demo: Require sample limit.

[libsigrok.git] / hardware / hantek-dso / api.c

/*
 * This file is part of the libsigrok project.
 *
 * Copyright (C) 2012 Bert Vermeulen <bert@biot.com>
 *
 * 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 3 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 <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <sys/time.h>
#include <inttypes.h>
#include <glib.h>
#include <libusb.h>
#include "libsigrok.h"
#include "libsigrok-internal.h"
#include "dso.h"

/* Max time in ms before we want to check on USB events */
/* TODO tune this properly */
#define TICK 1

#define NUM_TIMEBASE  10
#define NUM_VDIV      8

static const int32_t scanopts[] = {
	SR_CONF_CONN,
};

static const int32_t devopts[] = {
	SR_CONF_OSCILLOSCOPE,
	SR_CONF_LIMIT_FRAMES,
	SR_CONF_CONTINUOUS,
	SR_CONF_TIMEBASE,
	SR_CONF_BUFFERSIZE,
	SR_CONF_TRIGGER_SOURCE,
	SR_CONF_TRIGGER_SLOPE,
	SR_CONF_HORIZ_TRIGGERPOS,
	SR_CONF_FILTER,
	SR_CONF_VDIV,
	SR_CONF_COUPLING,
	SR_CONF_NUM_TIMEBASE,
	SR_CONF_NUM_VDIV,
};

static const char *probe_names[] = {
	"CH1", "CH2",
	NULL,
};

static const uint64_t buffersizes_32k[] = {
	10240, 32768,
};
static const uint64_t buffersizes_512k[] = {
	10240, 524288,
};
static const uint64_t buffersizes_14k[] = {
	10240, 14336,
};

static const struct dso_profile dev_profiles[] = {
	{	0x04b4, 0x2090, 0x04b5, 0x2090,
		"Hantek", "DSO-2090",
		buffersizes_32k,
		FIRMWARE_DIR "/hantek-dso-2090.fw" },
	{	0x04b4, 0x2150, 0x04b5, 0x2150,
		"Hantek", "DSO-2150",
		buffersizes_32k,
		FIRMWARE_DIR "/hantek-dso-2150.fw" },
	{	0x04b4, 0x2250, 0x04b5, 0x2250,
		"Hantek", "DSO-2250",
		buffersizes_512k,
		FIRMWARE_DIR "/hantek-dso-2250.fw" },
	{	0x04b4, 0x5200, 0x04b5, 0x5200,
		"Hantek", "DSO-5200",
		buffersizes_14k,
		FIRMWARE_DIR "/hantek-dso-5200.fw" },
	{	0x04b4, 0x520a, 0x04b5, 0x520a,
		"Hantek", "DSO-5200A",
		buffersizes_512k,
		FIRMWARE_DIR "/hantek-dso-5200A.fw" },
	{ 0, 0, 0, 0, 0, 0, 0, 0 },
};

static const uint64_t timebases[][2] = {
	/* microseconds */
	{ 10, 1000000 },
	{ 20, 1000000 },
	{ 40, 1000000 },
	{ 100, 1000000 },
	{ 200, 1000000 },
	{ 400, 1000000 },
	/* milliseconds */
	{ 1, 1000 },
	{ 2, 1000 },
	{ 4, 1000 },
	{ 10, 1000 },
	{ 20, 1000 },
	{ 40, 1000 },
	{ 100, 1000 },
	{ 200, 1000 },
	{ 400, 1000 },
};

static const uint64_t vdivs[][2] = {
	/* millivolts */
	{ 10, 1000 },
	{ 20, 1000 },
	{ 50, 1000 },
	{ 100, 1000 },
	{ 200, 1000 },
	{ 500, 1000 },
	/* volts */
	{ 1, 1 },
	{ 2, 1 },
	{ 5, 1 },
};

static const char *trigger_sources[] = {
	"CH1",
	"CH2",
	"EXT",
	/* TODO: forced */
};

static const char *filter_targets[] = {
	"CH1",
	"CH2",
	/* TODO: "TRIGGER", */
};

static const char *coupling[] = {
	"AC",
	"DC",
	"GND",
};

