git.oblomov.eu Git - wine/blob - programs/winedbg/memory.c

   1 /*
   2  * Debugger memory handling
   3  *
   4  * Copyright 1993 Eric Youngdale
   5  * Copyright 1995 Alexandre Julliard
   6  * Copyright 2000-2005 Eric Pouech
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  21  */
  22
  23 #include "config.h"
  24 #include "wine/port.h"
  25
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <stdio.h>
  29
  30 #include "debugger.h"
  31 #include "wine/debug.h"
  32
  33 WINE_DEFAULT_DEBUG_CHANNEL(winedbg);
  34
  35 void* be_cpu_linearize(HANDLE hThread, const ADDRESS64* addr)
  36 {
  37     assert(addr->Mode == AddrModeFlat);
  38     return (void*)(DWORD_PTR)addr->Offset;
  39 }
  40
  41 unsigned be_cpu_build_addr(HANDLE hThread, const CONTEXT* ctx, ADDRESS64* addr,
  42                            unsigned seg, unsigned long offset)
  43 {
  44     addr->Mode    = AddrModeFlat;
  45     addr->Segment = 0; /* don't need segment */
  46     addr->Offset  = offset;
  47     return TRUE;
  48 }
  49
  50 void* memory_to_linear_addr(const ADDRESS64* addr)
  51 {
  52     return be_cpu->linearize(dbg_curr_thread->handle, addr);
  53 }
  54
  55 BOOL memory_get_current_pc(ADDRESS64* addr)
  56 {
  57     assert(be_cpu->get_addr);
  58     return be_cpu->get_addr(dbg_curr_thread->handle, &dbg_context,
  59                             be_cpu_addr_pc, addr);
  60 }
  61
  62 BOOL memory_get_current_stack(ADDRESS64* addr)
  63 {
  64     assert(be_cpu->get_addr);
  65     return be_cpu->get_addr(dbg_curr_thread->handle, &dbg_context,
  66                             be_cpu_addr_stack, addr);
  67 }
  68
  69 BOOL memory_get_current_frame(ADDRESS64* addr)
  70 {
  71     assert(be_cpu->get_addr);
  72     return be_cpu->get_addr(dbg_curr_thread->handle, &dbg_context,
  73                             be_cpu_addr_frame, addr);
  74 }
  75
  76 static void     memory_report_invalid_addr(const void* addr)
  77 {
  78     ADDRESS64   address;
  79
  80     address.Mode    = AddrModeFlat;
  81     address.Segment = 0;
  82     address.Offset  = (unsigned long)addr;
  83     dbg_printf("*** Invalid address ");
  84     print_address(&address, FALSE);
  85     dbg_printf(" ***\n");
  86 }
  87
  88 /***********************************************************************
  89  *           memory_read_value
  90  *
  91  * Read a memory value.
  92  */
  93 BOOL memory_read_value(const struct dbg_lvalue* lvalue, DWORD size, void* result)
  94 {
  95     BOOL ret = FALSE;
  96
  97     if (lvalue->cookie == DLV_TARGET)
  98     {
  99         void*   linear = memory_to_linear_addr(&lvalue->addr);
 100         if (!(ret = dbg_read_memory(linear, result, size)))
 101             memory_report_invalid_addr(linear);
 102     }
 103     else
 104     {
 105         if (lvalue->addr.Offset)
 106         {
 107             memcpy(result, (void*)(DWORD_PTR)lvalue->addr.Offset, size);
 108             ret = TRUE;
 109         }
 110     }
 111     return ret;
 112 }
 113
 114 /***********************************************************************
 115  *           memory_write_value
 116  *
 117  * Store a value in memory.
 118  */
 119 BOOL memory_write_value(const struct dbg_lvalue* lvalue, DWORD size, void* value)
 120 {
 121     BOOL        ret = TRUE;
 122     DWORD64     os;
 123
 124     os = ~(DWORD64)size;
 125     types_get_info(&lvalue->type, TI_GET_LENGTH, &os);
 126     assert(size == os);
 127
 128     /* FIXME: only works on little endian systems */
 129     if (lvalue->cookie == DLV_TARGET)
 130     {
 131         void*       linear = memory_to_linear_addr(&lvalue->addr);
 132         if (!(ret = dbg_write_memory(linear, value, size)))
 133             memory_report_invalid_addr(linear);
 134     }
 135     else
 136     {
 137         memcpy((void*)(DWORD_PTR)lvalue->addr.Offset, value, size);
 138     }
 139     return ret;
 140 }
 141
 142 /***********************************************************************
 143  *           memory_examine
 144  *
 145  * Implementation of the 'x' command.
