/*
 * Copyright © 2008, Roland Roberts
 *
 * Modifications and extensions for DSI III support 2015, G. Schmidt (gs)
 *
 * References
 *
 *    [TRM] EZ-USB Technical Reference Manual, Document #001-13670 Rev. *A
 */

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#include <stdlib.h>
#include <errno.h>
#include <assert.h>
#include <unistd.h>
#include <math.h>

#include "DsiTypes.h"
#include "DsiException.h"
#include "DsiDevice.h"

#include "Util.h"

/* Convenient mnemonic for libusb timeouts which are always in this unit. */
#ifndef MILLISEC
#  define MILLISEC 2
#endif

using namespace std;
#include <cstring>
#include <iostream>
#include <sstream>
#include <iomanip>
#include <stdexcept>
#include <memory>

#include <sys/time.h>

static unsigned int last_time;

static unsigned int
get_sysclock_ms()
{
    struct timeval tv;
    gettimeofday(&tv, 0);
    return (tv.tv_sec * 1000 + tv.tv_usec/1000);
}

static std::unique_ptr<std::string>
format_buffer(unsigned char data[], size_t length)
{
    ostringstream buffer;
    for (int i = 0; i < length; i++) {
        if (i > 0 && (i % 8) == 0) {
            break;
            buffer << endl << "    " << setfill('0') << setw(8) << hex << i;
        }
        buffer << " " << setfill('0') << setw(2)
               << hex << (unsigned int) data[i];
    }
    for (int i = 8-length; i > 0; i--) {
        buffer << "   ";
    }
    std::string *s = new std::string(buffer.str());
    std::unique_ptr<std::string> result(s);
    return result;
}

static void
log_command_info(bool iswrite, const char *prefix,
                 unsigned int length, char *buffer, unsigned int *result)
{
    unsigned int now = get_sysclock_ms();
    stringstream tmp;
    tmp <<  prefix << " " << hex << (unsigned int) length;
    cerr << setfill(' ') << setw(40) << left << tmp.str();
    cerr << "[dt=" << dec << now-last_time << "]" << endl;
    last_time = now;

    tmp.str("");
    if (iswrite) {
        tmp << "    00000000:"
            << *format_buffer((unsigned char *) buffer, length);
        const DSI::DeviceCommand *command =
            DSI::DeviceCommand::find((int) buffer[2]);

        cerr << setfill(' ') << setw(60) << left
             << tmp.str() << command->name();
        if (result)
            cerr << " " << *result;
        cerr << endl;
    } else {
        if (strcmp(prefix, "r 86") != 0) {
            tmp << "    00000000:"
                << *format_buffer((unsigned char *) buffer, buffer[0]);
            cerr << setfill(' ') << setw(60) << left << tmp.str() << "ACK";
            if (result)
                cerr << " " << *result;
            cerr << endl;
        }
    }
}

/**
 * Initialize a generic (base class) DSI device.
 *
 * The generic device will initialize the image size parameters to correspond
 * to a test pattern as well as set the test pattern flag to true.  The
 * generic device has no way of knowing the correct CCD size parameters.
 * Derived classes are responsible for overriding these settings.  If they do
 * not, all you will be able to retrieve is a test pattern image.
 *
 * @param devname
 *
 * @return
 */
DSI::Device::Device(const char *devname) :
    usb_speed((UsbSpeed)UsbSpeed::FULL),
    readout_mode(ReadoutMode::DUAL)
{
    command_sequence_number = 0;
    eeprom_length    = -1;
    log_commands     = true;
    test_pattern     = true;
    vdd_on           = false; /* DSI III default due to amp glow issue (gs)   */
    exposure_time    = 10;
    read_width       = 540;
    read_height_even = 253;
    read_height_odd  = 252;
    read_height      = read_height_even + read_height_odd;
    read_bpp         = 2;
    image_width      = read_width;
    image_height     = read_height;
    image_offset_x   = 0;
    image_offset_y   = 0;

    framebuffer = (unsigned char *) 0;

    binning2x2 = false;
    ccd_temp = -128.5;

    initImager(devname);
}

DSI::Device::~Device()
{
    cerr << "in DSI::Device::~Device" << endl;
    int result;
    if (handle != 0) {
        result = libusb_release_interface(handle, 0);
        cerr << "usb_release_interface(handle, 0) -> " << result << endl;
        libusb_close(handle);
    }
    handle = 0;
    dev = 0;
    command_sequence_number = 0;
}

std::string
DSI::Device::getCameraName()
{
    if (camera_name.empty()) {
        loadCameraName();
    }
    return camera_name;
}

void
DSI::Device::setCameraName(std::string &newname)
{
    setString(newname, 0x1c, 0x20);
    loadCameraName();
    return;
}

void
DSI::Device::initImager(const char *devname) {
    int rc;
    int cnt;
    int i;
    libusb_device **list = NULL;
    struct libusb_device_descriptor desc;

    string bus_name, device_name;
    if (devname != 0) {
        vector<string> foo = tokenize_str(devname, ":,");
        if ((  (foo.size() != 3))
            || (foo[0] != "usb"))
            throw dsi_exception(string("invalid device specifier, ") + devname);
        bus_name = foo[1];
        device_name = foo[2];
    }

    int retcode;

    if (rc = libusb_init(NULL)) {
        throw dsi_exception(libusb_error_name(rc));
    }
    cnt = libusb_get_device_list(NULL, &list);

    handle = NULL;
    for (i = 0; i < cnt; ++i) {
        if (!libusb_get_device_descriptor(list[i], &desc)) {
            if ((desc.idVendor == 0x156c) && (desc.idProduct = 0x0101)) {
                dev = list[i];
                if (libusb_open(dev, &handle)) {
                    dev = NULL;
                }
                break;
            }
        }
    }
    libusb_free_device_list(list, 0);

    if (handle == 0) {
        throw dsi_exception("no DSI device found");
    }

    const size_t size = 0x400;
    unsigned char data[size];

    /* This is monkey code.  SniffUSB shows that the Meade driver is doing
     * this, but I can think of no reason why.  It does the equivalent of the
     * following sequence
     *
     *    - usb_get_descriptor 1
     *    - usb_get_descriptor 1
     *    - usb_get_descriptor 2
     *    - usb_set_configuration 1
     *    - get the serial number
     *    - get the chip name
     *    - ping the device
     *    - reset the device
     *    - load the firmware information
     *    - load the bus speed status
     *
     * libusb says I'm supposed to claim the interface before doing anything to
     * the device.  I'm not clear what "anything" includes, but I can't do it
     * before the usb_set_configuration command or else I get EBUSY.  So I
     * stick it in the middle of the above sequence at what appears to be the
     * first workable point.
     */

    /* According the the libusb 1.0 documentation (but remember this is libusb
     * 0.1 code), the "safe" way to set the configuration on a device is to
     *
     *  1. Query the configuration.
     *  2. If it is not the desired on, set the desired configuration.
     *  3. Claim the interface.
     *  4. Check the configuration to make sure it is what you selected.  If
     *     not, it means someone else got it.
     *
     * However, that does not seem to be what the USB trace is showing from
     * the Windows driver.  It shows the sequence below (sans the claim
     * interface call, but I'm not sure that actually sends data over the
     * wire).
     *
     */
    if ((retcode = libusb_get_descriptor(handle, 0x01, 0x00, data, size)) < 0)
        throw dsi_exception(std::string("failed to get descriptor, ")
                            + strerror(-retcode));

    if ((retcode = libusb_get_descriptor(handle, 0x01, 0x00, data, size)) < 0)
        throw dsi_exception(std::string("failed to get descriptor, ")
                            + strerror(-retcode));

    if ((retcode = libusb_get_descriptor(handle, 0x02, 0x00, data, size)) < 0)
        throw dsi_exception(std::string("failed to get descriptor, ")
                            + strerror(-retcode));

    if ((retcode = libusb_set_configuration(handle, 1)) < 0)
        throw dsi_exception(std::string("failed to set configuration, ")
                            + strerror(-retcode));

    if ((retcode = libusb_claim_interface(handle, 0)) < 0)
        throw dsi_exception(std::string("failed to claim interface, ")
                            + strerror(-retcode));

