1 /* Select disassembly routine for specified architecture.
2    Copyright (C) 1994-2020 Free Software Foundation, Inc.
3 
4    This file is part of the GNU opcodes library.
5 
6    This library is free software; you can redistribute it and/or modify
7    it under the terms of the GNU General Public License as published by
8    the Free Software Foundation; either version 3 of the License, or
9    (at your option) any later version.
10 
11    This program is distributed in the hope that it will be useful,
12    but WITHOUT ANY WARRANTY; without even the implied warranty of
13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14    GNU General Public License for more details.
15 
16    You should have received a copy of the GNU General Public License
17    along with this program; if not, write to the Free Software
18    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
19    MA 02110-1301, USA.  */
20 
21 #include "sysdep.h"
22 #include "disassemble.h"
23 #include "safe-ctype.h"
24 #include <assert.h>
25 
26 #ifdef ARCH_all
27 #define ARCH_aarch64
28 #define ARCH_alpha
29 #define ARCH_arc
30 #define ARCH_arm
31 #define ARCH_avr
32 #define ARCH_bfin
33 #define ARCH_cr16
34 #define ARCH_cris
35 #define ARCH_crx
36 #define ARCH_csky
37 #define ARCH_d10v
38 #define ARCH_d30v
39 #define ARCH_dlx
40 #define ARCH_bpf
41 #define ARCH_epiphany
42 #define ARCH_fr30
43 #define ARCH_frv
44 #define ARCH_ft32
45 #define ARCH_h8300
46 #define ARCH_hppa
47 #define ARCH_i386
48 #define ARCH_ia64
49 #define ARCH_ip2k
50 #define ARCH_iq2000
51 #define ARCH_lm32
52 #define ARCH_m32c
53 #define ARCH_m32r
54 #define ARCH_m68hc11
55 #define ARCH_m68hc12
56 #define ARCH_m68k
57 #define ARCH_mcore
58 #define ARCH_mep
59 #define ARCH_metag
60 #define ARCH_microblaze
61 #define ARCH_mips
62 #define ARCH_mmix
63 #define ARCH_mn10200
64 #define ARCH_mn10300
65 #define ARCH_moxie
66 #define ARCH_mt
67 #define ARCH_msp430
68 #define ARCH_nds32
69 #define ARCH_nfp
70 #define ARCH_nios2
71 #define ARCH_ns32k
72 #define ARCH_or1k
73 #define ARCH_pdp11
74 #define ARCH_pj
75 #define ARCH_powerpc
76 #define ARCH_pru
77 #define ARCH_riscv
78 #define ARCH_rs6000
79 #define ARCH_rl78
80 #define ARCH_rx
81 #define ARCH_s12z
82 #define ARCH_s390
83 #define ARCH_score
84 #define ARCH_sh
85 #define ARCH_sparc
86 #define ARCH_spu
87 #define ARCH_tic30
88 #define ARCH_tic4x
89 #define ARCH_tic54x
90 #define ARCH_tic6x
91 #define ARCH_tilegx
92 #define ARCH_tilepro
93 #define ARCH_v850
94 #define ARCH_vax
95 #define ARCH_visium
96 #define ARCH_wasm32
97 #define ARCH_xstormy16
98 #define ARCH_xc16x
99 #define ARCH_xgate
100 #define ARCH_xtensa
101 #define ARCH_z80
102 #define ARCH_z8k
103 #endif
104 
105 #ifdef ARCH_m32c
106 #include "m32c-desc.h"
107 #endif
108 
109 #ifdef ARCH_bpf
110 /* XXX this should be including bpf-desc.h instead of this hackery,
111    but at the moment it is not possible to include several CGEN
112    generated *-desc.h files simultaneously.  To be fixed in
113    CGEN...  */
114 
115 # ifdef ARCH_m32c
116 enum epbf_isa_attr
117 {
118  ISA_EBPFLE, ISA_EBPFBE, ISA_EBPFMAX
119 };
120 # else
121 #  include "bpf-desc.h"
122 #  define ISA_EBPFMAX ISA_MAX
123 # endif
124 #endif /* ARCH_bpf */
125 
126 disassembler_ftype
127 disassembler (enum bfd_architecture a,
128 	      bfd_boolean big ATTRIBUTE_UNUSED,
129 	      unsigned long mach ATTRIBUTE_UNUSED,
130 	      bfd *abfd ATTRIBUTE_UNUSED)
131 {
132   disassembler_ftype disassemble;
