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 (pre_trigger_samples > 0 && !stl->pre_trigger_buffer) {
  43                 /*
  44                  * Error out if g_try_malloc() failed (or was invoked as
  45                  * g_try_malloc(0)) *and* more than 0 pretrigger samples
  46                  * were requested.
  47                  */
  48                 soft_trigger_logic_free(stl);
  49                 return NULL;
  50         }
  51         stl->pre_trigger_head = stl->pre_trigger_buffer;
  52
  53         if (stl->pre_trigger_size > 0 && !stl->pre_trigger_buffer) {
  54                 soft_trigger_logic_free(stl);
  55                 return NULL;
  56         }
  57
  58         return stl;
  59 }
  60
  61 SR_PRIV void soft_trigger_logic_free(struct soft_trigger_logic *stl)
  62 {
  63         g_free(stl->pre_trigger_buffer);
  64         g_free(stl->prev_sample);
  65         g_free(stl);
  66 }
  67
  68 static void pre_trigger_append(struct soft_trigger_logic *stl,
  69                 uint8_t *buf, int len)
  70 {
  71         /* Avoid uselessly copying more than the pre-trigger size. */
  72         if (len > stl->pre_trigger_size) {
  73                 buf += len - stl->pre_trigger_size;
  74                 len = stl->pre_trigger_size;
  75         }
  76
  77         /* Update the filling level of the pre-trigger circular buffer. */
  78         stl->pre_trigger_fill = MIN(stl->pre_trigger_fill + len,
  79                                     stl->pre_trigger_size);
  80
  81         /* Actually copy data to the pre-trigger circular buffer. */
  82         while (len > 0) {
  83                 size_t size = MIN(stl->pre_trigger_buffer + stl->pre_trigger_size
  84                                   - stl->pre_trigger_head, len);
  85                 memcpy(stl->pre_trigger_head, buf, size);
  86                 stl->pre_trigger_head += size;
  87                 if (stl->pre_trigger_head >= stl->pre_trigger_buffer
  88                                              + stl->pre_trigger_size)
  89                         stl->pre_trigger_head = stl->pre_trigger_buffer;
  90                 buf += size;
  91                 len -= size;
  92         }
  93 }
  94
  95 static void pre_trigger_send(struct soft_trigger_logic *stl,
  96                 int *pre_trigger_samples)
  97 {
  98         struct sr_datafeed_packet packet;
  99         struct sr_datafeed_logic logic;
 100
 101         packet.type = SR_DF_LOGIC;
 102         packet.payload = &logic;
 103         logic.unitsize = stl->unitsize;
 104
 105         if (pre_trigger_samples)
 106                 *pre_trigger_samples = 0;
 107
 108         /* If pre-trigger buffer not full, rewind head to the first valid sample. */
 109         if (stl->pre_trigger_fill < stl->pre_trigger_size)
 110                 stl->pre_trigger_head = stl->pre_trigger_buffer;
 111
 112         /* Send logic packets for the pre-trigger circular buffer content. */
 113         while (stl->pre_trigger_fill > 0) {
 114                 size_t size = MIN(stl->pre_trigger_buffer + stl->pre_trigger_size
 115                                   - stl->pre_trigger_head, stl->pre_trigger_fill);
 116                 logic.length = size;
 117                 logic.data = stl->pre_trigger_head;
 118                 sr_session_send(stl->sdi, &packet);
 119                 stl->pre_trigger_head = stl->pre_trigger_buffer;
 120                 stl->pre_trigger_fill -= size;
 121                 if (pre_trigger_samples)
 122                         *pre_trigger_samples += size / stl->unitsize;
 123         }
 124 }
 125
 126 static gboolean logic_check_match(struct soft_trigger_logic *stl,
 127                 uint8_t *sample, struct sr_trigger_match *match)
 128 {
 129         int bit, prev_bit;
 130         gboolean result;
 131
 132         stl->count++;
 133         result = FALSE;
 134         bit = *(sample + match->channel->index / 8)
 135                         & (1 << (match->channel->index % 8));
 136         if (match->match == SR_TRIGGER_ZERO)
 137                 result = bit == 0;
 138         else if (match->match == SR_TRIGGER_ONE)
 139                 result = bit != 0;
 140         else {
 141                 /* Edge matches. */
 142                 if (stl->count == 1)