    /* This is included out of desperation, but it works :-|
     *
     * After running once, an attempt to run a second time appears, for some
     * unknown reason, to leave us unable to read from EP 0x81.  At the very
     * least, we need to clear this EP.  However, believing in the power of
     * magic, we clear them all.
     */

    if ((retcode = libusb_clear_halt(handle, 0x01)) < 0)
        throw dsi_exception(std::string("failed to clear EP 0x01, ")
                            + strerror(-retcode));

    if ((retcode = libusb_clear_halt(handle, 0x81)) < 0)
        throw dsi_exception(std::string("failed to clear EP 0x81, ")
                            + strerror(-retcode));

    if ((retcode = libusb_clear_halt(handle, 0x86)) < 0)
        throw dsi_exception(std::string("failed to clear EP 0x86, ")
                            + strerror(-retcode));


    command(DeviceCommand::PING);
    command(DeviceCommand::RESET);

    loadVersion();
    loadStatus();

    command(DeviceCommand::GET_READOUT_MODE);

    /* I thought this is what the Meade driver was doing but, while it
       appears to be retrieving EEPROM data, it is not this region of the
       EEPROM.  */
    loadCcdChipName();
    loadCameraName();
    // loadSerialNumber();

    // command(DeviceCommand::SET_EXP_MODE, ExposureMode::NORMAL.value());

}

void
DSI::Device::sendRegister(AdRegister adr, unsigned int arg)
{
    unsigned int val = (adr.value() << 9) | (arg & 0x1ff);
    command(DeviceCommand::AD_WRITE, val);
}


void
DSI::Device::loadCameraName()
{
    std::string *ptr = getString(0x1c, 0x20);
    camera_name = *ptr;
    delete ptr;
}

/**
 * Initialized DSI device version information.  This queries the device to
 * determine the device family, model, version, and revision.  However, the
 * device does not actually identify itself at all.  All DSI devices claim to
 * be family 10, model 1, revision 1.  If you really want to know what you
 * have, you need to @see getCCDNumber().
 *
 */
void
DSI::Device::loadVersion()
{
    unsigned int result = command(DeviceCommand::GET_VERSION);
    dsi_family   = (result >> 0x00) & 0xff;
    dsi_model    = (result >> 0x08) & 0xff;
    dsi_firmware_version  = (result >> 0x10) & 0xff;
    dsi_firmware_revision = (result >> 0x18) & 0xff;

    if (dsi_family != 10 || dsi_model != 1 || dsi_firmware_version != 1) {
        ostringstream msg;
        msg << "unsupported imager ("
            << dsi_family << "," << dsi_model << ","
            << dsi_firmware_version << "," << dsi_firmware_revision
            << ") should be (10,1,1,any)";
        throw out_of_range(msg.str());
    }
}

/**
 * Return the value of the specified A-D register.
 *
 * @param reg which register to query.
 *
 * @return register value.
 */
unsigned int
DSI::Device::getAdRegister(DSI::AdRegister reg)
{
    return command(DeviceCommand::AD_READ, reg.value());
}

/**
 * Set the value of the specified A-D register.
 *
 * @param reg which register to set.
 * @param newval new value to be assigned.
 *
 * XXX: What does the value mean?
 */
void
DSI::Device::setAdRegister(DSI::AdRegister reg, unsigned int newval)
{
    unsigned int key = reg.value();
    key = (key << 9) | (newval & 0x1ff);
    command(DeviceCommand::AD_READ, key);
}

/**
 * Retrieve the DSI device current readout mode.
 *
 * @return current readout mode.
 */
DSI::ReadoutMode
DSI::Device::getReadoutMode()
{
    int result = command(DeviceCommand::GET_READOUT_MODE);
    if (!ReadoutMode::isValidValue(result)) {
        ostringstream msg;
        msg << "ReadoutMode value (" << result << ") not recognized";
        throw out_of_range(msg.str());
    }
    return *ReadoutMode::find(result);
}

/**
 * Set the DSI device readout mode.
 *
 * @param rm
 */
void
DSI::Device::setReadoutMode(DSI::ReadoutMode rm)
{
    command(DeviceCommand::GET_READOUT_MODE, rm.value());
}

/**
 * Initialize the internal state to reflect the USB bus speed and whether or
 * not the DSI device has firmware debugging(?) enabled.
 *
 */
void
DSI::Device::loadStatus()
{
    int result = command(DeviceCommand::GET_STATUS);
    int _usbSpeed = (result & 0xff);
    int _fwDebug  = ((result << 8) & 0xff);

    if (!UsbSpeed::isValidValue(result)) {
        ostringstream msg;
        msg << "USB Speed value (" << _usbSpeed << ") not recognized";
        throw out_of_range(msg.str());
    }
    usb_speed = *UsbSpeed::find(result);

    firmware_debug  = (_fwDebug == 1);
}

/**
 * Retrieve the EEPROM length.
 *
 * @return EEPROM length, in bytes.
 */
unsigned int
DSI::Device::getEepromLength()
{
    if (eeprom_length < 0) {
        eeprom_length = command(DeviceCommand::GET_EEPROM_LENGTH);
    }
    return eeprom_length;
}

/**
 * Read one byte value from the EEPROM.
 *
 * @param __offset offset from EEPROM start of byte to read
 *
 * @return the value of the EEPROM byte at __offset.
 */
unsigned char
DSI::Device::getEepromByte(int __offset)
{
    return command(DeviceCommand::GET_EEPROM_BYTE, __offset);
}

unsigned char
DSI::Device::setEepromByte(unsigned char __val, int __offset) {
    return command(DeviceCommand::SET_EEPROM_BYTE, __offset | (__val << 8));
}

void
DSI::Device::setEepromData(unsigned char *__buffer, int __offset, int __length) {
    for (int i = 0; i < __length; i++) {
        setEepromByte(__buffer[i], __offset+i);
    }
}

/**
 * Retrieve a segment of the EEPROM data as a sequence of bytes.  The result
 * will be allocated on the heap as an array of unsigned bytes and must be
 * deleted by the caller.
 *
 *     unsigned char *eepromData = DSI::Device::getEepromData(0,8);
 *     ...
 *     delete [] eepromData;
 *
 * @param __offset EEPROM offset for start of data.
 * @param __length length of EEPROM region to read.
 *
 * @return
 */
unsigned char *
DSI::Device::getEepromData(int __offset, int __length)
{
    int eepromLength = getEepromLength();
    unsigned char *buffer = new unsigned char [__length];
    for (int i = 0; i < __length; i++) {
        if (__offset >= eepromLength)
            return buffer;
        buffer[i] = getEepromByte(__offset++);
    }
    return buffer;
}

/**
 * Initialize the DSI serial number by reading the EEPROM data.
 *
 * NB: the Meade driver appears to *write* to the EEPROM if the serial number
 * looks bogus.  It write a "serial number" generated from the current
 * date/time which is just plain weird.  I suspect that code was an artifact
 * of early engineering samples provided to the original developer that may
 * not have had serial number information burned in the EEPROM.  At least,
 * that would make some sense.
 */
void
DSI::Device::loadSerialNumber()
{
    unsigned char *eepromData = getEepromData(0, 8);
    serial_number = 0;
    for (int i = 0; i < 8; i++) {
        unsigned long long x = (unsigned int) eepromData[i];
        serial_number += x << (i * 8);
    }
    delete [] eepromData;
}

