]> sigrok.org Git - libsigrok.git/blobdiff - src/hardware/openbench-logic-sniffer/protocol.c
ols: Refactor: Extract trigger setup into private place
[libsigrok.git] / src / hardware / openbench-logic-sniffer / protocol.c
index 15f1b3c03e9ff42b27569ed6b0010cc880e9b925..949b2c0454e1b0fce154c53df624acaaad810374 100644 (file)
 #include <config.h>
 #include "protocol.h"
 
-extern SR_PRIV struct sr_dev_driver ols_driver_info;
+
+struct ols_basic_trigger_desc {
+       uint32_t trigger_mask[NUM_BASIC_TRIGGER_STAGES];
+       uint32_t trigger_value[NUM_BASIC_TRIGGER_STAGES];
+       int num_stages;
+};
 
 SR_PRIV int send_shortcommand(struct sr_serial_dev_inst *serial,
                uint8_t command)
@@ -32,7 +37,7 @@ SR_PRIV int send_shortcommand(struct sr_serial_dev_inst *serial,
        if (serial_write_blocking(serial, buf, 1, serial_timeout(serial, 1)) != 1)
                return SR_ERR;
 
-       if (serial_drain(serial) != 0)
+       if (serial_drain(serial) != SR_OK)
                return SR_ERR;
 
        return SR_OK;
@@ -53,53 +58,58 @@ SR_PRIV int send_longcommand(struct sr_serial_dev_inst *serial,
        if (serial_write_blocking(serial, buf, 5, serial_timeout(serial, 1)) != 5)
                return SR_ERR;
 
-       if (serial_drain(serial) != 0)
+       if (serial_drain(serial) != SR_OK)
                return SR_ERR;
 
        return SR_OK;
 }
 
-/* Configures the channel mask based on which channels are enabled. */
-SR_PRIV void ols_channel_mask(const struct sr_dev_inst *sdi)
+SR_PRIV int ols_send_reset(struct sr_serial_dev_inst *serial)
 {
-       struct dev_context *devc;
-       struct sr_channel *channel;
-       const GSList *l;
+       unsigned int i;
 
-       devc = sdi->priv;
+       for (i = 0; i < 5; i++) {
+               if (send_shortcommand(serial, CMD_RESET) != SR_OK)
+                       return SR_ERR;
+       }
+
+       return SR_OK;
+}
 
-       devc->channel_mask = 0;
-       for (l = sdi->channels; l; l = l->next) {
-               channel = l->data;
+/* Configures the channel mask based on which channels are enabled. */
+SR_PRIV uint32_t ols_channel_mask(const struct sr_dev_inst *sdi)
+{
+       uint32_t channel_mask = 0;
+       for (const GSList *l = sdi->channels; l; l = l->next) {
+               struct sr_channel *channel = l->data;
                if (channel->enabled)
-                       devc->channel_mask |= 1 << channel->index;
+                       channel_mask |= 1 << channel->index;
        }
+
+       return channel_mask;
 }
 
-SR_PRIV int ols_convert_trigger(const struct sr_dev_inst *sdi)
+static int convert_trigger(const struct sr_dev_inst *sdi, struct ols_basic_trigger_desc *ols_trigger)
 {
-       struct dev_context *devc;
        struct sr_trigger *trigger;
        struct sr_trigger_stage *stage;
        struct sr_trigger_match *match;
        const GSList *l, *m;
        int i;
 
-       devc = sdi->priv;
-
-       devc->num_stages = 0;
-       for (i = 0; i < NUM_TRIGGER_STAGES; i++) {
-               devc->trigger_mask[i] = 0;
-               devc->trigger_value[i] = 0;
+       ols_trigger->num_stages = 0;
+       for (i = 0; i < NUM_BASIC_TRIGGER_STAGES; i++) {
+               ols_trigger->trigger_mask[i] = 0;
+               ols_trigger->trigger_value[i] = 0;
        }
 
        if (!(trigger = sr_session_trigger_get(sdi->session)))
                return SR_OK;
 
