src/freedreno/rnn/rnndec.c

   1 /*
   2  * Copyright (C) 2010-2011 Marcin Kościelnicki <koriakin@0x04.net>
   3  * Copyright (C) 2010 Francisco Jerez <currojerez@riseup.net>
   4  * All Rights Reserved.
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a
   7  * copy of this software and associated documentation files (the "Software"),
   8  * to deal in the Software without restriction, including without limitation
   9  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  10  * and/or sell copies of the Software, and to permit persons to whom the
  11  * Software is furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice (including the next
  14  * paragraph) shall be included in all copies or substantial portions of the
  15  * Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  20  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  21  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  22  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  23  * OTHER DEALINGS IN THE SOFTWARE.
  24  */
  25
  26 #include "rnndec.h"
  27 #include <assert.h>
  28 #include <stdio.h>
  29 #include <string.h>
  30 #include <stdlib.h>
  31 #include <inttypes.h>
  32 #include "util.h"
  33
  34 struct rnndeccontext *rnndec_newcontext(struct rnndb *db) {
  35         struct rnndeccontext *res = calloc (sizeof *res, 1);
  36         res->db = db;
  37         res->colors = &envy_null_colors;
  38         return res;
  39 }
  40
  41 int rnndec_varadd(struct rnndeccontext *ctx, char *varset, const char *variant) {
  42         struct rnnenum *en = rnn_findenum(ctx->db, varset);
  43         if (!en) {
  44                 fprintf (stderr, "Enum %s doesn't exist in database!\n", varset);
  45                 return 0;
  46         }
  47         int i, j;
  48         for (i = 0; i < en->valsnum; i++)
  49                 if (!strcasecmp(en->vals[i]->name, variant)) {
  50                         struct rnndecvariant *ci = calloc (sizeof *ci, 1);
  51                         ci->en = en;
  52                         ci->variant = i;
  53                         ADDARRAY(ctx->vars, ci);
  54                         return 1;
  55                 }
  56
  57         if (i == en->valsnum) {
  58                 fprintf (stderr, "Variant %s doesn't exist in enum %s!\n", variant, varset);
  59                 return 0;
  60         }
  61
  62         for (j = 0; j < ctx->varsnum; j++) {
  63                 if (ctx->vars[j]->en == en) {
  64                         ctx->vars[j]->variant = i;
  65                         break;
  66                 }
  67         }
  68
  69         if (i == ctx->varsnum) {
  70                 struct rnndecvariant *ci = calloc (sizeof *ci, 1);
  71                 ci->en = en;
  72                 ci->variant = i;
  73                 ADDARRAY(ctx->vars, ci);
  74         }
  75
  76         return 1;
  77 }
  78
  79 int rnndec_varmatch(struct rnndeccontext *ctx, struct rnnvarinfo *vi) {
  80         if (vi->dead)
  81                 return 0;
  82         int i;
  83         for (i = 0; i < vi->varsetsnum; i++) {
  84                 int j;
  85                 for (j = 0; j < ctx->varsnum; j++)
  86                         if (vi->varsets[i]->venum == ctx->vars[j]->en)
  87                                 break;
  88                 if (j == ctx->varsnum) {
  89                         fprintf (stderr, "I don't know which %s variant to use!\n", vi->varsets[i]->venum->name);
  90                 } else {
  91                         if (!vi->varsets[i]->variants[ctx->vars[j]->variant])
  92                                 return 0;
  93                 }
  94         }
  95         return 1;
  96 }
  97
  98 /* see https://en.wikipedia.org/wiki/Half-precision_floating-point_format */
  99 static uint32_t float16i(uint16_t val)
 100 {
 101         uint32_t sign = ((uint32_t)(val & 0x8000)) << 16;
 102         uint32_t frac = val & 0x3ff;
 103         int32_t  expn = (val >> 10) & 0x1f;
 104
 105         if (expn == 0) {
 106                 if (frac) {
 107                         /* denormalized number: */
 108                         int shift = __builtin_clz(frac) - 21;
 109                         frac <<= shift;
 110                         expn = -shift;
 111                 } else {
 112                         /* +/- zero: */