SR_PRIV struct sr_dev_driver hantek_dso_driver_info;
static struct sr_dev_driver *di = &hantek_dso_driver_info;

static int dev_acquisition_stop(struct sr_dev_inst *sdi, void *cb_data);

static struct sr_dev_inst *dso_dev_new(int index, const struct dso_profile *prof)
{
	struct sr_dev_inst *sdi;
	struct sr_probe *probe;
	struct drv_context *drvc;
	struct dev_context *devc;
	int i;

	sdi = sr_dev_inst_new(index, SR_ST_INITIALIZING,
		prof->vendor, prof->model, NULL);
	if (!sdi)
		return NULL;
	sdi->driver = di;

	/*
	 * Add only the real probes -- EXT isn't a source of data, only
	 * a trigger source internal to the device.
	 */
	for (i = 0; probe_names[i]; i++) {
		if (!(probe = sr_probe_new(i, SR_PROBE_ANALOG, TRUE,
				probe_names[i])))
			return NULL;
		sdi->probes = g_slist_append(sdi->probes, probe);
	}

	if (!(devc = g_try_malloc0(sizeof(struct dev_context)))) {
		sr_err("Device context malloc failed.");
		return NULL;
	}

	devc->profile = prof;
	devc->dev_state = IDLE;
	devc->timebase = DEFAULT_TIMEBASE;
	devc->ch1_enabled = TRUE;
	devc->ch2_enabled = TRUE;
	devc->voltage_ch1 = DEFAULT_VOLTAGE;
	devc->voltage_ch2 = DEFAULT_VOLTAGE;
	devc->coupling_ch1 = DEFAULT_COUPLING;
	devc->coupling_ch2 = DEFAULT_COUPLING;
	devc->voffset_ch1 = DEFAULT_VERT_OFFSET;
	devc->voffset_ch2 = DEFAULT_VERT_OFFSET;
	devc->voffset_trigger = DEFAULT_VERT_TRIGGERPOS;
	devc->framesize = DEFAULT_FRAMESIZE;
	devc->triggerslope = SLOPE_POSITIVE;
	devc->triggersource = g_strdup(DEFAULT_TRIGGER_SOURCE);
	devc->triggerposition = DEFAULT_HORIZ_TRIGGERPOS;
	sdi->priv = devc;
	drvc = di->priv;
	drvc->instances = g_slist_append(drvc->instances, sdi);

	return sdi;
}

static int configure_probes(const struct sr_dev_inst *sdi)
{
	struct dev_context *devc;
	struct sr_probe *probe;
	const GSList *l;
	int p;

	devc = sdi->priv;

	g_slist_free(devc->enabled_probes);
	devc->ch1_enabled = devc->ch2_enabled = FALSE;
	for (l = sdi->probes, p = 0; l; l = l->next, p++) {
		probe = l->data;
		if (p == 0)
			devc->ch1_enabled = probe->enabled;
		else
			devc->ch2_enabled = probe->enabled;
		if (probe->enabled)
			devc->enabled_probes = g_slist_append(devc->enabled_probes, probe);
	}

	return SR_OK;
}

static void clear_dev_context(void *priv)
{
	struct dev_context *devc;

	devc = priv;
	g_free(devc->triggersource);
	g_slist_free(devc->enabled_probes);

}

static int dev_clear(void)
{
	return std_dev_clear(di, clear_dev_context);
}

static int init(struct sr_context *sr_ctx)
{
	return std_init(sr_ctx, di, LOG_PREFIX);
}

static GSList *scan(GSList *options)
{
	struct drv_context *drvc;
	struct dev_context *devc;
	struct sr_dev_inst *sdi;
	struct sr_usb_dev_inst *usb;
	struct sr_config *src;
	const struct dso_profile *prof;
	GSList *l, *devices, *conn_devices;
	struct libusb_device_descriptor des;
	libusb_device **devlist;
	int devcnt, ret, i, j;
	const char *conn;

	drvc = di->priv;

	devcnt = 0;
	devices = 0;

	conn = NULL;
	for (l = options; l; l = l->next) {
		src = l->data;
		if (src->key == SR_CONF_CONN) {
			conn = g_variant_get_string(src->data, NULL);
			break;
		}
	}
	if (conn)
		conn_devices = sr_usb_find(drvc->sr_ctx->libusb_ctx, conn);
	else
		conn_devices = NULL;

