NASM 0.98p7
[nasm/avx512.git] / disasm.c
blobe7e634ef7fc28a9a2f98f4d127cfcee3ea1e7049
1 /* disasm.c where all the _work_ gets done in the Netwide Disassembler
3 * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
4 * Julian Hall. All rights reserved. The software is
5 * redistributable under the licence given in the file "Licence"
6 * distributed in the NASM archive.
8 * initial version 27/iii/95 by Simon Tatham
9 */
11 #include <stdio.h>
12 #include <string.h>
14 #include "nasm.h"
15 #include "disasm.h"
16 #include "sync.h"
17 #include "insns.h"
19 #include "names.c"
21 extern struct itemplate **itable[];
24 * Flags that go into the `segment' field of `insn' structures
25 * during disassembly.
27 #define SEG_RELATIVE 1
28 #define SEG_32BIT 2
29 #define SEG_RMREG 4
30 #define SEG_DISP8 8
31 #define SEG_DISP16 16
32 #define SEG_DISP32 32
33 #define SEG_NODISP 64
34 #define SEG_SIGNED 128
36 static int whichreg(long regflags, int regval)
38 static int reg32[] = {
39 R_EAX, R_ECX, R_EDX, R_EBX, R_ESP, R_EBP, R_ESI, R_EDI };
40 static int reg16[] = {
41 R_AX, R_CX, R_DX, R_BX, R_SP, R_BP, R_SI, R_DI };
42 static int reg8[] = {
43 R_AL, R_CL, R_DL, R_BL, R_AH, R_CH, R_DH, R_BH };
44 static int sreg[] = {
45 R_ES, R_CS, R_SS, R_DS, R_FS, R_GS, 0, 0 };
46 static int creg[] = {
47 R_CR0, 0, R_CR2, R_CR3, R_CR4, 0, 0, 0 };
48 static int dreg[] = {
49 R_DR0, R_DR1, R_DR2, R_DR3, 0, 0, R_DR6, R_DR7 };
50 static int treg[] = {
51 0, 0, 0, R_TR3, R_TR4, R_TR5, R_TR6, R_TR7 };
52 static int fpureg[] = {
53 R_ST0, R_ST1, R_ST2, R_ST3, R_ST4, R_ST5, R_ST6, R_ST7 };
54 static int mmxreg[] = {
55 R_MM0, R_MM1, R_MM2, R_MM3, R_MM4, R_MM5, R_MM6, R_MM7 };
56 static int xmmreg[] = {
57 R_XMM0, R_XMM1, R_XMM2, R_XMM3, R_XMM4, R_XMM5, R_XMM6, R_XMM7 };
59 if (!(REG_AL & ~regflags))
60 return R_AL;
61 if (!(REG_AX & ~regflags))
62 return R_AX;
63 if (!(REG_EAX & ~regflags))
64 return R_EAX;
65 if (!(REG_DX & ~regflags))
66 return R_DX;
67 if (!(REG_CL & ~regflags))
68 return R_CL;
69 if (!(REG_CX & ~regflags))
70 return R_CX;
71 if (!(REG_ECX & ~regflags))
72 return R_ECX;
73 if (!(REG_CR4 & ~regflags))
74 return R_CR4;
75 if (!(FPU0 & ~regflags))
76 return R_ST0;
77 if (!(REG_CS & ~regflags))
78 return R_CS;
79 if (!(REG_DESS & ~regflags))
80 return (regval == 0 || regval == 2 || regval == 3 ? sreg[regval] : 0);
81 if (!(REG_FSGS & ~regflags))
82 return (regval == 4 || regval == 5 ? sreg[regval] : 0);
83 if (!((REGMEM|BITS8) & ~regflags))
84 return reg8[regval];
85 if (!((REGMEM|BITS16) & ~regflags))
86 return reg16[regval];
87 if (!((REGMEM|BITS32) & ~regflags))
88 return reg32[regval];
89 if (!(REG_SREG & ~regflags))
90 return sreg[regval];
91 if (!(REG_CREG & ~regflags))
92 return creg[regval];
93 if (!(REG_DREG & ~regflags))
94 return dreg[regval];
95 if (!(REG_TREG & ~regflags))
96 return treg[regval];
97 if (!(FPUREG & ~regflags))
98 return fpureg[regval];
99 if (!(MMXREG & ~regflags))
100 return mmxreg[regval];
101 if (!(XMMREG & ~regflags))
102 return xmmreg[regval];
103 return 0;
106 static char *whichcond(int condval)
108 static int conds[] = {
109 C_O, C_NO, C_C, C_NC, C_Z, C_NZ, C_NA, C_A,
110 C_S, C_NS, C_PE, C_PO, C_L, C_NL, C_NG, C_G
112 return conditions[conds[condval]];
116 * Process an effective address (ModRM) specification.