-       devc->num_stages = g_slist_length(trigger->stages);
-       if (devc->num_stages > NUM_TRIGGER_STAGES) {
+       ols_trigger->num_stages = g_slist_length(trigger->stages);
+       if (ols_trigger->num_stages > NUM_BASIC_TRIGGER_STAGES) {
                sr_err("This device only supports %d trigger stages.",
-                               NUM_TRIGGER_STAGES);
+                               NUM_BASIC_TRIGGER_STAGES);
                return SR_ERR;
        }
 
@@ -110,9 +120,9 @@ SR_PRIV int ols_convert_trigger(const struct sr_dev_inst *sdi)
                        if (!match->channel->enabled)
                                /* Ignore disabled channels with a trigger. */
                                continue;
-                       devc->trigger_mask[stage->stage] |= 1 << match->channel->index;
+                       ols_trigger->trigger_mask[stage->stage] |= 1 << match->channel->index;
                        if (match->match == SR_TRIGGER_ONE)
-                               devc->trigger_value[stage->stage] |= 1 << match->channel->index;
+                               ols_trigger->trigger_value[stage->stage] |= 1 << match->channel->index;
                }
        }
 
@@ -124,32 +134,60 @@ SR_PRIV struct dev_context *ols_dev_new(void)
        struct dev_context *devc;
 
        devc = g_malloc0(sizeof(struct dev_context));
+       devc->trigger_at_smpl = OLS_NO_TRIGGER;
 
-       /* Device-specific settings */
-       devc->max_samples = devc->max_samplerate = devc->protocol_version = 0;
+       return devc;
+}
 
-       /* Acquisition settings */
-       devc->limit_samples = devc->capture_ratio = 0;
-       devc->trigger_at = -1;
-       devc->channel_mask = 0xffffffff;
-       devc->flag_reg = 0;
+static void ols_channel_new(struct sr_dev_inst *sdi, int num_chan)
+{
+       struct dev_context *devc = sdi->priv;
+       int i;
 
-       return devc;
+       for (i = 0; i < num_chan; i++)
+               sr_channel_new(sdi, i, SR_CHANNEL_LOGIC, TRUE,
+                               ols_channel_names[i]);
+
+       devc->max_channels = num_chan;
+}
+
+static void ols_metadata_quirks(struct sr_dev_inst *sdi)
+{
+       struct dev_context *devc;
+       gboolean is_shrimp;
+
+       if (!sdi)
+               return;
+       devc = sdi->priv;
+       if (!devc)
+               return;
+
+       is_shrimp = sdi->model && strcmp(sdi->model, "Shrimp1.0") == 0;
+       if (is_shrimp) {
+               if (!devc->max_channels)
+                       ols_channel_new(sdi, 4);
+               if (!devc->max_samples)
+                       devc->max_samples = 256 * 1024;
+               if (!devc->max_samplerate)
+                       devc->max_samplerate = SR_MHZ(20);
+       }
+
+       if (sdi->version && strstr(sdi->version, "FPGA version 3.07"))
+               devc->device_flags |= DEVICE_FLAG_IS_DEMON_CORE;
 }
 
 SR_PRIV struct sr_dev_inst *get_metadata(struct sr_serial_dev_inst *serial)
 {
        struct sr_dev_inst *sdi;
        struct dev_context *devc;
-       uint32_t tmp_int, ui;
-       uint8_t key, type, token;
+       uint32_t tmp_int;
+       uint8_t key, type;
        int delay_ms;
        GString *tmp_str, *devname, *version;
        guchar tmp_c;
 
        sdi = g_malloc0(sizeof(struct sr_dev_inst));
        sdi->status = SR_ST_INACTIVE;
-       sdi->driver = &ols_driver_info;
        devc = ols_dev_new();
        sdi->priv = devc;
 