 113                         return sign;
 114                 }
 115         } else if (expn == 0x1f) {
 116                 /* Inf/NaN: */
 117                 return sign | 0x7f800000 | (frac << 13);
 118         }
 119
 120         return sign | ((expn + 127 - 15) << 23) | (frac << 13);
 121 }
 122 static float float16(uint16_t val)
 123 {
 124         union { uint32_t i; float f; } u;
 125         u.i = float16i(val);
 126         return u.f;
 127 }
 128
 129 static const char *rnndec_decode_enum_val(struct rnndeccontext *ctx,
 130                 struct rnnvalue **vals, int valsnum, uint64_t value)
 131 {
 132         int i;
 133         for (i = 0; i < valsnum; i++)
 134                 if (rnndec_varmatch(ctx, &vals[i]->varinfo) &&
 135                                 vals[i]->valvalid && vals[i]->value == value)
 136                         return vals[i]->name;
 137         return NULL;
 138 }
 139
 140 const char *rnndec_decode_enum(struct rnndeccontext *ctx, const char *enumname, uint64_t enumval)
 141 {
 142         struct rnnenum *en = rnn_findenum (ctx->db, enumname);
 143         if (en) {
 144                 return rnndec_decode_enum_val(ctx, en->vals, en->valsnum, enumval);
 145         }
 146         return NULL;
 147 }
 148
 149 /* The name UNK%u is used as a placeholder for bitfields that exist but
 150  * have an unknown function.
 151  */
 152 static int is_unknown(const char *name)
 153 {
 154         unsigned u;
 155         return sscanf(name, "UNK%u", &u) == 1;
 156 }
 157
 158 char *rnndec_decodeval(struct rnndeccontext *ctx, struct rnntypeinfo *ti, uint64_t value) {
 159         int width = ti->high - ti->low + 1;
 160         char *res = 0;
 161         int i;
 162         struct rnnvalue **vals;
 163         int valsnum;
 164         struct rnnbitfield **bitfields;
 165         int bitfieldsnum;
 166         char *tmp;
 167         const char *ctmp;
 168         uint64_t mask, value_orig;
 169         if (!ti)
 170                 goto failhex;
 171         value_orig = value;
 172         value = (value & typeinfo_mask(ti)) >> ti->low;
 173         value <<= ti->shr;
 174
 175         switch (ti->type) {
 176                 case RNN_TTYPE_ENUM:
 177                         vals = ti->eenum->vals;
 178                         valsnum = ti->eenum->valsnum;
 179                         goto doenum;
 180                 case RNN_TTYPE_INLINE_ENUM:
 181                         vals = ti->vals;
 182                         valsnum = ti->valsnum;
 183                         goto doenum;
 184                 doenum:
 185                         ctmp = rnndec_decode_enum_val(ctx, vals, valsnum, value);
 186                         if (ctmp) {
 187                                 asprintf (&res, "%s%s%s", ctx->colors->eval, ctmp, ctx->colors->reset);
 188                                 if (ti->addvariant) {
 189                                         rnndec_varadd(ctx, ti->eenum->name, ctmp);
 190                                 }
 191                                 break;
 192                         }
 193                         goto failhex;
 194                 case RNN_TTYPE_BITSET:
 195                         bitfields = ti->ebitset->bitfields;
 196                         bitfieldsnum = ti->ebitset->bitfieldsnum;
 197                         goto dobitset;
 198                 case RNN_TTYPE_INLINE_BITSET:
 199                         bitfields = ti->bitfields;
 200                         bitfieldsnum = ti->bitfieldsnum;
 201                         goto dobitset;
 202                 dobitset:
 203                         mask = 0;
 204                         for (i = 0; i < bitfieldsnum; i++) {
 205                                 if (!rnndec_varmatch(ctx, &bitfields[i]->varinfo))
 206                                         continue;
 207                                 uint64_t type_mask = typeinfo_mask(&bitfields[i]->typeinfo);
 208                                 if (((value & type_mask) == 0) && is_unknown(bitfields[i]->name))
 209                                         continue;
 210                                 mask |= type_mask;
 211                                 if (bitfields[i]->typeinfo.type == RNN_TTYPE_BOOLEAN) {
 212                                         const char *color = is_unknown(bitfields[i]->name) ?
