gas/itbl-ops.c

   1 /* itbl-ops.c
   2    Copyright 1997, 1999, 2000, 2001, 2002, 2003, 2005, 2006, 2007,
   3    2009  Free Software Foundation, Inc.
   4
   5    This file is part of GAS, the GNU Assembler.
   6
   7    GAS 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 3, or (at your option)
  10    any later version.
  11
  12    GAS 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 GAS; see the file COPYING.  If not, write to the Free
  19    Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
  20    02110-1301, USA.  */
  21
  22 /*======================================================================*/
  23 /*
  24  * Herein lies the support for dynamic specification of processor
  25  * instructions and registers.  Mnemonics, values, and formats for each
  26  * instruction and register are specified in an ascii file consisting of
  27  * table entries.  The grammar for the table is defined in the document
  28  * "Processor instruction table specification".
  29  *
  30  * Instructions use the gnu assembler syntax, with the addition of
  31  * allowing mnemonics for register.
  32  * Eg. "func $2,reg3,0x100,symbol ; comment"
  33  *      func - opcode name
  34  *      $n - register n
  35  *      reg3 - mnemonic for processor's register defined in table
  36  *      0xddd..d - immediate value
  37  *      symbol - address of label or external symbol
  38  *
  39  * First, itbl_parse reads in the table of register and instruction
  40  * names and formats, and builds a list of entries for each
  41  * processor/type combination.  lex and yacc are used to parse
  42  * the entries in the table and call functions defined here to
  43  * add each entry to our list.
  44  *
  45  * Then, when assembling or disassembling, these functions are called to
  46  * 1) get information on a processor's registers and
  47  * 2) assemble/disassemble an instruction.
  48  * To assemble(disassemble) an instruction, the function
  49  * itbl_assemble(itbl_disassemble) is called to search the list of
  50  * instruction entries, and if a match is found, uses the format
  51  * described in the instruction entry structure to complete the action.
  52  *
  53  * Eg. Suppose we have a Mips coprocessor "cop3" with data register "d2"
  54  * and we want to define function "pig" which takes two operands.
  55  *
  56  * Given the table entries:
  57  *      "p3 insn pig 0x1:24-21 dreg:20-16 immed:15-0"
  58  *      "p3 dreg d2 0x2"
  59  * and that the instruction encoding for coprocessor pz has encoding:
  60  *      #define MIPS_ENCODE_COP_NUM(z) ((0x21|(z<<1))<<25)
  61  *      #define ITBL_ENCODE_PNUM(pnum) MIPS_ENCODE_COP_NUM(pnum)
  62  *
  63  * a structure to describe the instruction might look something like:
  64  *      struct itbl_entry = {
  65  *      e_processor processor = e_p3
  66  *      e_type type = e_insn
  67  *      char *name = "pig"
  68  *      uint value = 0x1
  69  *      uint flags = 0
  70  *      struct itbl_range range = 24-21
  71  *      struct itbl_field *field = {
  72  *              e_type type = e_dreg
  73  *              struct itbl_range range = 20-16
  74  *              struct itbl_field *next = {
  75  *                      e_type type = e_immed
  76  *                      struct itbl_range range = 15-0
  77  *                      struct itbl_field *next = 0
  78  *                      };
  79  *              };
  80  *      struct itbl_entry *next = 0
  81  *      };
  82  *
  83  * And the assembler instructions:
  84  *      "pig d2,0x100"
  85  *      "pig $2,0x100"
  86  *
  87  * would both assemble to the hex value:
  88  *      "0x4e220100"
  89  *
  90  */
  91
  92 #include "as.h"
  93 #include "itbl-ops.h"
  94 #include <itbl-parse.h>
  95
  96 /* #define DEBUG */
  97
  98 #ifdef DEBUG
  99 #include <assert.h>
 100 #define ASSERT(x) assert(x)
 101 #define DBG(x) printf x
 102 #else
 103 #define ASSERT(x)
 104 #define DBG(x)
 105 #endif
 106
 107 #ifndef min
 108 #define min(a,b) (a<b?a:b)
 109 #endif
 110
 111 int itbl_have_entries = 0;
 112
 113 /*======================================================================*/
 114 /* structures for keeping itbl format entries */
 115
 116 struct itbl_range {
 117   int sbit;                     /* mask starting bit position */
 118   int ebit;                     /* mask ending bit position */
 119 };
 120
 121 struct itbl_field {
 122   e_type type;                  /* dreg/creg/greg/immed/symb */
 123   struct itbl_range range;      /* field's bitfield range within instruction */
 124   unsigned long flags;          /* field flags */
 125   struct itbl_field *next;      /* next field in list */
 126 };
 127
 128 /* These structures define the instructions and registers for a processor.