/**
 * Initialize the CCD chip name by reading the EEPROM data where it is stored.
 *
 */
void
DSI::Device::loadCcdChipName()
{
    std::string *ptr = getString(8, 20);
    ccd_chip_name = *ptr;
    delete ptr;
    if (ccd_chip_name == "None")
        ccd_chip_name = "ICX404AK";
}

/**
 * Return the CCD chip name for this device.
 *
 * @return string value for the CCD chip name.
 */
std::string
DSI::Device::getCcdChipName()
{
    return std::string(ccd_chip_name);
}

void
DSI::Device::setExposureTime(double exptime)
{
    exposure_time = (exptime > 0 ? 10000 * exptime : 1);
};

double
DSI::Device::getExposureTime()
{
    return 0.0001 * exposure_time;
};

/**
 * Retrieve a string value from the specified EEPROM region.  The string will
 * be allocated on the heap and must be deleted by the caller.
 *
 *     std::string *foo = DSI::Device::getString(8, 20);
 *     ...
 *     delete [] foo;
 *
 * @param __offset EEPROM offset for start of string.
 * @param __length length of EEPROM region to read.
 *
 * @return allocated string formed from EEPROM data.
 */

std::string *
DSI::Device::getString(int __offset, int __length) {
    unsigned char *eepromData = getEepromData(__offset, __length);
    std::string result;
    if ((eepromData[0] == 0xff) || (eepromData[1] == 0xff) || (eepromData[2] == 0xff)) {
        result.assign("None");
    } else {
        result.assign((char *)eepromData+1, eepromData[0]);
    }
    delete [] eepromData;
    return new string(result);
}

void
DSI::Device::setString(std::string __value, int __offset, int __length) {
    unsigned char *value = new unsigned char[__length];
    memset(value, 0xff, __length);
    int n;
    if (__value.length() > __length - 2) {
        n = __length - 2;
    } else {
        n = __value.length();
    }
    value[0] = n;
    for (int i = 1; i < n+1; i++) {
        value[i] = __value[i-1];
    }
    setEepromData(value, __offset, __length);
}

unsigned char *
DSI::Device::getTestPattern()
{
    return getImage(DeviceCommand::TEST_PATTERN, 10);

}

unsigned char *
DSI::Device::getImage()
{
    if (test_pattern)
        return getTestPattern();
    else {
        // unsigned char *image = getImage(DeviceCommand::TRIGGER, 10);
        // delete [] image;
        return getImage(DeviceCommand::TRIGGER, exposure_time);
    }
}

unsigned char *
DSI::Device::getImage(int howlong)
{
    if (test_pattern)
        return getTestPattern();
    else {
        return getImage(DeviceCommand::TRIGGER, howlong);
    }
}

int
DSI::Device::getGain()
{
    return command(DeviceCommand::GET_GAIN);
}

int
DSI::Device::setGain(int gain)
{
    if ((gain < 0) || (gain > 63)) {
        return -1;
    }
    return command(DeviceCommand::SET_GAIN, gain);
}

void
DSI::Device::setVddOn(bool s)
{
    vdd_on = s;
}

int
DSI::Device::startExposure(int howlong, int gain, int offs)
{
        // Monkey code.  Monkey see (SniffUSB), monkey do).  Some part of this
        // is required because w/o it, I get segfaults on the second attempt
        // to run the code.

        int status;
	int interlaced;

	/* for safety reasons, just in case howlong is zero (gs) */
	exposure_time = (howlong > 0 ? howlong : 1);


	// Check for DSI III: if not interlaced, it has to be DSI III.
	// Not very nice, but simplifies retrofitting the DSI I/II code (gs)

	if (read_height_even > 0)
	    interlaced = 1;
	else
	    interlaced = 0;

	if (binning2x2)
		enable2x2Binning();

	if (interlaced) // original DSI I/II code
	{		// better not touch otherwise it could break (gs)

            // status = command(DeviceCommand::GET_TEMP);
            // status = command(DeviceCommand::GET_EXP_MODE);
            // status = command(DeviceCommand::SET_GAIN,     0x3f);
            // status = command(DeviceCommand::SET_OFFSET,   0x00);
            status = command(DeviceCommand::SET_EXP_TIME, exposure_time);
            if (exposure_time < 10000) {
                status = command(DeviceCommand::SET_READOUT_SPD,
                                 ReadoutSpeed::HIGH.value());
                status = command(DeviceCommand::SET_NORM_READOUT_DELAY, 3);
                status = command(DeviceCommand::SET_READOUT_MODE,
                                 ReadoutMode::DUAL.value());
            } else {
                status = command(DeviceCommand::SET_READOUT_SPD,
                                 ReadoutSpeed::NORMAL.value());
                status = command(DeviceCommand::SET_NORM_READOUT_DELAY, 7);
                status = command(DeviceCommand::SET_READOUT_MODE,
                                 ReadoutMode::SINGLE.value());
            }

            status = command(DeviceCommand::GET_READOUT_MODE);
            if (exposure_time < VDD_TRH) {
                status = command(DeviceCommand::SET_VDD_MODE,
                                 VddMode::ON.value());
            } else {
                status = command(DeviceCommand::SET_VDD_MODE,
                                 VddMode::AUTO.value());
            }
            status = command(DeviceCommand::SET_GAIN, 0);
            // status = command(DeviceCommand::GET_READOUT_MODE);
            status = command(DeviceCommand::SET_OFFSET, 0x0ff);
            status = command(DeviceCommand::SET_FLUSH_MODE,
                             FlushMode::CONTINUOUS.value());
            status = command(DeviceCommand::GET_READOUT_MODE);
            status = command(DeviceCommand::GET_EXP_TIME);

            status = command(DeviceCommand::TRIGGER);

	}
	else // This is what the DSI III monkey found while sniffing USB (gs)
	{
	    cerr << "Epsosure time: " << exposure_time << ", Gain: "
                 << gain << ", Offset: " << offs << endl;

	    // first, set gain and offset
            status = command(DeviceCommand::SET_GAIN, gain);
            status = command(DeviceCommand::SET_OFFSET, offs);

	    // then, set exposure time
            status = command(DeviceCommand::SET_EXP_TIME, exposure_time);

	    // next, set readout speed and delay

	    // Readout speed appears to be always high for DSI III
            status = command(DeviceCommand::SET_READOUT_SPD,
                             ReadoutSpeed::HIGH.value());

	    // Norm readout delay appears to be always 4 for DSI III
            status = command(DeviceCommand::SET_NORM_READOUT_DELAY, 4);

	    // now, set readout mode, which appears to behave like DSI I/II

            if (exposure_time < 10000)
	    {
                status = command(DeviceCommand::SET_READOUT_MODE,
                                ReadoutMode::DUAL.value());
            }
            else
            {
                 status = command(DeviceCommand::SET_READOUT_MODE,
                                  ReadoutMode::SINGLE.value());
            }

	    // now, get readout mode
            status = command(DeviceCommand::GET_READOUT_MODE);

	    // next, set Vdd mode ...
            // Vdd appears to be always on in envisage for DSI III

	    if ((vdd_on) || (exposure_time < VDD_TRH))
            	status = command(DeviceCommand::SET_VDD_MODE,
                                 VddMode::ON.value());
            else
            	status = command(DeviceCommand::SET_VDD_MODE,
                                 VddMode::OFF.value());