118 static unsigned char *do_ea (unsigned char *data, int modrm, int asize,
119 int segsize, operand *op)
121 int mod, rm, scale, index, base;
123 mod = (modrm >> 6) & 03;
124 rm = modrm & 07;
126 if (mod == 3) { /* pure register version */
127 op->basereg = rm;
128 op->segment |= SEG_RMREG;
129 return data;
132 op->addr_size = 0;
134 if (asize == 16) {
136 * <mod> specifies the displacement size (none, byte or
137 * word), and <rm> specifies the register combination.
138 * Exception: mod=0,rm=6 does not specify [BP] as one might
139 * expect, but instead specifies [disp16].
141 op->indexreg = op->basereg = -1;
142 op->scale = 1; /* always, in 16 bits */
143 switch (rm) {
144 case 0: op->basereg = R_BX; op->indexreg = R_SI; break;
145 case 1: op->basereg = R_BX; op->indexreg = R_DI; break;
146 case 2: op->basereg = R_BP; op->indexreg = R_SI; break;
147 case 3: op->basereg = R_BP; op->indexreg = R_DI; break;
148 case 4: op->basereg = R_SI; break;
149 case 5: op->basereg = R_DI; break;
150 case 6: op->basereg = R_BP; break;
151 case 7: op->basereg = R_BX; break;
153 if (rm == 6 && mod == 0) { /* special case */
154 op->basereg = -1;
155 if (segsize != 16)
156 op->addr_size = 16;
157 mod = 2; /* fake disp16 */
159 switch (mod) {
160 case 0:
161 op->segment |= SEG_NODISP;
162 break;
163 case 1:
164 op->segment |= SEG_DISP8;
165 op->offset = (signed char) *data++;
166 break;
167 case 2:
168 op->segment |= SEG_DISP16;
169 op->offset = *data++;
170 op->offset |= (*data++) << 8;
171 break;
173 return data;
174 } else {
176 * Once again, <mod> specifies displacement size (this time
177 * none, byte or *dword*), while <rm> specifies the base
178 * register. Again, [EBP] is missing, replaced by a pure
179 * disp32 (this time that's mod=0,rm=*5*). However, rm=4
180 * indicates not a single base register, but instead the
181 * presence of a SIB byte...