 146  */
 147 void memory_examine(const struct dbg_lvalue *lvalue, int count, char format)
 148 {
 149     int                 i;
 150     char                buffer[256];
 151     ADDRESS64           addr;
 152     void               *linear;
 153
 154     types_extract_as_address(lvalue, &addr);
 155     linear = memory_to_linear_addr(&addr);
 156
 157     if (format != 'i' && count > 1)
 158     {
 159         print_address(&addr, FALSE);
 160         dbg_printf(": ");
 161     }
 162
 163     switch (format)
 164     {
 165     case 'u':
 166         if (count == 1) count = 256;
 167         memory_get_string(dbg_curr_process, linear,
 168                           TRUE, TRUE, buffer, min(count, sizeof(buffer)));
 169         dbg_printf("%s\n", buffer);
 170         return;
 171     case 's':
 172         if (count == 1) count = 256;
 173         memory_get_string(dbg_curr_process, linear,
 174                           TRUE, FALSE, buffer, min(count, sizeof(buffer)));
 175         dbg_printf("%s\n", buffer);
 176         return;
 177     case 'i':
 178         while (count-- && memory_disasm_one_insn(&addr));
 179         return;
 180     case 'g':
 181         while (count--)
 182         {
 183             GUID guid;
 184             if (!dbg_read_memory(linear, &guid, sizeof(guid)))
 185             {
 186                 memory_report_invalid_addr(linear);
 187                 break;
 188             }
 189             dbg_printf("{%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x}\n",
 190                        guid.Data1, guid.Data2, guid.Data3,
 191                        guid.Data4[0], guid.Data4[1], guid.Data4[2], guid.Data4[3],
 192                        guid.Data4[4], guid.Data4[5], guid.Data4[6], guid.Data4[7]);
 193             linear = (char*)linear + sizeof(guid);
 194             addr.Offset += sizeof(guid);
 195             if (count)
 196             {
 197                 print_address(&addr, FALSE);
 198                 dbg_printf(": ");
 199             }
 200         }
 201         return;
 202
 203 #define DO_DUMP2(_t,_l,_f,_vv) {                                        \
 204             _t _v;                                                      \
 205             for (i = 0; i < count; i++) {                               \
 206                 if (!dbg_read_memory(linear, &_v, sizeof(_t)))          \
 207                 { memory_report_invalid_addr(linear); break; }          \
 208                 dbg_printf(_f, (_vv));                                  \
 209                 addr.Offset += sizeof(_t);                              \
 210                 linear = (char*)linear + sizeof(_t);                    \
 211                 if ((i % (_l)) == (_l) - 1 && i != count - 1)           \
 212                 {                                                       \
 213                     dbg_printf("\n");                                   \
 214                     print_address(&addr, FALSE);                        \
 215                     dbg_printf(": ");                                   \
 216                 }                                                       \
 217             }                                                           \
 218             dbg_printf("\n");                                           \
 219         }                                                               \
 220         return
 221 #define DO_DUMP(_t,_l,_f) DO_DUMP2(_t,_l,_f,_v)
 222
 223     case 'x': DO_DUMP(int, 4, " %8.8x");
 224     case 'd': DO_DUMP(unsigned int, 4, " %4.4d");
 225     case 'w': DO_DUMP(unsigned short, 8, " %04x");
 226     case 'c': DO_DUMP2(char, 32, " %c", (_v < 0x20) ? ' ' : _v);
 227     case 'b': DO_DUMP2(char, 16, " %02x", (_v) & 0xff);
 228     }
 229 }
 230
 231 BOOL memory_get_string(struct dbg_process* pcs, void* addr, BOOL in_debuggee,