	    // next step is to set flush mode
            status = command(DeviceCommand::SET_FLUSH_MODE,
                             FlushMode::CONTINUOUS.value());

	    // for some reason, we have to get readout mode 
	    // and exposure time again
            // probably this is not necessary, but better mimic
            // the Meade driver here ...

            status = command(DeviceCommand::GET_READOUT_MODE);
            status = command(DeviceCommand::GET_EXP_TIME);

	    // and finally, we are ready to pull the trigger ...

            status = command(DeviceCommand::TRIGGER);

	}

	/* image download for short exposures (gs)
	   If exposure time is smaller than 2s, download image immediately
	   into framebuffer, otherwise there might be problems with
           short exposure frames at least with DSI III                        */

	if (exposure_time < LONGEXP)
	    downloadImage();

        return 0;
}

unsigned char *
DSI::Device::downloadImage()
{
        int status;
        int transfered;
	int interlaced;
	int rawtemp;
        unsigned int t_read_width;
        unsigned int t_read_height_even;
        unsigned int t_read_height_odd;
        unsigned int t_read_height;
        unsigned int t_read_bpp;
        unsigned int t_image_width;
        unsigned int t_image_height;
        unsigned int t_image_offset_x;
        unsigned int t_image_offset_y;

	if (read_height_even > 0)
	    interlaced = 1;
	else
	    interlaced = 0;

        /* binning currently only supported for DSI III (gs) */

	if (binning2x2)
	{
            t_read_width       = ((read_bpp * read_width / 512) + 1) * 128;
            t_read_height_even = read_height_even / 2;
            t_read_height_odd  = read_height_odd / 2;
            t_image_width      = image_width / 2;
            t_image_height     = image_height / 2;
            t_image_offset_x   = image_offset_x / 2;
            t_image_offset_y   = image_offset_y / 2;
        }
        else
	{
            t_read_width       = ((read_bpp * read_width / 512) + 1) * 256;
            t_read_height_even = read_height_even;
            t_read_height_odd  = read_height_odd;
            t_image_width      = image_width;
            t_image_height     = image_height;
            t_image_offset_x   = image_offset_x;
            t_image_offset_y   = image_offset_y;
        }

        t_read_height      = t_read_height_even + t_read_height_odd;
        t_read_bpp         = read_bpp;

        unsigned int odd_size  = t_read_bpp * t_read_width * t_read_height_odd;
        unsigned int even_size = t_read_bpp * t_read_width * t_read_height_even;
        unsigned int all_size  = t_read_bpp * t_read_width * t_read_height;

        unsigned char *odd_data = new unsigned char[odd_size];

	unsigned char *even_data;

	if (interlaced)
            even_data  = new unsigned char[even_size];

        framebuffer  = new unsigned char[all_size];

	if (interlaced)
	{

            /* XXX: There has to be  a way to calculate a more optimal readout
               time here. */
            status = libusb_bulk_transfer(handle, 0x86, even_data, even_size,
                                          &transfered, 60000*MILLISEC);
            if (log_commands) {
                log_command_info(false, "r 86", (status > 0 ? status : 0),
                                 (char *) even_data, 0);

                cerr << dec
                     << "read even data, status = (" << status << ") "
                     << (status > 0 ? "" : strerror(-status)) << endl
                     << "    requested " << even_size << " bytes "
                     << t_read_width << " x " << t_read_height_even
                     << " (even pixels)" << endl
                     << "Transfered: " << transfered << " bytes" << endl;

            }

            if (status != 0) {
                stringstream ss;
                ss << dec
                   << "read even data, status = (" << status << ") "
                   << strerror(-status);
                throw device_read_error(ss.str());
            }

            status = libusb_bulk_transfer(handle, 0x86, odd_data,  odd_size,
                                          &transfered, 60000*MILLISEC);
            if (log_commands) {
                log_command_info(false, "r 86", (status > 0 ? status : 0),
                                 (char *) odd_data, 0);

                cerr << dec
                     << "read odd data, status = (" << status <<  ") "
                     << (status > 0 ? "" : strerror(-status)) << endl
                     << "    requested " << odd_size << " bytes "
                     << t_read_width << " x " << t_read_height_odd
                     << " (odd pixels)" << endl
                     << "Transfered: " << transfered << " bytes" << endl;
            }

            if (status != 0) {
                stringstream ss;
                ss << dec
                   << "read odd data, status = (" << status <<  ") "
                   << strerror(-status);
                throw device_read_error(ss.str());
            }
	}
	else // progressive mode for DSI III (gs)
	{
	    if ((!vdd_on) && (exposure_time >= VDD_TRH))
                status = command(DeviceCommand::SET_VDD_MODE,
                                 VddMode::ON.value());

            status = libusb_bulk_transfer(handle, 0x86, odd_data, odd_size,
                                          &transfered, 60000*MILLISEC);
            if (log_commands) {
                log_command_info(false, "r 86", (status > 0 ? status : 0),
                                 (char *) odd_data, 0);

                cerr << dec
                     << "read progressive data, status = (" << status <<  ") "
                     << endl
                     << "    requested " << odd_size << " bytes "
                     << t_read_width << " x " << t_read_height_odd
                     << " (pixels)" << endl
                     << "Transfered: " << transfered << " bytes" << endl;
            }

            if (status != 0) {
                stringstream ss;
                ss << dec
                   << "read progressive data, status = (" << status <<  ") ";
                throw device_read_error(ss.str());
            }
	}

        /* Update temperature for devices with sensor (gs) */

	if (has_tempsensor)
	{
            rawtemp = command(DeviceCommand::GET_TEMP);
	    ccd_temp = floor((float) rawtemp / 25.6) / 10.0;
	}

        status = command(DeviceCommand::GET_EXP_MODE);

	/* disable 2x2 binning after downloading image (gs) */
	disable2x2Binning();

	unsigned char msb, lsb, is_odd;
	unsigned int x_ptr, line_start, y_ptr, read_ptr,write_ptr;
	char* even = (char *) even_data;
	char* odd  = (char *) odd_data;

        if (log_commands)
            cerr	<< "t_image_height  ="  << t_image_height
			<< endl
			<< "t_image_width   ="	<< t_image_width
			<< endl
			<< "t_image_offset_x="  << t_image_offset_x
			<< endl
			<< "t_image_offset_y="  << t_image_offset_y
			<< endl
			<< "t_read_width    ="  << t_read_width
			<< endl
			<< "t_read_height   ="  << t_read_height
			<< endl
			<< "t_read_bpp      ="  << t_read_bpp
			<< endl;

	if (interlaced)
	{
	    for (write_ptr = y_ptr = 0; y_ptr < t_image_height; y_ptr++)
	    {
                line_start = t_read_width * ((y_ptr + t_image_offset_y) /2);
                is_odd = (y_ptr + t_image_offset_y) % 2;

                cerr << "starting image row " << y_ptr
                     << ", write_ptr=" << write_ptr
                     << ", line_start=" << line_start
                     << ", is_odd=" << (is_odd == 0 ? 0 : 1)
                     << ", read_ptr=" << (line_start+t_image_offset_x)*2
                     << endl;

                for (x_ptr = 0; x_ptr < t_image_width ; x_ptr++)
                {
                    read_ptr =  (line_start + x_ptr + t_image_offset_x) * 2;
                    if (is_odd == 1) // odd line
                    {
                        msb=odd[read_ptr];
                        lsb=odd[read_ptr + 1];
                    } else {		// even line
                        msb=even[read_ptr];
                        lsb=even[read_ptr + 1];
                    }
                    framebuffer[write_ptr++] = msb;
                    framebuffer[write_ptr++] = lsb;
                }
            }
	}
	else
	{
	    for (write_ptr = y_ptr = 0; y_ptr < t_image_height; y_ptr++)
	    {
                line_start = t_read_width * (y_ptr + t_image_offset_y);