@@ -161,12 +199,11 @@ SR_PRIV struct sr_dev_inst *get_metadata(struct sr_serial_dev_inst *serial)
                delay_ms = serial_timeout(serial, 1);
                if (serial_read_blocking(serial, &key, 1, delay_ms) != 1)
                        break;
-               if (key == 0x00) {
+               if (key == METADATA_TOKEN_END) {
                        sr_dbg("Got metadata key 0x00, metadata ends.");
                        break;
                }
                type = key >> 5;
-               token = key & 0x1f;
                switch (type) {
                case 0:
                        /* NULL-terminated string */
@@ -174,21 +211,20 @@ SR_PRIV struct sr_dev_inst *get_metadata(struct sr_serial_dev_inst *serial)
                        delay_ms = serial_timeout(serial, 1);
                        while (serial_read_blocking(serial, &tmp_c, 1, delay_ms) == 1 && tmp_c != '\0')
                                g_string_append_c(tmp_str, tmp_c);
-                       sr_dbg("Got metadata key 0x%.2x value '%s'.",
-                              key, tmp_str->str);
-                       switch (token) {
-                       case 0x01:
+                       sr_dbg("Got metadata token 0x%.2x value '%s'.", key, tmp_str->str);
+                       switch (key) {
+                       case METADATA_TOKEN_DEVICE_NAME:
                                /* Device name */
                                devname = g_string_append(devname, tmp_str->str);
                                break;
-                       case 0x02:
+                       case METADATA_TOKEN_FPGA_VERSION:
                                /* FPGA firmware version */
                                if (version->len)
                                        g_string_append(version, ", ");
                                g_string_append(version, "FPGA version ");
                                g_string_append(version, tmp_str->str);
                                break;
-                       case 0x03:
+                       case METADATA_TOKEN_ANCILLARY_VERSION:
                                /* Ancillary version */
                                if (version->len)
                                        g_string_append(version, ", ");
@@ -196,8 +232,7 @@ SR_PRIV struct sr_dev_inst *get_metadata(struct sr_serial_dev_inst *serial)
                                g_string_append(version, tmp_str->str);
                                break;
                        default:
-                               sr_info("ols: unknown token 0x%.2x: '%s'",
-                                       token, tmp_str->str);
+                               sr_info("ols: unknown token 0x%.2x: '%s'", key, tmp_str->str);
                                break;
                        }
                        g_string_free(tmp_str, TRUE);
@@ -208,34 +243,30 @@ SR_PRIV struct sr_dev_inst *get_metadata(struct sr_serial_dev_inst *serial)
                        if (serial_read_blocking(serial, &tmp_int, 4, delay_ms) != 4)
                                break;
                        tmp_int = RB32(&tmp_int);
-                       sr_dbg("Got metadata key 0x%.2x value 0x%.8x.",
-                              key, tmp_int);
-                       switch (token) {
-                       case 0x00:
+                       sr_dbg("Got metadata token 0x%.2x value 0x%.8x.", key, tmp_int);
+                       switch (key) {
+                       case METADATA_TOKEN_NUM_PROBES_LONG:
                                /* Number of usable channels */
-                               for (ui = 0; ui < tmp_int; ui++)
-                                       sr_channel_new(sdi, ui, SR_CHANNEL_LOGIC, TRUE,
-                                                       ols_channel_names[ui]);
+                               ols_channel_new(sdi, tmp_int);
                                break;
-                       case 0x01:
+                       case METADATA_TOKEN_SAMPLE_MEMORY_BYTES:
                                /* Amount of sample memory available (bytes) */
                                devc->max_samples = tmp_int;
                                break;
-                       case 0x02:
+                       case METADATA_TOKEN_DYNAMIC_MEMORY_BYTES:
                                /* Amount of dynamic memory available (bytes) */
                                /* what is this for? */
                                break;
-                       case 0x03:
+                       case METADATA_TOKEN_MAX_SAMPLE_RATE_HZ:
                                /* Maximum sample rate (Hz) */
                                devc->max_samplerate = tmp_int;
                                break;
-                       case 0x04:
+                       case METADATA_TOKEN_PROTOCOL_VERSION_LONG:
                                /* protocol version */
                                devc->protocol_version = tmp_int;
                                break;
                        default:
-                               sr_info("Unknown token 0x%.2x: 0x%.8x.",
-                                       token, tmp_int);
+                               sr_info("Unknown token 0x%.2x: 0x%.8x.", key, tmp_int);
                                break;
                        }
                        break;
@@ -244,22 +275,18 @@ SR_PRIV struct sr_dev_inst *get_metadata(struct sr_serial_dev_inst *serial)
                        delay_ms = serial_timeout(serial, 1);
                        if (serial_read_blocking(serial, &tmp_c, 1, delay_ms) != 1)
                                break;
-                       sr_dbg("Got metadata key 0x%.2x value 0x%.2x.",
-                              key, tmp_c);
-                       switch (token) {
-                       case 0x00:
+                       sr_dbg("Got metadata token 0x%.2x value 0x%.2x.", key, tmp_c);
+                       switch (key) {
+                       case METADATA_TOKEN_NUM_PROBES_SHORT:
                                /* Number of usable channels */
-                               for (ui = 0; ui < tmp_c; ui++)
-                                       sr_channel_new(sdi, ui, SR_CHANNEL_LOGIC, TRUE,
-                                                       ols_channel_names[ui]);
+                               ols_channel_new(sdi, tmp_c);
                                break;
-                       case 0x01:
+                       case METADATA_TOKEN_PROTOCOL_VERSION_SHORT:
                                /* protocol version */
                                devc->protocol_version = tmp_c;
                                break;
                        default:
-                               sr_info("Unknown token 0x%.2x: 0x%.2x.",
-                                       token, tmp_c);
+                               sr_info("Unknown token 0x%.2x: 0x%.2x.", key, tmp_c);
                                break;
                        }
                        break;
@@ -274,6 +301,9 @@ SR_PRIV struct sr_dev_inst *get_metadata(struct sr_serial_dev_inst *serial)
        g_string_free(devname, FALSE);
        g_string_free(version, FALSE);
 
