Minor cosmetics and cleanups.

[libjaylink.git] / libjaylink / transport.c

/*
 * This file is part of the libjaylink project.
 *
 * Copyright (C) 2014-2015 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 <stdlib.h>
#include <stdint.h>
#include <string.h>

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

/**
 * @file
 *
 * Transport abstraction layer.
 */

/** Timeout of an USB transfer in milliseconds. */
#define USB_TIMEOUT     1000

/**
 * Number of consecutive timeouts before an USB transfer will be treated as
 * timed out.
 */
#define NUM_TIMEOUTS    2

/** Chunk size in bytes in which data is transferred. */
#define CHUNK_SIZE      2048

/**
 * Buffer size in bytes.
 *
 * Note that both write and read operations require a buffer size of at least
 * #CHUNK_SIZE bytes.
 */
#define BUFFER_SIZE     CHUNK_SIZE

static int initialize_handle(struct jaylink_device_handle *devh)
{
        int ret;
        struct jaylink_context *ctx;
        struct libusb_config_descriptor *config;
        const struct libusb_interface *interface;
        const struct libusb_interface_descriptor *desc;
        const struct libusb_endpoint_descriptor *epdesc;
        int found_interface;
        int found_endpoint_in;
        int found_endpoint_out;
        uint8_t i;

        ctx = devh->dev->ctx;
        devh->interface_number = 0;

        /*
         * Retrieve active configuration descriptor to determine the endpoints
         * for the interface number of the device.
         */
        ret = libusb_get_active_config_descriptor(devh->dev->usb_dev, &config);

        if (ret != LIBUSB_SUCCESS) {
                log_err(ctx, "Failed to get configuration descriptor: %s.",
                        libusb_error_name(ret));
                return JAYLINK_ERR;
        }

        found_interface = 0;

        for (i = 0; i < config->bNumInterfaces; i++) {
                interface = &config->interface[i];
                desc = &interface->altsetting[0];

                if (desc->bInterfaceClass != LIBUSB_CLASS_VENDOR_SPEC)
                        continue;

                if (desc->bInterfaceSubClass != LIBUSB_CLASS_VENDOR_SPEC)
                        continue;

                if (desc->bNumEndpoints < 2)
                        continue;

                found_interface = 1;
                devh->interface_number = i;
                break;
        }

        if (!found_interface) {
                log_err(ctx, "No suitable interface found.");
                libusb_free_config_descriptor(config);
                return JAYLINK_ERR;
        }

        found_endpoint_in = 0;
        found_endpoint_out = 0;

        for (i = 0; i < desc->bNumEndpoints; i++) {
                epdesc = &desc->endpoint[i];

                if (epdesc->bEndpointAddress & LIBUSB_ENDPOINT_IN) {
                        devh->endpoint_in = epdesc->bEndpointAddress;
                        found_endpoint_in = 1;
                } else {
                        devh->endpoint_out = epdesc->bEndpointAddress;
                        found_endpoint_out = 1;
                }
        }

        libusb_free_config_descriptor(config);

        if (!found_endpoint_in) {
                log_err(ctx, "Interface IN endpoint not found.");
                return JAYLINK_ERR;
        }

        if (!found_endpoint_out) {
                log_err(ctx, "Interface OUT endpoint not found.");
                return JAYLINK_ERR;
        }

        log_dbg(ctx, "Using endpoint %02x (IN) and %02x (OUT).",
                devh->endpoint_in, devh->endpoint_out);

        devh->buffer = malloc(BUFFER_SIZE);

        if (!devh->buffer) {
                log_err(ctx, "Transport buffer malloc failed.");
                return JAYLINK_ERR_MALLOC;
        }

        devh->read_length = 0;
        devh->bytes_available = 0;
        devh->read_pos = 0;

        devh->write_length = 0;
        devh->write_pos = 0;

        return JAYLINK_OK;
}

static void cleanup_handle(struct jaylink_device_handle *devh)
{
        free(devh->buffer);
}