133 
134   switch (a)
135     {
136       /* If you add a case to this table, also add it to the
137 	 ARCH_all definition right above this function.  */
138 #ifdef ARCH_aarch64
139     case bfd_arch_aarch64:
140       disassemble = print_insn_aarch64;
141       break;
142 #endif
143 #ifdef ARCH_alpha
144     case bfd_arch_alpha:
145       disassemble = print_insn_alpha;
146       break;
147 #endif
148 #ifdef ARCH_arc
149     case bfd_arch_arc:
150       disassemble = arc_get_disassembler (abfd);
151       break;
152 #endif
153 #ifdef ARCH_arm
154     case bfd_arch_arm:
155       if (big)
156 	disassemble = print_insn_big_arm;
157       else
158 	disassemble = print_insn_little_arm;
159       break;
160 #endif
161 #ifdef ARCH_avr
162     case bfd_arch_avr:
163       disassemble = print_insn_avr;
164       break;
165 #endif
166 #ifdef ARCH_bfin
167     case bfd_arch_bfin:
168       disassemble = print_insn_bfin;
169       break;
170 #endif
171 #ifdef ARCH_cr16
172     case bfd_arch_cr16:
173       disassemble = print_insn_cr16;
174       break;
175 #endif
176 #ifdef ARCH_cris
177     case bfd_arch_cris:
178       disassemble = cris_get_disassembler (abfd);
179       break;
180 #endif
181 #ifdef ARCH_crx
182     case bfd_arch_crx:
183       disassemble = print_insn_crx;
184       break;
185 #endif
186 #ifdef ARCH_csky
187     case bfd_arch_csky:
188       disassemble = csky_get_disassembler (abfd);
189       break;
190 #endif
191 
192 #ifdef ARCH_d10v
193     case bfd_arch_d10v:
194       disassemble = print_insn_d10v;
195       break;
196 #endif
197 #ifdef ARCH_d30v
198     case bfd_arch_d30v:
199       disassemble = print_insn_d30v;
200       break;
201 #endif
202 #ifdef ARCH_dlx
203     case bfd_arch_dlx:
204       /* As far as I know we only handle big-endian DLX objects.  */
205       disassemble = print_insn_dlx;
206       break;
207 #endif
208 #ifdef ARCH_h8300
209     case bfd_arch_h8300:
210       if (mach == bfd_mach_h8300h || mach == bfd_mach_h8300hn)
211 	disassemble = print_insn_h8300h;
212       else if (mach == bfd_mach_h8300s
213 	       || mach == bfd_mach_h8300sn
214 	       || mach == bfd_mach_h8300sx
215 	       || mach == bfd_mach_h8300sxn)
216 	disassemble = print_insn_h8300s;
217       else
218 	disassemble = print_insn_h8300;
219       break;
220 #endif
221 #ifdef ARCH_hppa
222     case bfd_arch_hppa:
223       disassemble = print_insn_hppa;
224       break;
225 #endif
226 #ifdef ARCH_i386
227     case bfd_arch_i386:
228     case bfd_arch_iamcu:
229     case bfd_arch_l1om:
230     case bfd_arch_k1om:
231       disassemble = print_insn_i386;
232       break;
233 #endif
234 #ifdef ARCH_ia64
235     case bfd_arch_ia64:
236       disassemble = print_insn_ia64;
237       break;
238 #endif
239 #ifdef ARCH_ip2k
240     case bfd_arch_ip2k:
241       disassemble = print_insn_ip2k;
242       break;
243 #endif
244 #ifdef ARCH_bpf
245     case bfd_arch_bpf:
246       disassemble = print_insn_bpf;
247       break;
248 #endif
249 #ifdef ARCH_epiphany
250     case bfd_arch_epiphany:
251       disassemble = print_insn_epiphany;
252       break;
253 #endif
254 #ifdef ARCH_fr30
255     case bfd_arch_fr30:
256       disassemble = print_insn_fr30;
257       break;
258 #endif
259 #ifdef ARCH_lm32
260     case bfd_arch_lm32:
261       disassemble = print_insn_lm32;
262       break;
263 #endif
264 #ifdef ARCH_m32r
265     case bfd_arch_m32r:
266       disassemble = print_insn_m32r;
267       break;
268 #endif
