocp",
    "CdlSetsession",
    "CdlGettn",
    "CdlGettd",
    "CdlSeekl",
    "CdlSeekp",
    "<unimplemented>",
    "<unimplemented>",
    "CdlTest",
    "CdlGetid",
    "CdlReads",
    "CdlReset",
    "CdlGetq",
    "CdlReadtoc",
    "CdlVideocd"
};

void cdrom_write_stat(psx_cdrom_t* cdrom, uint8_t data);
void cdrom_write_cmd(psx_cdrom_t* cdrom, uint8_t data);
void cdrom_write_null(psx_cdrom_t* cdrom, uint8_t data);
void cdrom_write_parm(psx_cdrom_t* cdrom, uint8_t data);
void cdrom_write_ier(psx_cdrom_t* cdrom, uint8_t data);
void cdrom_write_ifr(psx_cdrom_t* cdrom, uint8_t data);
void cdrom_write_req(psx_cdrom_t* cdrom, uint8_t data);
void cdrom_write_vol0(psx_cdrom_t* cdrom, uint8_t data);
void cdrom_write_vol1(psx_cdrom_t* cdrom, uint8_t data);
void cdrom_write_vol2(psx_cdrom_t* cdrom, uint8_t data);
void cdrom_write_vol3(psx_cdrom_t* cdrom, uint8_t data);
void cdrom_write_vapp(psx_cdrom_t* cdrom, uint8_t data);

psx_cdrom_t* psx_cdrom_create(void) {
    return malloc(sizeof(psx_cdrom_t));
}

void psx_cdrom_init(psx_cdrom_t* cdrom, psx_ic_t* ic) {
    memset(cdrom, 0, sizeof(psx_cdrom_t));

    cdrom->io_base = PSX_CDROM_BEGIN;
    cdrom->io_size = PSX_CDROM_SIZE;

    cdrom->data = queue_create();
    cdrom->response = queue_create();
    cdrom->parameters = queue_create();
    cdrom->ic = ic;

    queue_init(cdrom->data, CD_SECTOR_SIZE);
    queue_init(cdrom->response, 32);
    queue_init(cdrom->parameters, 32);

    cdrom->version = CDR_VERSION_C0A;
    cdrom->region = CDR_REGION_AMERICA;

    cdrom->vol[0] = 0x80;
    cdrom->vol[1] = 0x00;
    cdrom->vol[2] = 0x80;
    cdrom->vol[3] = 0x00;

    cdrom->pending_lba = 150;
    cdrom->lba = 150;
    cdrom->seek_precision = 1;
    cdrom->fake_getlocl_data = 1;
}

void psx_cdrom_reset(psx_cdrom_t* cdrom) {
    queue_clear(cdrom->data);
    queue_clear(cdrom->response);
    queue_clear(cdrom->parameters);

    cdrom->prev_state = CD_STATE_IDLE;
    cdrom->state = CD_STATE_IDLE;
    cdrom->pending_command = 0;
    cdrom->busy = 0;
    cdrom->cdda_playing = 0;
    cdrom->xa_playing = 0;
    cdrom->read_ongoing = 0;

    queue_clear(cdrom->data);
    queue_clear(cdrom->response);
    queue_clear(cdrom->parameters);

    cdrom->vol[0] = 0x80;
    cdrom->vol[1] = 0x00;
    cdrom->vol[2] = 0x80;
    cdrom->vol[3] = 0x00;
}

void psx_cdrom_set_version(psx_cdrom_t* cdrom, int version) {
    cdrom->version = version;
}

void psx_cdrom_set_region(psx_cdrom_t* cdrom, int region) {
    cdrom->region = region;
}

void psx_cdrom_open(psx_cdrom_t* cdrom, const char* path) {
    if (!path)
        return;

    cdrom_cmd_reset(cdrom);

    cdrom->disc = psx_disc_create();
    cdrom->disc_type = psx_disc_open(cdrom->disc, path);

    if (cdrom->disc_type == CDT_ERROR)
        psx_cdrom_close(cdrom);
}

void psx_cdrom_close(psx_cdrom_t* cdrom) {
    if (cdrom->disc) {
        psx_disc_destroy(cdrom->disc);

        cdrom->disc = NULL;
    }
}

void cdrom_process_setloc(psx_cdrom_t* cdrom) {
    if (!cdrom->pending_lba)
        return;

    cdrom->lba = cdrom->pending_lba;