+       /* Optionally amend received metadata, model specific quirks. */
+       ols_metadata_quirks(sdi);
+
        return sdi;
 }
 
@@ -288,15 +318,13 @@ SR_PRIV int ols_set_samplerate(const struct sr_dev_inst *sdi,
 
        if (samplerate > CLOCK_RATE) {
                sr_info("Enabling demux mode.");
-               devc->flag_reg |= FLAG_DEMUX;
-               devc->flag_reg &= ~FLAG_FILTER;
-               devc->max_channels = NUM_CHANNELS / 2;
+               devc->capture_flags |= CAPTURE_FLAG_DEMUX;
+               devc->capture_flags &= ~CAPTURE_FLAG_NOISE_FILTER;
                devc->cur_samplerate_divider = (CLOCK_RATE * 2 / samplerate) - 1;
        } else {
                sr_info("Disabling demux mode.");
-               devc->flag_reg &= ~FLAG_DEMUX;
-               devc->flag_reg |= FLAG_FILTER;
-               devc->max_channels = NUM_CHANNELS;
+               devc->capture_flags &= ~CAPTURE_FLAG_DEMUX;
+               devc->capture_flags |= CAPTURE_FLAG_NOISE_FILTER;
                devc->cur_samplerate_divider = (CLOCK_RATE / samplerate) - 1;
        }
 