 232                        BOOL unicode, char* buffer, int size)
 233 {
 234     SIZE_T      sz;
 235     WCHAR*      buffW;
 236
 237     buffer[0] = 0;
 238     if (!addr) return FALSE;
 239     if (in_debuggee)
 240     {
 241         BOOL ret;
 242
 243         if (!unicode) ret = pcs->process_io->read(pcs->handle, addr, buffer, size, &sz);
 244         else
 245         {
 246             buffW = HeapAlloc(GetProcessHeap(), 0, size * sizeof(WCHAR));
 247             ret = pcs->process_io->read(pcs->handle, addr, buffW, size * sizeof(WCHAR), &sz);
 248             WideCharToMultiByte(CP_ACP, 0, buffW, sz / sizeof(WCHAR), buffer, size,
 249                                 NULL, NULL);
 250             HeapFree(GetProcessHeap(), 0, buffW);
 251         }
 252         if (size) buffer[size-1] = 0;
 253         return ret;
 254     }
 255     else
 256     {
 257         lstrcpynA(buffer, addr, size);
 258     }
 259     return TRUE;
 260 }
 261
 262 BOOL memory_get_string_indirect(struct dbg_process* pcs, void* addr, BOOL unicode, char* buffer, int size)
 263 {
 264     void*       ad;
 265     SIZE_T      sz;
 266
 267     buffer[0] = 0;
 268     if (addr &&
 269         pcs->process_io->read(pcs->handle, addr, &ad, sizeof(ad), &sz) && sz == sizeof(ad) && ad)
 270     {
 271         return memory_get_string(pcs, ad, TRUE, unicode, buffer, size);
 272     }
 273     return FALSE;
 274 }
 275
 276 /*
 277  * Convert an address offset to hex string. If mode == 32, treat offset as
 278  * 32 bits (discard upper 32 bits), if mode == 64 use all 64 bits, if mode == 0
 279  * treat as either 32 or 64 bits, depending on whether we're running as
 280  * Wine32 or Wine64.
 281  */
 282 char* memory_offset_to_string(char *str, DWORD64 offset, unsigned mode)
 283 {
 284     if (mode != 32 && mode != 64)
 285     {
 286 #ifdef _WIN64
 287         mode = 64;
 288 #else
 289         mode = 32;
 290 #endif
 291     }
 292
 293     if (mode == 32)
 294         sprintf(str, "0x%08x", (unsigned int) offset);
 295     else
 296         sprintf(str, "0x%08x%08x", (unsigned int)(offset >> 32),
 297                 (unsigned int)offset);
 298
 299     return str;
 300 }
 301
 302 static void dbg_print_longlong(LONGLONG sv, BOOL is_signed)
 303 {
 304     char      tmp[24], *ptr = tmp + sizeof(tmp) - 1;
 305     ULONGLONG uv, div;
 306     *ptr = '\0';
 307     if (is_signed && sv < 0)    uv = -sv;
 308     else                        { uv = sv; is_signed = FALSE; }
 309     for (div = 10; uv; div *= 10, uv /= 10)
 310         *--ptr = '0' + (uv % 10);
 311     if (ptr == tmp + sizeof(tmp) - 1) *--ptr = '0';
 312     if (is_signed) *--ptr = '-';
 313     dbg_printf("%s", ptr);
 314 }
 315
 316 static void print_typed_basic(const struct dbg_lvalue* lvalue)
 317 {
 318     LONGLONG            val_int;
 319     void*               val_ptr;
 320     long double         val_real;
 321     DWORD64             size64;
 322     DWORD               tag, size, count, bt;
 323     struct dbg_type     type = lvalue->type;
 324     struct dbg_type     sub_type;
 325
 326     if (!types_get_real_type(&type, &tag)) return;
 327
 328     switch (tag)
 329     {
 330     case SymTagBaseType:
 331         if (!types_get_info(&type, TI_GET_LENGTH, &size64) ||
 332             !types_get_info(&type, TI_GET_BASETYPE, &bt))
 333         {
 334             WINE_ERR("Couldn't get information\n");
 335             RaiseException(DEBUG_STATUS_INTERNAL_ERROR, 0, 0, NULL);
 336         }
 337         size = (DWORD)size64;
 338         switch (bt)
 339         {
 340         case btInt:
 341         case btLong:
 342             if (!be_cpu->fetch_integer(lvalue, size, TRUE, &val_int)) return;
 343             dbg_print_longlong(val_int, TRUE);
 344             break;
 345         case btUInt:
 346         case btULong:
 347             if (!be_cpu->fetch_integer(lvalue, size, FALSE, &val_int)) return;