/**
 * Open a device.
 *
 * This function must be called before any other function of the transport
 * abstraction layer for the given device handle is called.
 *
 * @param devh Device handle.
 *
 * @retval JAYLINK_OK Success.
 * @retval JAYLINK_ERR Other error conditions.
 */
JAYLINK_PRIV int transport_open(struct jaylink_device_handle *devh)
{
        int ret;
        struct jaylink_device *dev;
        struct jaylink_context *ctx;
        struct libusb_device_handle *usb_devh;

        dev = devh->dev;
        ctx = dev->ctx;

        log_dbg(ctx, "Trying to open device (bus:address = %03u:%03u).",
                libusb_get_bus_number(dev->usb_dev),
                libusb_get_device_address(dev->usb_dev));

        ret = initialize_handle(devh);

        if (ret != JAYLINK_OK) {
                log_err(ctx, "Initialize device handle failed.");
                return ret;
        }

        ret = libusb_open(dev->usb_dev, &usb_devh);

        if (ret != LIBUSB_SUCCESS) {
                log_err(ctx, "Failed to open device: %s.",
                        libusb_error_name(ret));
                cleanup_handle(devh);
                return JAYLINK_ERR;
        }

        ret = libusb_claim_interface(usb_devh, devh->interface_number);

        if (ret != LIBUSB_SUCCESS) {
                log_err(ctx, "Failed to claim interface: %s.",
                        libusb_error_name(ret));
                cleanup_handle(devh);
                libusb_close(usb_devh);
                return JAYLINK_ERR;
        }

        log_dbg(ctx, "Device opened successfully.");

        devh->usb_devh = usb_devh;

        return JAYLINK_OK;
}

/**
 * Close a device.
 *
 * After this function has been called no other function of the transport
 * abstraction layer for the given device handle must be called.
 *
 * @param devh Device handle.
 *
 * @retval JAYLINK_OK Success.
 * @retval JAYLINK_ERR Other error conditions.
 */
JAYLINK_PRIV int transport_close(struct jaylink_device_handle *devh)
{
        int ret;
        struct jaylink_device *dev;
        struct jaylink_context *ctx;

        dev = devh->dev;
        ctx = dev->ctx;

        log_dbg(ctx, "Closing device (bus:address = %03u:%03u).",
                libusb_get_bus_number(dev->usb_dev),
                libusb_get_device_address(dev->usb_dev));

        ret = libusb_release_interface(devh->usb_devh, devh->interface_number);

        libusb_close(devh->usb_devh);
        cleanup_handle(devh);

        if (ret != LIBUSB_SUCCESS) {
                log_err(ctx, "Failed to release interface: %s.",
                        libusb_error_name(ret));
                return JAYLINK_ERR;
        }

        return JAYLINK_OK;
}

/**
 * Start a write operation for a device.
 *
 * The data of a write operation must be written with at least one call of
 * transport_write(). It is required that all data of a write operation is
 * written before an other write and/or read operation is started.
 *
 * @param devh Device handle.
 * @param length Number of bytes of the write operation.
 * @param has_command Determines whether the data of the write operation
 *                    contains the protocol command.
 *
 * @retval JAYLINK_OK Success.
 * @retval JAYLINK_ERR_ARG Invalid arguments.
 */
JAYLINK_PRIV int transport_start_write(struct jaylink_device_handle *devh,
                uint16_t length, int has_command)
{
        struct jaylink_context *ctx;

        (void)has_command;

        if (!length)
                return JAYLINK_ERR_ARG;

        ctx = devh->dev->ctx;

        log_dbg(ctx, "Starting write operation (length = %u bytes).", length);

        if (devh->write_pos > 0)
                log_warn(ctx, "Last write operation left %u bytes in the "
                        "buffer.", devh->write_pos);

        if (devh->write_length > 0)
                log_warn(ctx, "Last write operation was not performed.");

        devh->write_length = length;
        devh->write_pos = 0;