	/* Find all Hantek DSO devices and upload firmware to all of them. */
	libusb_get_device_list(drvc->sr_ctx->libusb_ctx, &devlist);
	for (i = 0; devlist[i]; i++) {
		if (conn) {
			usb = NULL;
			for (l = conn_devices; l; l = l->next) {
				usb = l->data;
				if (usb->bus == libusb_get_bus_number(devlist[i])
					&& usb->address == libusb_get_device_address(devlist[i]))
					break;
			}
			if (!l)
				/* This device matched none of the ones that
				 * matched the conn specification. */
				continue;
		}

		if ((ret = libusb_get_device_descriptor(devlist[i], &des))) {
			sr_err("Failed to get device descriptor: %s.",
					libusb_error_name(ret));
			continue;
		}

		prof = NULL;
		for (j = 0; dev_profiles[j].orig_vid; j++) {
			if (des.idVendor == dev_profiles[j].orig_vid
				&& des.idProduct == dev_profiles[j].orig_pid) {
				/* Device matches the pre-firmware profile. */
				prof = &dev_profiles[j];
				sr_dbg("Found a %s %s.", prof->vendor, prof->model);
				sdi = dso_dev_new(devcnt, prof);
				devices = g_slist_append(devices, sdi);
				devc = sdi->priv;
				if (ezusb_upload_firmware(devlist[i], USB_CONFIGURATION,
						prof->firmware) == SR_OK)
					/* Remember when the firmware on this device was updated */
					devc->fw_updated = g_get_monotonic_time();
				else
					sr_err("Firmware upload failed for "
					        "device %d.", devcnt);
				/* Dummy USB address of 0xff will get overwritten later. */
				sdi->conn = sr_usb_dev_inst_new(
						libusb_get_bus_number(devlist[i]), 0xff, NULL);
				devcnt++;
				break;
			} else if (des.idVendor == dev_profiles[j].fw_vid
				&& des.idProduct == dev_profiles[j].fw_pid) {
				/* Device matches the post-firmware profile. */
				prof = &dev_profiles[j];
				sr_dbg("Found a %s %s.", prof->vendor, prof->model);
				sdi = dso_dev_new(devcnt, prof);
				sdi->status = SR_ST_INACTIVE;
				devices = g_slist_append(devices, sdi);
				devc = sdi->priv;
				sdi->inst_type = SR_INST_USB;
				sdi->conn = sr_usb_dev_inst_new(
						libusb_get_bus_number(devlist[i]),
						libusb_get_device_address(devlist[i]), NULL);
				devcnt++;
				break;
			}
		}
		if (!prof)
			/* not a supported VID/PID */
			continue;
	}
	libusb_free_device_list(devlist, 1);

	return devices;
}

static GSList *dev_list(void)
{
	return ((struct drv_context *)(di->priv))->instances;
}

static int dev_open(struct sr_dev_inst *sdi)
{
	struct dev_context *devc;
	struct sr_usb_dev_inst *usb;
	int64_t timediff_us, timediff_ms;
	int err;

	devc = sdi->priv;
	usb = sdi->conn;

	/*
	 * If the firmware was recently uploaded, wait up to MAX_RENUM_DELAY_MS
	 * for the FX2 to renumerate.
	 */
	err = SR_ERR;
	if (devc->fw_updated > 0) {
		sr_info("Waiting for device to reset.");
		/* Takes >= 300ms for the FX2 to be gone from the USB bus. */
		g_usleep(300 * 1000);
		timediff_ms = 0;
		while (timediff_ms < MAX_RENUM_DELAY_MS) {
			if ((err = dso_open(sdi)) == SR_OK)
				break;
			g_usleep(100 * 1000);
			timediff_us = g_get_monotonic_time() - devc->fw_updated;
			timediff_ms = timediff_us / 1000;
			sr_spew("Waited %" PRIi64 " ms.", timediff_ms);
		}
		sr_info("Device came back after %d ms.", timediff_ms);
	} else {
		err = dso_open(sdi);
	}

