src/output/vcd.c

   1 /*
   2  * This file is part of the libsigrok project.
   3  *
   4  * Copyright (C) 2010 Uwe Hermann <uwe@hermann-uwe.de>
   5  * Copyright (C) 2013 Bert Vermeulen <bert@biot.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #include <config.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <glib.h>
  25 #include <libsigrok/libsigrok.h>
  26 #include "libsigrok-internal.h"
  27
  28 #define LOG_PREFIX "output/vcd"
  29
  30 struct context {
  31         int num_enabled_channels;
  32         uint8_t *prevsample;
  33         gboolean header_done;
  34         uint64_t period;
  35         int *channel_index;
  36         uint64_t samplerate;
  37         uint64_t samplecount;
  38 };
  39
  40 static int init(struct sr_output *o, GHashTable *options)
  41 {
  42         struct context *ctx;
  43         struct sr_channel *ch;
  44         GSList *l;
  45         int num_enabled_channels, i;
  46
  47         (void)options;
  48
  49         num_enabled_channels = 0;
  50         for (l = o->sdi->channels; l; l = l->next) {
  51                 ch = l->data;
  52                 if (ch->type != SR_CHANNEL_LOGIC)
  53                         continue;
  54                 if (!ch->enabled)
  55                         continue;
  56                 num_enabled_channels++;
  57         }
  58         if (num_enabled_channels > 94) {
  59                 sr_err("VCD only supports 94 channels.");
  60                 return SR_ERR;
  61         }
  62
  63         ctx = g_malloc0(sizeof(struct context));
  64         o->priv = ctx;
  65         ctx->num_enabled_channels = num_enabled_channels;
  66         ctx->channel_index = g_malloc(sizeof(int) * ctx->num_enabled_channels);
  67
  68         /* Once more to map the enabled channels. */
  69         for (i = 0, l = o->sdi->channels; l; l = l->next) {
  70                 ch = l->data;
  71                 if (ch->type != SR_CHANNEL_LOGIC)
  72                         continue;
  73                 if (!ch->enabled)
  74                         continue;
  75                 ctx->channel_index[i++] = ch->index;
  76         }
  77
  78         return SR_OK;
  79 }
  80
  81 /*
  82  * VCD can only handle 1/10/100 factors in the s to fs range. Find a
  83  * suitable timescale which satisfies this resolution constraint, yet
  84  * won't result in excessive overhead.
  85  */
  86 static uint64_t get_timescale_freq(uint64_t samplerate)
  87 {
  88         uint64_t timescale;
  89         int max_up_scale;
  90
  91         /* Go to the next full decade. */
  92         timescale = 1;
  93         while (timescale < samplerate) {
  94                 timescale *= 10;
  95         }
  96
  97         /*
  98          * Avoid loss of precision, go up a few more decades when needed.
  99          * For example switch to 10GHz timescale when samplerate is 400MHz.
 100          * Stop after at most factor 100 to not loop endlessly for odd
 101          * samplerates, yet provide good enough accuracy.
 102          */
 103         max_up_scale = 2;
 104         while (max_up_scale--) {
 105                 if (timescale / samplerate * samplerate == timescale)
 106                         break;
 107                 timescale *= 10;
 108         }
 109
 110         return timescale;
 111 }
 112
 113 static GString *gen_header(const struct sr_output *o)
 114 {
 115         struct context *ctx;
 116         struct sr_channel *ch;
 117         GVariant *gvar;
 118         GString *header;
 119         GSList *l;
 120         time_t t;
 121         int num_channels, i;
 122         char *samplerate_s, *frequency_s, *timestamp;
 123
 124         ctx = o->priv;
 125         header = g_string_sized_new(512);
 126         num_channels = g_slist_length(o->sdi->channels);
 127
 128         /* timestamp */
 129         t = time(NULL);
 130         timestamp = g_strdup(ctime(&t));
 131         timestamp[strlen(timestamp) - 1] = 0;
 132         g_string_printf(header, "$date %s $end\n", timestamp);
 133         g_free(timestamp);
 134
 135         /* generator */
 136         g_string_append_printf(header, "$version %s %s $end\n",
 137                         PACKAGE_NAME, sr_package_version_string_get());
 138         g_string_append_printf(header, "$comment\n  Acquisition with "
 139                         "%d/%d channels", ctx->num_enabled_channels, num_channels);
 140
 141         if (ctx->samplerate == 0) {
 142                 if (sr_config_get(o->sdi->driver, o->sdi, NULL, SR_CONF_SAMPLERATE,
 143                                 &gvar) == SR_OK) {
 144                         ctx->samplerate = g_variant_get_uint64(gvar);
 145                         g_variant_unref(gvar);
 146                 }
 147         }
 148         if (ctx->samplerate != 0) {
 149                 samplerate_s = sr_samplerate_string(ctx->samplerate);
 150                 g_string_append_printf(header, " at %s", samplerate_s);
 151                 g_free(samplerate_s);
 152         }
 153         g_string_append_printf(header, "\n$end\n");
 154
 155         /* timescale */
 156         ctx->period = get_timescale_freq(ctx->samplerate);
 157         frequency_s = sr_period_string(1, ctx->period);
 158         g_string_append_printf(header, "$timescale %s $end\n", frequency_s);
 159         g_free(frequency_s);
 160
 161         /* scope */
 162         g_string_append_printf(header, "$scope module %s $end\n", PACKAGE_NAME);
 163
 164         /* Wires / channels */
 165         for (i = 0, l = o->sdi->channels; l; l = l->next) {
 166                 ch = l->data;
 167                 if (ch->type != SR_CHANNEL_LOGIC)
 168                         continue;
 169                 if (!ch->enabled)
