xref: /netbsd-src/external/gpl3/gdb.old/dist/gdb/guile/scm-math.c (revision ccd9df534e375a4366c5b55f23782053c7a98d82)
1 /* GDB/Scheme support for math operations on values.
2 
3    Copyright (C) 2008-2020 Free Software Foundation, Inc.
4 
5    This file is part of GDB.
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 3 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 /* See README file in this directory for implementation notes, coding
21    conventions, et.al.  */
22 
23 #include "defs.h"
24 #include "arch-utils.h"
25 #include "charset.h"
26 #include "cp-abi.h"
27 #include "target-float.h"
28 #include "symtab.h" /* Needed by language.h.  */
29 #include "language.h"
30 #include "valprint.h"
31 #include "value.h"
32 #include "guile-internal.h"
33 
34 /* Note: Use target types here to remain consistent with the values system in
35    GDB (which uses target arithmetic).  */
36 
37 enum valscm_unary_opcode
38 {
39   VALSCM_NOT,
40   VALSCM_NEG,
41   VALSCM_NOP,
42   VALSCM_ABS,
43   /* Note: This is Scheme's "logical not", not GDB's.
44      GDB calls this UNOP_COMPLEMENT.  */
45   VALSCM_LOGNOT
46 };
47 
48 enum valscm_binary_opcode
49 {
50   VALSCM_ADD,
51   VALSCM_SUB,
52   VALSCM_MUL,
53   VALSCM_DIV,
54   VALSCM_REM,
55   VALSCM_MOD,
56   VALSCM_POW,
57   VALSCM_LSH,
58   VALSCM_RSH,
59   VALSCM_MIN,
60   VALSCM_MAX,
61   VALSCM_BITAND,
62   VALSCM_BITOR,
63   VALSCM_BITXOR
64 };
65 
66 /* If TYPE is a reference, return the target; otherwise return TYPE.  */
67 #define STRIP_REFERENCE(TYPE) \
68   ((TYPE->code () == TYPE_CODE_REF) ? (TYPE_TARGET_TYPE (TYPE)) : (TYPE))
69 
70 /* Helper for vlscm_unop.  Contains all the code that may throw a GDB
71    exception.  */
72 
73 static SCM
74 vlscm_unop_gdbthrow (enum valscm_unary_opcode opcode, SCM x,
75 		     const char *func_name)
76 {
77   struct gdbarch *gdbarch = get_current_arch ();
78   const struct language_defn *language = current_language;
79 
80   scoped_value_mark free_values;
81 
82   SCM except_scm;
83   value *arg1 = vlscm_convert_value_from_scheme (func_name, SCM_ARG1, x,
84 						 &except_scm, gdbarch,
85 						 language);
86   if (arg1 == NULL)
87     return except_scm;
88 
89   struct value *res_val = NULL;
90 
91   switch (opcode)
92     {
93     case VALSCM_NOT:
94       /* Alas gdb and guile use the opposite meaning for "logical
95 	 not".  */
96       {
97 	struct type *type = language_bool_type (language, gdbarch);
98 	res_val
99 	  = value_from_longest (type,
100 				(LONGEST) value_logical_not (arg1));
101       }
102       break;
103     case VALSCM_NEG:
104       res_val = value_neg (arg1);
105       break;
106     case VALSCM_NOP:
107       /* Seemingly a no-op, but if X was a Scheme value it is now a
108 	 <gdb:value> object.  */
109       res_val = arg1;
110       break;
111     case VALSCM_ABS:
112       if (value_less (arg1, value_zero (value_type (arg1), not_lval)))
113 	res_val = value_neg (arg1);
114       else
115 	res_val = arg1;
116       break;
117     case VALSCM_LOGNOT:
118       res_val = value_complement (arg1);
119       break;
120     default:
121       gdb_assert_not_reached ("unsupported operation");
122     }
123 
124   gdb_assert (res_val != NULL);
125   return vlscm_scm_from_value (res_val);
126 }
127 
128 static SCM
129 vlscm_unop (enum valscm_unary_opcode opcode, SCM x, const char *func_name)
130 {
131   return gdbscm_wrap (vlscm_unop_gdbthrow, opcode, x, func_name);
132 }
133 
134 /* Helper for vlscm_binop.  Contains all the code that may throw a GDB
135    exception.  */
136 
137 static SCM
138 vlscm_binop_gdbthrow (enum valscm_binary_opcode opcode, SCM x, SCM y,
139 		      const char *func_name)