	if (err != SR_OK) {
		sr_err("Unable to open device.");
		return SR_ERR;
	}

	err = libusb_claim_interface(usb->devhdl, USB_INTERFACE);
	if (err != 0) {
		sr_err("Unable to claim interface: %s.",
			   libusb_error_name(err));
		return SR_ERR;
	}

	return SR_OK;
}

static int dev_close(struct sr_dev_inst *sdi)
{
	dso_close(sdi);

	return SR_OK;
}

static int cleanup(void)
{
	return dev_clear();
}

static int config_get(int id, GVariant **data, const struct sr_dev_inst *sdi,
		const struct sr_probe_group *probe_group)
{
	struct sr_usb_dev_inst *usb;
	char str[128];

	(void)probe_group;

	switch (id) {
	case SR_CONF_CONN:
		if (!sdi || !sdi->conn)
			return SR_ERR_ARG;
		usb = sdi->conn;
		if (usb->address == 255)
			/* Device still needs to re-enumerate after firmware
			 * upload, so we don't know its (future) address. */
			return SR_ERR;
		snprintf(str, 128, "%d.%d", usb->bus, usb->address);
		*data = g_variant_new_string(str);
		break;
	case SR_CONF_NUM_TIMEBASE:
		*data = g_variant_new_int32(NUM_TIMEBASE);
		break;
	case SR_CONF_NUM_VDIV:
		*data = g_variant_new_int32(NUM_VDIV);
		break;
	default:
		return SR_ERR_NA;
	}

	return SR_OK;
}

static int config_set(int id, GVariant *data, const struct sr_dev_inst *sdi,
		const struct sr_probe_group *probe_group)
{
	struct dev_context *devc;
	double tmp_double;
	uint64_t tmp_u64, p, q;
	int tmp_int, ret;
	unsigned int i;
	const char *tmp_str;
	char **targets;

	(void)probe_group;

	if (sdi->status != SR_ST_ACTIVE)
		return SR_ERR_DEV_CLOSED;