@@ -304,7 +332,7 @@ SR_PRIV int ols_set_samplerate(const struct sr_dev_inst *sdi,
         * from the requested.
         */
        devc->cur_samplerate = CLOCK_RATE / (devc->cur_samplerate_divider + 1);
-       if (devc->flag_reg & FLAG_DEMUX)
+       if (devc->capture_flags & CAPTURE_FLAG_DEMUX)
                devc->cur_samplerate *= 2;
        if (devc->cur_samplerate != samplerate)
                sr_info("Can't match samplerate %" PRIu64 ", using %"
@@ -318,9 +346,11 @@ SR_PRIV void abort_acquisition(const struct sr_dev_inst *sdi)
        struct sr_serial_dev_inst *serial;
 
        serial = sdi->conn;
+       ols_send_reset(serial);
+
        serial_source_remove(sdi->session, serial);
 
-       std_session_send_df_end(sdi, LOG_PREFIX);
+       std_session_send_df_end(sdi);
 }
 
 SR_PRIV int ols_receive_data(int fd, int revents, void *cb_data)
@@ -331,7 +361,7 @@ SR_PRIV int ols_receive_data(int fd, int revents, void *cb_data)
        struct sr_datafeed_packet packet;
        struct sr_datafeed_logic logic;
        uint32_t sample;
-       int num_ols_changrp, offset, j;
+       int num_changroups, offset, j;
        unsigned int i;
        unsigned char byte;
 
@@ -356,10 +386,10 @@ SR_PRIV int ols_receive_data(int fd, int revents, void *cb_data)
                memset(devc->raw_sample_buf, 0x82, devc->limit_samples * 4);
        }
 
-       num_ols_changrp = 0;
-       for (i = NUM_CHANNELS; i > 0x02; i /= 2) {
-               if ((devc->flag_reg & i) == 0) {
-                       num_ols_changrp++;
+       num_changroups = 0;
+       for (i = 0x20; i > 0x02; i >>= 1) {
+               if ((devc->capture_flags & i) == 0) {
+                       num_changroups++;
                }
        }
 
@@ -374,7 +404,7 @@ SR_PRIV int ols_receive_data(int fd, int revents, void *cb_data)
 
                devc->sample[devc->num_bytes++] = byte;
                sr_spew("Received byte 0x%.2x.", byte);
-               if (devc->num_bytes == num_ols_changrp) {
+               if (devc->num_bytes == num_changroups) {
                        devc->cnt_samples++;
                        devc->cnt_samples_rle++;
                        /*
@@ -384,7 +414,7 @@ SR_PRIV int ols_receive_data(int fd, int revents, void *cb_data)
                        sample = devc->sample[0] | (devc->sample[1] << 8) \
                                        | (devc->sample[2] << 16) | (devc->sample[3] << 24);
                        sr_dbg("Received sample 0x%.*x.", devc->num_bytes * 2, sample);
-                       if (devc->flag_reg & FLAG_RLE) {
+                       if (devc->capture_flags & CAPTURE_FLAG_RLE) {
                                /*
                                 * In RLE mode the high bit of the sample is the
                                 * "count" flag, meaning this sample is the number
@@ -407,7 +437,7 @@ SR_PRIV int ols_receive_data(int fd, int revents, void *cb_data)
                                devc->num_samples = devc->limit_samples;
                        }
 
-                       if (num_ols_changrp < 4) {
+                       if (num_changroups < 4) {
                                /*
                                 * Some channel groups may have been turned
                                 * off, to speed up transfer between the
@@ -420,20 +450,21 @@ SR_PRIV int ols_receive_data(int fd, int revents, void *cb_data)
                                j = 0;
                                memset(devc->tmp_sample, 0, 4);
                                for (i = 0; i < 4; i++) {
-                                       if (((devc->flag_reg >> 2) & (1 << i)) == 0) {
+                                       if (((devc->capture_flags >> 2) & (1 << i)) == 0) {
                                                /*
                                                 * This channel group was
                                                 * enabled, copy from received
                                                 * sample.
                                                 */
                                                devc->tmp_sample[i] = devc->sample[j++];
-                                       } else if (devc->flag_reg & FLAG_DEMUX && (i > 2)) {
+                                       } else if (devc->capture_flags & CAPTURE_FLAG_DEMUX && (i > 2)) {
                                                /* group 2 & 3 get added to 0 & 1 */
                                                devc->tmp_sample[i - 2] = devc->sample[j++];
                                        }
                                }
                                memcpy(devc->sample, devc->tmp_sample, 4);
-                               sr_spew("Expanded sample: 0x%.8x.", sample);
+                               sr_spew("Expanded sample: 0x%.2hhx%.2hhx%.2hhx%.2hhx ",
+                                       devc->sample[3], devc->sample[2], devc->sample[1], devc->sample[0]);
                        }
 