140 {
141   struct gdbarch *gdbarch = get_current_arch ();
142   const struct language_defn *language = current_language;
143   struct value *arg1, *arg2;
144   struct value *res_val = NULL;
145   SCM except_scm;
146 
147   scoped_value_mark free_values;
148 
149   arg1 = vlscm_convert_value_from_scheme (func_name, SCM_ARG1, x,
150 					  &except_scm, gdbarch, language);
151   if (arg1 == NULL)
152     return except_scm;
153 
154   arg2 = vlscm_convert_value_from_scheme (func_name, SCM_ARG2, y,
155 					  &except_scm, gdbarch, language);
156   if (arg2 == NULL)
157     return except_scm;
158 
159   switch (opcode)
160     {
161     case VALSCM_ADD:
162       {
163 	struct type *ltype = value_type (arg1);
164 	struct type *rtype = value_type (arg2);
165 
166 	ltype = check_typedef (ltype);
167 	ltype = STRIP_REFERENCE (ltype);
168 	rtype = check_typedef (rtype);
169 	rtype = STRIP_REFERENCE (rtype);
170 
171 	if (ltype->code () == TYPE_CODE_PTR
172 	    && is_integral_type (rtype))
173 	  res_val = value_ptradd (arg1, value_as_long (arg2));
174 	else if (rtype->code () == TYPE_CODE_PTR
175 		 && is_integral_type (ltype))
176 	  res_val = value_ptradd (arg2, value_as_long (arg1));
177 	else
178 	  res_val = value_binop (arg1, arg2, BINOP_ADD);
179       }
180       break;
181     case VALSCM_SUB:
182       {
183 	struct type *ltype = value_type (arg1);
184 	struct type *rtype = value_type (arg2);
185 
186 	ltype = check_typedef (ltype);
187 	ltype = STRIP_REFERENCE (ltype);
188 	rtype = check_typedef (rtype);
189 	rtype = STRIP_REFERENCE (rtype);
190 
191 	if (ltype->code () == TYPE_CODE_PTR
192 	    && rtype->code () == TYPE_CODE_PTR)
193 	  {
194 	    /* A ptrdiff_t for the target would be preferable here.  */
195 	    res_val
196 	      = value_from_longest (builtin_type (gdbarch)->builtin_long,
197 				    value_ptrdiff (arg1, arg2));
198 	  }
199 	else if (ltype->code () == TYPE_CODE_PTR
200 		 && is_integral_type (rtype))
201 	  res_val = value_ptradd (arg1, - value_as_long (arg2));
202 	else
203 	  res_val = value_binop (arg1, arg2, BINOP_SUB);
204       }
205       break;
206     case VALSCM_MUL:
207       res_val = value_binop (arg1, arg2, BINOP_MUL);
208       break;
209     case VALSCM_DIV:
210       res_val = value_binop (arg1, arg2, BINOP_DIV);
211       break;
212     case VALSCM_REM:
213       res_val = value_binop (arg1, arg2, BINOP_REM);
214       break;
215     case VALSCM_MOD:
216       res_val = value_binop (arg1, arg2, BINOP_MOD);
217       break;
218     case VALSCM_POW:
219       res_val = value_binop (arg1, arg2, BINOP_EXP);
220       break;
221     case VALSCM_LSH:
222       res_val = value_binop (arg1, arg2, BINOP_LSH);
223       break;
224     case VALSCM_RSH:
225       res_val = value_binop (arg1, arg2, BINOP_RSH);
226       break;
227     case VALSCM_MIN:
228       res_val = value_binop (arg1, arg2, BINOP_MIN);
229       break;
230     case VALSCM_MAX:
231       res_val = value_binop (arg1, arg2, BINOP_MAX);
232       break;
233     case VALSCM_BITAND:
234       res_val = value_binop (arg1, arg2, BINOP_BITWISE_AND);
235       break;
236     case VALSCM_BITOR:
237       res_val = value_binop (arg1, arg2, BINOP_BITWISE_IOR);
238       break;
239     case VALSCM_BITXOR:
240       res_val = value_binop (arg1, arg2, BINOP_BITWISE_XOR);
241       break;
242     default:
243       gdb_assert_not_reached ("unsupported operation");
244     }
245 
246   gdb_assert (res_val != NULL);
247   return vlscm_scm_from_value (res_val);
248 }
249 
250 /* Returns a value object which is the result of applying the operation
251    specified by OPCODE to the given arguments.
