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 <string.h>
  21 #include <libsigrok/libsigrok.h>
  22 #include "libsigrok-internal.h"
  23
  24 /* @cond PRIVATE */
  25 #define LOG_PREFIX "soft-trigger"
  26 /* @endcond */
  27
  28 SR_PRIV struct soft_trigger_logic *soft_trigger_logic_new(
  29                 const struct sr_dev_inst *sdi, struct sr_trigger *trigger,
  30                 int pre_trigger_samples)
  31 {
  32         struct soft_trigger_logic *stl;
  33
  34         stl = g_malloc0(sizeof(struct soft_trigger_logic));
  35         stl->sdi = sdi;
  36         stl->trigger = trigger;
  37         stl->unitsize = (g_slist_length(sdi->channels) + 7) / 8;
  38         stl->prev_sample = g_malloc0(stl->unitsize);
  39         stl->pre_trigger_size = stl->unitsize * pre_trigger_samples;
  40         stl->pre_trigger_buffer = g_malloc(stl->pre_trigger_size);
  41         stl->pre_trigger_head = stl->pre_trigger_buffer;
  42
  43         if (stl->pre_trigger_size > 0 && !stl->pre_trigger_buffer) {
  44                 soft_trigger_logic_free(stl);
  45                 return NULL;
  46         }
  47
  48         return stl;
  49 }
  50
  51 SR_PRIV void soft_trigger_logic_free(struct soft_trigger_logic *stl)
  52 {
  53         g_free(stl->pre_trigger_buffer);
  54         g_free(stl->prev_sample);
  55         g_free(stl);
  56 }
  57
  58 static void pre_trigger_append(struct soft_trigger_logic *stl,
  59                 uint8_t *buf, int len)
  60 {
  61         /* Avoid uselessly copying more than the pre-trigger size. */
  62         if (len > stl->pre_trigger_size) {
  63                 buf += len - stl->pre_trigger_size;
  64                 len = stl->pre_trigger_size;
  65         }
  66
  67         /* Update the filling level of the pre-trigger circular buffer. */
  68         stl->pre_trigger_fill = MIN(stl->pre_trigger_fill + len,
  69                                     stl->pre_trigger_size);
  70
  71         /* Actually copy data to the pre-trigger circular buffer. */
  72         while (len > 0) {
  73                 size_t size = MIN(stl->pre_trigger_buffer + stl->pre_trigger_size
  74                                   - stl->pre_trigger_head, len);
  75                 memcpy(stl->pre_trigger_head, buf, size);
  76                 stl->pre_trigger_head += size;
  77                 if (stl->pre_trigger_head >= stl->pre_trigger_buffer
  78                                              + stl->pre_trigger_size)
  79                         stl->pre_trigger_head = stl->pre_trigger_buffer;
  80                 buf += size;
  81                 len -= size;
  82         }
  83 }
  84
  85 static void pre_trigger_send(struct soft_trigger_logic *stl,
  86                 int *pre_trigger_samples)
  87 {
  88         struct sr_datafeed_packet packet;
  89         struct sr_datafeed_logic logic;
  90
  91         packet.type = SR_DF_LOGIC;
  92         packet.payload = &logic;
  93         logic.unitsize = stl->unitsize;
  94
  95         if (pre_trigger_samples)
  96                 *pre_trigger_samples = 0;
  97
  98         /* If pre-trigger buffer not full, rewind head to the first valid sample. */
  99         if (stl->pre_trigger_fill < stl->pre_trigger_size)
 100                 stl->pre_trigger_head = stl->pre_trigger_buffer;
 101
 102         /* Send logic packets for the pre-trigger circular buffer content. */
 103         while (stl->pre_trigger_fill > 0) {
 104                 size_t size = MIN(stl->pre_trigger_buffer + stl->pre_trigger_size
 105                                   - stl->pre_trigger_head, stl->pre_trigger_fill);
 106                 logic.length = size;
 107                 logic.data = stl->pre_trigger_head;
 108                 sr_session_send(stl->sdi, &packet);
 109                 stl->pre_trigger_head = stl->pre_trigger_buffer;
 110                 stl->pre_trigger_fill -= size;
 111                 if (pre_trigger_samples)
 112                         *pre_trigger_samples += size / stl->unitsize;
 113         }
 114 }
 115
 116 static gboolean logic_check_match(struct soft_trigger_logic *stl,
 117                 uint8_t *sample, struct sr_trigger_match *match)
 118 {
 119         int bit, prev_bit;
 120         gboolean result;
 121
 122         stl->count++;
 123         result = FALSE;
 124         bit = *(sample + match->channel->index / 8)
 125                         & (1 << (match->channel->index % 8));
 126         if (match->match == SR_TRIGGER_ZERO)
 127                 result = bit == 0;