 348             dbg_print_longlong(val_int, FALSE);
 349             break;
 350         case btFloat:
 351             if (!be_cpu->fetch_float(lvalue, size, &val_real)) return;
 352             dbg_printf("%Lf", val_real);
 353             break;
 354         case btChar:
 355             if (!be_cpu->fetch_integer(lvalue, size, TRUE, &val_int)) return;
 356             /* FIXME: should do the same for a Unicode character (size == 2) */
 357             if (size == 1 && (val_int < 0x20 || val_int > 0x80))
 358                 dbg_printf("%d", (int)val_int);
 359             else
 360                 dbg_printf("'%c'", (char)val_int);
 361             break;
 362         default:
 363             WINE_FIXME("Unsupported basetype %u\n", bt);
 364             break;
 365         }
 366         break;
 367     case SymTagPointerType:
 368         if (!memory_read_value(lvalue, sizeof(void*), &val_ptr)) return;
 369
 370         sub_type.module = lvalue->type.module;
 371         if (!types_get_info(&type, TI_GET_TYPE, &sub_type.id) ||
 372             sub_type.id == dbg_itype_none)
 373         {
 374             dbg_printf("Internal symbol error: unable to access memory location %p", val_ptr);
 375             break;
 376         }
 377         if (!types_get_real_type(&sub_type, &tag)) return;
 378
 379         if (types_get_info(&sub_type, TI_GET_SYMTAG, &tag) && tag == SymTagBaseType &&
 380             types_get_info(&sub_type, TI_GET_BASETYPE, &bt) && bt == btChar &&
 381             types_get_info(&sub_type, TI_GET_LENGTH, &size64))
 382         {
 383             char    buffer[1024];
 384
 385             if (!val_ptr) dbg_printf("0x0");
 386             else if (memory_get_string(dbg_curr_process, val_ptr,
 387                                        lvalue->cookie == DLV_TARGET,
 388                                        size64 == 2, buffer, sizeof(buffer)))
 389                 dbg_printf("\"%s\"", buffer);
 390             else
 391                 dbg_printf("*** invalid address %p ***", val_ptr);
 392         }
 393         else dbg_printf("%p", val_ptr);
 394         break;
 395     case SymTagArrayType:
 396     case SymTagUDT:
 397         if (!memory_read_value(lvalue, sizeof(val_ptr), &val_ptr)) return;
 398         dbg_printf("%p", val_ptr);
 399         break;
 400     case SymTagEnum:
 401         {
 402             BOOL        ok = FALSE;
 403
 404             /* FIXME: it depends on underlying type for enums
 405              * (not supported yet in dbghelp)
 406              * Assuming 4 as for an int
 407              */
 408             if (!be_cpu->fetch_integer(lvalue, 4, TRUE, &val_int)) return;
 409
 410             if (types_get_info(&type, TI_GET_CHILDRENCOUNT, &count))
 411             {
 412                 char                    buffer[sizeof(TI_FINDCHILDREN_PARAMS) + 256 * sizeof(DWORD)];
 413                 TI_FINDCHILDREN_PARAMS* fcp = (TI_FINDCHILDREN_PARAMS*)buffer;
 414                 WCHAR*                  ptr;
 415                 char                    tmp[256];
 416                 VARIANT                 variant;
 417                 int                     i;
 418
 419                 fcp->Start = 0;
 420                 while (count)
 421                 {
 422                     fcp->Count = min(count, 256);
 423                     if (types_get_info(&type, TI_FINDCHILDREN, fcp))
 424                     {
 425                         sub_type.module = type.module;
 426                         for (i = 0; i < min(fcp->Count, count); i++)
 427                         {
 428                             sub_type.id = fcp->ChildId[i];
 429                             if (!types_get_info(&sub_type, TI_GET_VALUE, &variant))
 430                                 continue;
 431                             switch (variant.n1.n2.vt)