252    If there's an error a Scheme exception is thrown.  */
253 
254 static SCM
255 vlscm_binop (enum valscm_binary_opcode opcode, SCM x, SCM y,
256 	     const char *func_name)
257 {
258   return gdbscm_wrap (vlscm_binop_gdbthrow, opcode, x, y, func_name);
259 }
260 
261 /* (value-add x y) -> <gdb:value> */
262 
263 static SCM
264 gdbscm_value_add (SCM x, SCM y)
265 {
266   return vlscm_binop (VALSCM_ADD, x, y, FUNC_NAME);
267 }
268 
269 /* (value-sub x y) -> <gdb:value> */
270 
271 static SCM
272 gdbscm_value_sub (SCM x, SCM y)
273 {
274   return vlscm_binop (VALSCM_SUB, x, y, FUNC_NAME);
275 }
276 
277 /* (value-mul x y) -> <gdb:value> */
278 
279 static SCM
280 gdbscm_value_mul (SCM x, SCM y)
281 {
282   return vlscm_binop (VALSCM_MUL, x, y, FUNC_NAME);
283 }
284 
285 /* (value-div x y) -> <gdb:value> */
286 
287 static SCM
288 gdbscm_value_div (SCM x, SCM y)
289 {
290   return vlscm_binop (VALSCM_DIV, x, y, FUNC_NAME);
291 }
292 
293 /* (value-rem x y) -> <gdb:value> */
294 
295 static SCM
296 gdbscm_value_rem (SCM x, SCM y)
297 {
298   return vlscm_binop (VALSCM_REM, x, y, FUNC_NAME);
299 }
300 
301 /* (value-mod x y) -> <gdb:value> */
302 
303 static SCM
304 gdbscm_value_mod (SCM x, SCM y)
305 {
306   return vlscm_binop (VALSCM_MOD, x, y, FUNC_NAME);
307 }
308 
309 /* (value-pow x y) -> <gdb:value> */
310 
311 static SCM
312 gdbscm_value_pow (SCM x, SCM y)
313 {
314   return vlscm_binop (VALSCM_POW, x, y, FUNC_NAME);
315 }
316 
317 /* (value-neg x) -> <gdb:value> */
318 
319 static SCM
320 gdbscm_value_neg (SCM x)
321 {
322   return vlscm_unop (VALSCM_NEG, x, FUNC_NAME);
323 }
324 
325 /* (value-pos x) -> <gdb:value> */
326 
327 static SCM
328 gdbscm_value_pos (SCM x)
329 {
330   return vlscm_unop (VALSCM_NOP, x, FUNC_NAME);
331 }
332 
333 /* (value-abs x) -> <gdb:value> */
334 
335 static SCM
336 gdbscm_value_abs (SCM x)
337 {
338   return vlscm_unop (VALSCM_ABS, x, FUNC_NAME);
339 }
340 
341 /* (value-lsh x y) -> <gdb:value> */
342 
343 static SCM
344 gdbscm_value_lsh (SCM x, SCM y)
345 {
346   return vlscm_binop (VALSCM_LSH, x, y, FUNC_NAME);
347 }
348 
349 /* (value-rsh x y) -> <gdb:value> */
350 
351 static SCM
352 gdbscm_value_rsh (SCM x, SCM y)
353 {
354   return vlscm_binop (VALSCM_RSH, x, y, FUNC_NAME);
355 }
356 
357 /* (value-min x y) -> <gdb:value> */
358 
359 static SCM
360 gdbscm_value_min (SCM x, SCM y)
361 {
362   return vlscm_binop (VALSCM_MIN, x, y, FUNC_NAME);
363 }
364 
365 /* (value-max x y) -> <gdb:value> */
366 
367 static SCM
368 gdbscm_value_max (SCM x, SCM y)
369 {
370   return vlscm_binop (VALSCM_MAX, x, y, FUNC_NAME);
371 }
372 
373 /* (value-not x) -> <gdb:value> */
374 
375 static SCM
376 gdbscm_value_not (SCM x)
377 {
378   return vlscm_unop (VALSCM_NOT, x, FUNC_NAME);
379 }
380 
381 /* (value-lognot x) -> <gdb:value> */
382 
383 static SCM
384 gdbscm_value_lognot (SCM x)
385 {
386   return vlscm_unop (VALSCM_LOGNOT, x, FUNC_NAME);
387 }
388 
389 /* (value-logand x y) -> <gdb:value> */
390 
391 static SCM
392 gdbscm_value_logand (SCM x, SCM y)
393 {
394   return vlscm_binop (VALSCM_BITAND, x, y, FUNC_NAME);
395 }
396 
397 /* (value-logior x y) -> <gdb:value> */
398 
399 static SCM
400 gdbscm_value_logior (SCM x, SCM y)
401 {
402   return vlscm_binop (VALSCM_BITOR, x, y, FUNC_NAME);
403 }
404 
405 /* (value-logxor x y) -> <gdb:value> */
406 
407 static SCM
408 gdbscm_value_logxor (SCM x, SCM y)
409 {
410   return vlscm_binop (VALSCM_BITXOR, x, y, FUNC_NAME);
411 }
412 
413 /* Utility to perform all value comparisons.
