emucom.c

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/*
 * This file is part of the libjaylink project.
 *
 * Copyright (C) 2015-2016 Marc Schink <jaylink-dev@marcschink.de>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdint.h>
#include <stdbool.h>

#include "libjaylink.h"
#include "libjaylink-internal.h"

#define CMD_EMUCOM          0xee

#define EMUCOM_CMD_READ         0x00
#define EMUCOM_CMD_WRITE        0x01

#define EMUCOM_ERR          0x80000000

#define EMUCOM_ERR_NOT_SUPPORTED    0x80000001

#define EMUCOM_ERR_NOT_AVAILABLE    0x81000000

#define EMUCOM_AVAILABLE_BYTES_MASK 0x00ffffff

JAYLINK_API int jaylink_emucom_read(struct jaylink_device_handle *devh,
        uint32_t channel, uint8_t *buffer, uint32_t *length)
{
    int ret;
    struct jaylink_context *ctx;
    uint8_t buf[10];
    uint32_t tmp;

    if (!devh || !buffer || !length)
        return JAYLINK_ERR_ARG;

    ctx = devh->dev->ctx;
    ret = transport_start_write_read(devh, 10, 4, true);

    if (ret != JAYLINK_OK) {
        log_err(ctx, "transport_start_write_read() failed: %s.",
            jaylink_strerror(ret));
        return ret;
    }

    buf[0] = CMD_EMUCOM;
    buf[1] = EMUCOM_CMD_READ;

    buffer_set_u32(buf, channel, 2);
    buffer_set_u32(buf, *length, 6);

    ret = transport_write(devh, buf, 10);

    if (ret != JAYLINK_OK) {
        log_err(ctx, "transport_write() failed: %s.",
            jaylink_strerror(ret));
        return ret;
    }

    ret = transport_read(devh, buf, 4);

    if (ret != JAYLINK_OK) {
        log_err(ctx, "transport_read() failed: %s.",
            jaylink_strerror(ret));
        return ret;
    }

    tmp = buffer_get_u32(buf, 0);

    if (tmp == EMUCOM_ERR_NOT_SUPPORTED)
        return JAYLINK_ERR_DEV_NOT_SUPPORTED;

    if ((tmp & ~EMUCOM_AVAILABLE_BYTES_MASK) == EMUCOM_ERR_NOT_AVAILABLE) {
        *length = tmp & EMUCOM_AVAILABLE_BYTES_MASK;
        return JAYLINK_ERR_DEV_NOT_AVAILABLE;
    }

    if (tmp & EMUCOM_ERR) {
        log_err(ctx, "Failed to read from channel 0x%x: 0x%x.",
            channel, tmp);
        return JAYLINK_ERR_DEV;
    }

    if (tmp > *length) {
        log_err(ctx, "Requested at most %u bytes but device "
            "returned %u bytes.", *length, tmp);
        return JAYLINK_ERR_PROTO;
    }

    *length = tmp;

    if (!tmp)
        return JAYLINK_OK;

    ret = transport_start_read(devh, tmp);

    if (ret != JAYLINK_OK) {
        log_err(ctx, "transport_start_read() failed: %s.",
            jaylink_strerror(ret));
        return ret;
    }

    ret = transport_read(devh, buffer, tmp);

    if (ret != JAYLINK_OK) {
        log_err(ctx, "transport_read() failed: %s.",
            jaylink_strerror(ret));
        return ret;
    }

    return JAYLINK_OK;
}

JAYLINK_API int jaylink_emucom_write(struct jaylink_device_handle *devh,
        uint32_t channel, const uint8_t *buffer, uint32_t *length)
{
    int ret;
    struct jaylink_context *ctx;
    uint8_t buf[10];
    uint32_t tmp;

    if (!devh || !buffer || !length)
        return JAYLINK_ERR_ARG;

    if (!*length)
        return JAYLINK_ERR_ARG;

    ctx = devh->dev->ctx;
    ret = transport_start_write(devh, 10, true);

    if (ret != JAYLINK_OK) {
        log_err(ctx, "transport_start_write() failed: %s.",
            jaylink_strerror(ret));
        return ret;
    }

    buf[0] = CMD_EMUCOM;
    buf[1] = EMUCOM_CMD_WRITE;

    buffer_set_u32(buf, channel, 2);
    buffer_set_u32(buf, *length, 6);

    ret = transport_write(devh, buf, 10);

    if (ret != JAYLINK_OK) {
        log_err(ctx, "transport_write() failed: %s.",
            jaylink_strerror(ret));
        return ret;
    }

    ret = transport_start_write_read(devh, *length, 4, false);

    if (ret != JAYLINK_OK) {
        log_err(ctx, "transport_start_write_read() failed: %s.",
            jaylink_strerror(ret));
        return ret;
    }

    ret = transport_write(devh, buffer, *length);

    if (ret != JAYLINK_OK) {
        log_err(ctx, "transport_write() failed: %s.",
            jaylink_strerror(ret));
        return ret;
    }

    ret = transport_read(devh, buf, 4);

    if (ret != JAYLINK_OK) {
        log_err(ctx, "transport_read() failed: %s.",
            jaylink_strerror(ret));
        return ret;
    }

    tmp = buffer_get_u32(buf, 0);

    if (tmp == EMUCOM_ERR_NOT_SUPPORTED)
        return JAYLINK_ERR_DEV_NOT_SUPPORTED;

    if (tmp & EMUCOM_ERR) {
        log_err(ctx, "Failed to write to channel 0x%x: 0x%x.",
            channel, tmp);
        return JAYLINK_ERR_DEV;
    }

    if (tmp > *length) {
        log_err(ctx, "Only %u bytes were supposed to be written, but "
            "the device reported %u written bytes.", *length, tmp);
        return JAYLINK_ERR_PROTO;
    }

    *length = tmp;

    return JAYLINK_OK;
}