        return JAYLINK_OK;
}

/**
 * Start a read operation for a device.
 *
 * The data of a read operation must be read with at least one call of
 * transport_read(). It is required that all data of a read operation is read
 * before an other write and/or read operation is started.
 *
 * @param devh Device handle.
 * @param length Number of bytes of the read operation.
 *
 * @retval JAYLINK_OK Success.
 * @retval JAYLINK_ERR_ARG Invalid arguments.
 */
JAYLINK_PRIV int transport_start_read(struct jaylink_device_handle *devh,
                uint16_t length)
{
        struct jaylink_context *ctx;

        if (!length)
                return JAYLINK_ERR_ARG;

        ctx = devh->dev->ctx;

        log_dbg(ctx, "Starting read operation (length = %u bytes).", length);

        if (devh->bytes_available > 0)
                log_dbg(ctx, "Last read operation left %u bytes in the "
                        "buffer.", devh->bytes_available);

        if (devh->read_length > 0)
                log_warn(ctx, "Last read operation left %u bytes.",
                        devh->read_length);

        devh->read_length = length;

        return JAYLINK_OK;
}

/**
 * Start a write and read operation for a device.
 *
 * This function starts a write and read operation as the consecutive call of
 * transport_start_write() and transport_start_read() but has a different
 * meaning from the protocol perspective and can therefore not be replaced by
 * these functions and vice versa.
 *
 * @note The write operation must be completed first before the read operation
 *       must be processed.
 *
 * @param devh Device handle.
 * @param write_length Number of bytes of the write operation.
 * @param read_length Number of bytes of the read operation.
 * @param has_command Determines whether the data of the write operation
 *                    contains the protocol command.
 *
 * @retval JAYLINK_OK Success.
 * @retval JAYLINK_ERR_ARG Invalid arguments.
 */
JAYLINK_PRIV int transport_start_write_read(struct jaylink_device_handle *devh,
                uint16_t write_length, uint16_t read_length, int has_command)
{
        struct jaylink_context *ctx;

        (void)has_command;

        if (!read_length || !write_length)
                return JAYLINK_ERR_ARG;

        ctx = devh->dev->ctx;

        log_dbg(ctx, "Starting write / read operation (length = "
                "%u / %u bytes).", write_length, read_length);

        if (devh->write_pos > 0)
                log_warn(ctx, "Last write operation left %u bytes in the "
                        "buffer.", devh->write_pos);

        if (devh->write_length > 0)
                log_warn(ctx, "Last write operation was not performed.");

        if (devh->bytes_available > 0)
                log_warn(ctx, "Last read operation left %u bytes in the "
                        "buffer.", devh->bytes_available);

        if (devh->read_length > 0)
                log_warn(ctx, "Last read operation left %u bytes.",
                        devh->read_length);

        devh->write_length = write_length;
        devh->write_pos = 0;

        devh->read_length = read_length;
        devh->bytes_available = 0;
        devh->read_pos = 0;

        return JAYLINK_OK;
}

static int usb_recv(struct jaylink_device_handle *devh, uint8_t *buffer,
                uint16_t *length)
{
        int ret;
        struct jaylink_context *ctx;
        unsigned int tries;
        int transferred;

        ctx = devh->dev->ctx;
        tries = NUM_TIMEOUTS;
        transferred = 0;

        while (tries > 0 && !transferred) {
                /* Always request CHUNK_SIZE bytes from the device. */
                ret = libusb_bulk_transfer(devh->usb_devh, devh->endpoint_in,
                        (unsigned char *)buffer, CHUNK_SIZE, &transferred,
                        USB_TIMEOUT);

                if (ret == LIBUSB_ERROR_TIMEOUT) {
                        log_warn(ctx, "Failed to receive data from "
                                "device: %s.", libusb_error_name(ret));
                        tries--;
                        continue;
                } else if (ret != LIBUSB_SUCCESS) {
                        log_err(ctx, "Failed to receive data from "
                                "device: %s.", libusb_error_name(ret));
                        return JAYLINK_ERR;
                }

                log_dbg(ctx, "Received %u bytes from device.", transferred);
        }

        /* Ignore a possible timeout if at least one byte was received. */
        if (transferred > 0) {
                *length = transferred;
                return JAYLINK_OK;
        }

        log_err(ctx, "Receiving data from device timed out.");