	ret = SR_OK;
	devc = sdi->priv;
	switch (id) {
	case SR_CONF_LIMIT_FRAMES:
		devc->limit_frames = g_variant_get_uint64(data);
		break;
	case SR_CONF_TRIGGER_SLOPE:
		tmp_u64 = g_variant_get_uint64(data);
		if (tmp_u64 != SLOPE_NEGATIVE && tmp_u64 != SLOPE_POSITIVE)
			ret = SR_ERR_ARG;
		devc->triggerslope = tmp_u64;
		break;
	case SR_CONF_HORIZ_TRIGGERPOS:
		tmp_double = g_variant_get_double(data);
		if (tmp_double < 0.0 || tmp_double > 1.0) {
			sr_err("Trigger position should be between 0.0 and 1.0.");
			ret = SR_ERR_ARG;
		} else
			devc->triggerposition = tmp_double;
		break;
	case SR_CONF_BUFFERSIZE:
		tmp_u64 = g_variant_get_uint64(data);
		for (i = 0; i < 2; i++) {
			if (devc->profile->buffersizes[i] == tmp_u64) {
				devc->framesize = tmp_u64;
				break;
			}
		}
		if (i == 2)
			ret = SR_ERR_ARG;
		break;
	case SR_CONF_TIMEBASE:
		g_variant_get(data, "(tt)", &p, &q);
		tmp_int = -1;
		for (i = 0; i < ARRAY_SIZE(timebases); i++) {
			if (timebases[i][0] == p && timebases[i][1] == q) {
				tmp_int = i;
				break;
			}
		}
		if (tmp_int >= 0)
			devc->timebase = tmp_int;
		else
			ret = SR_ERR_ARG;
		break;
	case SR_CONF_TRIGGER_SOURCE:
		tmp_str = g_variant_get_string(data, NULL);
		for (i = 0; trigger_sources[i]; i++) {
			if (!strcmp(tmp_str, trigger_sources[i])) {
				devc->triggersource = g_strdup(tmp_str);
				break;
			}
		}
		if (trigger_sources[i] == 0)
			ret = SR_ERR_ARG;
		break;
	case SR_CONF_FILTER:
		tmp_str = g_variant_get_string(data, NULL);
		devc->filter_ch1 = devc->filter_ch2 = devc->filter_trigger = 0;
		targets = g_strsplit(tmp_str, ",", 0);
		for (i = 0; targets[i]; i++) {
			if (targets[i] == '\0')
				/* Empty filter string can be used to clear them all. */
				;
			else if (!strcmp(targets[i], "CH1"))
				devc->filter_ch1 = TRUE;
			else if (!strcmp(targets[i], "CH2"))
				devc->filter_ch2 = TRUE;
			else if (!strcmp(targets[i], "TRIGGER"))
				devc->filter_trigger = TRUE;
			else {
				sr_err("Invalid filter target %s.", targets[i]);
				ret = SR_ERR_ARG;
			}
		}
		g_strfreev(targets);
		break;
	case SR_CONF_VDIV:
		/* TODO: Not supporting vdiv per channel yet. */
		g_variant_get(data, "(tt)", &p, &q);
		tmp_int = -1;
		for (i = 0; i < ARRAY_SIZE(vdivs); i++) {
			if (vdivs[i][0] == p && vdivs[i][1] == q) {
				tmp_int = i;
				break;
			}
		}
		if (tmp_int >= 0) {
			devc->voltage_ch1 = tmp_int;
			devc->voltage_ch2 = tmp_int;
		} else
			ret = SR_ERR_ARG;
		break;
	case SR_CONF_COUPLING:
		tmp_str = g_variant_get_string(data, NULL);
		/* TODO: Not supporting coupling per channel yet. */
		for (i = 0; coupling[i]; i++) {
			if (!strcmp(tmp_str, coupling[i])) {
				devc->coupling_ch1 = i;
				devc->coupling_ch2 = i;
				break;
			}
		}
		if (coupling[i] == 0)
			ret = SR_ERR_ARG;
		break;
	default:
		ret = SR_ERR_NA;
		break;
	}

	return ret;
}

static int config_list(int key, GVariant **data, const struct sr_dev_inst *sdi,
		const struct sr_probe_group *probe_group)
{
	struct dev_context *devc;
	GVariant *tuple, *rational[2];
	GVariantBuilder gvb;
	unsigned int i;

	(void)probe_group;

	switch (key) {
	case SR_CONF_SCAN_OPTIONS:
		*data = g_variant_new_fixed_array(G_VARIANT_TYPE_INT32,
				scanopts, ARRAY_SIZE(scanopts), sizeof(int32_t));
		break;
	case SR_CONF_DEVICE_OPTIONS:
		*data = g_variant_new_fixed_array(G_VARIANT_TYPE_INT32,
				devopts, ARRAY_SIZE(devopts), sizeof(int32_t));
		break;
	case SR_CONF_BUFFERSIZE:
		if (!sdi)
			return SR_ERR_ARG;
		devc = sdi->priv;
		*data = g_variant_new_fixed_array(G_VARIANT_TYPE_UINT64,
				devc->profile->buffersizes, 2, sizeof(uint64_t));
		break;
	case SR_CONF_COUPLING:
		*data = g_variant_new_strv(coupling, ARRAY_SIZE(coupling));
		break;
	case SR_CONF_VDIV:
		g_variant_builder_init(&gvb, G_VARIANT_TYPE_ARRAY);
		for (i = 0; i < ARRAY_SIZE(vdivs); i++) {
			rational[0] = g_variant_new_uint64(vdivs[i][0]);
			rational[1] = g_variant_new_uint64(vdivs[i][1]);
			tuple = g_variant_new_tuple(rational, 2);
			g_variant_builder_add_value(&gvb, tuple);
		}
		*data = g_variant_builder_end(&gvb);
		break;
	case SR_CONF_FILTER:
		*data = g_variant_new_strv(filter_targets,
				ARRAY_SIZE(filter_targets));
		break;
	case SR_CONF_TIMEBASE:
		g_variant_builder_init(&gvb, G_VARIANT_TYPE_ARRAY);
		for (i = 0; i < ARRAY_SIZE(timebases); i++) {
			rational[0] = g_variant_new_uint64(timebases[i][0]);
			rational[1] = g_variant_new_uint64(timebases[i][1]);
			tuple = g_variant_new_tuple(rational, 2);
			g_variant_builder_add_value(&gvb, tuple);
		}
		*data = g_variant_builder_end(&gvb);
		break;
	case SR_CONF_TRIGGER_SOURCE:
		*data = g_variant_new_strv(trigger_sources,
				ARRAY_SIZE(trigger_sources));
		break;
	default:
		return SR_ERR_NA;
	}