 129  * If the type is an instruction, the structure defines the format of an
 130  * instruction where the fields are the list of operands.
 131  * The flags field below uses the same values as those defined in the
 132  * gnu assembler and are machine specific.  */
 133 struct itbl_entry {
 134   e_processor processor;        /* processor number */
 135   e_type type;                  /* dreg/creg/greg/insn */
 136   char *name;                   /* mnemionic name for insn/register */
 137   unsigned long value;          /* opcode/instruction mask/register number */
 138   unsigned long flags;          /* effects of the instruction */
 139   struct itbl_range range;      /* bit range within instruction for value */
 140   struct itbl_field *fields;    /* list of operand definitions (if any) */
 141   struct itbl_entry *next;      /* next entry */
 142 };
 143
 144 /* local data and structures */
 145
 146 static int itbl_num_opcodes = 0;
 147 /* Array of entries for each processor and entry type */
 148 static struct itbl_entry *entries[e_nprocs][e_ntypes];
 149
 150 /* local prototypes */
 151 static unsigned long build_opcode (struct itbl_entry *e);
 152 static e_type get_type (int yytype);
 153 static e_processor get_processor (int yyproc);
 154 static struct itbl_entry **get_entries (e_processor processor,
 155                                         e_type type);
 156 static struct itbl_entry *find_entry_byname (e_processor processor,
 157                                         e_type type, char *name);
 158 static struct itbl_entry *find_entry_byval (e_processor processor,
 159                         e_type type, unsigned long val, struct itbl_range *r);
 160 static struct itbl_entry *alloc_entry (e_processor processor,
 161                 e_type type, char *name, unsigned long value);
 162 static unsigned long apply_range (unsigned long value, struct itbl_range r);
 163 static unsigned long extract_range (unsigned long value, struct itbl_range r);
 164 static struct itbl_field *alloc_field (e_type type, int sbit,
 165                                         int ebit, unsigned long flags);
 166
 167 /*======================================================================*/
 168 /* Interfaces to the parser */
 169
 170 /* Open the table and use lex and yacc to parse the entries.
 171  * Return 1 for failure; 0 for success.  */
 172
 173 int
 174 itbl_parse (char *insntbl)
 175 {
 176   extern FILE *yyin;
 177   extern int yyparse (void);
 178
 179   yyin = fopen (insntbl, FOPEN_RT);
 180   if (yyin == 0)
 181     {
 182       printf ("Can't open processor instruction specification file \"%s\"\n",
 183               insntbl);
 184       return 1;
 185     }
 186
 187   while (yyparse ())
 188     ;
 189
 190   fclose (yyin);
 191   itbl_have_entries = 1;
 192   return 0;
 193 }
 194
 195 /* Add a register entry */
 196
 197 struct itbl_entry *
 198 itbl_add_reg (int yyprocessor, int yytype, char *regname,
 199               int regnum)
 200 {
 201   return alloc_entry (get_processor (yyprocessor), get_type (yytype), regname,
 202                       (unsigned long) regnum);
 203 }
 204
 205 /* Add an instruction entry */
 206
 207 struct itbl_entry *
 208 itbl_add_insn (int yyprocessor, char *name, unsigned long value,
 209                int sbit, int ebit, unsigned long flags)
 210 {
 211   struct itbl_entry *e;
 212   e = alloc_entry (get_processor (yyprocessor), e_insn, name, value);
 213   if (e)
 214     {
 215       e->range.sbit = sbit;
 216       e->range.ebit = ebit;
 217       e->flags = flags;
 218       itbl_num_opcodes++;
 219     }
 220   return e;
 221 }
 222
 223 /* Add an operand to an instruction entry */
 224
 225 struct itbl_field *
 226 itbl_add_operand (struct itbl_entry *e, int yytype, int sbit,