 143                         /* First sample, don't have enough for an edge match yet. */
 144                         return FALSE;
 145                 prev_bit = *(stl->prev_sample + match->channel->index / 8)
 146                                 & (1 << (match->channel->index % 8));
 147                 if (match->match == SR_TRIGGER_RISING)
 148                         result = prev_bit == 0 && bit != 0;
 149                 else if (match->match == SR_TRIGGER_FALLING)
 150                         result = prev_bit != 0 && bit == 0;
 151                 else if (match->match == SR_TRIGGER_EDGE)
 152                         result = prev_bit != bit;
 153         }
 154
 155         return result;
 156 }
 157
 158 /* Returns the offset (in samples) within buf of where the trigger
 159  * occurred, or -1 if not triggered. */
 160 SR_PRIV int soft_trigger_logic_check(struct soft_trigger_logic *stl,
 161                 uint8_t *buf, int len, int *pre_trigger_samples)
 162 {
 163         struct sr_datafeed_packet packet;
 164         struct sr_trigger_stage *stage;
 165         struct sr_trigger_match *match;
 166         GSList *l, *l_stage;
 167         int offset;
 168         int i;
 169         gboolean match_found;
 170
 171         offset = -1;
 172         for (i = 0; i < len; i += stl->unitsize) {
 173                 l_stage = g_slist_nth(stl->trigger->stages, stl->cur_stage);
 174                 stage = l_stage->data;
 175                 if (!stage->matches)
 176                         /* No matches supplied, client error. */
 177                         return SR_ERR_ARG;
 178
 179                 match_found = TRUE;
 180                 for (l = stage->matches; l; l = l->next) {
 181                         match = l->data;
 182                         if (!match->channel->enabled)
 183                                 /* Ignore disabled channels with a trigger. */
 184                                 continue;
 185                         if (!logic_check_match(stl, buf + i, match)) {
 186                                 match_found = FALSE;
 187                                 break;
 188                         }
 189                 }
 190                 memcpy(stl->prev_sample, buf + i, stl->unitsize);
 191                 if (match_found) {
 192                         /* Matched on the current stage. */
 193                         if (l_stage->next) {
 194                                 /* Advance to next stage. */
 195                                 stl->cur_stage++;
 196                         } else {
 197                                 /* Matched on last stage, send pre-trigger data. */
 198                                 pre_trigger_append(stl, buf, i);
 199                                 pre_trigger_send(stl, pre_trigger_samples);
 200
 201                                 /* Fire trigger. */
 202                                 offset = i / stl->unitsize;
 203
 204                                 packet.type = SR_DF_TRIGGER;
 205                                 packet.payload = NULL;
 206                                 sr_session_send(stl->sdi, &packet);
 207                                 break;
 208                         }
 209                 } else if (stl->cur_stage > 0) {
 210                         /*
 211                          * We had a match at an earlier stage, but failed on the
 212                          * current stage. However, we may have a match on this
 213                          * stage in the next bit -- trigger on 0001 will fail on
 214                          * seeing 00001, so we need to go back to stage 0 -- but
 215                          * at the next sample from the one that matched originally,
 216                          * which the counter increment at the end of the loop
 217                          * takes care of.
 218                          */
 219                         i -= stl->cur_stage * stl->unitsize;
 220                         if (i < -1)
 221                                 i = -1; /* Oops, went back past this buffer. */
 222                         /* Reset trigger stage. */
 223                         stl->cur_stage = 0;
 224                 }
 225         }
 226
 227         if (offset == -1)
 228                 pre_trigger_append(stl, buf, len);
 229
 230         return offset;
 231 }