183 op->indexreg = -1;
184 switch (rm) {
185 case 0: op->basereg = R_EAX; break;
186 case 1: op->basereg = R_ECX; break;
187 case 2: op->basereg = R_EDX; break;
188 case 3: op->basereg = R_EBX; break;
189 case 5: op->basereg = R_EBP; break;
190 case 6: op->basereg = R_ESI; break;
191 case 7: op->basereg = R_EDI; break;
193 if (rm == 5 && mod == 0) {
194 op->basereg = -1;
195 if (segsize != 32)
196 op->addr_size = 32;
197 mod = 2; /* fake disp32 */
199 if (rm == 4) { /* process SIB */
200 scale = (*data >> 6) & 03;
201 index = (*data >> 3) & 07;
202 base = *data & 07;
203 data++;
205 op->scale = 1 << scale;
206 switch (index) {
207 case 0: op->indexreg = R_EAX; break;
208 case 1: op->indexreg = R_ECX; break;
209 case 2: op->indexreg = R_EDX; break;
210 case 3: op->indexreg = R_EBX; break;
211 case 4: op->indexreg = -1; break;
212 case 5: op->indexreg = R_EBP; break;
213 case 6: op->indexreg = R_ESI; break;
214 case 7: op->indexreg = R_EDI; break;
217 switch (base) {
218 case 0: op->basereg = R_EAX; break;
219 case 1: op->basereg = R_ECX; break;
220 case 2: op->basereg = R_EDX; break;
221 case 3: op->basereg = R_EBX; break;
222 case 4: op->basereg = R_ESP; break;
223 case 6: op->basereg = R_ESI; break;
224 case 7: op->basereg = R_EDI; break;
225 case 5:
226 if (mod == 0) {
227 mod = 2;
228 op->basereg = -1;
229 } else
230 op->basereg = R_EBP;
231 break;
234 switch (mod) {
235 case 0:
236 op->segment |= SEG_NODISP;
237 break;
238 case 1:
239 op->segment |= SEG_DISP8;
240 op->offset = (signed char) *data++;
241 break;
242 case 2:
243 op->segment |= SEG_DISP32;
244 op->offset = *data++;
245 op->offset |= (*data++) << 8;
246 op->offset |= ((long) *data++) << 16;
247 op->offset |= ((long) *data++) << 24;
248 break;
250 return data;
255 * Determine whether the instruction template in t corresponds to the data
256 * stream in data. Return the number of bytes matched if so.
258 static int matches (struct itemplate *t, unsigned char *data, int asize,
259 int osize, int segsize, int rep, insn *ins)
261 unsigned char * r = (unsigned char *)(t->code);
262 unsigned char * origdata = data;
263 int a_used = FALSE, o_used = FALSE;
264 int drep = 0;
266 if ( rep == 0xF2 )
267 drep = P_REPNE;
268 else if ( rep == 0xF3 )
269 drep = P_REP;
271 while (*r)
273 int c = *r++;
274 if (c >= 01 && c <= 03) {
275 while (c--)
276 if (*r++ != *data++)
277 return FALSE;
279 if (c == 04) {
280 switch (*data++) {
281 case 0x07: ins->oprs[0].basereg = 0; break;
282 case 0x17: ins->oprs[0].basereg = 2; break;
283 case 0x1F: ins->oprs[0].basereg = 3; break;
284 default: return FALSE;
287 if (c == 05) {
288 switch (*data++) {
289 case 0xA1: ins->oprs[0].basereg = 4; break;
290 case 0xA9: ins->oprs[0].basereg = 5; break;
291 default: return FALSE;
294 if (c == 06) {
295 switch (*data++) {
296 case 0x06: ins->oprs[0].basereg = 0; break;
297 case 0x0E: ins->oprs[0].basereg = 1; break;
298 case 0x16: ins->oprs[0].basereg = 2; break;
299 case 0x1E: ins->oprs[0].basereg = 3; break;
300 default: return FALSE;
303 if (c == 07) {
304 switch (*data++) {
305 case 0xA0: ins->oprs[0].basereg = 4; break;
306 case 0xA8: ins->oprs[0].basereg = 5; break;
307 default: return FALSE;
310 if (c >= 010 && c <= 012) {
311 int t = *r++, d = *data++;
312 if (d < t || d > t+7)
313 return FALSE;
314 else {
315 ins->oprs[c-010].basereg = d-t;
316 ins->oprs[c-010].segment |= SEG_RMREG;
319 if (c == 017)
320 if (*data++)
321 return FALSE;
322 if (c >= 014 && c <= 016) {
323 ins->oprs[c-014].offset = (signed char) *data++;