 227                   int ebit, unsigned long flags)
 228 {
 229   struct itbl_field *f, **last_f;
 230   if (!e)
 231     return 0;
 232   /* Add to end of fields' list.  */
 233   f = alloc_field (get_type (yytype), sbit, ebit, flags);
 234   if (f)
 235     {
 236       last_f = &e->fields;
 237       while (*last_f)
 238         last_f = &(*last_f)->next;
 239       *last_f = f;
 240       f->next = 0;
 241     }
 242   return f;
 243 }
 244
 245 /*======================================================================*/
 246 /* Interfaces for assembler and disassembler */
 247
 248 #ifndef STAND_ALONE
 249 static void append_insns_as_macros (void);
 250
 251 /* Initialize for gas.  */
 252
 253 void
 254 itbl_init (void)
 255 {
 256   struct itbl_entry *e, **es;
 257   e_processor procn;
 258   e_type type;
 259
 260   if (!itbl_have_entries)
 261     return;
 262
 263   /* Since register names don't have a prefix, put them in the symbol table so
 264      they can't be used as symbols.  This simplifies argument parsing as
 265      we can let gas parse registers for us.  */
 266   /* Use symbol_create instead of symbol_new so we don't try to
 267      output registers into the object file's symbol table.  */
 268
 269   for (type = e_regtype0; type < e_nregtypes; type++)
 270     for (procn = e_p0; procn < e_nprocs; procn++)
 271       {
 272         es = get_entries (procn, type);
 273         for (e = *es; e; e = e->next)
 274           {
 275             symbol_table_insert (symbol_create (e->name, reg_section,
 276                                                 e->value, &zero_address_frag));
 277           }
 278       }
 279   append_insns_as_macros ();
 280 }
 281
 282 /* Append insns to opcodes table and increase number of opcodes
 283  * Structure of opcodes table:
 284  * struct itbl_opcode
 285  * {
 286  *   const char *name;
 287  *   const char *args;          - string describing the arguments.
 288  *   unsigned long match;       - opcode, or ISA level if pinfo=INSN_MACRO
 289  *   unsigned long mask;        - opcode mask, or macro id if pinfo=INSN_MACRO
 290  *   unsigned long pinfo;       - insn flags, or INSN_MACRO
 291  * };
 292  * examples:
 293  *      {"li",      "t,i",  0x34000000, 0xffe00000, WR_t    },
 294  *      {"li",      "t,I",  0,    (int) M_LI,   INSN_MACRO  },
 295  */
 296
 297 static char *form_args (struct itbl_entry *e);
 298 static void
 299 append_insns_as_macros (void)
 300 {
 301   struct ITBL_OPCODE_STRUCT *new_opcodes, *o;
 302   struct itbl_entry *e, **es;
 303   int n, id, size, new_size, new_num_opcodes;
 304
 305   if (!itbl_have_entries)
 306     return;
 307
 308   if (!itbl_num_opcodes)        /* no new instructions to add! */
 309     {
 310       return;
 311     }
 312   DBG (("previous num_opcodes=%d\n", ITBL_NUM_OPCODES));
 313
 314   new_num_opcodes = ITBL_NUM_OPCODES + itbl_num_opcodes;
 315   ASSERT (new_num_opcodes >= itbl_num_opcodes);
 316
 317   size = sizeof (struct ITBL_OPCODE_STRUCT) * ITBL_NUM_OPCODES;
 318   ASSERT (size >= 0);
 319   DBG (("I get=%d\n", size / sizeof (ITBL_OPCODES[0])));
 320
 321   new_size = sizeof (struct ITBL_OPCODE_STRUCT) * new_num_opcodes;
 322   ASSERT (new_size > size);
 323
 324   /* FIXME since ITBL_OPCODES culd be a static table,
 325                 we can't realloc or delete the old memory.  */
 326   new_opcodes = (struct ITBL_OPCODE_STRUCT *) malloc (new_size);
 327   if (!new_opcodes)
 328     {
 329       printf (_("Unable to allocate memory for new instructions\n"));
 330       return;
 331     }
 332   if (size)                     /* copy preexisting opcodes table */
 333     memcpy (new_opcodes, ITBL_OPCODES, size);
 334
 335   /* FIXME! some NUMOPCODES are calculated expressions.