 170                         continue;
 171                 g_string_append_printf(header, "$var wire 1 %c %s $end\n",
 172                                 (char)('!' + i), ch->name);
 173                 i++;
 174         }
 175
 176         g_string_append(header, "$upscope $end\n$enddefinitions $end\n");
 177
 178         return header;
 179 }
 180
 181 static int receive(const struct sr_output *o, const struct sr_datafeed_packet *packet,
 182                 GString **out)
 183 {
 184         const struct sr_datafeed_meta *meta;
 185         const struct sr_datafeed_logic *logic;
 186         const struct sr_config *src;
 187         GSList *l;
 188         struct context *ctx;
 189         unsigned int i;
 190         int p, curbit, prevbit, index;
 191         uint8_t *sample;
 192         gboolean timestamp_written;
 193
 194         *out = NULL;
 195         if (!o || !o->priv)
 196                 return SR_ERR_BUG;
 197         ctx = o->priv;
 198
 199         switch (packet->type) {
 200         case SR_DF_META:
 201                 meta = packet->payload;
 202                 for (l = meta->config; l; l = l->next) {
 203                         src = l->data;
 204                         if (src->key != SR_CONF_SAMPLERATE)
 205                                 continue;
 206                         ctx->samplerate = g_variant_get_uint64(src->data);
 207                 }
 208                 break;
 209         case SR_DF_LOGIC:
 210                 logic = packet->payload;
 211
 212                 if (!ctx->header_done) {
 213                         *out = gen_header(o);
 214                         ctx->header_done = TRUE;
 215                 } else {
 216                         *out = g_string_sized_new(512);
 217                 }
 218
 219                 if (!ctx->prevsample) {
 220                         /* Can't allocate this until we know the stream's unitsize. */
 221                         ctx->prevsample = g_malloc0(logic->unitsize);
 222                 }
 223
 224                 for (i = 0; i <= logic->length - logic->unitsize; i += logic->unitsize) {
 225                         sample = logic->data + i;
 226                         timestamp_written = FALSE;
 227
 228                         for (p = 0; p < ctx->num_enabled_channels; p++) {
 229                                 /*
 230                                  * TODO Check whether the mapping from
 231                                  * data image positions to channel numbers
 232                                  * is required. Experiments suggest that
 233                                  * the data image "is dense", and packs
 234                                  * bits of enabled channels, and leaves no
 235                                  * room for positions of disabled channels.
 236                                  */
 237                                 /* index = ctx->channel_index[p]; */
 238                                 index = p;
 239
 240                                 curbit = ((unsigned)sample[index / 8]
 241                                                 >> (index % 8)) & 1;
 242                                 prevbit = ((unsigned)ctx->prevsample[index / 8]
 243                                                 >> (index % 8)) & 1;
 244
 245                                 /* VCD only contains deltas/changes of signals. */
 246                                 if (prevbit == curbit && ctx->samplecount > 0)
 247                                         continue;
 248
 249                                 /* Output timestamp of subsequent signal changes. */
 250                                 if (!timestamp_written)
 251                                         g_string_append_printf(*out, "#%.0f",
 252                                                 (double)ctx->samplecount /
 253                                                         ctx->samplerate * ctx->period);
 254
 255                                 /* Output which signal changed to which value. */
 256                                 g_string_append_c(*out, ' ');
 257                                 g_string_append_c(*out, '0' + curbit);
 258                                 g_string_append_c(*out, '!' + p);
 259
 260                                 timestamp_written = TRUE;
 261                         }
 262
 263                         if (timestamp_written)
 264                                 g_string_append_c(*out, '\n');
 265
 266                         ctx->samplecount++;
 267                         memcpy(ctx->prevsample, sample, logic->unitsize);
 268                 }
 269                 break;
 270         case SR_DF_END:
 271                 /* Write final timestamp as length indicator. */
 272                 *out = g_string_sized_new(512);
 273                 g_string_printf(*out, "#%.0f\n",
 274                                 (double)ctx->samplecount / ctx->samplerate * ctx->period);
 275                 break;
 276         }
 277
 278         return SR_OK;
 279 }
 280
 281 static int cleanup(struct sr_output *o)
 282 {
 283         struct context *ctx;
 284
 285         if (!o || !o->priv)
 286                 return SR_ERR_ARG;
 287
 288         ctx = o->priv;
 289         g_free(ctx->prevsample);
 290         g_free(ctx->channel_index);
 291         g_free(ctx);
 292
 293         return SR_OK;
 294 }
 295
 296 struct sr_output_module output_vcd = {
 297         .id = "vcd",
 298         .name = "VCD",
 299         .desc = "Value Change Dump data",
 300         .exts = (const char*[]){"vcd", NULL},
 301         .flags = 0,
 302         .options = NULL,
 303         .init = init,
 304         .receive = receive,
 305         .cleanup = cleanup,
 306 };