324 ins->oprs[c-014].segment |= SEG_SIGNED;
326 if (c >= 020 && c <= 022)
327 ins->oprs[c-020].offset = *data++;
328 if (c >= 024 && c <= 026)
329 ins->oprs[c-024].offset = *data++;
330 if (c >= 030 && c <= 032) {
331 ins->oprs[c-030].offset = *data++;
332 ins->oprs[c-030].offset |= (*data++ << 8);
334 if (c >= 034 && c <= 036) {
335 ins->oprs[c-034].offset = *data++;
336 ins->oprs[c-034].offset |= (*data++ << 8);
337 if (asize == 32) {
338 ins->oprs[c-034].offset |= (((long) *data++) << 16);
339 ins->oprs[c-034].offset |= (((long) *data++) << 24);
341 if (segsize != asize)
342 ins->oprs[c-034].addr_size = asize;
344 if (c >= 040 && c <= 042) {
345 ins->oprs[c-040].offset = *data++;
346 ins->oprs[c-040].offset |= (*data++ << 8);
347 ins->oprs[c-040].offset |= (((long) *data++) << 16);
348 ins->oprs[c-040].offset |= (((long) *data++) << 24);
350 if (c >= 050 && c <= 052) {
351 ins->oprs[c-050].offset = (signed char) *data++;
352 ins->oprs[c-050].segment |= SEG_RELATIVE;
354 if (c >= 060 && c <= 062) {
355 ins->oprs[c-060].offset = *data++;
356 ins->oprs[c-060].offset |= (*data++ << 8);
357 ins->oprs[c-060].segment |= SEG_RELATIVE;
358 ins->oprs[c-060].segment &= ~SEG_32BIT;
360 if (c >= 064 && c <= 066) {
361 ins->oprs[c-064].offset = *data++;
362 ins->oprs[c-064].offset |= (*data++ << 8);
363 if (asize == 32) {
364 ins->oprs[c-064].offset |= (((long) *data++) << 16);
365 ins->oprs[c-064].offset |= (((long) *data++) << 24);
366 ins->oprs[c-064].segment |= SEG_32BIT;
367 } else
368 ins->oprs[c-064].segment &= ~SEG_32BIT;
369 ins->oprs[c-064].segment |= SEG_RELATIVE;
370 if (segsize != asize)
371 ins->oprs[c-064].addr_size = asize;
373 if (c >= 070 && c <= 072) {
374 ins->oprs[c-070].offset = *data++;
375 ins->oprs[c-070].offset |= (*data++ << 8);
376 ins->oprs[c-070].offset |= (((long) *data++) << 16);
377 ins->oprs[c-070].offset |= (((long) *data++) << 24);
378 ins->oprs[c-070].segment |= SEG_32BIT | SEG_RELATIVE;
380 if (c >= 0100 && c <= 0177) {
381 int modrm = *data++;
382 ins->oprs[c & 07].basereg = (modrm >> 3) & 07;
383 ins->oprs[c & 07].segment |= SEG_RMREG;
384 data = do_ea (data, modrm, asize, segsize,
385 &ins->oprs[(c >> 3) & 07]);
387 if (c >= 0200 && c <= 0277) {
388 int modrm = *data++;
389 if (((modrm >> 3) & 07) != (c & 07))
390 return FALSE; /* spare field doesn't match up */
391 data = do_ea (data, modrm, asize, segsize,
392 &ins->oprs[(c >> 3) & 07]);
394 if (c >= 0300 && c <= 0302) {
395 if (asize)
396 ins->oprs[c-0300].segment |= SEG_32BIT;
397 else
398 ins->oprs[c-0300].segment &= ~SEG_32BIT;
399 a_used = TRUE;
401 if (c == 0310) {
402 if (asize == 32)
403 return FALSE;
404 else
405 a_used = TRUE;
407 if (c == 0311) {
408 if (asize == 16)
409 return FALSE;
410 else
411 a_used = TRUE;
413 if (c == 0312) {
414 if (asize != segsize)
415 return FALSE;
416 else
417 a_used = TRUE;
419 if (c == 0320) {
420 if (osize == 32)
421 return FALSE;
422 else
423 o_used = TRUE;
425 if (c == 0321) {
426 if (osize == 16)
427 return FALSE;
428 else
429 o_used = TRUE;
431 if (c == 0322) {
432 if (osize != segsize)
433 return FALSE;
434 else
435 o_used = TRUE;
437 if (c == 0330) {
438 int t = *r++, d = *data++;
439 if (d < t || d > t+15)
440 return FALSE;
441 else
442 ins->condition = d - t;
444 if (c == 0331) {
445 if ( rep )
446 return FALSE;
448 if (c == 0332) {
449 if (drep == P_REP)
450 drep = P_REPE;
452 if (c == 0333) {
453 if ( rep != 0xF3 )
454 return FALSE;
455 drep = 0;
460 * Check for unused rep or a/o prefixes.
