src/soft-trigger.c

   1 /*
   2  * This file is part of the libsigrok project.
   3  *
   4  * Copyright (C) 2014 Bert Vermeulen <bert@biot.com>
   5  *
   6  * This program is free software: you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation, either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <config.h>
  21 #include <string.h>
  22 #include <libsigrok/libsigrok.h>
  23 #include "libsigrok-internal.h"
  24
  25 /* @cond PRIVATE */
  26 #define LOG_PREFIX "soft-trigger"
  27 /* @endcond */
  28
  29 static size_t logic_channel_unitsize(GSList *channels)
  30 {
  31         size_t number = 0;
  32         struct sr_channel *channel;
  33         GSList *l;
  34
  35         for (l = channels; l; l = l->next) {
  36                 channel = l->data;
  37                 if (channel->type == SR_CHANNEL_LOGIC)
  38                         number += 1;
  39         }
  40         sr_dbg("number of logic channels: %d", (int) number);
  41         return (number + 7) / 8;
  42 }
  43
  44
  45 SR_PRIV struct soft_trigger_logic *soft_trigger_logic_new(
  46                 const struct sr_dev_inst *sdi, struct sr_trigger *trigger,
  47                 int pre_trigger_samples)
  48 {
  49         struct soft_trigger_logic *stl;
  50
  51         stl = g_malloc0(sizeof(struct soft_trigger_logic));
  52         stl->sdi = sdi;
  53         stl->trigger = trigger;
  54         /* Retreive number of logic channels, unitsize */
  55         stl->unitsize = logic_channel_unitsize(sdi->channels);
  56         stl->prev_sample = g_malloc0(stl->unitsize);
  57         stl->pre_trigger_size = stl->unitsize * pre_trigger_samples;
  58         stl->pre_trigger_buffer = g_try_malloc(stl->pre_trigger_size);
  59         if (pre_trigger_samples > 0 && !stl->pre_trigger_buffer) {
  60                 /*
  61                  * Error out if g_try_malloc() failed (or was invoked as
  62                  * g_try_malloc(0)) *and* more than 0 pretrigger samples
  63                  * were requested.
  64                  */
  65                 soft_trigger_logic_free(stl);
  66                 return NULL;
  67         }
  68         stl->pre_trigger_head = stl->pre_trigger_buffer;
  69
  70         if (stl->pre_trigger_size > 0 && !stl->pre_trigger_buffer) {
  71                 soft_trigger_logic_free(stl);
  72                 return NULL;
  73         }
  74
  75         return stl;
  76 }
  77
  78 SR_PRIV void soft_trigger_logic_free(struct soft_trigger_logic *stl)
  79 {
  80         g_free(stl->pre_trigger_buffer);
  81         g_free(stl->prev_sample);
  82         g_free(stl);
  83 }
  84
  85 static void pre_trigger_append(struct soft_trigger_logic *stl,
  86                 uint8_t *buf, int len)
  87 {
  88         /* Avoid uselessly copying more than the pre-trigger size. */
  89         if (len > stl->pre_trigger_size) {
  90                 buf += len - stl->pre_trigger_size;
  91                 len = stl->pre_trigger_size;
  92         }
  93
  94         /* Update the filling level of the pre-trigger circular buffer. */
  95         stl->pre_trigger_fill = MIN(stl->pre_trigger_fill + len,
  96                                     stl->pre_trigger_size);
  97
  98         /* Actually copy data to the pre-trigger circular buffer. */
  99         while (len > 0) {
 100                 size_t size = MIN(stl->pre_trigger_buffer + stl->pre_trigger_size
 101                                   - stl->pre_trigger_head, len);
 102                 memcpy(stl->pre_trigger_head, buf, size);
 103                 stl->pre_trigger_head += size;
 104                 if (stl->pre_trigger_head >= stl->pre_trigger_buffer
 105                                              + stl->pre_trigger_size)
 106                         stl->pre_trigger_head = stl->pre_trigger_buffer;
 107                 buf += size;
 108                 len -= size;
 109         }
 110 }
 111
 112 static void pre_trigger_send(struct soft_trigger_logic *stl,
 113                 int *pre_trigger_samples)
 114 {
 115         struct sr_datafeed_packet packet;
 116         struct sr_datafeed_logic logic;
 117
 118         packet.type = SR_DF_LOGIC;
 119         packet.payload = &logic;
 120         logic.unitsize = stl->unitsize;
 121
 122         if (pre_trigger_samples)
 123                 *pre_trigger_samples = 0;
 124
 125         /* If pre-trigger buffer not full, rewind head to the first valid sample. */
 126         if (stl->pre_trigger_fill < stl->pre_trigger_size)
 127                 stl->pre_trigger_head = stl->pre_trigger_buffer;
 128
 129         /* Send logic packets for the pre-trigger circular buffer content. */
 130         while (stl->pre_trigger_fill > 0) {
 131                 size_t size = MIN(stl->pre_trigger_buffer + stl->pre_trigger_size
 132                                   - stl->pre_trigger_head, stl->pre_trigger_fill);
 133                 logic.length = size;
 134                 logic.data = stl->pre_trigger_head;
 135                 sr_session_send(stl->sdi, &packet);
 136                 stl->pre_trigger_head = stl->pre_trigger_buffer;
 137                 stl->pre_trigger_fill -= size;