    cdrom->pending_lba = 0;
}

void cdrom_set_int(psx_cdrom_t* cdrom, int n) {
    cdrom->ifr = n;
}

int cdrom_get_read_delay(psx_cdrom_t* cdrom) {
    return (cdrom->mode & MODE_SPEED) ? CD_DELAY_READ_DS : CD_DELAY_READ_SS;
}

int cdrom_get_pause_delay(psx_cdrom_t* cdrom) {
    if (!cdrom->read_ongoing)
        return 7000;

    return CD_DELAY_1MS * ((cdrom->mode & MODE_SPEED) ? 35 : 70);
}

int cdrom_get_seek_delay(psx_cdrom_t* cdrom, int ts) {
    int delay = cdrom->pending_speed_switch_delay;

    cdrom->pending_speed_switch_delay = 0;

    // Ridiculous delays for seeking to an audio sector
    // or out of the disk
    if (ts == TS_FAR)   delay = 650 * CD_DELAY_1MS;
    if (ts == TS_AUDIO) delay = 4000 * CD_DELAY_1MS;
    // if (ts == TS_PREGAP) delay = 4000 * CD_DELAY_1MS;

    return delay;
}

void cdrom_error(psx_cdrom_t* cdrom, uint8_t stat, uint8_t err) {
    cdrom->ifr = 5;

    queue_reset(cdrom->parameters);
    queue_reset(cdrom->response);

    if ((stat & CD_STAT_IDERROR) || (stat & CD_STAT_SEEKERROR)) {
        queue_push(cdrom->response, stat);
    } else {
        queue_push(cdrom->response, CD_STAT_ERROR | stat);
    }

    queue_push(cdrom->response, err);

    cdrom->prev_state = CD_STATE_IDLE;
    cdrom->state = CD_STATE_IDLE;
    cdrom->pending_command = 0;
    cdrom->busy = 0;
}

void cdrom_handle_resp1(psx_cdrom_t* cdrom) {
    cdrom->busy = 0;

    // Check for no disc, some commands can be issued with no disc
    // in the drive (e.g. Test, Setmode, Init, etc.)
    // i.e. INT5(11h, 80h)
    if (!cdrom->disc) {
        switch (cdrom->pending_command) {
            case CDL_SETLOC:
            case CDL_PLAY:
            case CDL_FORWARD:
            case CDL_BACKWARD:
            case CDL_READN:
            case CDL_MOTORON:
            case CDL_STOP:
            case CDL_PAUSE:
            case CDL_MUTE:
            case CDL_DEMUTE:
            case CDL_SETFILTER:
            case CDL_GETLOCL:
            case CDL_GETLOCP:
            case CDL_SETSESSION:
            case CDL_GETTN:
            case CDL_GETTD:
            case CDL_SEEKL:
            case CDL_SEEKP:
            case CDL_GETID:
            case CDL_READS:
            case CDL_GETQ: {
                cdrom_error(cdrom, CD_STAT_SHELLOPEN, CD_ERR_NO_DISC);

                return;
            } break;
        }
    }

    // Check for version-specific unsupported commands
    switch (cdrom->pending_command) {
        case CDL_RESET: {
            if (cdrom->version == CDR_VERSION_01) {
                cdrom_error(cdrom,
                    CD_STAT_SPINDLE,
                    CD_ERR_INVALID_COMMAND
                );

                return;
            }
        } break;

        case CDL_GETQ:
        case CDL_READTOC: {
            if (cdrom->version < CDR_VERSION_C1A) {
                cdrom_error(cdrom,
                    CD_STAT_SPINDLE,
                    CD_ERR_INVALID_COMMAND
                );

                return;
            }
        } break;
    }

    // Check for wrong number of parameters and invalid commands
    // i.e. INT5(03h, 20h), INT5(03h, 40h)
    switch (cdrom->pending_command) {
        case CDL_GETSTAT:
        case CDL_FORWARD:
        case CDL_BACKWARD:
        case CDL_READN:
        case CDL_MOTORON:
        case CDL_STOP:
        case CDL_PAUSE:
        case CDL_INIT:
        case CDL_MUTE:
        case CDL_DEMUTE:
        case CDL_GETPARAM:
        case CDL_GETLOCL:
        case CDL_GETLOCP:
        case CDL_GETTN:
        case CDL_SEEKL:
        case CDL_SEEKP:
        case CDL_GETID:
        case CDL_READS:
        case CDL_RESET:
        case CDL_READTOC: {
            // These commands take no parameters
            if (queue_size(cdrom->parameters)) {
                cdrom_error(cdrom,
                    CD_STAT_SPINDLE,
                    CD_ERR_WRONG_PARAMETER_COUNT
                );