	return SR_OK;
}

static void send_chunk(struct sr_dev_inst *sdi, unsigned char *buf,
		int num_samples)
{
	struct sr_datafeed_packet packet;
	struct sr_datafeed_analog analog;
	struct dev_context *devc;
	float ch1, ch2, range;
	int num_probes, data_offset, i;

	devc = sdi->priv;
	num_probes = (devc->ch1_enabled && devc->ch2_enabled) ? 2 : 1;
	packet.type = SR_DF_ANALOG;
	packet.payload = &analog;
	/* TODO: support for 5xxx series 9-bit samples */
	analog.probes = devc->enabled_probes;
	analog.num_samples = num_samples;
	analog.mq = SR_MQ_VOLTAGE;
	analog.unit = SR_UNIT_VOLT;
	/* TODO: Check malloc return value. */
	analog.data = g_try_malloc(analog.num_samples * sizeof(float) * num_probes);
	data_offset = 0;
	for (i = 0; i < analog.num_samples; i++) {
		/*
		 * The device always sends data for both channels. If a channel
		 * is disabled, it contains a copy of the enabled channel's
		 * data. However, we only send the requested channels to
		 * the bus.
		 *
		 * Voltage values are encoded as a value 0-255 (0-512 on the
		 * DSO-5200*), where the value is a point in the range
		 * represented by the vdiv setting. There are 8 vertical divs,
		 * so e.g. 500mV/div represents 4V peak-to-peak where 0 = -2V
		 * and 255 = +2V.
		 */
		/* TODO: Support for DSO-5xxx series 9-bit samples. */
		if (devc->ch1_enabled) {
			range = ((float)vdivs[devc->voltage_ch1][0] / vdivs[devc->voltage_ch1][1]) * 8;
			ch1 = range / 255 * *(buf + i * 2 + 1);
			/* Value is centered around 0V. */
			ch1 -= range / 2;
			analog.data[data_offset++] = ch1;
		}
		if (devc->ch2_enabled) {
			range = ((float)vdivs[devc->voltage_ch2][0] / vdivs[devc->voltage_ch2][1]) * 8;
			ch2 = range / 255 * *(buf + i * 2);
			ch2 -= range / 2;
			analog.data[data_offset++] = ch2;
		}
	}
	sr_session_send(devc->cb_data, &packet);
}

/*
 * Called by libusb (as triggered by handle_event()) when a transfer comes in.
 * Only channel data comes in asynchronously, and all transfers for this are
 * queued up beforehand, so this just needs to chuck the incoming data onto
 * the libsigrok session bus.
 */
static void receive_transfer(struct libusb_transfer *transfer)
{
	struct sr_datafeed_packet packet;
	struct sr_dev_inst *sdi;
	struct dev_context *devc;
	int num_samples, pre;

	sdi = transfer->user_data;
	devc = sdi->priv;
	sr_spew("receive_transfer(): status %d received %d bytes.",
		   transfer->status, transfer->actual_length);

	if (transfer->actual_length == 0)
		/* Nothing to send to the bus. */
		return;

	num_samples = transfer->actual_length / 2;

	sr_spew("Got %d-%d/%d samples in frame.", devc->samp_received + 1,
		   devc->samp_received + num_samples, devc->framesize);