                        /*
@@ -459,16 +490,16 @@ SR_PRIV int ols_receive_data(int fd, int revents, void *cb_data)
                sr_dbg("Received %d bytes, %d samples, %d decompressed samples.",
                                devc->cnt_bytes, devc->cnt_samples,
                                devc->cnt_samples_rle);
-               if (devc->trigger_at != -1) {
+               if (devc->trigger_at_smpl != OLS_NO_TRIGGER) {
                        /*
                         * A trigger was set up, so we need to tell the frontend
                         * about it.
                         */
-                       if (devc->trigger_at > 0) {
+                       if (devc->trigger_at_smpl > 0) {
                                /* There are pre-trigger samples, send those first. */
                                packet.type = SR_DF_LOGIC;
                                packet.payload = &logic;
-                               logic.length = devc->trigger_at * 4;
+                               logic.length = devc->trigger_at_smpl * 4;
                                logic.unitsize = 4;
                                logic.data = devc->raw_sample_buf +
                                        (devc->limit_samples - devc->num_samples) * 4;
@@ -476,27 +507,20 @@ SR_PRIV int ols_receive_data(int fd, int revents, void *cb_data)
                        }
 
                        /* Send the trigger. */
-                       packet.type = SR_DF_TRIGGER;
-                       sr_session_send(sdi, &packet);
-
-                       /* Send post-trigger samples. */
-                       packet.type = SR_DF_LOGIC;
-                       packet.payload = &logic;
-                       logic.length = (devc->num_samples * 4) - (devc->trigger_at * 4);
-                       logic.unitsize = 4;
-                       logic.data = devc->raw_sample_buf + devc->trigger_at * 4 +
-                               (devc->limit_samples - devc->num_samples) * 4;
-                       sr_session_send(sdi, &packet);
-               } else {
-                       /* no trigger was used */
-                       packet.type = SR_DF_LOGIC;
-                       packet.payload = &logic;
-                       logic.length = devc->num_samples * 4;
-                       logic.unitsize = 4;
-                       logic.data = devc->raw_sample_buf +
-                               (devc->limit_samples - devc->num_samples) * 4;
-                       sr_session_send(sdi, &packet);
+                       std_session_send_df_trigger(sdi);
                }
+
+               /* Send post-trigger / all captured samples. */
+               int num_pre_trigger_samples = devc->trigger_at_smpl == OLS_NO_TRIGGER
+                       ? 0 : devc->trigger_at_smpl;
+               packet.type = SR_DF_LOGIC;
+               packet.payload = &logic;
+               logic.length = (devc->num_samples - num_pre_trigger_samples) * 4;
+               logic.unitsize = 4;
+               logic.data = devc->raw_sample_buf + (num_pre_trigger_samples +
+                       devc->limit_samples - devc->num_samples) * 4;
+               sr_session_send(sdi, &packet);
+
                g_free(devc->raw_sample_buf);
 
                serial_flush(serial);
@@ -505,3 +529,155 @@ SR_PRIV int ols_receive_data(int fd, int revents, void *cb_data)
 