 213                                                         ctx->colors->err : ctx->colors->mod;
 214                                         if (value & type_mask) {
 215                                                 if (!res)
 216                                                         asprintf (&res, "%s%s%s", color, bitfields[i]->name, ctx->colors->reset);
 217                                                 else {
 218                                                         asprintf (&tmp, "%s | %s%s%s", res, color, bitfields[i]->name, ctx->colors->reset);
 219                                                         free(res);
 220                                                         res = tmp;
 221                                                 }
 222                                         }
 223                                         continue;
 224                                 }
 225                                 char *subval;
 226                                 if (is_unknown(bitfields[i]->name) && (bitfields[i]->typeinfo.type != RNN_TTYPE_A3XX_REGID)) {
 227                                         uint64_t field_val = value & type_mask;
 228                                         field_val = (field_val & typeinfo_mask(&bitfields[i]->typeinfo)) >> bitfields[i]->typeinfo.low;
 229                                         field_val <<= bitfields[i]->typeinfo.shr;
 230                                         asprintf (&subval, "%s%#"PRIx64"%s", ctx->colors->err, field_val, ctx->colors->reset);
 231                                 } else {
 232                                         subval = rnndec_decodeval(ctx, &bitfields[i]->typeinfo, value & type_mask);
 233                                 }
 234                                 if (!res)
 235                                         asprintf (&res, "%s%s%s = %s", ctx->colors->rname, bitfields[i]->name, ctx->colors->reset, subval);
 236                                 else {
 237                                         asprintf (&tmp, "%s | %s%s%s = %s", res, ctx->colors->rname, bitfields[i]->name, ctx->colors->reset, subval);
 238                                         free(res);
 239                                         res = tmp;
 240                                 }
 241                                 free(subval);
 242                         }
 243                         if (value & ~mask) {
 244                                 if (!res)
 245                                         asprintf (&res, "%s%#"PRIx64"%s", ctx->colors->err, value & ~mask, ctx->colors->reset);
 246                                 else {
 247                                         asprintf (&tmp, "%s | %s%#"PRIx64"%s", res, ctx->colors->err, value & ~mask, ctx->colors->reset);
 248                                         free(res);
 249                                         res = tmp;
 250                                 }
 251                         }
 252                         if (!res)
 253                                 asprintf (&res, "%s0%s", ctx->colors->num, ctx->colors->reset);
 254                         asprintf (&tmp, "{ %s }", res);
 255                         free(res);
 256                         return tmp;
 257                 case RNN_TTYPE_SPECTYPE:
 258                         return rnndec_decodeval(ctx, &ti->spectype->typeinfo, value);
 259                 case RNN_TTYPE_HEX:
 260                         asprintf (&res, "%s%#"PRIx64"%s", ctx->colors->num, value, ctx->colors->reset);
 261                         break;
 262                 case RNN_TTYPE_FIXED:
 263                         if (value & UINT64_C(1) << (width-1)) {
 264                                 asprintf (&res, "%s-%lf%s", ctx->colors->num,
 265                                                 ((double)((UINT64_C(1) << width) - value)) / ((double)(1 << ti->radix)),
 266                                                 ctx->colors->reset);
 267                                 break;
 268                         }
 269                         /* fallthrough */
 270                 case RNN_TTYPE_UFIXED:
 271                         asprintf (&res, "%s%lf%s", ctx->colors->num,
 272                                         ((double)value) / ((double)(1LL << ti->radix)),
 273                                         ctx->colors->reset);
 274                         break;
 275                 case RNN_TTYPE_A3XX_REGID:
 276                         asprintf (&res, "%sr%"PRIu64".%c%s", ctx->colors->num, (value >> 2), "xyzw"[value & 0x3], ctx->colors->reset);
 277                         break;
 278                 case RNN_TTYPE_UINT:
 279                         asprintf (&res, "%s%"PRIu64"%s", ctx->colors->num, value, ctx->colors->reset);
 280                         break;
 281                 case RNN_TTYPE_INT:
 282                         if (value & UINT64_C(1) << (width-1))