414    If there's an error a Scheme exception is thrown.  */
415 
416 static SCM
417 vlscm_rich_compare (int op, SCM x, SCM y, const char *func_name)
418 {
419   return gdbscm_wrap ([=]
420     {
421       struct gdbarch *gdbarch = get_current_arch ();
422       const struct language_defn *language = current_language;
423       SCM except_scm;
424 
425       scoped_value_mark free_values;
426 
427       value *v1
428 	= vlscm_convert_value_from_scheme (func_name, SCM_ARG1, x,
429 					   &except_scm, gdbarch, language);
430       if (v1 == NULL)
431 	return except_scm;
432 
433       value *v2
434 	= vlscm_convert_value_from_scheme (func_name, SCM_ARG2, y,
435 					   &except_scm, gdbarch, language);
436       if (v2 == NULL)
437 	return except_scm;
438 
439       int result;
440       switch (op)
441 	{
442         case BINOP_LESS:
443 	  result = value_less (v1, v2);
444 	  break;
445 	case BINOP_LEQ:
446 	  result = (value_less (v1, v2)
447 		    || value_equal (v1, v2));
448 	  break;
449 	case BINOP_EQUAL:
450 	  result = value_equal (v1, v2);
451 	  break;
452 	case BINOP_NOTEQUAL:
453 	  gdb_assert_not_reached ("not-equal not implemented");
454         case BINOP_GTR:
455 	  result = value_less (v2, v1);
456 	  break;
457 	case BINOP_GEQ:
458 	  result = (value_less (v2, v1)
459 		    || value_equal (v1, v2));
460 	  break;
461 	default:
462 	  gdb_assert_not_reached ("invalid <gdb:value> comparison");
463 	}
464       return scm_from_bool (result);
465     });
466 }
467 
468 /* (value=? x y) -> boolean
469    There is no "not-equal?" function (value!= ?) on purpose.
470    We're following string=?, etc. as our Guide here.  */
471 
472 static SCM
473 gdbscm_value_eq_p (SCM x, SCM y)
474 {
475   return vlscm_rich_compare (BINOP_EQUAL, x, y, FUNC_NAME);
476 }
477 
478 /* (value<? x y) -> boolean */
479 
480 static SCM
481 gdbscm_value_lt_p (SCM x, SCM y)
482 {
483   return vlscm_rich_compare (BINOP_LESS, x, y, FUNC_NAME);
484 }
485 
486 /* (value<=? x y) -> boolean */
487 
488 static SCM
489 gdbscm_value_le_p (SCM x, SCM y)
490 {
491   return vlscm_rich_compare (BINOP_LEQ, x, y, FUNC_NAME);
492 }
493 
494 /* (value>? x y) -> boolean */
495 
496 static SCM
497 gdbscm_value_gt_p (SCM x, SCM y)
498 {
499   return vlscm_rich_compare (BINOP_GTR, x, y, FUNC_NAME);
500 }
501 
502 /* (value>=? x y) -> boolean */
503 
504 static SCM
505 gdbscm_value_ge_p (SCM x, SCM y)
506 {
507   return vlscm_rich_compare (BINOP_GEQ, x, y, FUNC_NAME);
508 }
509 
510 /* Subroutine of vlscm_convert_typed_value_from_scheme to simplify it.