        return TRUE;
 }
+
+static int ols_set_basic_trigger_stage(const struct ols_basic_trigger_desc *trigger_desc, struct sr_serial_dev_inst *serial, int stage)
+{
+       uint8_t cmd, arg[4];
+
+       cmd = CMD_SET_BASIC_TRIGGER_MASK0 + stage * 4;
+       arg[0] = trigger_desc->trigger_mask[stage] & 0xff;
+       arg[1] = (trigger_desc->trigger_mask[stage] >> 8) & 0xff;
+       arg[2] = (trigger_desc->trigger_mask[stage] >> 16) & 0xff;
+       arg[3] = (trigger_desc->trigger_mask[stage] >> 24) & 0xff;
+       if (send_longcommand(serial, cmd, arg) != SR_OK)
+               return SR_ERR;
+
+       cmd = CMD_SET_BASIC_TRIGGER_VALUE0 + stage * 4;
+       arg[0] = trigger_desc->trigger_value[stage] & 0xff;
+       arg[1] = (trigger_desc->trigger_value[stage] >> 8) & 0xff;
+       arg[2] = (trigger_desc->trigger_value[stage] >> 16) & 0xff;
+       arg[3] = (trigger_desc->trigger_value[stage] >> 24) & 0xff;
+       if (send_longcommand(serial, cmd, arg) != SR_OK)
+               return SR_ERR;
+
+       cmd = CMD_SET_BASIC_TRIGGER_CONFIG0 + stage * 4;
+       arg[0] = arg[1] = arg[3] = 0x00;
+       arg[2] = stage;
+       if (stage == trigger_desc->num_stages)
+               /* Last stage, fire when this one matches. */
+               arg[3] |= TRIGGER_START;
+       if (send_longcommand(serial, cmd, arg) != SR_OK)
+               return SR_ERR;
+
+       return SR_OK;
+}
+
+SR_PRIV int ols_prepare_acquisition(const struct sr_dev_inst *sdi) {
+       int ret;
+       uint8_t arg[4];
+
+       struct dev_context *devc = sdi->priv;
+       struct sr_serial_dev_inst *serial = sdi->conn;
+
+       int num_changroups = 0;
+       uint8_t changroup_mask = 0;
+       uint32_t channel_mask = ols_channel_mask(sdi);
+       for (unsigned int i = 0; i < 4; i++) {
+               if (channel_mask & (0xff << (i * 8))) {
+                       changroup_mask |= (1 << i);
+                       num_changroups++;
+               }
+       }
+
+       /*
+        * Limit readcount to prevent reading past the end of the hardware
+        * buffer. Rather read too many samples than too few.
+        */
+       uint32_t samplecount = MIN(devc->max_samples / num_changroups, devc->limit_samples);
+       uint32_t readcount = (samplecount + 3) / 4;
+       uint32_t delaycount;
+
+       /* Basic triggers. */
+       struct ols_basic_trigger_desc basic_trigger_desc;
+       if (convert_trigger(sdi, &basic_trigger_desc) != SR_OK) {
+               sr_err("Failed to configure channels.");
+               return SR_ERR;
+       }
+       if (basic_trigger_desc.num_stages > 0) {
+               /*
+                * According to http://mygizmos.org/ols/Logic-Sniffer-FPGA-Spec.pdf
+                * reset command must be send prior each arm command
+                */
+               sr_dbg("Send reset command before trigger configure");
+               if (ols_send_reset(serial) != SR_OK)
+                       return SR_ERR;
+
+               delaycount = readcount * (1 - devc->capture_ratio / 100.0);
+               devc->trigger_at_smpl = (readcount - delaycount) * 4 - basic_trigger_desc.num_stages;
+               for (int i = 0; i <= basic_trigger_desc.num_stages; i++) {
+                       sr_dbg("Setting OLS stage %d trigger.", i);
+                       if ((ret = ols_set_basic_trigger_stage(&basic_trigger_desc, serial, i)) != SR_OK)
+                               return ret;
+               }
+       } else {
+               /* No triggers configured, force trigger on first stage. */