                return;
            }
        } break;

        case CDL_SETLOC: {
            // Setloc takes exactly 3 parameters
            if (queue_size(cdrom->parameters) != 3) {
                cdrom_error(cdrom,
                    CD_STAT_SPINDLE,
                    CD_ERR_WRONG_PARAMETER_COUNT
                );

                return;
            }
        } break;

        case CDL_PLAY: {
            // Play may take either 0 or 1 parameter
            if (queue_size(cdrom->parameters) > 1) {
                cdrom_error(cdrom,
                    CD_STAT_SPINDLE,
                    CD_ERR_WRONG_PARAMETER_COUNT
                );

                return;
            }
        } break;

        case CDL_SETFILTER:
        case CDL_GETQ: {
            // Setfilter and GetQ both take exactly 2 parameters
            if (queue_size(cdrom->parameters) != 2) {
                cdrom_error(cdrom,
                    CD_STAT_SPINDLE,
                    CD_ERR_WRONG_PARAMETER_COUNT
                );

                return;
            }
        } break;

        case CDL_SETMODE:
        case CDL_GETTD:
        case CDL_TEST: {
            // Setmode and GetTD both take exactly 1 parameter

            // Test may actually take additional parameters depending
            // on the subfunction, but we only emulate subfunction 20h
            // for now, which takes no extra parameters
            if (queue_size(cdrom->parameters) != 1) {
                cdrom_error(cdrom,
                    CD_STAT_SPINDLE,
                    CD_ERR_WRONG_PARAMETER_COUNT
                );

                return;
            }
        } break;

        case CDL_VIDEOCD: {
            // To-do: Check for model
            // VideoCD is only supported on the SCPH-5903
            // Should return invalid command normally

            // VideoCD takes exactly 6 parameters
            if (queue_size(cdrom->parameters) != 6) {
                cdrom_error(cdrom,
                    CD_STAT_SPINDLE,
                    CD_ERR_WRONG_PARAMETER_COUNT
                );

                return;
            }
        } break;

        default: {
            // Invalid command
            cdrom_error(cdrom,
                CD_STAT_SPINDLE,
                CD_ERR_INVALID_COMMAND
            );

            return;
        } break;
    }

    // If everything is alright (i.e. disc present, valid command,
    // correct number of parameters) then send "execute command"
    cdrom_cmd_table[cdrom->pending_command](cdrom);
}

uint8_t cdrom_get_stat(psx_cdrom_t* cdrom) {
    return ((cdrom->cdda_playing) ? CD_STAT_PLAY : 0) |
           ((cdrom->read_ongoing) ? CD_STAT_READ : 0) |
           ((cdrom->mode & 0x10) ? CD_STAT_IDERROR : 0) |
           ((!cdrom->disc) ? CD_STAT_SHELLOPEN : 0) |
           CD_STAT_SPINDLE;
}

void cdrom_handle_read(psx_cdrom_t* cdrom) {
    cdrom_process_setloc(cdrom);

    int ts = psx_disc_query(cdrom->disc, cdrom->lba);

    if (ts == TS_FAR) {
        cdrom_error(cdrom,
            CD_STAT_SPINDLE | CD_STAT_SEEKERROR,
            CD_ERR_INVALID_SUBFUNCTION
        );

        return;
    }

    //if (ts == TS_AUDIO || ts == TS_PREGAP) {
    if (ts == TS_AUDIO) {
        cdrom_error(cdrom,
            CD_STAT_SPINDLE | CD_STAT_SEEKERROR,
            CD_ERR_SEEK_FAILED
        );

        return;
    }

    cdrom_set_int(cdrom, 1);
    queue_push(cdrom->response, cdrom_get_stat(cdrom));

    // Read sector into our data FIFO
    psx_disc_read(cdrom->disc, cdrom->lba, cdrom->data->buf);

    int size_bit = cdrom->mode & MODE_SECTOR_SIZE;

    cdrom->data->read_index = size_bit ? 12 : 24;
    cdrom->data->write_index = size_bit ? 0x924 : 0x800;
    cdrom->data->write_index += cdrom->data->read_index;

    cdrom->pending_lba = cdrom->lba + 1;
    cdrom->delay = cdrom_get_read_delay(cdrom);