511    Convert OBJ, a Scheme number, to a <gdb:value> object.
512    OBJ_ARG_POS is its position in the argument list, used in exception text.
513 
514    TYPE is the result type.  TYPE_ARG_POS is its position in
515    the argument list, used in exception text.
516    TYPE_SCM is Scheme object wrapping TYPE, used in exception text.
517 
518    If the number isn't representable, e.g. it's too big, a <gdb:exception>
519    object is stored in *EXCEPT_SCMP and NULL is returned.
520    The conversion may throw a gdb error, e.g., if TYPE is invalid.  */
521 
522 static struct value *
523 vlscm_convert_typed_number (const char *func_name, int obj_arg_pos, SCM obj,
524 			    int type_arg_pos, SCM type_scm, struct type *type,
525 			    struct gdbarch *gdbarch, SCM *except_scmp)
526 {
527   if (is_integral_type (type)
528       || type->code () == TYPE_CODE_PTR)
529     {
530       if (TYPE_UNSIGNED (type))
531 	{
532 	  ULONGEST max;
533 
534 	  get_unsigned_type_max (type, &max);
535 	  if (!scm_is_unsigned_integer (obj, 0, max))
536 	    {
537 	      *except_scmp
538 		= gdbscm_make_out_of_range_error (func_name,
539 						  obj_arg_pos, obj,
540 					_("value out of range for type"));
541 	      return NULL;
542 	    }
543 	  return value_from_longest (type, gdbscm_scm_to_ulongest (obj));
544 	}
545       else
546 	{
547 	  LONGEST min, max;
548 
549 	  get_signed_type_minmax (type, &min, &max);
550 	  if (!scm_is_signed_integer (obj, min, max))
551 	    {
552 	      *except_scmp
553 		= gdbscm_make_out_of_range_error (func_name,
554 						  obj_arg_pos, obj,
555 					_("value out of range for type"));
556 	      return NULL;
557 	    }
558 	  return value_from_longest (type, gdbscm_scm_to_longest (obj));
559 	}
560     }
561   else if (type->code () == TYPE_CODE_FLT)
562     return value_from_host_double (type, scm_to_double (obj));
563   else
564     {
565       *except_scmp = gdbscm_make_type_error (func_name, obj_arg_pos, obj,
566 					     NULL);
567       return NULL;
568     }
569 }
570 
571 /* Return non-zero if OBJ, an integer, fits in TYPE.  */
572 
573 static int
574 vlscm_integer_fits_p (SCM obj, struct type *type)
575 {
576   if (TYPE_UNSIGNED (type))
577     {
578       ULONGEST max;
579 
580       /* If scm_is_unsigned_integer can't work with this type, just punt.  */
581       if (TYPE_LENGTH (type) > sizeof (uintmax_t))
582 	return 0;
583       get_unsigned_type_max (type, &max);
584       return scm_is_unsigned_integer (obj, 0, max);
585     }
586   else
587     {
588       LONGEST min, max;
589 
590       /* If scm_is_signed_integer can't work with this type, just punt.  */
591       if (TYPE_LENGTH (type) > sizeof (intmax_t))
592 	return 0;
593       get_signed_type_minmax (type, &min, &max);
594       return scm_is_signed_integer (obj, min, max);
595     }
596 }
597 
598 /* Subroutine of vlscm_convert_typed_value_from_scheme to simplify it.
599    Convert OBJ, a Scheme number, to a <gdb:value> object.
600    OBJ_ARG_POS is its position in the argument list, used in exception text.
601 
602    If OBJ is an integer, then the smallest int that will hold the value in
603    the following progression is chosen:
604    int, unsigned int, long, unsigned long, long long, unsigned long long.