462 ins->nprefix = 0;
463 if (drep)
464 ins->prefixes[ins->nprefix++] = drep;
465 if (!a_used && asize != segsize)
466 ins->prefixes[ins->nprefix++] = (asize == 16 ? P_A16 : P_A32);
467 if (!o_used && osize != segsize)
468 ins->prefixes[ins->nprefix++] = (osize == 16 ? P_O16 : P_O32);
470 return data - origdata;
473 long disasm (unsigned char *data, char *output, int segsize, long offset,
474 int autosync, unsigned long prefer)
476 struct itemplate **p, **best_p;
477 int length, best_length = 0;
478 char *segover;
479 int rep, lock, asize, osize, i, slen, colon;
480 unsigned char *origdata;
481 int works;
482 insn tmp_ins, ins;
483 unsigned long goodness, best;
486 * Scan for prefixes.
488 asize = osize = segsize;
489 segover = NULL;
490 rep = lock = 0;
491 origdata = data;
492 for (;;) {
493 if (*data == 0xF3 || *data == 0xF2)
494 rep = *data++;
495 else if (*data == 0xF0)
496 lock = *data++;
497 else if (*data == 0x2E || *data == 0x36 || *data == 0x3E ||
498 *data == 0x26 || *data == 0x64 || *data == 0x65) {
499 switch (*data++) {
500 case 0x2E: segover = "cs"; break;
501 case 0x36: segover = "ss"; break;
502 case 0x3E: segover = "ds"; break;
503 case 0x26: segover = "es"; break;
504 case 0x64: segover = "fs"; break;
505 case 0x65: segover = "gs"; break;
507 } else if (*data == 0x66)
508 osize = 48 - segsize, data++;
509 else if (*data == 0x67)
510 asize = 48 - segsize, data++;
511 else
512 break;
515 tmp_ins.oprs[0].segment = tmp_ins.oprs[1].segment =
516 tmp_ins.oprs[2].segment =
517 tmp_ins.oprs[0].addr_size = tmp_ins.oprs[1].addr_size =
518 tmp_ins.oprs[2].addr_size = (segsize == 16 ? 0 : SEG_32BIT);
519 tmp_ins.condition = -1;
520 best = ~0UL; /* Worst possible */
521 best_p = NULL;
522 for (p = itable[*data]; *p; p++) {
523 if ( (length = matches(*p, data, asize, osize,
524 segsize, rep, &tmp_ins)) ) {
525 works = TRUE;
527 * Final check to make sure the types of r/m match up.