                // cerr << "starting image row " << y_ptr
                //      << ", write_ptr=" << write_ptr
                //      << ", line_start=" << line_start
                //      << ", read_ptr=" << (line_start+t_image_offset_x)*2
                //      << endl;
                for (x_ptr = 0; x_ptr < t_image_width ; x_ptr++)
                {
                    read_ptr =  (line_start + x_ptr + t_image_offset_x) * 2;

                    msb=odd[read_ptr];
                    lsb=odd[read_ptr + 1];

                    framebuffer[write_ptr++] = msb;
                    framebuffer[write_ptr++] = lsb;
                }
            }
	}

    if (log_commands)
            cerr << "write_ptr=" << write_ptr << endl;

    delete [] odd_data;

    if (interlaced)
    	delete [] even_data;

    return framebuffer;

    throw dsi_exception("unsupported image command");
}

/* ask camera for remaining exposure time for long exposures (gs) */

int
DSI::Device::ExposureInProgress()
{
    int time_left;

    if (exposure_time >= LONGEXP)
    {
	time_left = command(DeviceCommand::GET_EXP_TIMER_COUNT);

	if (time_left > 14000)
	{
	    usleep(5e5); /* wait half a second before checking again */
	    return(1);
	}
	else
	{
	    downloadImage();
	    return(0);
	}
    }

    return(0);
}

unsigned char *
DSI::Device::ccdFramebuffer()
{
    return(framebuffer);
}

void
DSI::Device::set1x1Binning()
{
    binning2x2 = false;
}

void
DSI::Device::set2x2Binning()
{
    if (is_binnable)
    {
        binning2x2 = true;
    }

}

void
DSI::Device::enable2x2Binning()
{
    unsigned int t_read_height_odd = read_height_odd/2;

    if (is_binnable)
    {
        command(DeviceCommand::GET_EXP_MODE);
        command(DeviceCommand::SET_EXP_MODE, ExposureMode::BIN2X2.value());
        command(DeviceCommand::SET_ROW_COUNT_ODD, t_read_height_odd);
    }
}

void
DSI::Device::disable2x2Binning()
{
    unsigned int t_read_height_odd = read_height_odd;

    command(DeviceCommand::GET_EXP_MODE);
    command(DeviceCommand::SET_EXP_MODE, ExposureMode::NORMAL.value());
    command(DeviceCommand::SET_ROW_COUNT_ODD, t_read_height_odd);
}

unsigned char *
DSI::Device::getImage(DeviceCommand __command, int howlong)
{
    int transfered;

    if ((  (__command == DeviceCommand::TRIGGER))
        || (__command == DeviceCommand::TEST_PATTERN)) {

        // Monkey code.  Monkey see (SniffUSB), monkey do).  Some part of this
        // is required because w/o it, I get segfaults on the second attempt
        // to run the code.
        int status;
        int interlaced;
	int rawtemp;

	if (read_height_even > 0)
	    interlaced = 1;
	else
	    interlaced = 0;

	if (binning2x2)
		enable2x2Binning();

	if (interlaced) // original DSI I/II code
	{		// better not touch otherwise it could break

            // status = command(DeviceCommand::GET_TEMP);
            // status = command(DeviceCommand::GET_EXP_MODE);
            // status = command(DeviceCommand::SET_GAIN,     0x3f);
            // status = command(DeviceCommand::SET_OFFSET,   0x00);
            status = command(DeviceCommand::SET_EXP_TIME, howlong);
            if (howlong < 10000) {
                status = command(DeviceCommand::SET_READOUT_SPD,
                                 ReadoutSpeed::HIGH.value());
                status = command(DeviceCommand::SET_NORM_READOUT_DELAY, 3);
                status = command(DeviceCommand::SET_READOUT_MODE,
                                 ReadoutMode::DUAL.value());
            } else {
                status = command(DeviceCommand::SET_READOUT_SPD,
                                 ReadoutSpeed::NORMAL.value());
                status = command(DeviceCommand::SET_NORM_READOUT_DELAY, 7);
                status = command(DeviceCommand::SET_READOUT_MODE,
                                 ReadoutMode::SINGLE.value());
            }

            status = command(DeviceCommand::GET_READOUT_MODE);
            if (howlong < VDD_TRH) {
                status = command(DeviceCommand::SET_VDD_MODE,
                                 VddMode::ON.value());
            } else {
                status = command(DeviceCommand::SET_VDD_MODE,
                                 VddMode::AUTO.value());
            }
            status = command(DeviceCommand::SET_GAIN, 0);
            // status = command(DeviceCommand::GET_READOUT_MODE);
            status = command(DeviceCommand::SET_OFFSET, 0x0ff);
            status = command(DeviceCommand::SET_FLUSH_MODE,
                             FlushMode::CONTINUOUS.value());
            status = command(DeviceCommand::GET_READOUT_MODE);
            status = command(DeviceCommand::GET_EXP_TIME);

            status = command(__command);

            // XXX: wait for exposure to complete. signal handler to set abort
            // flag then clean up connection.
	}
	else // This is what the DSI III monkey found while sniffing USB
	{
	    // first, set exposure time to zero
            status = command(DeviceCommand::SET_EXP_TIME, 0);

	    // next, set readout speed and delay

	    // Readout speed appears to be always high for DSI III
            status = command(DeviceCommand::SET_READOUT_SPD,
                             ReadoutSpeed::HIGH.value());

            status = command(DeviceCommand::SET_NORM_READOUT_DELAY, 3);

	    // now, set readout mode, which appears to behaves like DSI I/II

            if (howlong < 10000)
	    {
                status = command(DeviceCommand::SET_READOUT_MODE,
                                ReadoutMode::DUAL.value());
            }
            else
            {
                 status = command(DeviceCommand::SET_READOUT_MODE,
                                  ReadoutMode::SINGLE.value());
            }

	    // now, get readout mode
            status = command(DeviceCommand::GET_READOUT_MODE);

	    // next, set Vdd mode ...
            // Vdd appears to be always on in envisage for DSI III
            status = command(DeviceCommand::SET_VDD_MODE,VddMode::ON.value());

	    // next step is to set flush mode
            status = command(DeviceCommand::SET_FLUSH_MODE,
                             FlushMode::CONTINUOUS.value());

	    // then, set gain and offset
            // here, we use default values for gain and offset 
            status = command(DeviceCommand::SET_GAIN, 0x00);
            status = command(DeviceCommand::SET_OFFSET, 0x7f);

	    // next, set real exposure time
            status = command(DeviceCommand::SET_EXP_TIME, howlong);

	    // again, set readout speed and delay

	    // Readout speed appears to be always high for DSI III
            status = command(DeviceCommand::SET_READOUT_SPD,
                             ReadoutSpeed::HIGH.value());

            status = command(DeviceCommand::SET_NORM_READOUT_DELAY, 4);

	    // now, set readout mode again

            if (howlong < 10000)
	    {
                status = command(DeviceCommand::SET_READOUT_MODE,
                                ReadoutMode::DUAL.value());
            }
            else
            {
                 status = command(DeviceCommand::SET_READOUT_MODE,
                                  ReadoutMode::SINGLE.value());
            }

	    // next, get readout mode one more
            status = command(DeviceCommand::GET_READOUT_MODE);

	    // again, set Vdd mode ...