 336                 These need to be changed before itbls can be supported.  */
 337
 338   id = ITBL_NUM_MACROS;         /* begin the next macro id after the last */
 339   o = &new_opcodes[ITBL_NUM_OPCODES];   /* append macro to opcodes list */
 340   for (n = e_p0; n < e_nprocs; n++)
 341     {
 342       es = get_entries (n, e_insn);
 343       for (e = *es; e; e = e->next)
 344         {
 345           /* name,    args,   mask,       match,  pinfo
 346                  * {"li",      "t,i",  0x34000000, 0xffe00000, WR_t    },
 347                  * {"li",      "t,I",  0,    (int) M_LI,   INSN_MACRO  },
 348                  * Construct args from itbl_fields.
 349                 */
 350           o->name = e->name;
 351           o->args = strdup (form_args (e));
 352           o->mask = apply_range (e->value, e->range);
 353           /* FIXME how to catch during assembly? */
 354           /* mask to identify this insn */
 355           o->match = apply_range (e->value, e->range);
 356           o->pinfo = 0;
 357
 358 #ifdef USE_MACROS
 359           o->mask = id++;       /* FIXME how to catch during assembly? */
 360           o->match = 0;         /* for macros, the insn_isa number */
 361           o->pinfo = INSN_MACRO;
 362 #endif
 363
 364           /* Don't add instructions which caused an error */
 365           if (o->args)
 366             o++;
 367           else
 368             new_num_opcodes--;
 369         }
 370     }
 371   ITBL_OPCODES = new_opcodes;
 372   ITBL_NUM_OPCODES = new_num_opcodes;
 373
 374   /* FIXME
 375                 At this point, we can free the entries, as they should have
 376                 been added to the assembler's tables.
 377                 Don't free name though, since name is being used by the new
 378                 opcodes table.
 379
 380                 Eventually, we should also free the new opcodes table itself
 381                 on exit.
 382         */
 383 }
 384
 385 static char *
 386 form_args (struct itbl_entry *e)
 387 {
 388   static char s[31];
 389   char c = 0, *p = s;
 390   struct itbl_field *f;
 391
 392   ASSERT (e);
 393   for (f = e->fields; f; f = f->next)
 394     {
 395       switch (f->type)
 396         {
 397         case e_dreg:
 398           c = 'd';
 399           break;
 400         case e_creg:
 401           c = 't';
 402           break;
 403         case e_greg:
 404           c = 's';
 405           break;
 406         case e_immed:
 407           c = 'i';
 408           break;
 409         case e_addr:
 410           c = 'a';
 411           break;
 412         default:
 413           c = 0;                /* ignore; unknown field type */
 414         }
 415       if (c)
 416         {
 417           if (p != s)
 418             *p++ = ',';
 419           *p++ = c;
 420         }
 421     }
 422   *p = 0;
 423   return s;
 424 }
 425 #endif /* !STAND_ALONE */
 426
 427 /* Get processor's register name from val */
 428
 429 int
 430 itbl_get_reg_val (char *name, unsigned long *pval)
 431 {
 432   e_type t;
 433   e_processor p;
 434
 435   for (p = e_p0; p < e_nprocs; p++)
 436     {
 437       for (t = e_regtype0; t < e_nregtypes; t++)
 438         {
 439           if (itbl_get_val (p, t, name, pval))
 440             return 1;
 441         }
 442     }
 443   return 0;
 444 }
 445
 446 char *
 447 itbl_get_name (e_processor processor, e_type type, unsigned long val)
 448 {
 449   struct itbl_entry *r;
 450   /* type depends on instruction passed */
 451   r = find_entry_byval (processor, type, val, 0);
 452   if (r)
 453     return r->name;
 454   else
 455     return 0;                   /* error; invalid operand */
 456 }
 457
 458 /* Get processor's register value from name */
 459
 460 int
 461 itbl_get_val (e_processor processor, e_type type, char *name,
 462               unsigned long *pval)
 463 {
 464   struct itbl_entry *r;
 465   /* type depends on instruction passed */
 466   r = find_entry_byname (processor, type, name);
 467   if (r == NULL)
 468     return 0;
 469   *pval = r->value;
 470   return 1;
 471 }
 472
 473 /* Assemble instruction "name" with operands "s".