529 for (i = 0; i < (*p)->operands; i++) {
530 if (
531 /* If it's a mem-only EA but we have a register, die. */
532 ((tmp_ins.oprs[i].segment & SEG_RMREG) &&
533 !(MEMORY & ~(*p)->opd[i])) ||
535 /* If it's a reg-only EA but we have a memory ref, die. */
536 (!(tmp_ins.oprs[i].segment & SEG_RMREG) &&
537 !(REGNORM & ~(*p)->opd[i]) &&
538 !((*p)->opd[i] & REG_SMASK)) ||
540 /* Register type mismatch (eg FS vs REG_DESS): die. */
541 ((((*p)->opd[i] & (REGISTER | FPUREG)) ||
542 (tmp_ins.oprs[i].segment & SEG_RMREG)) &&
543 !whichreg ((*p)->opd[i], tmp_ins.oprs[i].basereg))) {
544 works = FALSE;
545 break;
549 if (works) {
550 goodness = ((*p)->flags & IF_PFMASK) ^ prefer;
551 if ( goodness < best ) {
552 /* This is the best one found so far */
553 best = goodness;
554 best_p = p;
555 best_length = length;
556 ins = tmp_ins;
562 if (!best_p)
563 return 0; /* no instruction was matched */
565 /* Pick the best match */
566 p = best_p;
567 length = best_length;
569 slen = 0;
571 if (lock)
572 slen += sprintf(output+slen, "lock ");
573 for (i = 0; i < ins.nprefix; i++)
574 switch (ins.prefixes[i]) {
575 case P_REP: slen += sprintf(output+slen, "rep "); break;
576 case P_REPE: slen += sprintf(output+slen, "repe "); break;
577 case P_REPNE: slen += sprintf(output+slen, "repne "); break;
578 case P_A16: slen += sprintf(output+slen, "a16 "); break;
579 case P_A32: slen += sprintf(output+slen, "a32 "); break;
580 case P_O16: slen += sprintf(output+slen, "o16 "); break;
581 case P_O32: slen += sprintf(output+slen, "o32 "); break;
584 for (i = 0; i < elements(ico); i++)
585 if ((*p)->opcode == ico[i]) {
586 slen += sprintf(output+slen, "%s%s", icn[i],
587 whichcond(ins.condition));
588 break;
590 if (i >= elements(ico))
591 slen += sprintf(output+slen, "%s", insn_names[(*p)->opcode]);
592 colon = FALSE;
593 length += data - origdata; /* fix up for prefixes */
594 for (i=0; i<(*p)->operands; i++) {
595 output[slen++] = (colon ? ':' : i==0 ? ' ' : ',');
597 if (ins.oprs[i].segment & SEG_RELATIVE) {
598 ins.oprs[i].offset += offset + length;
600 * sort out wraparound
602 if (!(ins.oprs[i].segment & SEG_32BIT))
603 ins.oprs[i].offset &= 0xFFFF;
605 * add sync marker, if autosync is on
607 if (autosync)
608 add_sync (ins.oprs[i].offset, 0L);
611 if ((*p)->opd[i] & COLON)
612 colon = TRUE;
613 else
614 colon = FALSE;
616 if (((*p)->opd[i] & (REGISTER | FPUREG)) ||
617 (ins.oprs[i].segment & SEG_RMREG))
619 ins.oprs[i].basereg = whichreg ((*p)->opd[i],
620 ins.oprs[i].basereg);
621 if ( (*p)->opd[i] & TO )
622 slen += sprintf(output+slen, "to ");
623 slen += sprintf(output+slen, "%s",
624 reg_names[ins.oprs[i].basereg-EXPR_REG_START]);
625 } else if (!(UNITY & ~(*p)->opd[i])) {
626 output[slen++] = '1';
627 } else if ( (*p)->opd[i] & IMMEDIATE ) {
628 if ( (*p)->opd[i] & BITS8 ) {
629 slen += sprintf(output+slen, "byte ");
630 if (ins.oprs[i].segment & SEG_SIGNED) {
631 if (ins.oprs[i].offset < 0) {
632 ins.oprs[i].offset *= -1;
633 output[slen++] = '-';
634 } else
635 output[slen++] = '+';