           status = command(DeviceCommand::SET_VDD_MODE,VddMode::ON.value());

	    // next, again set flush mode
            status = command(DeviceCommand::SET_FLUSH_MODE,
                             FlushMode::CONTINUOUS.value());

	    // for some reason, we have to get readout mode 
	    // and exposure time again
            status = command(DeviceCommand::GET_READOUT_MODE);
            status = command(DeviceCommand::GET_EXP_TIME);

	    // and finally, we are ready to pull the trigger ...

            status = command(__command);
	}

        unsigned int t_read_width;
        unsigned int t_read_height_even;
        unsigned int t_read_height_odd;
        unsigned int t_read_height;
        unsigned int t_read_bpp;
        unsigned int t_image_width;
        unsigned int t_image_height;
        unsigned int t_image_offset_x;
        unsigned int t_image_offset_y;

        /* XXX: I'm a bit confused about the test pattern.  It *looks* like
         * the camera always sends back the same amount of data, but the
         * interpretation is different for the test pattern.  So,
         */

        if (__command == DeviceCommand::TRIGGER) {

	    if (binning2x2)
	    {
                t_read_width       = ((read_bpp * read_width / 512) + 1) * 128;
                t_read_height_even = read_height_even / 2;
                t_read_height_odd  = read_height_odd / 2;
                t_image_width      = image_width / 2;
                t_image_height     = image_height / 2;
                t_image_offset_x   = image_offset_x / 2;
                t_image_offset_y   = image_offset_y /2;
            }
            else
	    {
                t_read_width       = ((read_bpp * read_width / 512) + 1) * 256;
                t_read_height_even = read_height_even;
                t_read_height_odd  = read_height_odd;
                t_image_width      = image_width;
                t_image_height     = image_height;
                t_image_offset_x   = image_offset_x;
                t_image_offset_y   = image_offset_y;
            }

            t_image_offset_x   = image_offset_x;
            t_image_offset_y   = image_offset_y;
            t_read_height      = t_read_height_even + t_read_height_odd;
            t_read_bpp         = read_bpp;

        } else {

            /* We ignore the actual CCD chip size information for the test
             * pattern image and use our temporary values.
             */

            t_read_width       = 540;

	    if (interlaced)
	    {
                t_read_height_even = 0xfd;
                t_read_height_odd  = 0xfc;
            }
	    else // progressive mode
	    {
                t_read_height_even = 0x000;
                t_read_height_odd  = 0x1f9;
            }

            t_read_height      = t_read_height_even + t_read_height_odd;
            t_read_bpp         = 2;
            t_image_width      = t_read_width;
            t_image_height     = t_read_height;
            t_image_offset_x   = 0;
            t_image_offset_y   = 0;
        }

        unsigned int odd_size  = t_read_bpp * t_read_width * t_read_height_odd;
        unsigned int even_size = t_read_bpp * t_read_width * t_read_height_even;
        unsigned int all_size  = t_read_bpp * t_read_width * t_read_height;

        unsigned char *odd_data = new unsigned char[odd_size];

	unsigned char *even_data;

	if (interlaced)
            even_data  = new unsigned char[even_size];

        framebuffer  = new unsigned char[all_size];

        /* The Meade driver seems to only issue a GET_EXP_TIME_COUNT command
         * when the exposure is over about 2 seconds (count = 20,000).  From
         * testing, it looks like if I try to issue this command for exposures
         * shorter, the camera locks up and has to be physically disconnected
         * and reconnected.
         */

        int time_left = howlong;
        while (time_left > 5000) {
            int sleep_time = 100 * (time_left - 5000);
            usleep(sleep_time);
            time_left = command(DeviceCommand::GET_EXP_TIMER_COUNT);
        }

        if (last_time == 0)
            last_time = get_sysclock_ms();

	if (interlaced)
	{

            /* XXX: There has to be  a way to calculate a more optimal readout
               time here. */
            status = libusb_bulk_transfer(handle, 0x86, even_data, even_size,
                                          &transfered, 60000*MILLISEC);
            if (log_commands) {
                log_command_info(false, "r 86", (status > 0 ? status : 0),
                                 (char *) even_data, 0);

                cerr << dec
                     << "read even data, status = (" << status << ") "
                     << (status > 0 ? "" : strerror(-status)) << endl
                     << "    requested " << even_size << " bytes "
                     << t_read_width << " x "
                     << t_read_height_even << " (even pixels)" << endl;

            }

            if (status < 0) {
                stringstream ss;
                ss << dec
                   << "read even data, status = (" << status << ") "
                   << strerror(-status);
                throw device_read_error(ss.str());
            }

	}

        status = libusb_bulk_transfer(handle, 0x86, odd_data,
                                      odd_size, &transfered, 60000*MILLISEC);
        if (log_commands) {
            log_command_info(false, "r 86",
                             (status > 0 ? status : 0), (char *) even_data, 0);

            cerr << dec
                 << "read odd data, status = (" << status <<  ") "
                 << (status > 0 ? "" : strerror(-status)) << endl
                 << "    requested " << odd_size << " bytes "
                 << t_read_width << " x "
                 << t_read_height_odd << " (odd pixels)" << endl;
        }

        if (status < 0) {
            stringstream ss;
            ss << dec
               << "read odd data, status = (" << status <<  ") "
               << strerror(-status);
            throw device_read_error(ss.str());
        }


	if (has_tempsensor)
	{
            rawtemp = command(DeviceCommand::GET_TEMP);
	    ccd_temp = floor((float) rawtemp / 25.6) / 10.0;
	}

        status = command(DeviceCommand::GET_EXP_MODE);

	disable2x2Binning();

	unsigned char msb, lsb, is_odd;
	unsigned int x_ptr, line_start, y_ptr, read_ptr,write_ptr;
	char* even = (char *) even_data;
	char* odd  = (char *) odd_data;

        if (log_commands)
            cerr	<< "t_image_height  ="  << t_image_height
			<< endl
			<< "t_image_width   ="	<< t_image_width
			<< endl
			<< "t_image_offset_x="  << t_image_offset_x
			<< endl
			<< "t_image_offset_y="  << t_image_offset_y
			<< endl
			<< "t_read_width    ="  << t_read_width
			<< endl
			<< "t_read_height   ="  << t_read_height
			<< endl
			<< "t_read_bpp      ="  << t_read_bpp
			<< endl;

	if (interlaced)
	{
	    for (write_ptr = y_ptr = 0; y_ptr < t_image_height; y_ptr++)
	    {
                line_start = t_read_width * ((y_ptr + t_image_offset_y) /2);
                is_odd = (y_ptr + t_image_offset_y) % 2;

                cerr << "starting image row " << y_ptr
                     << ", write_ptr=" << write_ptr
                     << ", line_start=" << line_start
                     << ", is_odd=" << (is_odd == 0 ? 0 : 1)
                     << ", read_ptr=" << (line_start+t_image_offset_x)*2 << endl;
                for (x_ptr = 0; x_ptr < t_image_width ; x_ptr++)
                {
                    read_ptr =  (line_start + x_ptr + t_image_offset_x) * 2;
                    if (is_odd == 1) // odd line
                    {
                        msb=odd[read_ptr];
                        lsb=odd[read_ptr + 1];
                    } else {		// even line
                        msb=even[read_ptr];
                        lsb=even[read_ptr + 1];
                    }
                    framebuffer[write_ptr++] = msb;
                    framebuffer[write_ptr++] = lsb;
                }
	    }
	}
	else
	{
	    for (write_ptr = y_ptr = 0; y_ptr < t_image_height; y_ptr++)
	    {
                line_start = t_read_width * (y_ptr + t_image_offset_y);