 432                             {
 433                             case VT_I4: ok = (val_int == variant.n1.n2.n3.lVal); break;
 434                             default: WINE_FIXME("Unsupported variant type (%u)\n", variant.n1.n2.vt);
 435                             }
 436                             if (ok)
 437                             {
 438                                 ptr = NULL;
 439                                 types_get_info(&sub_type, TI_GET_SYMNAME, &ptr);
 440                                 if (!ptr) continue;
 441                                 WideCharToMultiByte(CP_ACP, 0, ptr, -1, tmp, sizeof(tmp), NULL, NULL);
 442                                 HeapFree(GetProcessHeap(), 0, ptr);
 443                                 dbg_printf("%s", tmp);
 444                                 count = 0; /* so that we'll get away from outter loop */
 445                                 break;
 446                             }
 447                         }
 448                     }
 449                 }
 450                 count -= min(count, 256);
 451                 fcp->Start += 256;
 452             }
 453             if (!ok) dbg_print_longlong(val_int, TRUE);
 454         }
 455         break;
 456     default:
 457         WINE_FIXME("Unsupported tag %u\n", tag);
 458         break;
 459     }
 460 }
 461
 462 /***********************************************************************
 463  *           print_basic
 464  *
 465  * Implementation of the 'print' command.
 466  */
 467 void print_basic(const struct dbg_lvalue* lvalue, int count, char format)
 468 {
 469     LONGLONG res;
 470
 471     if (lvalue->type.id == dbg_itype_none)
 472     {
 473         dbg_printf("Unable to evaluate expression\n");
 474         return;
 475     }
 476
 477     res = types_extract_as_longlong(lvalue);
 478
 479     /* FIXME: this implies i386 byte ordering */
 480     switch (format)
 481     {
 482     case 'x':
 483         dbg_printf("0x%x", (DWORD)(ULONG64)res);
 484         break;
 485
 486     case 'd':
 487         dbg_print_longlong(res, TRUE);
 488         dbg_printf("\n");
 489         break;
 490
 491     case 'c':
 492         dbg_printf("%d = '%c'", (char)(res & 0xff), (char)(res & 0xff));
 493         break;
 494
 495     case 'u':
 496         {
 497             WCHAR wch = (WCHAR)(res & 0xFFFF);
 498             dbg_printf("%d = '", wch);
 499             dbg_outputW(&wch, 1);
 500             dbg_printf("'");
 501         }
 502         break;
 503
 504     case 'i':
 505     case 's':
 506     case 'w':
 507     case 'b':
 508         dbg_printf("Format specifier '%c' is meaningless in 'print' command\n", format);
 509     case 0:
 510         if (lvalue->type.id == dbg_itype_segptr)
 511         {
 512             dbg_print_longlong(res, TRUE);
 513             dbg_printf("\n");
 514         }
 515         else
 516             print_typed_basic(lvalue);
 517         break;
 518     }
 519 }
 520
 521 void print_bare_address(const ADDRESS64* addr)
 522 {
 523     char hexbuf[MAX_OFFSET_TO_STR_LEN];
 524
 525     switch (addr->Mode)
 526     {
 527     case AddrModeFlat:
 528         dbg_printf("%s", memory_offset_to_string(hexbuf, addr->Offset, 0));
 529         break;
 530     case AddrModeReal:
 531     case AddrMode1616:
 532         dbg_printf("0x%04x:0x%04x", addr->Segment, (unsigned) addr->Offset);
 533         break;
 534     case AddrMode1632:
 535         dbg_printf("0x%04x:%s", addr->Segment,
 536                    memory_offset_to_string(hexbuf, addr->Offset, 32));
 537         break;
 538     default:
 539         dbg_printf("Unknown mode %x\n", addr->Mode);
 540         break;
 541     }
 542 }
 543
 544 /***********************************************************************
 545  *           print_address
 546  *
 547  * Print an 16- or 32-bit address, with the nearest symbol if any.