 474  * name - name of instruction
 475  * s - operands
 476  * returns - long word for assembled instruction */
 477
 478 unsigned long
 479 itbl_assemble (char *name, char *s)
 480 {
 481   unsigned long opcode;
 482   struct itbl_entry *e = NULL;
 483   struct itbl_field *f;
 484   char *n;
 485   int processor;
 486
 487   if (!name || !*name)
 488     return 0;                   /* error!  must have an opcode name/expr */
 489
 490   /* find entry in list of instructions for all processors */
 491   for (processor = 0; processor < e_nprocs; processor++)
 492     {
 493       e = find_entry_byname (processor, e_insn, name);
 494       if (e)
 495         break;
 496     }
 497   if (!e)
 498     return 0;                   /* opcode not in table; invalid instruction */
 499   opcode = build_opcode (e);
 500
 501   /* parse opcode's args (if any) */
 502   for (f = e->fields; f; f = f->next)   /* for each arg, ...  */
 503     {
 504       struct itbl_entry *r;
 505       unsigned long value;
 506       if (!s || !*s)
 507         return 0;               /* error - not enough operands */
 508       n = itbl_get_field (&s);
 509       /* n should be in form $n or 0xhhh (are symbol names valid?? */
 510       switch (f->type)
 511         {
 512         case e_dreg:
 513         case e_creg:
 514         case e_greg:
 515           /* Accept either a string name
 516                          * or '$' followed by the register number */
 517           if (*n == '$')
 518             {
 519               n++;
 520               value = strtol (n, 0, 10);
 521               /* FIXME! could have "0l"... then what?? */
 522               if (value == 0 && *n != '0')
 523                 return 0;       /* error; invalid operand */
 524             }
 525           else
 526             {
 527               r = find_entry_byname (e->processor, f->type, n);
 528               if (r)
 529                 value = r->value;
 530               else
 531                 return 0;       /* error; invalid operand */
 532             }
 533           break;
 534         case e_addr:
 535           /* use assembler's symbol table to find symbol */
 536           /* FIXME!! Do we need this?
 537                                 if so, what about relocs??
 538                                 my_getExpression (&imm_expr, s);
 539                                 return 0;       /-* error; invalid operand *-/
 540                                 break;
 541                         */
 542           /* If not a symbol, fall thru to IMMED */
 543         case e_immed:
 544           if (*n == '0' && *(n + 1) == 'x')     /* hex begins 0x...  */
 545             {
 546               n += 2;
 547               value = strtol (n, 0, 16);
 548               /* FIXME! could have "0xl"... then what?? */
 549             }
 550           else
 551             {
 552               value = strtol (n, 0, 10);
 553               /* FIXME! could have "0l"... then what?? */
 554               if (value == 0 && *n != '0')
 555                 return 0;       /* error; invalid operand */
 556             }
 557           break;
 558         default:
 559           return 0;             /* error; invalid field spec */
 560         }
 561       opcode |= apply_range (value, f->range);
 562     }
 563   if (s && *s)
 564     return 0;                   /* error - too many operands */
 565   return opcode;                /* done! */
 566 }
 567
 568 /* Disassemble instruction "insn".
 569  * insn - instruction
 570  * s - buffer to hold disassembled instruction
 571  * returns - 1 if succeeded; 0 if failed
 572  */
 573
 574 int
 575 itbl_disassemble (char *s, unsigned long insn)
 576 {
 577   e_processor processor;
 578   struct itbl_entry *e;
 579   struct itbl_field *f;
 580
 581   if (!ITBL_IS_INSN (insn))
 582     return 0;                   /* error */
 583   processor = get_processor (ITBL_DECODE_PNUM (insn));
 584
 585   /* find entry in list */
 586   e = find_entry_byval (processor, e_insn, insn, 0);
 587   if (!e)
 588     return 0;                   /* opcode not in table; invalid instruction */
 589   strcpy (s, e->name);
 590
 591   /* Parse insn's args (if any).  */
 592   for (f = e->fields; f; f = f->next)   /* for each arg, ...  */
 593     {
 594       struct itbl_entry *r;
 595       unsigned long value;
 596       char s_value[20];
 597
 598       if (f == e->fields)       /* First operand is preceded by tab.  */
 599         strcat (s, "\t");
 600       else                      /* ','s separate following operands.  */
 601         strcat (s, ",");
 602       value = extract_range (insn, f->range);
 603       /* n should be in form $n or 0xhhh (are symbol names valid?? */
 604       switch (f->type)
 605         {
 606         case e_dreg:
 607         case e_creg:
 608         case e_greg:
 609           /* Accept either a string name
 610              or '$' followed by the register number.  */
 611           r = find_entry_byval (e->processor, f->type, value, &f->range);
 612           if (r)
 613             strcat (s, r->name);
 614           else
 615             {
 616               sprintf (s_value, "$%lu", value);
 617               strcat (s, s_value);
 618             }
 619           break;
 620         case e_addr:
 621           /* Use assembler's symbol table to find symbol.  */
 622           /* FIXME!! Do we need this?  If so, what about relocs??  */
 623           /* If not a symbol, fall through to IMMED.  */
 624         case e_immed:
 625           sprintf (s_value, "0x%lx", value);
 626           strcat (s, s_value);
 627           break;
 628         default:
 629           return 0;             /* error; invalid field spec */
 630         }
 631     }
 632   return 1;                     /* Done!  */
 633 }
 634
 635 /*======================================================================*/
 636 /*
 637  * Local functions for manipulating private structures containing
 638  * the names and format for the new instructions and registers
 639  * for each processor.