 283                                 asprintf (&res, "%s-%"PRIi64"%s", ctx->colors->num, (UINT64_C(1) << width) - value, ctx->colors->reset);
 284                         else
 285                                 asprintf (&res, "%s%"PRIi64"%s", ctx->colors->num, value, ctx->colors->reset);
 286                         break;
 287                 case RNN_TTYPE_BOOLEAN:
 288                         if (value == 0) {
 289                                 asprintf (&res, "%sFALSE%s", ctx->colors->eval, ctx->colors->reset);
 290                         } else if (value == 1) {
 291                                 asprintf (&res, "%sTRUE%s", ctx->colors->eval, ctx->colors->reset);
 292                         }
 293                         break;
 294                 case RNN_TTYPE_FLOAT: {
 295                         union { uint64_t i; float f; double d; } val;
 296                         val.i = value;
 297                         if (width == 64)
 298                                 asprintf(&res, "%s%f%s", ctx->colors->num,
 299                                         val.d, ctx->colors->reset);
 300                         else if (width == 32)
 301                                 asprintf(&res, "%s%f%s", ctx->colors->num,
 302                                         val.f, ctx->colors->reset);
 303                         else if (width == 16)
 304                                 asprintf(&res, "%s%f%s", ctx->colors->num,
 305                                         float16(value), ctx->colors->reset);
 306                         else
 307                                 goto failhex;
 308
 309                         break;
 310                 }
 311                 failhex:
 312                 default:
 313                         asprintf (&res, "%s%#"PRIx64"%s", ctx->colors->num, value, ctx->colors->reset);
 314                         break;
 315         }
 316         if (value_orig & ~typeinfo_mask(ti)) {
 317                 asprintf (&tmp, "%s | %s%#"PRIx64"%s", res, ctx->colors->err, value_orig & ~typeinfo_mask(ti), ctx->colors->reset);
 318                 free(res);
 319                 res = tmp;
 320         }
 321         return res;
 322 }
 323
 324 static char *appendidx (struct rnndeccontext *ctx, char *name, uint64_t idx, struct rnnenum *index) {
 325         char *res;
 326         const char *index_name = NULL;
 327
 328         if (index)
 329                 index_name = rnndec_decode_enum_val(ctx, index->vals, index->valsnum, idx);
 330
 331         if (index_name)
 332                 asprintf (&res, "%s[%s%s%s]", name, ctx->colors->eval, index_name, ctx->colors->reset);
 333         else
 334                 asprintf (&res, "%s[%s%#"PRIx64"%s]", name, ctx->colors->num, idx, ctx->colors->reset);
 335
 336         free (name);
 337         return res;
 338 }
 339
 340 /* This could probably be made to work for stripes too.. */
 341 static int get_array_idx_offset(struct rnndelem *elem, uint64_t addr, uint64_t *idx, uint64_t *offset)
 342 {
 343         if (elem->offsets) {
 344                 int i;
 345                 for (i = 0; i < elem->offsetsnum; i++) {
 346                         uint64_t o = elem->offsets[i];
 347                         if ((o <= addr) && (addr < (o + elem->stride))) {
 348                                 *idx = i;
 349                                 *offset = addr - o;
 350                                 return 0;
 351                         }
 352                 }
 353                 return -1;
 354         } else {
 355                 if (addr < elem->offset)
 356                         return -1;
 357
 358                 *idx = (addr - elem->offset) / elem->stride;
 359                 *offset = (addr - elem->offset) % elem->stride;
 360
 361                 if (elem->length && (*idx >= elem->length))
 362                         return -1;
 363
 364                 return 0;
 365         }
 366 }
 367
 368 static struct rnndecaddrinfo *trymatch (struct rnndeccontext *ctx, struct rnndelem **elems, int elemsnum, uint64_t addr, int write, int dwidth, uint64_t *indices, int indicesnum) {
 369         struct rnndecaddrinfo *res;
 370         int i, j;
 371         for (i = 0; i < elemsnum; i++) {
 372                 if (!rnndec_varmatch(ctx, &elems[i]->varinfo))
 373                         continue;
 374                 uint64_t offset, idx;
 375                 char *tmp, *name;
 376                 switch (elems[i]->type) {
 377                         case RNN_ETYPE_REG:
 378                                 if (addr < elems[i]->offset)
 379                                         break;
 380                                 if (elems[i]->stride) {
 381                                         idx = (addr-elems[i]->offset)/elems[i]->stride;
 382                                         offset = (addr-elems[i]->offset)%elems[i]->stride;
 383                                 } else {