 548  */
 549 void print_address(const ADDRESS64* addr, BOOLEAN with_line)
 550 {
 551     char                buffer[sizeof(SYMBOL_INFO) + 256];
 552     SYMBOL_INFO*        si = (SYMBOL_INFO*)buffer;
 553     void*               lin = memory_to_linear_addr(addr);
 554     DWORD64             disp64;
 555     DWORD               disp;
 556
 557     print_bare_address(addr);
 558
 559     si->SizeOfStruct = sizeof(*si);
 560     si->MaxNameLen   = 256;
 561     if (!SymFromAddr(dbg_curr_process->handle, (DWORD_PTR)lin, &disp64, si)) return;
 562     dbg_printf(" %s", si->Name);
 563     if (disp64) dbg_printf("+0x%lx", (DWORD_PTR)disp64);
 564     if (with_line)
 565     {
 566         IMAGEHLP_LINE               il;
 567         IMAGEHLP_MODULE             im;
 568
 569         il.SizeOfStruct = sizeof(il);
 570         if (SymGetLineFromAddr(dbg_curr_process->handle, (DWORD_PTR)lin, &disp, &il))
 571             dbg_printf(" [%s:%u]", il.FileName, il.LineNumber);
 572         im.SizeOfStruct = sizeof(im);
 573         if (SymGetModuleInfo(dbg_curr_process->handle, (DWORD_PTR)lin, &im))
 574             dbg_printf(" in %s", im.ModuleName);
 575     }
 576 }
 577
 578 BOOL memory_disasm_one_insn(ADDRESS64* addr)
 579 {
 580     char        ch;
 581
 582     print_address(addr, TRUE);
 583     dbg_printf(": ");
 584     if (!dbg_read_memory(memory_to_linear_addr(addr), &ch, sizeof(ch)))
 585     {
 586         dbg_printf("-- no code accessible --\n");
 587         return FALSE;
 588     }
 589     be_cpu->disasm_one_insn(addr, TRUE);
 590     dbg_printf("\n");
 591     return TRUE;
 592 }
 593
 594 void memory_disassemble(const struct dbg_lvalue* xstart,
 595                         const struct dbg_lvalue* xend, int instruction_count)
 596 {
 597     static ADDRESS64 last = {0,0,0};
 598     int stop = 0;
 599     int i;
 600
 601     if (!xstart && !xend)
 602     {
 603         if (!last.Segment && !last.Offset) memory_get_current_pc(&last);
 604     }
 605     else
 606     {
 607         if (xstart)
 608             types_extract_as_address(xstart, &last);
 609         if (xend)
 610             stop = types_extract_as_integer(xend);
 611     }
 612     for (i = 0; (instruction_count == 0 || i < instruction_count)  &&
 613                 (stop == 0 || last.Offset <= stop); i++)
 614         memory_disasm_one_insn(&last);
 615 }
 616
 617 BOOL memory_get_register(DWORD regno, DWORD** value, char* buffer, int len)
 618 {
 619     const struct dbg_internal_var*  div;
 620
 621     /* negative register values are wine's dbghelp hacks
 622      * see dlls/dbghelp/dbghelp_internal.h for the details
 623      */
 624     switch (regno)
 625     {
 626     case -1:
 627         if (buffer) snprintf(buffer, len, "<internal error>");
 628         return FALSE;
 629     case -2:
 630         if (buffer) snprintf(buffer, len, "<couldn't compute location>");
 631         return FALSE;
 632     case -3:
 633         if (buffer) snprintf(buffer, len, "<is not available>");
 634         return FALSE;
 635     case -4:
 636         if (buffer) snprintf(buffer, len, "<couldn't read memory>");
 637         return FALSE;
 638     }
 639
 640     for (div = dbg_context_vars; div->name; div++)
 641     {
 642         if (div->val == regno)
 643         {
 644             if (dbg_curr_thread->curr_frame != 0)
 645             {
 646                 if (!stack_get_register_current_frame(regno, value))
 647                 {
 648                     if (buffer) snprintf(buffer, len, "<register %s not in topmost frame>", div->name);
 649                     return FALSE;
 650                 }
 651             }
 652             else
 653                 *value = div->pval;
 654
 655             if (buffer) snprintf(buffer, len, div->name);
 656             return TRUE;
 657         }
 658     }
 659     if (buffer) snprintf(buffer, len, "<unknown register %u>", regno);
 660     return FALSE;
 661 }