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 int logic_channel_unitsize(GSList *channels)
  30 {
  31         int 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++;
  39         }
  40
  41         return (number + 7) / 8;
  42 }
  43
  44 SR_PRIV struct soft_trigger_logic *soft_trigger_logic_new(
  45                 const struct sr_dev_inst *sdi, struct sr_trigger *trigger,
  46                 int pre_trigger_samples)
  47 {
  48         struct soft_trigger_logic *stl;
  49
  50         stl = g_malloc0(sizeof(struct soft_trigger_logic));
  51         stl->sdi = sdi;
  52         stl->trigger = trigger;
  53         stl->unitsize = logic_channel_unitsize(sdi->channels);
  54         stl->prev_sample = g_malloc0(stl->unitsize);
  55         stl->pre_trigger_size = stl->unitsize * pre_trigger_samples;
  56         stl->pre_trigger_buffer = g_try_malloc(stl->pre_trigger_size);
  57         if (pre_trigger_samples > 0 && !stl->pre_trigger_buffer) {
  58                 /*
  59                  * Error out if g_try_malloc() failed (or was invoked as
  60                  * g_try_malloc(0)) *and* more than 0 pretrigger samples
  61                  * were requested.
  62                  */
  63                 soft_trigger_logic_free(stl);
  64                 return NULL;
  65         }
  66         stl->pre_trigger_head = stl->pre_trigger_buffer;
  67
  68         if (stl->pre_trigger_size > 0 && !stl->pre_trigger_buffer) {
  69                 soft_trigger_logic_free(stl);
  70                 return NULL;
  71         }
  72
  73         return stl;
  74 }
  75
  76 SR_PRIV void soft_trigger_logic_free(struct soft_trigger_logic *stl)
  77 {
  78         g_free(stl->pre_trigger_buffer);
  79         g_free(stl->prev_sample);
  80         g_free(stl);
  81 }
  82
  83 static void pre_trigger_append(struct soft_trigger_logic *stl,
  84                 uint8_t *buf, int len)
  85 {
  86         /* Avoid uselessly copying more than the pre-trigger size. */
  87         if (len > stl->pre_trigger_size) {
  88                 buf += len - stl->pre_trigger_size;
  89                 len = stl->pre_trigger_size;
  90         }
  91
  92         /* Update the filling level of the pre-trigger circular buffer. */
  93         stl->pre_trigger_fill = MIN(stl->pre_trigger_fill + len,
  94                                     stl->pre_trigger_size);
  95
  96         /* Actually copy data to the pre-trigger circular buffer. */
  97         while (len > 0) {
  98                 size_t size = MIN(stl->pre_trigger_buffer + stl->pre_trigger_size
  99                                   - stl->pre_trigger_head, len);
 100                 memcpy(stl->pre_trigger_head, buf, size);
 101                 stl->pre_trigger_head += size;
 102                 if (stl->pre_trigger_head >= stl->pre_trigger_buffer
 103                                              + stl->pre_trigger_size)
 104                         stl->pre_trigger_head = stl->pre_trigger_buffer;
 105                 buf += size;
 106                 len -= size;
 107         }
 108 }
 109
 110 static void pre_trigger_send(struct soft_trigger_logic *stl,
 111                 int *pre_trigger_samples)
 112 {
 113         struct sr_datafeed_packet packet;
 114         struct sr_datafeed_logic logic;
 115
 116         packet.type = SR_DF_LOGIC;
 117         packet.payload = &logic;
 118         logic.unitsize = stl->unitsize;
 119
 120         if (pre_trigger_samples)
 121                 *pre_trigger_samples = 0;
 122
 123         /* If pre-trigger buffer not full, rewind head to the first valid sample. */
 124         if (stl->pre_trigger_fill < stl->pre_trigger_size)
 125                 stl->pre_trigger_head = stl->pre_trigger_buffer;
 126
 127         /* Send logic packets for the pre-trigger circular buffer content. */
 128         while (stl->pre_trigger_fill > 0) {
 129                 size_t size = MIN(stl->pre_trigger_buffer + stl->pre_trigger_size
 130                                   - stl->pre_trigger_head, stl->pre_trigger_fill);
 131                 logic.length = size;
 132                 logic.data = stl->pre_trigger_head;
 133                 sr_session_send(stl->sdi, &packet);
 134                 stl->pre_trigger_head = stl->pre_trigger_buffer;
 135                 stl->pre_trigger_fill -= size;
 136                 if (pre_trigger_samples)
 137                         *pre_trigger_samples += size / stl->unitsize;
 138         }
 139 }
 140
 141 static gboolean logic_check_match(struct soft_trigger_logic *stl,
 142                 uint8_t *sample, struct sr_trigger_match *match)
 143 {
 144         int bit, prev_bit;