269 #if defined(ARCH_m68hc11) || defined(ARCH_m68hc12) \
270     || defined(ARCH_9s12x) || defined(ARCH_m9s12xg)
271     case bfd_arch_m68hc11:
272       disassemble = print_insn_m68hc11;
273       break;
274     case bfd_arch_m68hc12:
275       disassemble = print_insn_m68hc12;
276       break;
277     case bfd_arch_m9s12x:
278       disassemble = print_insn_m9s12x;
279       break;
280     case bfd_arch_m9s12xg:
281       disassemble = print_insn_m9s12xg;
282       break;
283 #endif
284 #if defined(ARCH_s12z)
285     case bfd_arch_s12z:
286       disassemble = print_insn_s12z;
287       break;
288 #endif
289 #ifdef ARCH_m68k
290     case bfd_arch_m68k:
291       disassemble = print_insn_m68k;
292       break;
293 #endif
294 #ifdef ARCH_mt
295     case bfd_arch_mt:
296       disassemble = print_insn_mt;
297       break;
298 #endif
299 #ifdef ARCH_microblaze
300     case bfd_arch_microblaze:
301       disassemble = print_insn_microblaze;
302       break;
303 #endif
304 #ifdef ARCH_msp430
305     case bfd_arch_msp430:
306       disassemble = print_insn_msp430;
307       break;
308 #endif
309 #ifdef ARCH_nds32
310     case bfd_arch_nds32:
311       disassemble = print_insn_nds32;
312       break;
313 #endif
314 #ifdef ARCH_nfp
315     case bfd_arch_nfp:
316       disassemble = print_insn_nfp;
317       break;
318 #endif
319 #ifdef ARCH_ns32k
320     case bfd_arch_ns32k:
321       disassemble = print_insn_ns32k;
322       break;
323 #endif
324 #ifdef ARCH_mcore
325     case bfd_arch_mcore:
326       disassemble = print_insn_mcore;
327       break;
328 #endif
329 #ifdef ARCH_mep
330     case bfd_arch_mep:
331       disassemble = print_insn_mep;
332       break;
333 #endif
334 #ifdef ARCH_metag
335     case bfd_arch_metag:
336       disassemble = print_insn_metag;
337       break;
338 #endif
339 #ifdef ARCH_mips
340     case bfd_arch_mips:
341       if (big)
342 	disassemble = print_insn_big_mips;
343       else
344 	disassemble = print_insn_little_mips;
345       break;
346 #endif
347 #ifdef ARCH_mmix
348     case bfd_arch_mmix:
349       disassemble = print_insn_mmix;
350       break;
351 #endif
352 #ifdef ARCH_mn10200
353     case bfd_arch_mn10200:
354       disassemble = print_insn_mn10200;
355       break;
356 #endif
357 #ifdef ARCH_mn10300
358     case bfd_arch_mn10300:
359       disassemble = print_insn_mn10300;
360       break;
361 #endif
362 #ifdef ARCH_nios2
363     case bfd_arch_nios2:
364       if (big)
365 	disassemble = print_insn_big_nios2;
366       else
367 	disassemble = print_insn_little_nios2;
368       break;
369 #endif
370 #ifdef ARCH_or1k
371     case bfd_arch_or1k:
372       disassemble = print_insn_or1k;
373       break;
374 #endif
375 #ifdef ARCH_pdp11
376     case bfd_arch_pdp11:
377       disassemble = print_insn_pdp11;
378       break;
379 #endif
380 #ifdef ARCH_pj
381     case bfd_arch_pj:
382       disassemble = print_insn_pj;
383       break;
384 #endif
385 #ifdef ARCH_powerpc
386     case bfd_arch_powerpc:
387 #endif
388 #ifdef ARCH_rs6000
389     case bfd_arch_rs6000:
390 #endif
391 #if defined ARCH_powerpc || defined ARCH_rs6000
392       if (big)
393 	disassemble = print_insn_big_powerpc;
394       else
395 	disassemble = print_insn_little_powerpc;
396       break;
397 #endif
398 #ifdef ARCH_pru
399     case bfd_arch_pru:
400       disassemble = print_insn_pru;
401       break;
402 #endif
403 #ifdef ARCH_riscv
404     case bfd_arch_riscv:
405       disassemble = print_insn_riscv;