605    Otherwise, if OBJ is a real number, then it is converted to a double.
606    Otherwise an exception is thrown.
607 
608    If the number isn't representable, e.g. it's too big, a <gdb:exception>
609    object is stored in *EXCEPT_SCMP and NULL is returned.  */
610 
611 static struct value *
612 vlscm_convert_number (const char *func_name, int obj_arg_pos, SCM obj,
613 		      struct gdbarch *gdbarch, SCM *except_scmp)
614 {
615   const struct builtin_type *bt = builtin_type (gdbarch);
616 
617   /* One thing to keep in mind here is that we are interested in the
618      target's representation of OBJ, not the host's.  */
619 
620   if (scm_is_exact (obj) && scm_is_integer (obj))
621     {
622       if (vlscm_integer_fits_p (obj, bt->builtin_int))
623 	return value_from_longest (bt->builtin_int,
624 				   gdbscm_scm_to_longest (obj));
625       if (vlscm_integer_fits_p (obj, bt->builtin_unsigned_int))
626 	return value_from_longest (bt->builtin_unsigned_int,
627 				   gdbscm_scm_to_ulongest (obj));
628       if (vlscm_integer_fits_p (obj, bt->builtin_long))
629 	return value_from_longest (bt->builtin_long,
630 				   gdbscm_scm_to_longest (obj));
631       if (vlscm_integer_fits_p (obj, bt->builtin_unsigned_long))
632 	return value_from_longest (bt->builtin_unsigned_long,
633 				   gdbscm_scm_to_ulongest (obj));
634       if (vlscm_integer_fits_p (obj, bt->builtin_long_long))
635 	return value_from_longest (bt->builtin_long_long,
636 				   gdbscm_scm_to_longest (obj));
637       if (vlscm_integer_fits_p (obj, bt->builtin_unsigned_long_long))
638 	return value_from_longest (bt->builtin_unsigned_long_long,
639 				   gdbscm_scm_to_ulongest (obj));
640     }
641   else if (scm_is_real (obj))
642     return value_from_host_double (bt->builtin_double, scm_to_double (obj));
643 
644   *except_scmp = gdbscm_make_out_of_range_error (func_name, obj_arg_pos, obj,
645 			_("value not a number representable on the target"));
646   return NULL;
647 }
648 
649 /* Subroutine of vlscm_convert_typed_value_from_scheme to simplify it.
650    Convert BV, a Scheme bytevector, to a <gdb:value> object.
651 
652    TYPE, if non-NULL, is the result type.  Otherwise, a vector of type
653    uint8_t is used.
654    TYPE_SCM is Scheme object wrapping TYPE, used in exception text,
655    or #f if TYPE is NULL.
656 
657    If the bytevector isn't the same size as the type, then a <gdb:exception>
658    object is stored in *EXCEPT_SCMP, and NULL is returned.  */
659 
660 static struct value *
661 vlscm_convert_bytevector (SCM bv, struct type *type, SCM type_scm,
662 			  int arg_pos, const char *func_name,
663 			  SCM *except_scmp, struct gdbarch *gdbarch)
664 {
665   LONGEST length = SCM_BYTEVECTOR_LENGTH (bv);
666   struct value *value;
667 
668   if (type == NULL)
669     {
670       type = builtin_type (gdbarch)->builtin_uint8;
671       type = lookup_array_range_type (type, 0, length);
672       make_vector_type (type);
673     }
674   type = check_typedef (type);
675   if (TYPE_LENGTH (type) != length)
676     {
677       *except_scmp = gdbscm_make_out_of_range_error (func_name, arg_pos,
678 						     type_scm,
679 			_("size of type does not match size of bytevector"));
680       return NULL;
681     }
682 
683   value = value_from_contents (type,
684 			       (gdb_byte *) SCM_BYTEVECTOR_CONTENTS (bv));
685   return value;
686 }
687 
688 /* Convert OBJ, a Scheme value, to a <gdb:value> object.
689    OBJ_ARG_POS is its position in the argument list, used in exception text.
690 
691    TYPE, if non-NULL, is the result type which must be compatible with
692    the value being converted.
693    If TYPE is NULL then a suitable default type is chosen.
694    TYPE_SCM is Scheme object wrapping TYPE, used in exception text,
695    or SCM_UNDEFINED if TYPE is NULL.
696    TYPE_ARG_POS is its position in the argument list, used in exception text,
697    or -1 if TYPE is NULL.
698 
699    OBJ may also be a <gdb:value> object, in which case a copy is returned
700    and TYPE must be NULL.
701 
702    If the value cannot be converted, NULL is returned and a gdb:exception
703    object is stored in *EXCEPT_SCMP.