 384                                         idx = 0;
 385                                         offset = addr-elems[i]->offset;
 386                                 }
 387                                 if (offset >= elems[i]->width/dwidth)
 388                                         break;
 389                                 if (elems[i]->length && idx >= elems[i]->length)
 390                                         break;
 391                                 res = calloc (sizeof *res, 1);
 392                                 res->typeinfo = &elems[i]->typeinfo;
 393                                 res->width = elems[i]->width;
 394                                 asprintf (&res->name, "%s%s%s", ctx->colors->rname, elems[i]->name, ctx->colors->reset);
 395                                 for (j = 0; j < indicesnum; j++)
 396                                         res->name = appendidx(ctx, res->name, indices[j], NULL);
 397                                 if (elems[i]->length != 1)
 398                                         res->name = appendidx(ctx, res->name, idx, elems[i]->index);
 399                                 if (offset) {
 400                                         asprintf (&tmp, "%s+%s%#"PRIx64"%s", res->name, ctx->colors->err, offset, ctx->colors->reset);
 401                                         free(res->name);
 402                                         res->name = tmp;
 403                                 }
 404                                 return res;
 405                         case RNN_ETYPE_STRIPE:
 406                                 for (idx = 0; idx < elems[i]->length || !elems[i]->length; idx++) {
 407                                         if (addr < elems[i]->offset + elems[i]->stride * idx)
 408                                                 break;
 409                                         offset = addr - (elems[i]->offset + elems[i]->stride * idx);
 410                                         int extraidx = (elems[i]->length != 1);
 411                                         int nindnum = (elems[i]->name ? 0 : indicesnum + extraidx);
 412                                         uint64_t nind[nindnum];
 413                                         if (!elems[i]->name) {
 414                                                 for (j = 0; j < indicesnum; j++)
 415                                                         nind[j] = indices[j];
 416                                                 if (extraidx)
 417                                                         nind[indicesnum] = idx;
 418                                         }
 419                                         res = trymatch (ctx, elems[i]->subelems, elems[i]->subelemsnum, offset, write, dwidth, nind, nindnum);
 420                                         if (!res)
 421                                                 continue;
 422                                         if (!elems[i]->name)
 423                                                 return res;
 424                                         asprintf (&name, "%s%s%s", ctx->colors->rname, elems[i]->name, ctx->colors->reset);
 425                                         for (j = 0; j < indicesnum; j++)
 426                                                 name = appendidx(ctx, name, indices[j], NULL);
 427                                         if (elems[i]->length != 1)
 428                                                 name = appendidx(ctx, name, idx, elems[i]->index);
 429                                         asprintf (&tmp, "%s.%s", name, res->name);
 430                                         free(name);
 431                                         free(res->name);
 432                                         res->name = tmp;
 433                                         return res;
 434                                 }
 435                                 break;
 436                         case RNN_ETYPE_ARRAY:
 437                                 if (get_array_idx_offset(elems[i], addr, &idx, &offset))
 438                                         break;
 439                                 asprintf (&name, "%s%s%s", ctx->colors->rname, elems[i]->name, ctx->colors->reset);
 440                                 for (j = 0; j < indicesnum; j++)
 441                                         name = appendidx(ctx, name, indices[j], NULL);
 442                                 if (elems[i]->length != 1)
 443                                         name = appendidx(ctx, name, idx, elems[i]->index);
 444                                 if ((res = trymatch (ctx, elems[i]->subelems, elems[i]->subelemsnum, offset, write, dwidth, 0, 0))) {
 445                                         asprintf (&tmp, "%s.%s", name, res->name);
 446                                         free(name);
 447                                         free(res->name);