406       break;
407 #endif
408 #ifdef ARCH_rl78
409     case bfd_arch_rl78:
410       disassemble = rl78_get_disassembler (abfd);
411       break;
412 #endif
413 #ifdef ARCH_rx
414     case bfd_arch_rx:
415       disassemble = print_insn_rx;
416       break;
417 #endif
418 #ifdef ARCH_s390
419     case bfd_arch_s390:
420       disassemble = print_insn_s390;
421       break;
422 #endif
423 #ifdef ARCH_score
424     case bfd_arch_score:
425       if (big)
426 	disassemble = print_insn_big_score;
427       else
428 	disassemble = print_insn_little_score;
429      break;
430 #endif
431 #ifdef ARCH_sh
432     case bfd_arch_sh:
433       disassemble = print_insn_sh;
434       break;
435 #endif
436 #ifdef ARCH_sparc
437     case bfd_arch_sparc:
438       disassemble = print_insn_sparc;
439       break;
440 #endif
441 #ifdef ARCH_spu
442     case bfd_arch_spu:
443       disassemble = print_insn_spu;
444       break;
445 #endif
446 #ifdef ARCH_tic30
447     case bfd_arch_tic30:
448       disassemble = print_insn_tic30;
449       break;
450 #endif
451 #ifdef ARCH_tic4x
452     case bfd_arch_tic4x:
453       disassemble = print_insn_tic4x;
454       break;
455 #endif
456 #ifdef ARCH_tic54x
457     case bfd_arch_tic54x:
458       disassemble = print_insn_tic54x;
459       break;
460 #endif
461 #ifdef ARCH_tic6x
462     case bfd_arch_tic6x:
463       disassemble = print_insn_tic6x;
464       break;
465 #endif
466 #ifdef ARCH_ft32
467     case bfd_arch_ft32:
468       disassemble = print_insn_ft32;
469       break;
470 #endif
471 #ifdef ARCH_v850
472     case bfd_arch_v850:
473     case bfd_arch_v850_rh850:
474       disassemble = print_insn_v850;
475       break;
476 #endif
477 #ifdef ARCH_wasm32
478     case bfd_arch_wasm32:
479       disassemble = print_insn_wasm32;
480       break;
481 #endif
482 #ifdef ARCH_xgate
483     case bfd_arch_xgate:
484       disassemble = print_insn_xgate;
485       break;
486 #endif
487 #ifdef ARCH_xstormy16
488     case bfd_arch_xstormy16:
489       disassemble = print_insn_xstormy16;
490       break;
491 #endif
492 #ifdef ARCH_xc16x
493     case bfd_arch_xc16x:
494       disassemble = print_insn_xc16x;
495       break;
496 #endif
497 #ifdef ARCH_xtensa
498     case bfd_arch_xtensa:
499       disassemble = print_insn_xtensa;
500       break;
501 #endif
502 #ifdef ARCH_z80
503     case bfd_arch_z80:
504       disassemble = print_insn_z80;
505       break;
506 #endif
507 #ifdef ARCH_z8k
508     case bfd_arch_z8k:
509       if (mach == bfd_mach_z8001)
510 	disassemble = print_insn_z8001;
511       else
512 	disassemble = print_insn_z8002;
513       break;
514 #endif
515 #ifdef ARCH_vax
516     case bfd_arch_vax:
517       disassemble = print_insn_vax;
518       break;
519 #endif
520 #ifdef ARCH_visium
521      case bfd_arch_visium:
522        disassemble = print_insn_visium;
523        break;
524 #endif
525 #ifdef ARCH_frv
526     case bfd_arch_frv:
527       disassemble = print_insn_frv;
528       break;
529 #endif
530 #ifdef ARCH_moxie
531     case bfd_arch_moxie:
532       disassemble = print_insn_moxie;
533       break;
534 #endif
535 #ifdef ARCH_iq2000
536     case bfd_arch_iq2000:
537       disassemble = print_insn_iq2000;
538       break;
539 #endif
540 #ifdef ARCH_m32c
541     case bfd_arch_m32c:
542       disassemble = print_insn_m32c;
543       break;
544 #endif
545 #ifdef ARCH_tilegx
546     case bfd_arch_tilegx:
547       disassemble = print_insn_tilegx;
548       break;
549 #endif
