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 SR_PRIV struct soft_trigger_logic *soft_trigger_logic_new(
  30                 const struct sr_dev_inst *sdi, struct sr_trigger *trigger,
  31                 int pre_trigger_samples)
  32 {
  33         struct soft_trigger_logic *stl;
  34
  35         stl = g_malloc0(sizeof(struct soft_trigger_logic));
  36         stl->sdi = sdi;
  37         stl->trigger = trigger;
  38         stl->unitsize = (g_slist_length(sdi->channels) + 7) / 8;
  39         stl->prev_sample = g_malloc0(stl->unitsize);
  40         stl->pre_trigger_size = stl->unitsize * pre_trigger_samples;
  41         stl->pre_trigger_buffer = g_malloc(stl->pre_trigger_size);
  42         stl->pre_trigger_head = stl->pre_trigger_buffer;
  43
  44         if (stl->pre_trigger_size > 0 && !stl->pre_trigger_buffer) {
  45                 soft_trigger_logic_free(stl);
  46                 return NULL;
  47         }
  48
  49         return stl;
  50 }
  51
  52 SR_PRIV void soft_trigger_logic_free(struct soft_trigger_logic *stl)
  53 {
  54         g_free(stl->pre_trigger_buffer);
  55         g_free(stl->prev_sample);
  56         g_free(stl);
  57 }
  58
  59 static void pre_trigger_append(struct soft_trigger_logic *stl,
  60                 uint8_t *buf, int len)
  61 {
  62         /* Avoid uselessly copying more than the pre-trigger size. */
  63         if (len > stl->pre_trigger_size) {
  64                 buf += len - stl->pre_trigger_size;
  65                 len = stl->pre_trigger_size;
  66         }
  67
  68         /* Update the filling level of the pre-trigger circular buffer. */
  69         stl->pre_trigger_fill = MIN(stl->pre_trigger_fill + len,
  70                                     stl->pre_trigger_size);
  71
  72         /* Actually copy data to the pre-trigger circular buffer. */
  73         while (len > 0) {
  74                 size_t size = MIN(stl->pre_trigger_buffer + stl->pre_trigger_size
  75                                   - stl->pre_trigger_head, len);
  76                 memcpy(stl->pre_trigger_head, buf, size);
  77                 stl->pre_trigger_head += size;
  78                 if (stl->pre_trigger_head >= stl->pre_trigger_buffer
  79                                              + stl->pre_trigger_size)
  80                         stl->pre_trigger_head = stl->pre_trigger_buffer;
  81                 buf += size;
  82                 len -= size;
  83         }
  84 }
  85
  86 static void pre_trigger_send(struct soft_trigger_logic *stl,
  87                 int *pre_trigger_samples)
  88 {
  89         struct sr_datafeed_packet packet;
  90         struct sr_datafeed_logic logic;
  91
  92         packet.type = SR_DF_LOGIC;
  93         packet.payload = &logic;
  94         logic.unitsize = stl->unitsize;
  95
  96         if (pre_trigger_samples)
  97                 *pre_trigger_samples = 0;
  98
  99         /* If pre-trigger buffer not full, rewind head to the first valid sample. */
 100         if (stl->pre_trigger_fill < stl->pre_trigger_size)
 101                 stl->pre_trigger_head = stl->pre_trigger_buffer;
 102
 103         /* Send logic packets for the pre-trigger circular buffer content. */
 104         while (stl->pre_trigger_fill > 0) {
 105                 size_t size = MIN(stl->pre_trigger_buffer + stl->pre_trigger_size
 106                                   - stl->pre_trigger_head, stl->pre_trigger_fill);
 107                 logic.length = size;
 108                 logic.data = stl->pre_trigger_head;
 109                 sr_session_send(stl->sdi, &packet);
 110                 stl->pre_trigger_head = stl->pre_trigger_buffer;
 111                 stl->pre_trigger_fill -= size;
 112                 if (pre_trigger_samples)
 113                         *pre_trigger_samples += size / stl->unitsize;
 114         }
 115 }
 116
 117 static gboolean logic_check_match(struct soft_trigger_logic *stl,
 118                 uint8_t *sample, struct sr_trigger_match *match)
 119 {
 120         int bit, prev_bit;
 121         gboolean result;
 122
 123         stl->count++;
 124         result = FALSE;
 125         bit = *(sample + match->channel->index / 8)
 126                         & (1 << (match->channel->index % 8));
 127         if (match->match == SR_TRIGGER_ZERO)
 128                 result = bit == 0;
 129         else if (match->match == SR_TRIGGER_ONE)
 130                 result = bit != 0;