    // printf("size=%x off=%u lba=%d: %02x:%02x:%02x delay=%u\n",
    //     cdrom->data->write_index,
    //     cdrom->data->read_index,
    //     cdrom->lba,
    //     cdrom->data->buf[0xc],
    //     cdrom->data->buf[0xd],
    //     cdrom->data->buf[0xe],
    //     cdrom->data->buf[0xf],
    //     cdrom->delay
    // );
}

void psx_cdrom_update(psx_cdrom_t* cdrom, int cycles) {
    if (cdrom->delay > 0) {
        cdrom->delay -= cycles;

        if (cdrom->delay > 0)
            return;
    }

    cdrom->delay = 0;

    if (cdrom->state == CD_STATE_IDLE)
        return;

    if (cdrom->state == CD_STATE_PLAY)
        return;

    // Hold IRQ until IFR is acknowledged
    if (cdrom->ifr & 0x1f) {
        cdrom->delay = 2;

        return;
    }

    switch (cdrom->state) {
        case CD_STATE_TX_RESP1: {
            cdrom_handle_resp1(cdrom);

            switch (cdrom->pending_command) {
                case CDL_READN:
                case CDL_READS:
                    break;
            }

            // Switching to read mode after executing a command
            // has a 500ms penalty
            if (cdrom->state == CD_STATE_READ) {
                cdrom_process_setloc(cdrom);

                cdrom->state = CD_STATE_READ;
                cdrom->prev_state = CD_STATE_READ;
                cdrom->delay = CD_DELAY_ONGOING_READ;
            }
        } break;

        case CD_STATE_TX_RESP2: {
            cdrom_cmd_table[cdrom->pending_command](cdrom);

            // Switching to read mode after executing a command
            // has a 500ms penalty
            if (cdrom->state == CD_STATE_READ) {
                cdrom_process_setloc(cdrom);

                cdrom->state = CD_STATE_READ;
                cdrom->prev_state = CD_STATE_READ;
                cdrom->delay = CD_DELAY_ONGOING_READ;
            }
        } break;

        case CD_STATE_READ: {
            cdrom_handle_read(cdrom);
        } break;
    }

    if ((cdrom->ifr & cdrom->ier) == 0)
        return;

    psx_ic_irq(cdrom->ic, IC_CDROM);
}

uint8_t cdrom_read_status(psx_cdrom_t* cdrom) {
    int data_empty = queue_is_empty(cdrom->data) || !cdrom->data_req;

    return (cdrom->index                        << 0) |
           (cdrom->xa_playing                   << 2) |
           (queue_is_empty(cdrom->parameters)   << 3) |
           ((!queue_is_full(cdrom->parameters)) << 4) |
           ((!queue_is_empty(cdrom->response))  << 5) |
           ((!data_empty)                       << 6) |
           (cdrom->busy                         << 7);
}

uint8_t cdrom_read_data(psx_cdrom_t* cdrom) {
    if (!cdrom->data_req)
        return 0;

    // printf("read=%x write=%x data=%02x |%c|\n",
    //     cdrom->data->read_index,
    //     cdrom->data->write_index,
    //     queue_peek(cdrom->data),
    //     isprint(queue_peek(cdrom->data)) ? queue_peek(cdrom->data) : '.'
    // );

    return queue_pop(cdrom->data);
}

uint32_t psx_cdrom_read8(psx_cdrom_t* cdrom, uint32_t addr) {
    switch (addr) {
        case 0: return cdrom_read_status(cdrom);
        case 1: return queue_pop(cdrom->response);
        case 2: return cdrom_read_data(cdrom);
        case 3: return (cdrom->index & 1) ? (0xe0 | cdrom->ifr) : cdrom->ier;
    }

    return 0;
}

void psx_cdrom_write8(psx_cdrom_t* cdrom, uint32_t addr, uint32_t value) {
    switch ((cdrom->index << 2) | addr) {
        case 0: cdrom_write_stat(cdrom, value); break;
        case 1: cdrom_write_cmd(cdrom, value); break;
        case 2: cdrom_write_parm(cdrom, value); break;
        case 3: cdrom_write_req(cdrom, value); break;
        case 4: cdrom_write_stat(cdrom, value); break;
        case 5: cdrom_write_null(cdrom, value); break;
        case 6: cdrom_write_ier(cdrom, value); break;
        case 7: cdrom_write_ifr(cdrom, value); break;
        case 8: cdrom_write_stat(cdrom, value); break;
        case 9: cdrom_write_null(cdrom, value); break;
        case 10: cdrom_write_vol0(cdrom, value); break;
        case 11: cdrom_write_vol1(cdrom, value); break;
        case 12: cdrom_write_stat(cdrom, value); break;
        case 13: cdrom_write_vol2(cdrom, value); break;
        case 14: cdrom_write_vol3(cdrom, value); break;
        case 15: cdrom_write_vapp(cdrom, value); break;
    }
}