 138                 if (pre_trigger_samples)
 139                         *pre_trigger_samples += size / stl->unitsize;
 140         }
 141 }
 142
 143 static gboolean logic_check_match(struct soft_trigger_logic *stl,
 144                 uint8_t *sample, struct sr_trigger_match *match)
 145 {
 146         int bit, prev_bit;
 147         gboolean result;
 148
 149         stl->count++;
 150         result = FALSE;
 151         bit = *(sample + match->channel->index / 8)
 152                         & (1 << (match->channel->index % 8));
 153         if (match->match == SR_TRIGGER_ZERO)
 154                 result = bit == 0;
 155         else if (match->match == SR_TRIGGER_ONE)
 156                 result = bit != 0;
 157         else {
 158                 /* Edge matches. */
 159                 if (stl->count == 1)
 160                         /* First sample, don't have enough for an edge match yet. */
 161                         return FALSE;
 162                 prev_bit = *(stl->prev_sample + match->channel->index / 8)
 163                                 & (1 << (match->channel->index % 8));
 164                 if (match->match == SR_TRIGGER_RISING)
 165                         result = prev_bit == 0 && bit != 0;
 166                 else if (match->match == SR_TRIGGER_FALLING)
 167                         result = prev_bit != 0 && bit == 0;
 168                 else if (match->match == SR_TRIGGER_EDGE)
 169                         result = prev_bit != bit;
 170         }
 171
 172         return result;
 173 }
 174
 175 /* Returns the offset (in samples) within buf of where the trigger
 176  * occurred, or -1 if not triggered. */
 177 SR_PRIV int soft_trigger_logic_check(struct soft_trigger_logic *stl,
 178                 uint8_t *buf, int len, int *pre_trigger_samples)
 179 {
 180         struct sr_datafeed_packet packet;
 181         struct sr_trigger_stage *stage;
 182         struct sr_trigger_match *match;
 183         GSList *l, *l_stage;
 184         int offset;
 185         int i;
 186         gboolean match_found;
 187
 188         offset = -1;
 189         for (i = 0; i < len; i += stl->unitsize) {
 190                 l_stage = g_slist_nth(stl->trigger->stages, stl->cur_stage);
 191                 stage = l_stage->data;
 192                 if (!stage->matches)
 193                         /* No matches supplied, client error. */
 194                         return SR_ERR_ARG;
 195
 196                 match_found = TRUE;
 197                 for (l = stage->matches; l; l = l->next) {
 198                         match = l->data;
 199                         if (!match->channel->enabled)
 200                                 /* Ignore disabled channels with a trigger. */
 201                                 continue;
 202                         if (!logic_check_match(stl, buf + i, match)) {
 203                                 match_found = FALSE;
 204                                 break;
 205                         }
 206                 }
 207                 memcpy(stl->prev_sample, buf + i, stl->unitsize);
 208                 if (match_found) {
 209                         /* Matched on the current stage. */
 210                         if (l_stage->next) {
 211                                 /* Advance to next stage. */
 212                                 stl->cur_stage++;
 213                         } else {
 214                                 /* Matched on last stage, send pre-trigger data. */
 215                                 pre_trigger_append(stl, buf, i);
 216                                 pre_trigger_send(stl, pre_trigger_samples);
 217
 218                                 /* Fire trigger. */
 219                                 offset = i / stl->unitsize;
 220
 221                                 packet.type = SR_DF_TRIGGER;
 222                                 packet.payload = NULL;
 223                                 sr_session_send(stl->sdi, &packet);
 224                                 break;
 225                         }
 226                 } else if (stl->cur_stage > 0) {
 227                         /*
 228                          * We had a match at an earlier stage, but failed on the
 229                          * current stage. However, we may have a match on this
 230                          * stage in the next bit -- trigger on 0001 will fail on
 231                          * seeing 00001, so we need to go back to stage 0 -- but
 232                          * at the next sample from the one that matched originally,
 233                          * which the counter increment at the end of the loop
 234                          * takes care of.
 235                          */
 236                         i -= stl->cur_stage * stl->unitsize;
 237                         if (i < -1)
 238                                 i = -1; /* Oops, went back past this buffer. */
 239                         /* Reset trigger stage. */
 240                         stl->cur_stage = 0;
 241                 }
 242         }
 243
 244         if (offset == -1)
 245                 pre_trigger_append(stl, buf, len);
 246
 247         return offset;
 248 }