                //cerr << "starting image row " << y_ptr
                //     << ", write_ptr=" << write_ptr
                //     << ", line_start=" << line_start
                //     << ", read_ptr=" << (line_start+t_image_offset_x)*2 << endl;
                for (x_ptr = 0; x_ptr < t_image_width ; x_ptr++)
                {
                    read_ptr =  (line_start + x_ptr + t_image_offset_x) * 2;

                    msb=odd[read_ptr];
                    lsb=odd[read_ptr + 1];

                    framebuffer[write_ptr++] = msb;
                    framebuffer[write_ptr++] = lsb;
                }
            }
	}


        if (log_commands)
            cerr << "write_ptr=" << write_ptr << endl;

        delete [] odd_data;

	if (interlaced)
        	delete [] even_data;

        return framebuffer;

    }

    throw dsi_exception("unsupported image command");

}

/**
 * Internal helper for sending a command to the DSI device.  If the command is
 * one which requires no parameters, then the actual execution will be
 * delegated to command(DeviceCommand,int,int), otherwise a dsi_exception is
 * thrown.
 *
 * @param __command command to be executed.
 *
 * @return decoded command response.
 */
unsigned int
DSI::Device::command(DeviceCommand __command)
{

    // This is the one place where having class-based enums instead of
    // built-in enums is annoying: you can't use a switch statement here.
    if ((  (__command == DeviceCommand::PING))
        || (__command == DeviceCommand::RESET)
        || (__command == DeviceCommand::ABORT)
        || (__command == DeviceCommand::TRIGGER)
        || (__command == DeviceCommand::PS_ON)
        || (__command == DeviceCommand::PS_OFF)
        || (__command == DeviceCommand::CCD_VDD_ON)
        || (__command == DeviceCommand::CCD_VDD_OFF)
        || (__command == DeviceCommand::TEST_PATTERN)
        || (__command == DeviceCommand::ERASE_EEPROM)
        || (__command == DeviceCommand::GET_VERSION)
        || (__command == DeviceCommand::GET_STATUS)
        || (__command == DeviceCommand::GET_TIMESTAMP)
        || (__command == DeviceCommand::GET_EXP_TIME)
        || (__command == DeviceCommand::GET_EXP_TIMER_COUNT)
        || (__command == DeviceCommand::GET_EEPROM_VIDPID)
        || (__command == DeviceCommand::GET_EEPROM_LENGTH)
        || (__command == DeviceCommand::GET_GAIN)
        || (__command == DeviceCommand::GET_EXP_MODE)
        || (__command == DeviceCommand::GET_VDD_MODE)
        || (__command == DeviceCommand::GET_FLUSH_MODE)
        || (__command == DeviceCommand::GET_CLEAN_MODE)
        || (__command == DeviceCommand::GET_READOUT_SPD)
        || (__command == DeviceCommand::GET_READOUT_MODE)
        || (__command == DeviceCommand::GET_OFFSET)
        || (__command == DeviceCommand::GET_NORM_READOUT_DELAY)
        || (__command == DeviceCommand::GET_TEMP))
        return command(__command, 0, 3);

    throw dsi_exception("unsupported device command " + __command.name());
};

/**
 * Internal helper for sending a command to the DSI device.  This determines
 * what the length of the actual command will be and then delgates to
 * command(DeviceCommand,int,int) or command(DeviceCommand).
 *
 * @param __command command to be executed.
 * @param __option command argument, ignored for SOME commands.
 *
 * @return decoded command response.
 */
unsigned int
DSI::Device::command(DeviceCommand __command, int __option)
{
    // This is the one place where having class-based enums instead of
    // built-in enums is annoying: you can't use a switch statement here.
    if ((   __command == DeviceCommand::GET_EEPROM_BYTE)
        || (__command == DeviceCommand::SET_GAIN)
        || (__command == DeviceCommand::SET_EXP_MODE)
        || (__command == DeviceCommand::SET_VDD_MODE)
        || (__command == DeviceCommand::SET_FLUSH_MODE)
        || (__command == DeviceCommand::SET_CLEAN_MODE)
        || (__command == DeviceCommand::SET_READOUT_SPD)
        || (__command == DeviceCommand::SET_READOUT_MODE)
        || (__command == DeviceCommand::AD_READ)
        || (__command == DeviceCommand::GET_DEBUG_VALUE)) {
        return command(__command, __option, 4);
    } else if ((   __command == DeviceCommand::SET_EEPROM_BYTE)
               || (__command == DeviceCommand::SET_OFFSET)
               || (__command == DeviceCommand::SET_NORM_READOUT_DELAY)
               || (__command == DeviceCommand::SET_ROW_COUNT_ODD)
               || (__command == DeviceCommand::SET_ROW_COUNT_EVEN)
               || (__command == DeviceCommand::AD_WRITE)) {
        return command(__command, __option, 5);
    } else if ((   __command == DeviceCommand::SET_EXP_TIME)
               || (__command == DeviceCommand::SET_EEPROM_VIDPID)) {
        return command(__command, __option, 7);
    } else {
        return command(__command);
    }

    throw dsi_exception("unsupported device command " + __command.name());
}

/**
 * Internal helper for sending a command to the DSI device.  This determines
 * what the expected response length is and then delegates actually processing
 * to command(DeviceCommand,int,int,int).
 *
 * @param __command command to be executed.
 * @param __option
 * @param __length
 *
 * @return decoded command response.
 */
unsigned int
DSI::Device::command(DeviceCommand __command, int __option, int __length)
{
    // This is the one place where having class-based enums instead of
    // built-in enums is annoying: you can't use a switch statement here.
    if ((  (__command == DeviceCommand::PING))
        || (__command == DeviceCommand::RESET)
        || (__command == DeviceCommand::ABORT)
        || (__command == DeviceCommand::TRIGGER)
        || (__command == DeviceCommand::TEST_PATTERN)
        || (__command == DeviceCommand::SET_EEPROM_BYTE)
        || (__command == DeviceCommand::SET_GAIN)
        || (__command == DeviceCommand::SET_OFFSET)
        || (__command == DeviceCommand::SET_EXP_TIME)
        || (__command == DeviceCommand::SET_VDD_MODE)
        || (__command == DeviceCommand::SET_FLUSH_MODE)
        || (__command == DeviceCommand::SET_CLEAN_MODE)
        || (__command == DeviceCommand::SET_READOUT_SPD)
        || (__command == DeviceCommand::SET_READOUT_MODE)
        || (__command == DeviceCommand::SET_NORM_READOUT_DELAY)
        || (__command == DeviceCommand::SET_ROW_COUNT_ODD)
        || (__command == DeviceCommand::SET_ROW_COUNT_EVEN)
        || (__command == DeviceCommand::PS_ON)
        || (__command == DeviceCommand::PS_OFF)
        || (__command == DeviceCommand::CCD_VDD_ON)
        || (__command == DeviceCommand::CCD_VDD_OFF)
        || (__command == DeviceCommand::AD_WRITE)
        || (__command == DeviceCommand::SET_EEPROM_VIDPID)
        || (__command == DeviceCommand::ERASE_EEPROM)) {
        return command(__command, __option, __length, 0);
    }

    if ((  (__command == DeviceCommand::GET_EEPROM_LENGTH))
        || (__command == DeviceCommand::GET_EEPROM_BYTE)
        || (__command == DeviceCommand::GET_GAIN)
        || (__command == DeviceCommand::GET_EXP_MODE)
        || (__command == DeviceCommand::GET_VDD_MODE)
        || (__command == DeviceCommand::GET_FLUSH_MODE)
        || (__command == DeviceCommand::GET_CLEAN_MODE)
        || (__command == DeviceCommand::GET_READOUT_SPD)
        || (__command == DeviceCommand::GET_READOUT_MODE)) {
        return command(__command, __option, __length, 1);
    }