void psx_cdrom_destroy(psx_cdrom_t* cdrom) {
    psx_cdrom_close(cdrom);
    queue_destroy(cdrom->data);
    queue_destroy(cdrom->response);
    queue_destroy(cdrom->parameters);
    free(cdrom);
}

void cdrom_write_stat(psx_cdrom_t* cdrom, uint8_t data) {
    cdrom->index = data & 3;
}

void cdrom_write_cmd(psx_cdrom_t* cdrom, uint8_t data) {
    cdrom->prev_state = cdrom->state;
    cdrom->state = CD_STATE_TX_RESP1;

    cdrom->pending_command = data;

    switch (cdrom->pending_command) {
        case CDL_INIT:
            cdrom->delay = CD_DELAY_INIT_FR;
        break;

        default:
            cdrom->delay = CD_DELAY_FR;
        break;
    }

    if (cdrom->state == CD_STATE_READ)
        cdrom->busy = 1;

    printf("cdrom: %-16s (%02x) params: ", cdrom_cmd_names[data], data);

    if (queue_is_empty(cdrom->parameters)) {
        puts("(none)");

        return;
    }

    for (int i = 0; i < cdrom->parameters->write_index; i++)
        printf("%02x ", cdrom->parameters->buf[i]);

    putchar('\n');

    return;
}

void cdrom_write_null(psx_cdrom_t* cdrom, uint8_t data) {
    /* Ignore writes */
}

void cdrom_write_parm(psx_cdrom_t* cdrom, uint8_t data) {
    queue_push(cdrom->parameters, data);
}

void cdrom_write_ier(psx_cdrom_t* cdrom, uint8_t data) {
    cdrom->ier = data;
}

void cdrom_write_ifr(psx_cdrom_t* cdrom, uint8_t data) {
    if (data & 0x40)
        queue_clear(cdrom->parameters);

    // uint8_t prev_ifr = cdrom->ifr & 0x1f;

    cdrom->ifr &= ~(data & 0x1f);

    // If an INT is acknowledged, then the response
    // FIFO is cleared
    // if (((cdrom->ifr & 0x1f) == 0) && (prev_ifr != 0))
    //     queue_clear(cdrom->response);
}

void cdrom_write_req(psx_cdrom_t* cdrom, uint8_t data) {
    cdrom->data_req = data & 0x80;
}

void cdrom_write_vol0(psx_cdrom_t* cdrom, uint8_t data) {
    cdrom->vol_pending[0] = data;
}

void cdrom_write_vol1(psx_cdrom_t* cdrom, uint8_t data) {
    cdrom->vol_pending[1] = data;
}

void cdrom_write_vol2(psx_cdrom_t* cdrom, uint8_t data) {
    cdrom->vol_pending[2] = data;
}

void cdrom_write_vol3(psx_cdrom_t* cdrom, uint8_t data) {
    cdrom->vol_pending[3] = data;
}

void cdrom_write_vapp(psx_cdrom_t* cdrom, uint8_t data) {
    cdrom->xa_mute = data & 1;
    cdrom->vol[0] = cdrom->vol_pending[0];
    cdrom->vol[1] = cdrom->vol_pending[1];
    cdrom->vol[2] = cdrom->vol_pending[2];
    cdrom->vol[3] = cdrom->vol_pending[3];
}

uint32_t psx_cdrom_read32(psx_cdrom_t* cdrom, uint32_t addr) {
    assert("32-bit CDROM reads are not supported" && 0);

    return 0;
}

uint32_t psx_cdrom_read16(psx_cdrom_t* cdrom, uint32_t addr) {
    assert("16-bit CDROM reads are not supported" && 0);

    // The CDROM controller is connected to the SUB-BUS which is a 16-bit
    // bus, but the output from the controller itself is 8-bit. I think
    // 16-bit accesses are handled as a pair of 8-bit accesses
    return psx_cdrom_read8(cdrom, addr) << 8 | psx_cdrom_read8(cdrom, addr+1);
}

void psx_cdrom_write32(psx_cdrom_t* cdrom, uint32_t addr, uint32_t value) {
    assert("32-bit CDROM writes are not supported" && 0);
}

void psx_cdrom_write16(psx_cdrom_t* cdrom, uint32_t addr, uint32_t value) {
    assert("16-bit CDROM writes are not supported" && 0);
}