        return JAYLINK_ERR_TIMEOUT;
}

static int usb_send(struct jaylink_device_handle *devh, const uint8_t *buffer,
                uint16_t length)
{
        int ret;
        struct jaylink_context *ctx;
        unsigned int tries;
        int transferred;

        ctx = devh->dev->ctx;
        tries = NUM_TIMEOUTS;

        while (tries > 0 && length > 0) {
                /* Send data in chunks of CHUNK_SIZE bytes to the device. */
                ret = libusb_bulk_transfer(devh->usb_devh, devh->endpoint_out,
                        (unsigned char *)buffer, MIN(CHUNK_SIZE, length),
                        &transferred, USB_TIMEOUT);

                if (ret == LIBUSB_SUCCESS) {
                        tries = NUM_TIMEOUTS;
                } else if (ret == LIBUSB_ERROR_TIMEOUT) {
                        log_warn(ctx, "Failed to send data to device: %s.",
                                libusb_error_name(ret));
                        tries--;
                } else {
                        log_err(ctx, "Failed to send data to device: %s.",
                                libusb_error_name(ret));
                        return JAYLINK_ERR;
                }

                buffer += transferred;
                length -= transferred;

                log_dbg(ctx, "Sent %u bytes to device.", transferred);
        }

        if (!length)
                return JAYLINK_OK;

        log_err(ctx, "Sending data to device timed out.");

        return JAYLINK_ERR_TIMEOUT;
}

/**
 * Write data to a device.
 *
 * Before this function is used transport_start_write() or
 * transport_start_write_read() must be called to start a write operation. The
 * total number of written bytes must not exceed the number of bytes of the
 * write operation.
 *
 * @note A write operation will be performed and the data will be sent to the
 *       device when the number of written bytes reaches the number of bytes of
 *       the write operation. Before that the data will be written into a
 *       buffer.
 *
 * @param devh Device handle.
 * @param buffer Buffer to write data from.
 * @param length Number of bytes to write.
 *
 * @retval JAYLINK_OK Success.
 * @retval JAYLINK_ERR_ARG Invalid arguments.
 * @retval JAYLINK_ERR_TIMEOUT A timeout occurred.
 * @retval JAYLINK_ERR Other error conditions.
 */
JAYLINK_PRIV int transport_write(struct jaylink_device_handle *devh,
                const uint8_t *buffer, uint16_t length)
{
        int ret;
        struct jaylink_context *ctx;
        uint8_t num_chunks;
        uint16_t fill_bytes;
        uint16_t tmp;

        ctx = devh->dev->ctx;

        if (length > devh->write_length) {
                log_err(ctx, "Requested to write %u bytes but only %u bytes "
                        "are expected for the write operation.", length,
                        devh->write_length);
                return JAYLINK_ERR_ARG;
        }

        /*
         * Store data in the buffer if the expected number of bytes for the
         * write operation is not reached.
         */
        if (length < devh->write_length) {
                if (devh->write_pos + length > BUFFER_SIZE) {
                        log_err(ctx, "Write request is too large for the "
                                "buffer.");
                        return JAYLINK_ERR_ARG;
                }

                memcpy(devh->buffer + devh->write_pos, buffer, length);

                devh->write_length -= length;
                devh->write_pos += length;

                log_dbg(ctx, "Wrote %u bytes into buffer.", length);
                return JAYLINK_OK;
        }

        /*
         * Expected number of bytes for this write operation is reached and
         * therefore the write operation will be performed.
         */
        devh->write_length = 0;

        /* Send data directly to the device if the buffer is empty. */
        if (!devh->write_pos)
                return usb_send(devh, buffer, length);