 448                                         res->name = tmp;
 449                                         return res;
 450                                 }
 451                                 res = calloc (sizeof *res, 1);
 452                                 asprintf (&tmp, "%s+%s%#"PRIx64"%s", name, ctx->colors->err, offset, ctx->colors->reset);
 453                                 free(name);
 454                                 res->name = tmp;
 455                                 return res;
 456                         default:
 457                                 break;
 458                 }
 459         }
 460         return 0;
 461 }
 462
 463 int rnndec_checkaddr(struct rnndeccontext *ctx, struct rnndomain *domain, uint64_t addr, int write) {
 464         struct rnndecaddrinfo *res = trymatch(ctx, domain->subelems, domain->subelemsnum, addr, write, domain->width, 0, 0);
 465         if (res) {
 466                 free(res->name);
 467                 free(res);
 468         }
 469         return res != NULL;
 470 }
 471
 472 struct rnndecaddrinfo *rnndec_decodeaddr(struct rnndeccontext *ctx, struct rnndomain *domain, uint64_t addr, int write) {
 473         struct rnndecaddrinfo *res = trymatch(ctx, domain->subelems, domain->subelemsnum, addr, write, domain->width, 0, 0);
 474         if (res)
 475                 return res;
 476         res = calloc (sizeof *res, 1);
 477         asprintf (&res->name, "%s%#"PRIx64"%s", ctx->colors->err, addr, ctx->colors->reset);
 478         return res;
 479 }
 480
 481 static unsigned tryreg(struct rnndeccontext *ctx, struct rnndelem **elems, int elemsnum,
 482                 int dwidth, const char *name, uint64_t *offset)
 483 {
 484         int i;
 485         unsigned ret;
 486         const char *suffix = strchr(name, '[');
 487         unsigned n = suffix ? (suffix - name) : strlen(name);
 488         const char *dotsuffix = strchr(name, '.');
 489         unsigned dotn = dotsuffix ? (dotsuffix - name) : strlen(name);
 490
 491         const char *child = NULL;
 492         unsigned idx = 0;
 493
 494         if (suffix) {
 495                 const char *tmp = strchr(suffix, ']');
 496                 idx = strtol(suffix+1, NULL, 0);
 497                 child = tmp+2;
 498         }
 499
 500         for (i = 0; i < elemsnum; i++) {
 501                 struct rnndelem *elem = elems[i];
 502                 if (!rnndec_varmatch(ctx, &elem->varinfo))
 503                         continue;
 504                 int match = elem->name && (strlen(elem->name) == n) && !strncmp(elem->name, name, n);
 505                 switch (elem->type) {
 506                         case RNN_ETYPE_REG:
 507                                 if (match) {
 508                                         assert(!suffix);
 509                                         *offset = elem->offset;
 510                                         return 1;
 511                                 }
 512                                 break;
 513                         case RNN_ETYPE_STRIPE:
 514                                 if (elem->name) {
 515                                         if (!dotsuffix)
 516                                                 break;
 517                                         if (strlen(elem->name) != dotn || strncmp(elem->name, name, dotn))
 518                                                 break;
 519                                 }
 520                                 ret = tryreg(ctx, elem->subelems, elem->subelemsnum, dwidth,
 521                                         elem->name ? dotsuffix : name, offset);
 522                                 if (ret)
 523                                         return 1;
 524                                 break;
 525                         case RNN_ETYPE_ARRAY:
 526                                 if (match) {
 527                                         assert(suffix);
 528                                         ret = tryreg(ctx, elem->subelems, elem->subelemsnum, dwidth, child, offset);
 529                                         if (ret) {
 530                                                 *offset += elem->offset + (idx * elem->stride);
 531                                                 return 1;
 532                                         }
 533                                 }
 534                                 break;
 535                         default:
 536                                 break;
 537                 }
 538         }
 539         return 0;
 540 }
 541
 542 uint64_t rnndec_decodereg(struct rnndeccontext *ctx, struct rnndomain *domain, const char *name)
 543 {
 544         uint64_t offset;
 545         if (tryreg(ctx, domain->subelems, domain->subelemsnum, domain->width, name, &offset)) {
 546                 return offset;
 547         } else {
 548                 return 0;
 549         }
 550 }