704    Otherwise the new value is returned, added to the all_values chain.  */
705 
706 struct value *
707 vlscm_convert_typed_value_from_scheme (const char *func_name,
708 				       int obj_arg_pos, SCM obj,
709 				       int type_arg_pos, SCM type_scm,
710 				       struct type *type,
711 				       SCM *except_scmp,
712 				       struct gdbarch *gdbarch,
713 				       const struct language_defn *language)
714 {
715   struct value *value = NULL;
716   SCM except_scm = SCM_BOOL_F;
717 
718   if (type == NULL)
719     {
720       gdb_assert (type_arg_pos == -1);
721       gdb_assert (SCM_UNBNDP (type_scm));
722     }
723 
724   *except_scmp = SCM_BOOL_F;
725 
726   try
727     {
728       if (vlscm_is_value (obj))
729 	{
730 	  if (type != NULL)
731 	    {
732 	      except_scm = gdbscm_make_misc_error (func_name, type_arg_pos,
733 						   type_scm,
734 						   _("No type allowed"));
735 	      value = NULL;
736 	    }
737 	  else
738 	    value = value_copy (vlscm_scm_to_value (obj));
739 	}
740       else if (gdbscm_is_true (scm_bytevector_p (obj)))
741 	{
742 	  value = vlscm_convert_bytevector (obj, type, type_scm,
743 					    obj_arg_pos, func_name,
744 					    &except_scm, gdbarch);
745 	}
746       else if (gdbscm_is_bool (obj))
747 	{
748 	  if (type != NULL
749 	      && !is_integral_type (type))
750 	    {
751 	      except_scm = gdbscm_make_type_error (func_name, type_arg_pos,
752 						   type_scm, NULL);
753 	    }
754 	  else
755 	    {
756 	      value = value_from_longest (type
757 					  ? type
758 					  : language_bool_type (language,
759 								gdbarch),
760 					  gdbscm_is_true (obj));
761 	    }
762 	}
763       else if (scm_is_number (obj))
764 	{
765 	  if (type != NULL)
766 	    {
767 	      value = vlscm_convert_typed_number (func_name, obj_arg_pos, obj,
768 						  type_arg_pos, type_scm, type,
769 						  gdbarch, &except_scm);
770 	    }
771 	  else
772 	    {
773 	      value = vlscm_convert_number (func_name, obj_arg_pos, obj,
774 					    gdbarch, &except_scm);
775 	    }
776 	}
777       else if (scm_is_string (obj))
778 	{
779 	  size_t len;
780 
781 	  if (type != NULL)
782 	    {
783 	      except_scm = gdbscm_make_misc_error (func_name, type_arg_pos,
784 						   type_scm,
785 						   _("No type allowed"));
786 	      value = NULL;
787 	    }
788 	  else
789 	    {
790 	      /* TODO: Provide option to specify conversion strategy.  */
791 	      gdb::unique_xmalloc_ptr<char> s
792 		= gdbscm_scm_to_string (obj, &len,
793 					target_charset (gdbarch),
794 					0 /*non-strict*/,
795 					&except_scm);
796 	      if (s != NULL)
797 		value = value_cstring (s.get (), len,
798 				       language_string_char_type (language,
799 								  gdbarch));
800 	      else
801 		value = NULL;
802 	    }
803 	}
804       else if (lsscm_is_lazy_string (obj))
805 	{
806 	  if (type != NULL)
807 	    {
808 	      except_scm = gdbscm_make_misc_error (func_name, type_arg_pos,
809 						   type_scm,
810 						   _("No type allowed"));
811 	      value = NULL;
812 	    }
813 	  else
814 	    {
815 	      value = lsscm_safe_lazy_string_to_value (obj, obj_arg_pos,
816 						       func_name,
817 						       &except_scm);
818 	    }
819 	}
820       else /* OBJ isn't anything we support.  */
821 	{
822 	  except_scm = gdbscm_make_type_error (func_name, obj_arg_pos, obj,
823 					       NULL);
824 	  value = NULL;
825 	}
826     }
827   catch (const gdb_exception &except)
828     {
829       except_scm = gdbscm_scm_from_gdb_exception (unpack (except));
830     }