	/*
	 * The device always sends a full frame, but the beginning of the frame
	 * doesn't represent the trigger point. The offset at which the trigger
	 * happened came in with the capture state, so we need to start sending
	 * from there up the session bus. The samples in the frame buffer
	 * before that trigger point came after the end of the device's frame
	 * buffer was reached, and it wrapped around to overwrite up until the
	 * trigger point.
	 */
	if (devc->samp_received < devc->trigger_offset) {
		/* Trigger point not yet reached. */
		if (devc->samp_received + num_samples < devc->trigger_offset) {
			/* The entire chunk is before the trigger point. */
			memcpy(devc->framebuf + devc->samp_buffered * 2,
					transfer->buffer, num_samples * 2);
			devc->samp_buffered += num_samples;
		} else {
			/*
			 * This chunk hits or overruns the trigger point.
			 * Store the part before the trigger fired, and
			 * send the rest up to the session bus.
			 */
			pre = devc->trigger_offset - devc->samp_received;
			memcpy(devc->framebuf + devc->samp_buffered * 2,
					transfer->buffer, pre * 2);
			devc->samp_buffered += pre;

			/* The rest of this chunk starts with the trigger point. */
			sr_dbg("Reached trigger point, %d samples buffered.",
				   devc->samp_buffered);

			/* Avoid the corner case where the chunk ended at
			 * exactly the trigger point. */
			if (num_samples > pre)
				send_chunk(sdi, transfer->buffer + pre * 2,
						num_samples - pre);
		}
	} else {
		/* Already past the trigger point, just send it all out. */
		send_chunk(sdi, transfer->buffer,
				num_samples);
	}

	devc->samp_received += num_samples;

	/* Everything in this transfer was either copied to the buffer or
	 * sent to the session bus. */
	g_free(transfer->buffer);
	libusb_free_transfer(transfer);

	if (devc->samp_received >= devc->framesize) {
		/* That was the last chunk in this frame. Send the buffered
		 * pre-trigger samples out now, in one big chunk. */
		sr_dbg("End of frame, sending %d pre-trigger buffered samples.",
			   devc->samp_buffered);
		send_chunk(sdi, devc->framebuf, devc->samp_buffered);

		/* Mark the end of this frame. */
		packet.type = SR_DF_FRAME_END;
		sr_session_send(devc->cb_data, &packet);

		if (devc->limit_frames && ++devc->num_frames == devc->limit_frames) {
			/* Terminate session */
			devc->dev_state = STOPPING;
		} else {
			devc->dev_state = NEW_CAPTURE;
		}
	}
}

static int handle_event(int fd, int revents, void *cb_data)
{
	const struct sr_dev_inst *sdi;
	struct sr_datafeed_packet packet;
	struct timeval tv;
	struct dev_context *devc;
	struct drv_context *drvc = di->priv;
	int num_probes;
	uint32_t trigger_offset;
	uint8_t capturestate;

	(void)fd;
	(void)revents;

	sdi = cb_data;
	devc = sdi->priv;
	if (devc->dev_state == STOPPING) {
		/* We've been told to wind up the acquisition. */
		sr_dbg("Stopping acquisition.");
		/*
		 * TODO: Doesn't really cancel pending transfers so they might
		 * come in after SR_DF_END is sent.
		 */
		usb_source_remove(drvc->sr_ctx);

		packet.type = SR_DF_END;
		sr_session_send(sdi, &packet);

		devc->dev_state = IDLE;

		return TRUE;
	}

	/* Always handle pending libusb events. */
	tv.tv_sec = tv.tv_usec = 0;
	libusb_handle_events_timeout(drvc->sr_ctx->libusb_ctx, &tv);