 131         else {
 132                 /* Edge matches. */
 133                 if (stl->count == 1)
 134                         /* First sample, don't have enough for an edge match yet. */
 135                         return FALSE;
 136                 prev_bit = *(stl->prev_sample + match->channel->index / 8)
 137                                 & (1 << (match->channel->index % 8));
 138                 if (match->match == SR_TRIGGER_RISING)
 139                         result = prev_bit == 0 && bit != 0;
 140                 else if (match->match == SR_TRIGGER_FALLING)
 141                         result = prev_bit != 0 && bit == 0;
 142                 else if (match->match == SR_TRIGGER_EDGE)
 143                         result = prev_bit != bit;
 144         }
 145
 146         return result;
 147 }
 148
 149 /* Returns the offset (in samples) within buf of where the trigger
 150  * occurred, or -1 if not triggered. */
 151 SR_PRIV int soft_trigger_logic_check(struct soft_trigger_logic *stl,
 152                 uint8_t *buf, int len, int *pre_trigger_samples)
 153 {
 154         struct sr_datafeed_packet packet;
 155         struct sr_trigger_stage *stage;
 156         struct sr_trigger_match *match;
 157         GSList *l, *l_stage;
 158         int offset;
 159         int i;
 160         gboolean match_found;
 161
 162         offset = -1;
 163         for (i = 0; i < len; i += stl->unitsize) {
 164                 l_stage = g_slist_nth(stl->trigger->stages, stl->cur_stage);
 165                 stage = l_stage->data;
 166                 if (!stage->matches)
 167                         /* No matches supplied, client error. */
 168                         return SR_ERR_ARG;
 169
 170                 match_found = TRUE;
 171                 for (l = stage->matches; l; l = l->next) {
 172                         match = l->data;
 173                         if (!match->channel->enabled)
 174                                 /* Ignore disabled channels with a trigger. */
 175                                 continue;
 176                         if (!logic_check_match(stl, buf + i, match)) {
 177                                 match_found = FALSE;
 178                                 break;
 179                         }
 180                 }
 181                 memcpy(stl->prev_sample, buf + i, stl->unitsize);
 182                 if (match_found) {
 183                         /* Matched on the current stage. */
 184                         if (l_stage->next) {
 185                                 /* Advance to next stage. */
 186                                 stl->cur_stage++;
 187                         } else {
 188                                 /* Matched on last stage, send pre-trigger data. */
 189                                 pre_trigger_append(stl, buf, i);
 190                                 pre_trigger_send(stl, pre_trigger_samples);
 191
 192                                 /* Fire trigger. */
 193                                 offset = i / stl->unitsize;
 194
 195                                 packet.type = SR_DF_TRIGGER;
 196                                 packet.payload = NULL;
 197                                 sr_session_send(stl->sdi, &packet);
 198                                 break;
 199                         }
 200                 } else if (stl->cur_stage > 0) {
 201                         /*
 202                          * We had a match at an earlier stage, but failed on the
 203                          * current stage. However, we may have a match on this
 204                          * stage in the next bit -- trigger on 0001 will fail on
 205                          * seeing 00001, so we need to go back to stage 0 -- but
 206                          * at the next sample from the one that matched originally,
 207                          * which the counter increment at the end of the loop
 208                          * takes care of.
 209                          */
 210                         i -= stl->cur_stage * stl->unitsize;
 211                         if (i < -1)
 212                                 i = -1; /* Oops, went back past this buffer. */
 213                         /* Reset trigger stage. */
 214                         stl->cur_stage = 0;
 215                 }
 216         }
 217
 218         if (offset == -1)
 219                 pre_trigger_append(stl, buf, len);
 220
 221         return offset;
 222 }