 640  */
 641
 642 /* Calculate instruction's opcode and function values from entry */
 643
 644 static unsigned long
 645 build_opcode (struct itbl_entry *e)
 646 {
 647   unsigned long opcode;
 648
 649   opcode = apply_range (e->value, e->range);
 650   opcode |= ITBL_ENCODE_PNUM (e->processor);
 651   return opcode;
 652 }
 653
 654 /* Calculate absolute value given the relative value and bit position range
 655  * within the instruction.
 656  * The range is inclusive where 0 is least significant bit.
 657  * A range of { 24, 20 } will have a mask of
 658  * bit   3           2            1
 659  * pos: 1098 7654 3210 9876 5432 1098 7654 3210
 660  * bin: 0000 0001 1111 0000 0000 0000 0000 0000
 661  * hex:    0    1    f    0    0    0    0    0
 662  * mask: 0x01f00000.
 663  */
 664
 665 static unsigned long
 666 apply_range (unsigned long rval, struct itbl_range r)
 667 {
 668   unsigned long mask;
 669   unsigned long aval;
 670   int len = MAX_BITPOS - r.sbit;
 671
 672   ASSERT (r.sbit >= r.ebit);
 673   ASSERT (MAX_BITPOS >= r.sbit);
 674   ASSERT (r.ebit >= 0);
 675
 676   /* create mask by truncating 1s by shifting */
 677   mask = 0xffffffff << len;
 678   mask = mask >> len;
 679   mask = mask >> r.ebit;
 680   mask = mask << r.ebit;
 681
 682   aval = (rval << r.ebit) & mask;
 683   return aval;
 684 }
 685
 686 /* Calculate relative value given the absolute value and bit position range
 687  * within the instruction.  */
 688
 689 static unsigned long
 690 extract_range (unsigned long aval, struct itbl_range r)
 691 {
 692   unsigned long mask;
 693   unsigned long rval;
 694   int len = MAX_BITPOS - r.sbit;
 695
 696   /* create mask by truncating 1s by shifting */
 697   mask = 0xffffffff << len;
 698   mask = mask >> len;
 699   mask = mask >> r.ebit;
 700   mask = mask << r.ebit;
 701
 702   rval = (aval & mask) >> r.ebit;
 703   return rval;
 704 }
 705
 706 /* Extract processor's assembly instruction field name from s;
 707  * forms are "n args" "n,args" or "n" */
 708 /* Return next argument from string pointer "s" and advance s.
 709  * delimiters are " ,()" */
 710
 711 char *
 712 itbl_get_field (char **S)
 713 {
 714   static char n[128];
 715   char *s;
 716   int len;
 717
 718   s = *S;
 719   if (!s || !*s)
 720     return 0;
 721   /* FIXME: This is a weird set of delimiters.  */
 722   len = strcspn (s, " \t,()");
 723   ASSERT (128 > len + 1);
 724   strncpy (n, s, len);
 725   n[len] = 0;
 726   if (s[len] == '\0')
 727     s = 0;                      /* no more args */
 728   else
 729     s += len + 1;               /* advance to next arg */
 730
 731   *S = s;
 732   return n;
 733 }
 734
 735 /* Search entries for a given processor and type
 736  * to find one matching the name "n".
 737  * Return a pointer to the entry */
 738
 739 static struct itbl_entry *
 740 find_entry_byname (e_processor processor,
 741                    e_type type, char *n)
 742 {
 743   struct itbl_entry *e, **es;
 744
 745   es = get_entries (processor, type);
 746   for (e = *es; e; e = e->next) /* for each entry, ...  */
 747     {
 748       if (!strcmp (e->name, n))
 749         return e;
 750     }
 751   return 0;
 752 }
 753
 754 /* Search entries for a given processor and type
 755  * to find one matching the value "val" for the range "r".