	/* TODO: ugh */
	if (devc->dev_state == NEW_CAPTURE) {
		if (dso_capture_start(sdi) != SR_OK)
			return TRUE;
		if (dso_enable_trigger(sdi) != SR_OK)
			return TRUE;
//		if (dso_force_trigger(sdi) != SR_OK)
//			return TRUE;
		sr_dbg("Successfully requested next chunk.");
		devc->dev_state = CAPTURE;
		return TRUE;
	}
	if (devc->dev_state != CAPTURE)
		return TRUE;

	if ((dso_get_capturestate(sdi, &capturestate, &trigger_offset)) != SR_OK)
		return TRUE;

	sr_dbg("Capturestate %d.", capturestate);
	sr_dbg("Trigger offset 0x%.6x.", trigger_offset);
	switch (capturestate) {
	case CAPTURE_EMPTY:
		if (++devc->capture_empty_count >= MAX_CAPTURE_EMPTY) {
			devc->capture_empty_count = 0;
			if (dso_capture_start(sdi) != SR_OK)
				break;
			if (dso_enable_trigger(sdi) != SR_OK)
				break;
//			if (dso_force_trigger(sdi) != SR_OK)
//				break;
			sr_dbg("Successfully requested next chunk.");
		}
		break;
	case CAPTURE_FILLING:
		/* No data yet. */
		break;
	case CAPTURE_READY_8BIT:
		/* Remember where in the captured frame the trigger is. */
		devc->trigger_offset = trigger_offset;

		num_probes = (devc->ch1_enabled && devc->ch2_enabled) ? 2 : 1;
		/* TODO: Check malloc return value. */
		devc->framebuf = g_try_malloc(devc->framesize * num_probes * 2);
		devc->samp_buffered = devc->samp_received = 0;

		/* Tell the scope to send us the first frame. */
		if (dso_get_channeldata(sdi, receive_transfer) != SR_OK)
			break;

		/*
		 * Don't hit the state machine again until we're done fetching
		 * the data we just told the scope to send.
		 */
		devc->dev_state = FETCH_DATA;

		/* Tell the frontend a new frame is on the way. */
		packet.type = SR_DF_FRAME_BEGIN;
		sr_session_send(sdi, &packet);
		break;
	case CAPTURE_READY_9BIT:
		/* TODO */
		sr_err("Not yet supported.");
		break;
	case CAPTURE_TIMEOUT:
		/* Doesn't matter, we'll try again next time. */
		break;
	default:
		sr_dbg("Unknown capture state: %d.", capturestate);
		break;
	}

	return TRUE;
}

static int dev_acquisition_start(const struct sr_dev_inst *sdi, void *cb_data)
{
	struct dev_context *devc;
	struct drv_context *drvc = di->priv;

	if (sdi->status != SR_ST_ACTIVE)
		return SR_ERR_DEV_CLOSED;

	devc = sdi->priv;
	devc->cb_data = cb_data;

	if (configure_probes(sdi) != SR_OK) {
		sr_err("Failed to configure probes.");
		return SR_ERR;
	}

	if (dso_init(sdi) != SR_OK)
		return SR_ERR;

	if (dso_capture_start(sdi) != SR_OK)
		return SR_ERR;

	devc->dev_state = CAPTURE;
	usb_source_add(drvc->sr_ctx, TICK, handle_event, (void *)sdi);

	/* Send header packet to the session bus. */
	std_session_send_df_header(cb_data, LOG_PREFIX);

	return SR_OK;
}

static int dev_acquisition_stop(struct sr_dev_inst *sdi, void *cb_data)
{
	struct dev_context *devc;

	(void)cb_data;

	if (sdi->status != SR_ST_ACTIVE)
		return SR_ERR;

	devc = sdi->priv;
	devc->dev_state = STOPPING;

	return SR_OK;
}

SR_PRIV struct sr_dev_driver hantek_dso_driver_info = {
	.name = "hantek-dso",
	.longname = "Hantek DSO",
	.api_version = 1,
	.init = init,
	.cleanup = cleanup,
	.scan = scan,
	.dev_list = dev_list,
	.dev_clear = dev_clear,
	.config_get = config_get,
	.config_set = config_set,
	.config_list = config_list,
	.dev_open = dev_open,
	.dev_close = dev_close,
	.dev_acquisition_start = dev_acquisition_start,
	.dev_acquisition_stop = dev_acquisition_stop,
	.priv = NULL,
};