        /*
         * Calculate the number of bytes to fill up the buffer to reach a
         * multiple of CHUNK_SIZE bytes. This ensures that the data from the
         * buffer will be sent to the device in chunks of CHUNK_SIZE bytes.
         * Note that this is why the buffer size must be at least CHUNK_SIZE
         * bytes.
         */
        num_chunks = devh->write_pos / CHUNK_SIZE;

        if (devh->write_pos % CHUNK_SIZE)
                num_chunks++;

        fill_bytes = (num_chunks * CHUNK_SIZE) - devh->write_pos;
        tmp = MIN(length, fill_bytes);

        if (tmp > 0) {
                memcpy(devh->buffer + devh->write_pos, buffer, tmp);

                length -= tmp;
                buffer += tmp;

                log_dbg(ctx, "Buffer filled up with %u bytes.", tmp);
        }

        /* Send buffered data to the device. */
        ret = usb_send(devh, devh->buffer, devh->write_pos + tmp);
        devh->write_pos = 0;

        if (ret != JAYLINK_OK)
                return ret;

        if (!length)
                return JAYLINK_OK;

        /* Send remaining data to the device. */
        return usb_send(devh, buffer, length);
}

/**
 * Read data from a device.
 *
 * Before this function is used transport_start_read() or
 * transport_start_write_read() must be called to start a read operation. The
 * total number of read bytes must not exceed the number of bytes of the read
 * operation.
 *
 * @param devh Device handle.
 * @param buffer Buffer to read data into on success. Its content is undefined
 *               on failure.
 * @param length Number of bytes to read.
 *
 * @retval JAYLINK_OK Success.
 * @retval JAYLINK_ERR_ARG Invalid arguments.
 * @retval JAYLINK_ERR_TIMEOUT A timeout occurred.
 * @retval JAYLINK_ERR Other error conditions.
 */
JAYLINK_PRIV int transport_read(struct jaylink_device_handle *devh,
                uint8_t *buffer, uint16_t length)
{
        int ret;
        struct jaylink_context *ctx;
        uint16_t bytes_received;
        uint16_t tmp;

        ctx = devh->dev->ctx;

        if (length > devh->read_length) {
                log_err(ctx, "Requested to read %u bytes but only %u bytes "
                        "are expected for the read operation.", length,
                        devh->read_length);
                return JAYLINK_ERR_ARG;
        }

        if (length <= devh->bytes_available) {
                memcpy(buffer, devh->buffer + devh->read_pos, length);

                devh->read_length -= length;
                devh->bytes_available -= length;
                devh->read_pos += length;

                log_dbg(ctx, "Read %u bytes from buffer.", length);
                return JAYLINK_OK;
        }

        if (devh->bytes_available) {
                memcpy(buffer, devh->buffer + devh->read_pos,
                        devh->bytes_available);

                buffer += devh->bytes_available;
                length -= devh->bytes_available;
                devh->read_length -= devh->bytes_available;

                log_dbg(ctx, "Read %u bytes from buffer to flush it.",
                        devh->bytes_available);

                devh->bytes_available = 0;
                devh->read_pos = 0;
        }

        while (length > 0) {
                /*
                 * If less than CHUNK_SIZE bytes are requested from the device,
                 * store the received data in the internal buffer instead of
                 * directly into the user provided buffer. This is necessary to
                 * prevent a possible buffer overflow because the number of
                 * requested bytes from the device is always CHUNK_SIZE and
                 * therefore up to CHUNK_SIZE bytes may be received.
                 */
                if (length < CHUNK_SIZE) {
                        ret = usb_recv(devh, devh->buffer, &bytes_received);

                        if (ret != JAYLINK_OK)
                                return ret;

                        tmp = MIN(bytes_received, length);
                        memcpy(buffer, devh->buffer, tmp);

                        /*
                         * Setup the buffer for the remaining data if more data
                         * was received from the device than was requested.
                         */
                        if (bytes_received > length) {
                                devh->bytes_available = bytes_received - tmp;
                                devh->read_pos = tmp;
                        }

                        buffer += tmp;
                        length -= tmp;
                        devh->read_length -= tmp;

                        log_dbg(ctx, "Read %u bytes from buffer.", tmp);
                } else {
                        ret = usb_recv(devh, buffer, &bytes_received);

                        if (ret != JAYLINK_OK)
                                return ret;

                        buffer += bytes_received;
                        length -= bytes_received;
                        devh->read_length -= bytes_received;

                        log_dbg(ctx, "Read %u bytes from device.",
                                bytes_received);
                }
        }

        return JAYLINK_OK;
}