831 
832   if (gdbscm_is_true (except_scm))
833     {
834       gdb_assert (value == NULL);
835       *except_scmp = except_scm;
836     }
837 
838   return value;
839 }
840 
841 /* Wrapper around vlscm_convert_typed_value_from_scheme for cases where there
842    is no supplied type.  See vlscm_convert_typed_value_from_scheme for
843    details.  */
844 
845 struct value *
846 vlscm_convert_value_from_scheme (const char *func_name,
847 				 int obj_arg_pos, SCM obj,
848 				 SCM *except_scmp, struct gdbarch *gdbarch,
849 				 const struct language_defn *language)
850 {
851   return vlscm_convert_typed_value_from_scheme (func_name, obj_arg_pos, obj,
852 						-1, SCM_UNDEFINED, NULL,
853 						except_scmp,
854 						gdbarch, language);
855 }
856 
857 /* Initialize value math support.  */
858 
859 static const scheme_function math_functions[] =
860 {
861   { "value-add", 2, 0, 0, as_a_scm_t_subr (gdbscm_value_add),
862     "\
863 Return a + b." },
864 
865   { "value-sub", 2, 0, 0, as_a_scm_t_subr (gdbscm_value_sub),
866     "\
867 Return a - b." },
868 
869   { "value-mul", 2, 0, 0, as_a_scm_t_subr (gdbscm_value_mul),
870     "\
871 Return a * b." },
872 
873   { "value-div", 2, 0, 0, as_a_scm_t_subr (gdbscm_value_div),
874     "\
875 Return a / b." },
876 
877   { "value-rem", 2, 0, 0, as_a_scm_t_subr (gdbscm_value_rem),
878     "\
879 Return a % b." },
880 
881   { "value-mod", 2, 0, 0, as_a_scm_t_subr (gdbscm_value_mod),
882     "\
883 Return a mod b.  See Knuth 1.2.4." },
884 
885   { "value-pow", 2, 0, 0, as_a_scm_t_subr (gdbscm_value_pow),
886     "\
887 Return pow (x, y)." },
888 
889   { "value-not", 1, 0, 0, as_a_scm_t_subr (gdbscm_value_not),
890     "\
891 Return !a." },
892 
893   { "value-neg", 1, 0, 0, as_a_scm_t_subr (gdbscm_value_neg),
894     "\
895 Return -a." },
896 
897   { "value-pos", 1, 0, 0, as_a_scm_t_subr (gdbscm_value_pos),
898     "\
899 Return a." },
900 
901   { "value-abs", 1, 0, 0, as_a_scm_t_subr (gdbscm_value_abs),
902     "\
903 Return abs (a)." },
904 
905   { "value-lsh", 2, 0, 0, as_a_scm_t_subr (gdbscm_value_lsh),
906     "\
907 Return a << b." },
908 
909   { "value-rsh", 2, 0, 0, as_a_scm_t_subr (gdbscm_value_rsh),
910     "\
911 Return a >> b." },
912 
913   { "value-min", 2, 0, 0, as_a_scm_t_subr (gdbscm_value_min),
914     "\
915 Return min (a, b)." },
916 
917   { "value-max", 2, 0, 0, as_a_scm_t_subr (gdbscm_value_max),
918     "\
919 Return max (a, b)." },
920 
921   { "value-lognot", 1, 0, 0, as_a_scm_t_subr (gdbscm_value_lognot),
922     "\
923 Return ~a." },
924 
925   { "value-logand", 2, 0, 0, as_a_scm_t_subr (gdbscm_value_logand),
926     "\
927 Return a & b." },
928 
929   { "value-logior", 2, 0, 0, as_a_scm_t_subr (gdbscm_value_logior),
930     "\
931 Return a | b." },
932 
933   { "value-logxor", 2, 0, 0, as_a_scm_t_subr (gdbscm_value_logxor),
934     "\
935 Return a ^ b." },
936 
937   { "value=?", 2, 0, 0, as_a_scm_t_subr (gdbscm_value_eq_p),
938     "\
939 Return a == b." },
940 
941   { "value<?", 2, 0, 0, as_a_scm_t_subr (gdbscm_value_lt_p),
942     "\
943 Return a < b." },
944 
945   { "value<=?", 2, 0, 0, as_a_scm_t_subr (gdbscm_value_le_p),
946     "\
947 Return a <= b." },
948 
949   { "value>?", 2, 0, 0, as_a_scm_t_subr (gdbscm_value_gt_p),
950     "\
951 Return a > b." },
952 
953   { "value>=?", 2, 0, 0, as_a_scm_t_subr (gdbscm_value_ge_p),
954     "\
955 Return a >= b." },
956 
957   END_FUNCTIONS
958 };
959 
960 void
961 gdbscm_initialize_math (void)
962 {
963   gdbscm_define_functions (math_functions, 1);
964 }
965