    if ((  (__command == DeviceCommand::GET_VERSION))
        || (__command == DeviceCommand::GET_STATUS)
        || (__command == DeviceCommand::GET_TIMESTAMP)
        || (__command == DeviceCommand::GET_EXP_TIME)
        || (__command == DeviceCommand::GET_EXP_TIMER_COUNT)
        || (__command == DeviceCommand::GET_EEPROM_VIDPID)) {
        return command(__command, __option, __length, 4);
    }

    if ((  (__command == DeviceCommand::GET_OFFSET))
        || (__command == DeviceCommand::GET_NORM_READOUT_DELAY)
        || (__command == DeviceCommand::SET_EXP_MODE)
        || (__command == DeviceCommand::GET_ROW_COUNT_ODD)
        || (__command == DeviceCommand::GET_ROW_COUNT_EVEN)
        || (__command == DeviceCommand::GET_TEMP)
        || (__command == DeviceCommand::AD_READ)
        || (__command == DeviceCommand::GET_DEBUG_VALUE)) {
        return command(__command, __option, __length, 2);
    }

    throw dsi_exception("unsupported device command " + __command.name());
}

/**
 * Internal helper for sending a command to the DSI device.  This formats the
 * command as a sequence of bytes and delegates to command(unsigned char *,int,int)
 *
 * @param __command command to be executed.
 * @param __option
 * @param __length
 * @param __expected
 *
 * @return decoded command response.
 */
unsigned int
DSI::Device::command(DeviceCommand __command, int __option, int __length, int __expected)
{
    const size_t __size = 0x40;
    unsigned char buffer[__size];
    command_sequence_number++;
    // XXX: Or do I omit this and shift things down for libusb?
    buffer[0] = __length;
    buffer[1] = command_sequence_number;
    buffer[2] = __command.value();
    switch (__length) {
        case 3:
            break;
        case 4:
            buffer[3] = __option;
            break;
        case 5:
            buffer[3] = 0x0ff & __option;
            buffer[4] = 0x0ff & (__option >> 8);
            break;
        case 7:
            buffer[3] = 0x0ff & __option;
            buffer[4] = 0x0ff & (__option >>  8);
            buffer[5] = 0x0ff & (__option >> 16);
            buffer[6] = 0x0ff & (__option >> 24);
            break;
        default:
            throw dsi_exception("unsupported command length");
    }
    return command(buffer, __length, __expected);
}

/**
 * Write a command buffer to the DSI device and decode the return buffer.
 *
 * @param __buffer raw command buffer.
 * @param __length length of the command buffer, in bytes.
 * @param __expected expected length of the response buffer, in bytes.
 *
 * @return decoded response as appropriate for the command.
 *
 * DSI commands return either 0, 1, 2, or 4 byte results.  The results are
 * nominally unsigned integers although in some cases (e.g. GET_VERSION),
 * the 4 bytes are actually 4 separate bytes.  However, all 4-byte responses
 * are treated as 32-bit unsigned integers and are decoded and returned that
 * way.  Similarly, 2-byte responses are treated as 16-bit unsigned integers
 * and are decoded and returned that way.
 */
unsigned int
DSI::Device::command(unsigned char *__buffer, int __length, int __expected)
{
    int transfered;

    const DeviceCommand *command = DeviceCommand::find((int) __buffer[2]);
    //    if (command == 0)
    //        throw dsi_exception(std::string("unrecognized command in buffer: ") + __buffer[2]);

    unsigned int value;
    switch (__length) {
        case 3:
            break;
        case 4:
            value = getByteResult((unsigned char *) __buffer);
            break;
        case 5:
            value = getShortResult((unsigned char *) __buffer);
            break;
        case 7:
            value = getIntResult((unsigned char *) __buffer);
            break;
        default:
            throw dsi_exception("unsupported command length");
            break;
    }


    if (last_time == 0) {
        last_time = get_sysclock_ms();
    }

    int retcode = libusb_bulk_transfer(handle, 0x01, __buffer, __buffer[0], &transfered, 100*MILLISEC);
    if (retcode != 0) {
        throw device_write_error(std::string("libusb_bulk_transfer error ") + strerror(-retcode));
    }

    if (log_commands)
        log_command_info(true, "w 1", __buffer[0], (char *) __buffer, (__length > 3 ? &value : 0));

    const size_t size = 0x40;
    char buffer[size];
    retcode = libusb_bulk_transfer(handle, 0x81, (unsigned char *) buffer, size, &transfered, 100*MILLISEC);

    if (retcode != 0) {
        throw device_read_error(std::string("libusb_bulk_transfer error ") + strerror(-retcode));
    }

    if (buffer[0] != transfered) {
        ostringstream msg;
        msg << "response length " << dec << (int) buffer[0]
            << " does not match bytes read " << transfered << endl;
        throw bad_length(msg.str());
    }

    if ((unsigned char) buffer[1] != command_sequence_number) {
        if (log_commands) {
            log_command_info(false, "r 81", buffer[0], (char *) buffer, 0);
        }
        ostringstream msg;
        msg << "response sequence number (" << (unsigned int) buffer[1]
            << ") does not match request (" << command_sequence_number
            << ") for command " << command->name();
        throw bad_command(msg.str());
    }

    if (buffer[2] != (&DeviceResponse::ACK)->value()) {
        ostringstream msg;
        msg << "command " << command->name() << " did not get ACK (was "
            << setfill('0') << setw(2) << buffer[2] << ")";
        throw bad_response(msg.str());
    }

    unsigned int result = 0;
    switch (__expected) {
        case 0:
            break;
        case 1:
            result = getByteResult((unsigned char *) buffer);
            break;
        case 2:
            result = getShortResult((unsigned char *) buffer);
            break;
        case 4:
            result = getIntResult((unsigned char *) buffer);
            break;
        default:
            throw dsi_exception("unsupported result length");
            break;
    }

    if (log_commands)
        log_command_info(false, "r 81", 0x40, buffer, (__expected > 0 ? &result : 0));


    return result;
}

/**
 * Decode byte 4 of the buffer as an 8-bit unsigned integer.
 *
 * @param __buffer raw query result buffer from DSI.
 *
 * @return decoded value as an unsigned integer.
 */
unsigned int
DSI::Device::getByteResult(unsigned char *__buffer)
{
    return (unsigned int) __buffer[3];
}

/**
 * Decode bytes 4-5 of the buffer as a 16-bit big-endian unsigned integer.
 *
 * @param __buffer raw query result buffer from DSI.
 *
 * @return decoded value as an unsigned integer.
 */
unsigned int
DSI::Device::getShortResult(unsigned char *__buffer)
{
    return (unsigned int) ((__buffer[4] << 8) | __buffer[3]);
}

/**
 * Decode bytes 4-7 of the buffer as a 32-bit big-endian unsigned integer.
 *
 * @param __buffer raw query result buffer from DSI.
 *
 * @return decoded value as an unsigned integer.
 */
unsigned int
DSI::Device::getIntResult(unsigned char *__buffer)
{
    unsigned int result;
    result =                 __buffer[6];
    result = (result << 8) | __buffer[5];
    result = (result << 8) | __buffer[4];
    result = (result << 8) | __buffer[3];
    return result;
}

/**
 * Set the device state to "abort exposure requested." The exposure will not
 * be aborted as soon as possible
 *
 */
void
DSI::Device::abortExposure()
{
    abort_requested = true;
}

/******************************************************************************/