+               sr_dbg("Forcing trigger at stage 0.");
+               if ((ret = ols_set_basic_trigger_stage(&basic_trigger_desc, serial, 0)) != SR_OK)
+                       return ret;
+               delaycount = readcount;
+       }
+
+       /* Samplerate. */
+       sr_dbg("Setting samplerate to %" PRIu64 "Hz (divider %u)",
+                       devc->cur_samplerate, devc->cur_samplerate_divider);
+       arg[0] = devc->cur_samplerate_divider & 0xff;
+       arg[1] = (devc->cur_samplerate_divider & 0xff00) >> 8;
+       arg[2] = (devc->cur_samplerate_divider & 0xff0000) >> 16;
+       arg[3] = 0x00;
+       if (send_longcommand(serial, CMD_SET_DIVIDER, arg) != SR_OK)
+               return SR_ERR;
+
+       /* Send sample limit and pre/post-trigger capture ratio. */
+       sr_dbg("Setting sample limit %d, trigger point at %d",
+                       (readcount - 1) * 4, (delaycount - 1) * 4);
+
+       if (devc->max_samples > 256 * 1024) {
+               arg[0] = ((readcount - 1) & 0xff);
+               arg[1] = ((readcount - 1) & 0xff00) >> 8;
+               arg[2] = ((readcount - 1) & 0xff0000) >> 16;
+               arg[3] = ((readcount - 1) & 0xff000000) >> 24;
+               if (send_longcommand(serial, CMD_CAPTURE_READCOUNT, arg) != SR_OK)
+                       return SR_ERR;
+               arg[0] = ((delaycount - 1) & 0xff);
+               arg[1] = ((delaycount - 1) & 0xff00) >> 8;
+               arg[2] = ((delaycount - 1) & 0xff0000) >> 16;
+               arg[3] = ((delaycount - 1) & 0xff000000) >> 24;
+               if (send_longcommand(serial, CMD_CAPTURE_DELAYCOUNT, arg) != SR_OK)
+                       return SR_ERR;
+       } else {
+               arg[0] = ((readcount - 1) & 0xff);
+               arg[1] = ((readcount - 1) & 0xff00) >> 8;
+               arg[2] = ((delaycount - 1) & 0xff);
+               arg[3] = ((delaycount - 1) & 0xff00) >> 8;
+               if (send_longcommand(serial, CMD_CAPTURE_SIZE, arg) != SR_OK)
+                       return SR_ERR;
+       }
+
+       /* Flag register. */
+       sr_dbg("Setting intpat %s, extpat %s, RLE %s, noise_filter %s, demux %s, %s clock%s",
+                       devc->capture_flags & CAPTURE_FLAG_INTERNAL_TEST_MODE ? "on": "off",
+                       devc->capture_flags & CAPTURE_FLAG_EXTERNAL_TEST_MODE ? "on": "off",
+                       devc->capture_flags & CAPTURE_FLAG_RLE ? "on" : "off",
+                       devc->capture_flags & CAPTURE_FLAG_NOISE_FILTER ? "on": "off",
+                       devc->capture_flags & CAPTURE_FLAG_DEMUX ? "on" : "off",
+                       devc->capture_flags & CAPTURE_FLAG_CLOCK_EXTERNAL ? "external" : "internal",
+                       devc->capture_flags & CAPTURE_FLAG_CLOCK_EXTERNAL ? (devc->capture_flags & CAPTURE_FLAG_INVERT_EXT_CLOCK
+                               ? " on falling edge" : "on rising edge") : "");
+
+       /*
+        * Enable/disable OLS channel groups in the flag register according
+        * to the channel mask. 1 means "disable channel".
+        */
+       devc->capture_flags &= ~0x3c;
+       devc->capture_flags |= ~(changroup_mask << 2) & 0x3c;
+
+       /* RLE mode is always zero, for now. */
+
+       arg[0] = devc->capture_flags & 0xff;
+       arg[1] = devc->capture_flags >> 8;
+       arg[2] = arg[3] = 0x00;
+       if (send_longcommand(serial, CMD_SET_FLAGS, arg) != SR_OK)
+               return SR_ERR;
+
+       return SR_OK;
+}