550 #ifdef ARCH_tilepro
551     case bfd_arch_tilepro:
552       disassemble = print_insn_tilepro;
553       break;
554 #endif
555     default:
556       return 0;
557     }
558   return disassemble;
559 }
560 
561 void
562 disassembler_usage (FILE *stream ATTRIBUTE_UNUSED)
563 {
564 #ifdef ARCH_aarch64
565   print_aarch64_disassembler_options (stream);
566 #endif
567 #ifdef ARCH_arc
568   print_arc_disassembler_options (stream);
569 #endif
570 #ifdef ARCH_arm
571   print_arm_disassembler_options (stream);
572 #endif
573 #ifdef ARCH_mips
574   print_mips_disassembler_options (stream);
575 #endif
576 #ifdef ARCH_nfp
577   print_nfp_disassembler_options (stream);
578 #endif
579 #ifdef ARCH_powerpc
580   print_ppc_disassembler_options (stream);
581 #endif
582 #ifdef ARCH_riscv
583   print_riscv_disassembler_options (stream);
584 #endif
585 #ifdef ARCH_i386
586   print_i386_disassembler_options (stream);
587 #endif
588 #ifdef ARCH_s390
589   print_s390_disassembler_options (stream);
590 #endif
591 #ifdef ARCH_wasm32
592   print_wasm32_disassembler_options (stream);
593 #endif
594 
595   return;
596 }
597 
598 void
599 disassemble_init_for_target (struct disassemble_info * info)
600 {
601   if (info == NULL)
602     return;
603 
604   switch (info->arch)
605     {
606 #ifdef ARCH_aarch64
607     case bfd_arch_aarch64:
608       info->symbol_is_valid = aarch64_symbol_is_valid;
609       info->disassembler_needs_relocs = TRUE;
610       break;
611 #endif
612 #ifdef ARCH_arm
613     case bfd_arch_arm:
614       info->symbol_is_valid = arm_symbol_is_valid;
615       info->disassembler_needs_relocs = TRUE;
616       break;
617 #endif
618 #ifdef ARCH_csky
619     case bfd_arch_csky:
620       info->symbol_is_valid = csky_symbol_is_valid;
621       info->disassembler_needs_relocs = TRUE;
622       break;
623 #endif
624 
625 #ifdef ARCH_ia64
626     case bfd_arch_ia64:
627       info->skip_zeroes = 16;
628       break;
629 #endif
630 #ifdef ARCH_tic4x
631     case bfd_arch_tic4x:
632       info->skip_zeroes = 32;
633       break;
634 #endif
635 #ifdef ARCH_mep
636     case bfd_arch_mep:
637       info->skip_zeroes = 256;
638       info->skip_zeroes_at_end = 0;
639       break;
640 #endif
641 #ifdef ARCH_metag
642     case bfd_arch_metag:
643       info->disassembler_needs_relocs = TRUE;
644       break;
645 #endif
646 #ifdef ARCH_m32c
647     case bfd_arch_m32c:
648       /* This processor in fact is little endian.  The value set here
649 	 reflects the way opcodes are written in the cgen description.  */
650       info->endian = BFD_ENDIAN_BIG;
651       if (!info->private_data)
652 	{
653 	  info->private_data = cgen_bitset_create (ISA_MAX);
654 	  if (info->mach == bfd_mach_m16c)
655 	    cgen_bitset_set (info->private_data, ISA_M16C);
656 	  else
657 	    cgen_bitset_set (info->private_data, ISA_M32C);
658 	}
659       break;
660 #endif
661 #ifdef ARCH_bpf
662     case bfd_arch_bpf:
663       if (!info->private_data)
664 	{
665 	  info->private_data = cgen_bitset_create (ISA_EBPFMAX);
666 	  if (info->endian == BFD_ENDIAN_BIG)
667 	    cgen_bitset_set (info->private_data, ISA_EBPFBE);
668 	  else
669 	    cgen_bitset_set (info->private_data, ISA_EBPFLE);
670 	}
671       break;
672 #endif
673 #ifdef ARCH_pru
674     case bfd_arch_pru:
675       info->disassembler_needs_relocs = TRUE;
676       break;
677 #endif
678 #ifdef ARCH_powerpc
679     case bfd_arch_powerpc:
680 #endif
681 #ifdef ARCH_rs6000
682     case bfd_arch_rs6000:
683 #endif
684 #if defined (ARCH_powerpc) || defined (ARCH_rs6000)
685       disassemble_init_powerpc (info);
686       break;
687 #endif
688 #ifdef ARCH_riscv
689     case bfd_arch_riscv:
690       info->symbol_is_valid = riscv_symbol_is_valid;
691       break;
692 #endif
693 #ifdef ARCH_wasm32
694     case bfd_arch_wasm32:
695       disassemble_init_wasm32 (info);
696       break;
697 #endif
698 #ifdef ARCH_s390
699     case bfd_arch_s390:
700       disassemble_init_s390 (info);
701       break;
702 #endif
703 #ifdef ARCH_nds32
704     case bfd_arch_nds32:
705       disassemble_init_nds32 (info);
706       break;
707  #endif
708     default:
709       break;
710     }
711 }
712 
713 void
714 disassemble_free_target (struct disassemble_info *info)
715 {
716   if (info == NULL)
717     return;
718 
719   switch (info->arch)
720     {
721     default:
722       return;
723 
724 #ifdef ARCH_bpf
725     case bfd_arch_bpf:
726 #endif
727 #ifdef ARCH_m32c
728     case bfd_arch_m32c:
729 #endif
730 #if defined ARCH_bpf || defined ARCH_m32c
731       if (info->private_data)
732 	{
733 	  CGEN_BITSET *mask = info->private_data;
734 	  free (mask->bits);
735 	}
736       break;
737 #endif
738 
739 #ifdef ARCH_arc
740     case bfd_arch_arc:
741       break;
742 #endif
743 #ifdef ARCH_cris
744     case bfd_arch_cris:
745       break;
746 #endif
747 #ifdef ARCH_mmix
748     case bfd_arch_mmix:
749       break;
750 #endif
751 #ifdef ARCH_nfp
752     case bfd_arch_nfp:
753       break;
754 #endif
755 #ifdef ARCH_powerpc
756     case bfd_arch_powerpc:
757       break;
758 #endif
759 #ifdef ARCH_riscv
760     case bfd_arch_riscv:
761       break;
762 #endif
763 #ifdef ARCH_rs6000
764     case bfd_arch_rs6000:
765       break;
766 #endif
767     }
768 
769   free (info->private_data);
770 }
771 
772 /* Remove whitespace and consecutive commas from OPTIONS.  */
773 
774 char *
775 remove_whitespace_and_extra_commas (char *options)
776 {
777   char *str;
778   size_t i, len;
779 
780   if (options == NULL)
781     return NULL;
782 
783   /* Strip off all trailing whitespace and commas.  */
784   for (len = strlen (options); len > 0; len--)
785     {
786       if (!ISSPACE (options[len - 1]) && options[len - 1] != ',')
787 	break;
788       options[len - 1] = '\0';
789     }
790 
791   /* Convert all remaining whitespace to commas.  */
792   for (i = 0; options[i] != '\0'; i++)
793     if (ISSPACE (options[i]))
794       options[i] = ',';
795 
796   /* Remove consecutive commas.  */
797   for (str = options; *str != '\0'; str++)
798     if (*str == ',' && (*(str + 1) == ',' || str == options))
799       {
800 	char *next = str + 1;
801 	while (*next == ',')
802 	  next++;
803 	len = strlen (next);
804 	if (str != options)
805 	  str++;
806 	memmove (str, next, len);
807 	next[len - (size_t)(next - str)] = '\0';
808       }
809   return (strlen (options) != 0) ? options : NULL;
810 }
811 
812 /* Like STRCMP, but treat ',' the same as '\0' so that we match
813    strings like "foobar" against "foobar,xxyyzz,...".  */
814 
815 int
816 disassembler_options_cmp (const char *s1, const char *s2)
817 {
818   unsigned char c1, c2;
819 
820   do
821     {
822       c1 = (unsigned char) *s1++;
823       if (c1 == ',')
824 	c1 = '\0';
825       c2 = (unsigned char) *s2++;
826       if (c2 == ',')
827 	c2 = '\0';
828       if (c1 == '\0')
829 	return c1 - c2;
830     }
831   while (c1 == c2);
832 
833   return c1 - c2;
834 }
835