 145         gboolean result;
 146
 147         stl->count++;
 148         result = FALSE;
 149         bit = *(sample + match->channel->index / 8)
 150                         & (1 << (match->channel->index % 8));
 151         if (match->match == SR_TRIGGER_ZERO)
 152                 result = bit == 0;
 153         else if (match->match == SR_TRIGGER_ONE)
 154                 result = bit != 0;
 155         else {
 156                 /* Edge matches. */
 157                 if (stl->count == 1)
 158                         /* First sample, don't have enough for an edge match yet. */
 159                         return FALSE;
 160                 prev_bit = *(stl->prev_sample + match->channel->index / 8)
 161                                 & (1 << (match->channel->index % 8));
 162                 if (match->match == SR_TRIGGER_RISING)
 163                         result = prev_bit == 0 && bit != 0;
 164                 else if (match->match == SR_TRIGGER_FALLING)
 165                         result = prev_bit != 0 && bit == 0;
 166                 else if (match->match == SR_TRIGGER_EDGE)
 167                         result = prev_bit != bit;
 168         }
 169
 170         return result;
 171 }
 172
 173 /* Returns the offset (in samples) within buf of where the trigger
 174  * occurred, or -1 if not triggered. */
 175 SR_PRIV int soft_trigger_logic_check(struct soft_trigger_logic *stl,
 176                 uint8_t *buf, int len, int *pre_trigger_samples)
 177 {
 178         struct sr_trigger_stage *stage;
 179         struct sr_trigger_match *match;
 180         GSList *l, *l_stage;
 181         int offset;
 182         int i;
 183         gboolean match_found;
 184
 185         offset = -1;
 186         for (i = 0; i < len; i += stl->unitsize) {
 187                 l_stage = g_slist_nth(stl->trigger->stages, stl->cur_stage);
 188                 stage = l_stage->data;
 189                 if (!stage->matches)
 190                         /* No matches supplied, client error. */
 191                         return SR_ERR_ARG;
 192
 193                 match_found = TRUE;
 194                 for (l = stage->matches; l; l = l->next) {
 195                         match = l->data;
 196                         if (!match->channel->enabled)
 197                                 /* Ignore disabled channels with a trigger. */
 198                                 continue;
 199                         if (!logic_check_match(stl, buf + i, match)) {
 200                                 match_found = FALSE;
 201                                 break;
 202                         }
 203                 }
 204                 memcpy(stl->prev_sample, buf + i, stl->unitsize);
 205                 if (match_found) {
 206                         /* Matched on the current stage. */
 207                         if (l_stage->next) {
 208                                 /* Advance to next stage. */
 209                                 stl->cur_stage++;
 210                         } else {
 211                                 /* Matched on last stage, send pre-trigger data. */
 212                                 pre_trigger_append(stl, buf, i);
 213                                 pre_trigger_send(stl, pre_trigger_samples);
 214
 215                                 /* Fire trigger. */
 216                                 offset = i / stl->unitsize;
 217
 218                                 std_session_send_df_trigger(stl->sdi);
 219                                 break;
 220                         }
 221                 } else if (stl->cur_stage > 0) {
 222                         /*
 223                          * We had a match at an earlier stage, but failed on the
 224                          * current stage. However, we may have a match on this
 225                          * stage in the next bit -- trigger on 0001 will fail on
 226                          * seeing 00001, so we need to go back to stage 0 -- but
 227                          * at the next sample from the one that matched originally,
 228                          * which the counter increment at the end of the loop
 229                          * takes care of.
 230                          */
 231                         i -= stl->cur_stage * stl->unitsize;
 232                         if (i < -1)
 233                                 i = -1; /* Oops, went back past this buffer. */
 234                         /* Reset trigger stage. */
 235                         stl->cur_stage = 0;
 236                 }
 237         }
 238
 239         if (offset == -1)
 240                 pre_trigger_append(stl, buf, len);
 241
 242         return offset;
 243 }