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_try_malloc(stl->pre_trigger_size);
  42         if (!stl->pre_trigger_buffer) {
  43                 soft_trigger_logic_free(stl);
  44                 return NULL;
  45         }
  46         stl->pre_trigger_head = stl->pre_trigger_buffer;
  47
  48         if (stl->pre_trigger_size > 0 && !stl->pre_trigger_buffer) {
  49                 soft_trigger_logic_free(stl);
  50                 return NULL;
  51         }
  52
  53         return stl;
  54 }
  55
  56 SR_PRIV void soft_trigger_logic_free(struct soft_trigger_logic *stl)
  57 {
  58         g_free(stl->pre_trigger_buffer);
  59         g_free(stl->prev_sample);
  60         g_free(stl);
  61 }
  62
  63 static void pre_trigger_append(struct soft_trigger_logic *stl,
  64                 uint8_t *buf, int len)
  65 {
  66         /* Avoid uselessly copying more than the pre-trigger size. */
  67         if (len > stl->pre_trigger_size) {
  68                 buf += len - stl->pre_trigger_size;
  69                 len = stl->pre_trigger_size;
  70         }
  71
  72         /* Update the filling level of the pre-trigger circular buffer. */
  73         stl->pre_trigger_fill = MIN(stl->pre_trigger_fill + len,
  74                                     stl->pre_trigger_size);
  75
  76         /* Actually copy data to the pre-trigger circular buffer. */
  77         while (len > 0) {
  78                 size_t size = MIN(stl->pre_trigger_buffer + stl->pre_trigger_size
  79                                   - stl->pre_trigger_head, len);
  80                 memcpy(stl->pre_trigger_head, buf, size);
  81                 stl->pre_trigger_head += size;
  82                 if (stl->pre_trigger_head >= stl->pre_trigger_buffer
  83                                              + stl->pre_trigger_size)
  84                         stl->pre_trigger_head = stl->pre_trigger_buffer;
  85                 buf += size;
  86                 len -= size;
  87         }
  88 }
  89
  90 static void pre_trigger_send(struct soft_trigger_logic *stl,
  91                 int *pre_trigger_samples)
  92 {
  93         struct sr_datafeed_packet packet;
  94         struct sr_datafeed_logic logic;
  95
  96         packet.type = SR_DF_LOGIC;
  97         packet.payload = &logic;
  98         logic.unitsize = stl->unitsize;
  99
 100         if (pre_trigger_samples)
 101                 *pre_trigger_samples = 0;
 102
 103         /* If pre-trigger buffer not full, rewind head to the first valid sample. */
 104         if (stl->pre_trigger_fill < stl->pre_trigger_size)
 105                 stl->pre_trigger_head = stl->pre_trigger_buffer;
 106
 107         /* Send logic packets for the pre-trigger circular buffer content. */
 108         while (stl->pre_trigger_fill > 0) {
 109                 size_t size = MIN(stl->pre_trigger_buffer + stl->pre_trigger_size
 110                                   - stl->pre_trigger_head, stl->pre_trigger_fill);
 111                 logic.length = size;
 112                 logic.data = stl->pre_trigger_head;
 113                 sr_session_send(stl->sdi, &packet);
 114                 stl->pre_trigger_head = stl->pre_trigger_buffer;
 115                 stl->pre_trigger_fill -= size;
 116                 if (pre_trigger_samples)
 117                         *pre_trigger_samples += size / stl->unitsize;
 118         }
 119 }
 120
 121 static gboolean logic_check_match(struct soft_trigger_logic *stl,
 122                 uint8_t *sample, struct sr_trigger_match *match)
 123 {
 124         int bit, prev_bit;
 125         gboolean result;
 126
 127         stl->count++;
 128         result = FALSE;
 129         bit = *(sample + match->channel->index / 8)
 130                         & (1 << (match->channel->index % 8));
 131         if (match->match == SR_TRIGGER_ZERO)
 132                 result = bit == 0;
 133         else if (match->match == SR_TRIGGER_ONE)
 134                 result = bit != 0;
 135         else {
 136                 /* Edge matches. */
 137                 if (stl->count == 1)
 138                         /* First sample, don't have enough for an edge match yet. */
 139                         return FALSE;
 140                 prev_bit = *(stl->prev_sample + match->channel->index / 8)
 141                                 & (1 << (match->channel->index % 8));
 142                 if (match->match == SR_TRIGGER_RISING)
 143                         result = prev_bit == 0 && bit != 0;
 144                 else if (match->match == SR_TRIGGER_FALLING)
 145                         result = prev_bit != 0 && bit == 0;
 146                 else if (match->match == SR_TRIGGER_EDGE)
 147                         result = prev_bit != bit;
 148         }
 149
 150         return result;
 151 }
 152
 153 /* Returns the offset (in samples) within buf of where the trigger
 154  * occurred, or -1 if not triggered. */
 155 SR_PRIV int soft_trigger_logic_check(struct soft_trigger_logic *stl,
 156                 uint8_t *buf, int len, int *pre_trigger_samples)
 157 {
 158         struct sr_datafeed_packet packet;
 159         struct sr_trigger_stage *stage;
 160         struct sr_trigger_match *match;
 161         GSList *l, *l_stage;
 162         int offset;
 163         int i;
 164         gboolean match_found;
 165
 166         offset = -1;
 167         for (i = 0; i < len; i += stl->unitsize) {
 168                 l_stage = g_slist_nth(stl->trigger->stages, stl->cur_stage);
 169                 stage = l_stage->data;
 170                 if (!stage->matches)
 171                         /* No matches supplied, client error. */
 172                         return SR_ERR_ARG;
 173
 174                 match_found = TRUE;
 175                 for (l = stage->matches; l; l = l->next) {
 176                         match = l->data;
 177                         if (!match->channel->enabled)
 178                                 /* Ignore disabled channels with a trigger. */
 179                                 continue;
 180                         if (!logic_check_match(stl, buf + i, match)) {
 181                                 match_found = FALSE;
 182                                 break;
 183                         }
 184                 }
 185                 memcpy(stl->prev_sample, buf + i, stl->unitsize);
 186                 if (match_found) {
 187                         /* Matched on the current stage. */
 188                         if (l_stage->next) {
 189                                 /* Advance to next stage. */
 190                                 stl->cur_stage++;
 191                         } else {
 192                                 /* Matched on last stage, send pre-trigger data. */
 193                                 pre_trigger_append(stl, buf, i);
 194                                 pre_trigger_send(stl, pre_trigger_samples);
 195
 196                                 /* Fire trigger. */
 197                                 offset = i / stl->unitsize;
 198
 199                                 packet.type = SR_DF_TRIGGER;
 200                                 packet.payload = NULL;
 201                                 sr_session_send(stl->sdi, &packet);
 202                                 break;
 203                         }
 204                 } else if (stl->cur_stage > 0) {
 205                         /*
 206                          * We had a match at an earlier stage, but failed on the
 207                          * current stage. However, we may have a match on this
 208                          * stage in the next bit -- trigger on 0001 will fail on
 209                          * seeing 00001, so we need to go back to stage 0 -- but
 210                          * at the next sample from the one that matched originally,
 211                          * which the counter increment at the end of the loop
 212                          * takes care of.
 213                          */
 214                         i -= stl->cur_stage * stl->unitsize;
 215                         if (i < -1)
 216                                 i = -1; /* Oops, went back past this buffer. */
 217                         /* Reset trigger stage. */
 218                         stl->cur_stage = 0;
 219                 }
 220         }
 221
 222         if (offset == -1)
 223                 pre_trigger_append(stl, buf, len);
 224
 225         return offset;
 226 }