 756  * Return a pointer to the entry.
 757  * This function is used for disassembling fields of an instruction.
 758  */
 759
 760 static struct itbl_entry *
 761 find_entry_byval (e_processor processor, e_type type,
 762                   unsigned long val, struct itbl_range *r)
 763 {
 764   struct itbl_entry *e, **es;
 765   unsigned long eval;
 766
 767   es = get_entries (processor, type);
 768   for (e = *es; e; e = e->next) /* for each entry, ...  */
 769     {
 770       if (processor != e->processor)
 771         continue;
 772       /* For insns, we might not know the range of the opcode,
 773          * so a range of 0 will allow this routine to match against
 774          * the range of the entry to be compared with.
 775          * This could cause ambiguities.
 776          * For operands, we get an extracted value and a range.
 777          */
 778       /* if range is 0, mask val against the range of the compared entry.  */
 779       if (r == 0)               /* if no range passed, must be whole 32-bits
 780                          * so create 32-bit value from entry's range */
 781         {
 782           eval = apply_range (e->value, e->range);
 783           val &= apply_range (0xffffffff, e->range);
 784         }
 785       else if ((r->sbit == e->range.sbit && r->ebit == e->range.ebit)
 786                || (e->range.sbit == 0 && e->range.ebit == 0))
 787         {
 788           eval = apply_range (e->value, *r);
 789           val = apply_range (val, *r);
 790         }
 791       else
 792         continue;
 793       if (val == eval)
 794         return e;
 795     }
 796   return 0;
 797 }
 798
 799 /* Return a pointer to the list of entries for a given processor and type.  */
 800
 801 static struct itbl_entry **
 802 get_entries (e_processor processor, e_type type)
 803 {
 804   return &entries[processor][type];
 805 }
 806
 807 /* Return an integral value for the processor passed from yyparse.  */
 808
 809 static e_processor
 810 get_processor (int yyproc)
 811 {
 812   /* translate from yacc's processor to enum */
 813   if (yyproc >= e_p0 && yyproc < e_nprocs)
 814     return (e_processor) yyproc;
 815   return e_invproc;             /* error; invalid processor */
 816 }
 817
 818 /* Return an integral value for the entry type passed from yyparse.  */
 819
 820 static e_type
 821 get_type (int yytype)
 822 {
 823   switch (yytype)
 824     {
 825       /* translate from yacc's type to enum */
 826     case INSN:
 827       return e_insn;
 828     case DREG:
 829       return e_dreg;
 830     case CREG:
 831       return e_creg;
 832     case GREG:
 833       return e_greg;
 834     case ADDR:
 835       return e_addr;
 836     case IMMED:
 837       return e_immed;
 838     default:
 839       return e_invtype;         /* error; invalid type */
 840     }
 841 }
 842
 843 /* Allocate and initialize an entry */
 844
 845 static struct itbl_entry *
 846 alloc_entry (e_processor processor, e_type type,
 847              char *name, unsigned long value)
 848 {
 849   struct itbl_entry *e, **es;
 850   if (!name)
 851     return 0;
 852   e = (struct itbl_entry *) malloc (sizeof (struct itbl_entry));
 853   if (e)
 854     {
 855       memset (e, 0, sizeof (struct itbl_entry));
 856       e->name = (char *) malloc (sizeof (strlen (name)) + 1);
 857       if (e->name)
 858         strcpy (e->name, name);
 859       e->processor = processor;
 860       e->type = type;
 861       e->value = value;
 862       es = get_entries (e->processor, e->type);
 863       e->next = *es;
 864       *es = e;
 865     }
 866   return e;
 867 }
 868
 869 /* Allocate and initialize an entry's field */
 870
 871 static struct itbl_field *
 872 alloc_field (e_type type, int sbit, int ebit,
 873              unsigned long flags)
 874 {
 875   struct itbl_field *f;
 876   f = (struct itbl_field *) malloc (sizeof (struct itbl_field));
 877   if (f)
 878     {
 879       memset (f, 0, sizeof (struct itbl_field));
 880       f->type = type;
 881       f->range.sbit = sbit;
 882       f->range.ebit = ebit;
 883       f->flags = flags;
 884     }
 885   return f;
 886 }