637 } else if ( (*p)->opd[i] & BITS16 ) {
638 slen += sprintf(output+slen, "word ");
639 } else if ( (*p)->opd[i] & BITS32 ) {
640 slen += sprintf(output+slen, "dword ");
641 } else if ( (*p)->opd[i] & NEAR ) {
642 slen += sprintf(output+slen, "near ");
643 } else if ( (*p)->opd[i] & SHORT ) {
644 slen += sprintf(output+slen, "short ");
646 slen += sprintf(output+slen, "0x%lx", ins.oprs[i].offset);
647 } else if ( !(MEM_OFFS & ~(*p)->opd[i]) ) {
648 slen += sprintf(output+slen, "[%s%s%s0x%lx]",
649 (segover ? segover : ""),
650 (segover ? ":" : ""),
651 (ins.oprs[i].addr_size == 32 ? "dword " :
652 ins.oprs[i].addr_size == 16 ? "word " : ""),
653 ins.oprs[i].offset);
654 segover = NULL;
655 } else if ( !(REGMEM & ~(*p)->opd[i]) ) {
656 int started = FALSE;
657 if ( (*p)->opd[i] & BITS8 )
658 slen += sprintf(output+slen, "byte ");
659 if ( (*p)->opd[i] & BITS16 )
660 slen += sprintf(output+slen, "word ");
661 if ( (*p)->opd[i] & BITS32 )
662 slen += sprintf(output+slen, "dword ");
663 if ( (*p)->opd[i] & BITS64 )
664 slen += sprintf(output+slen, "qword ");
665 if ( (*p)->opd[i] & BITS80 )
666 slen += sprintf(output+slen, "tword ");
667 if ( (*p)->opd[i] & FAR )
668 slen += sprintf(output+slen, "far ");
669 if ( (*p)->opd[i] & NEAR )
670 slen += sprintf(output+slen, "near ");
671 output[slen++] = '[';
672 if (ins.oprs[i].addr_size)
673 slen += sprintf(output+slen, "%s",
674 (ins.oprs[i].addr_size == 32 ? "dword " :
675 ins.oprs[i].addr_size == 16 ? "word " : ""));
676 if (segover) {
677 slen += sprintf(output+slen, "%s:", segover);
678 segover = NULL;
680 if (ins.oprs[i].basereg != -1) {
681 slen += sprintf(output+slen, "%s",
682 reg_names[(ins.oprs[i].basereg -
683 EXPR_REG_START)]);
684 started = TRUE;
686 if (ins.oprs[i].indexreg != -1) {
687 if (started)
688 output[slen++] = '+';
689 slen += sprintf(output+slen, "%s",
690 reg_names[(ins.oprs[i].indexreg -
691 EXPR_REG_START)]);
692 if (ins.oprs[i].scale > 1)
693 slen += sprintf(output+slen, "*%d", ins.oprs[i].scale);
694 started = TRUE;
696 if (ins.oprs[i].segment & SEG_DISP8) {
697 int sign = '+';
698 if (ins.oprs[i].offset & 0x80) {
699 ins.oprs[i].offset = - (signed char) ins.oprs[i].offset;
700 sign = '-';
702 slen += sprintf(output+slen, "%c0x%lx", sign,
703 ins.oprs[i].offset);
704 } else if (ins.oprs[i].segment & SEG_DISP16) {
705 if (started)
706 output[slen++] = '+';
707 slen += sprintf(output+slen, "0x%lx", ins.oprs[i].offset);
708 } else if (ins.oprs[i].segment & SEG_DISP32) {
709 if (started)
710 output[slen++] = '+';
711 slen += sprintf(output+slen, "0x%lx", ins.oprs[i].offset);
713 output[slen++] = ']';
714 } else {
715 slen += sprintf(output+slen, "<operand%d>", i);
718 output[slen] = '\0';
719 if (segover) { /* unused segment override */
720 char *p = output;
721 int count = slen+1;
722 while (count--)
723 p[count+3] = p[count];
724 strncpy (output, segover, 2);
725 output[2] = ' ';
727 return length;
730 long eatbyte (unsigned char *data, char *output)
732 sprintf(output, "db 0x%02X", *data);
733 return 1;