 128         else if (match->match == SR_TRIGGER_ONE)
 129                 result = bit != 0;
 130         else {
 131                 /* Edge matches. */
 132                 if (stl->count == 1)
 133                         /* First sample, don't have enough for an edge match yet. */
 134                         return FALSE;
 135                 prev_bit = *(stl->prev_sample + match->channel->index / 8)
 136                                 & (1 << (match->channel->index % 8));
 137                 if (match->match == SR_TRIGGER_RISING)
 138                         result = prev_bit == 0 && bit != 0;
 139                 else if (match->match == SR_TRIGGER_FALLING)
 140                         result = prev_bit != 0 && bit == 0;
 141                 else if (match->match == SR_TRIGGER_EDGE)
 142                         result = prev_bit != bit;
 143         }
 144
 145         return result;
 146 }
 147
 148 /* Returns the offset (in samples) within buf of where the trigger
 149  * occurred, or -1 if not triggered. */
 150 SR_PRIV int soft_trigger_logic_check(struct soft_trigger_logic *stl,
 151                 uint8_t *buf, int len, int *pre_trigger_samples)
 152 {
 153         struct sr_datafeed_packet packet;
 154         struct sr_trigger_stage *stage;
 155         struct sr_trigger_match *match;
 156         GSList *l, *l_stage;
 157         int offset;
 158         int i;
 159         gboolean match_found;
 160
 161         offset = -1;
 162         for (i = 0; i < len; i += stl->unitsize) {
 163                 l_stage = g_slist_nth(stl->trigger->stages, stl->cur_stage);
 164                 stage = l_stage->data;
 165                 if (!stage->matches)
 166                         /* No matches supplied, client error. */
 167                         return SR_ERR_ARG;
 168
 169                 match_found = TRUE;
 170                 for (l = stage->matches; l; l = l->next) {
 171                         match = l->data;
 172                         if (!match->channel->enabled)
 173                                 /* Ignore disabled channels with a trigger. */
 174                                 continue;
 175                         if (!logic_check_match(stl, buf + i, match)) {
 176                                 match_found = FALSE;
 177                                 break;
 178                         }
 179                 }
 180                 memcpy(stl->prev_sample, buf + i, stl->unitsize);
 181                 if (match_found) {
 182                         /* Matched on the current stage. */
 183                         if (l_stage->next) {
 184                                 /* Advance to next stage. */
 185                                 stl->cur_stage++;
 186                         } else {
 187                                 /* Matched on last stage, send pre-trigger data. */
 188                                 pre_trigger_append(stl, buf, i);
 189                                 pre_trigger_send(stl, pre_trigger_samples);
 190
 191                                 /* Fire trigger. */
 192                                 offset = i / stl->unitsize;
 193
 194                                 packet.type = SR_DF_TRIGGER;
 195                                 packet.payload = NULL;
 196                                 sr_session_send(stl->sdi, &packet);
 197                                 break;
 198                         }
 199                 } else if (stl->cur_stage > 0) {
 200                         /*
 201                          * We had a match at an earlier stage, but failed on the
 202                          * current stage. However, we may have a match on this
 203                          * stage in the next bit -- trigger on 0001 will fail on
 204                          * seeing 00001, so we need to go back to stage 0 -- but
 205                          * at the next sample from the one that matched originally,
 206                          * which the counter increment at the end of the loop
 207                          * takes care of.
 208                          */
 209                         i -= stl->cur_stage * stl->unitsize;
 210                         if (i < -1)
 211                                 i = -1; /* Oops, went back past this buffer. */
 212                         /* Reset trigger stage. */
 213                         stl->cur_stage = 0;
 214                 }
 215         }
 216
 217         if (offset == -1)
 218                 pre_trigger_append(stl, buf, len);
 219
 220         return offset;
 221 }