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1.1 root 1: /*
2: * A debugger.
3: * Intel 8086.
4: */
5: #include <stdio.h>
6: #include <sys/const.h>
7: #include "trace.h"
8: #include "i8086.h"
9:
10: /*
11: * Disassemble an Intel 8086 instruction.
12: */
13: char *
14: coninst(sp, s)
15: register char *sp;
16: {
17: register INS *ip;
18: register char *cp;
19: register int r;
20: register long a;
21: unsigned char b[1];
22:
23: r = -1;
24: for (;;) {
25: if (getb(s, b, sizeof(b)) == 0)
26: return (NULL);
27: if ((b[0]&0xE7) == 0x26) { /* Segment override */
28: r = (b[0]>>3)&0x3;
29: continue;
30: }
31: a = add;
32: for (ip=insrtab; ip->i_name!=NULL; ip++) {
33: if ((b[0]&ip->i_mask) != ip->i_code)
34: continue;
35: add = a;
36: if ((cp=putifmt(sp, s, ip->i_name, b[0], r, 1))!=NULL)
37: return (cp);
38: }
39: break;
40: }
41: sprintf(sp, ".byte\t0x%02x", b[0]);
42: return (&sp[8]);
43: }
44:
45: /*
46: * Print out the operands to a Intel 8086 instruction according to a
47: * format string.
48: */
49: char *
50: putifmt(sp, s, fp, ins0, segm, t)
51: register char *sp;
52: register char *fp;
53: unsigned ins0;
54: {
55: register char *cp;
56: register int c;
57: register int e;
58: register int m;
59: register int n;
60: unsigned insn;
61: int insk;
62: char x[1];
63: unsigned char b[1];
64: register INS *ip;
65:
66: e = 0;
67: m = 0;
68: n = 0;
69: insn = ins0;
70: while ((c=*fp++) != '\0') {
71: if (c != '%') {
72: *sp++ = c;
73: continue;
74: }
75: next:
76: switch (c=*fp++) {
77: case '0':
78: case '1':
79: case '2':
80: case '3':
81: case '4':
82: case '5':
83: case '6':
84: case '7':
85: n = c - '0';
86: m = 1 << n;
87: goto next;
88: case ':':
89: if (segm >= 0) {
90: *sp++ = "ecsd"[segm];
91: *sp++ = 's';
92: *sp++ = ':';
93: }
94: goto next;
95: /*
96: case 'a':
97: v = (i>=-0x100 && i<=0x100) ? -1 : I;
98: sp = conaddr(sp, 0, (long)(unsigned)i, v);
99: */
100: case 'b':
101: if (getb(s, x, sizeof(x)) == 0)
102: return (NULL);
103: insk = x[0];
104: goto next;
105: case 'd':
106: cp = (insn&m) ? "%n3r,%m" : "%nm,%3r";
107: sp = putifmt(sp, s, cp, ins0, segm, t);
108: continue;
109: case 'e':
110: e = insn&m;
111: goto next;
112: case 'f':
113: if (((insn>>3)&0x7) != *fp++-'0')
114: return (NULL);
115: goto next;
116: case 'g':
117: if (insn != 10)
118: sprintf(sp, "\t$0x%04x", insn);
119: continue;
120: case 'h': /* 8087 escape */
121: insk = ((ins0&0x7)<<3) | ((insn>>3)&0x7);
122: sprintf(sp, "%x", insk);
123: goto skip;
124: case 'i':
125: if (e==0 && t!=0) {
126: if (getb(s, &insk, sizeof(insk)) == 0)
127: return (NULL);
128: } else {
129: if (getb(s, b, sizeof(b)) == 0)
130: return (NULL);
131: if (e == 0)
132: insk = b[0];
133: else
134: insk = x[0] = b[0];
135: }
136: goto next;
137: case 'j':
138: cp = jumptab[ins0&0xF];
139: goto copy;
140: case 'k':
141: sp = conaddr(sp, 2, (long)(unsigned)insk,
142: (unsigned)insk>0x100 ? 16 : -1);
143: goto skip;
144: case 'l':
145: sprintf(sp, "0x%04x", insk);
146: goto skip;
147: case 'm':
148: if ((insk=(insn>>6)&0x03) == 3) {
149: n = 0;
150: goto regn;
151: }
152: if (segm >= 0) {
153: *sp++ = "ecsd"[segm];
154: *sp++ = 's';
155: *sp++ = ':';
156: }
157: switch (insk) {
158: case 0:
159: if ((insn&0x7) == 0x6) {
160: sp = putifmt(sp, s, "%wp", ins0,
161: segm, t);
162: continue;
163: }
164: insk = 0;
165: break;
166: case 1:
167: if (getb(s, x, sizeof(x)) == 0)
168: return (NULL);
169: insk = x[0];
170: break;
171: case 2:
172: if (getb(s, &insk, sizeof(insk)) == 0)
173: return (NULL);
174: break;
175: case 3:
176: n = 0;
177: goto regn;
178: }
179: if (insk != 0) {
180: if (insk>=-0x100 && insk<=0x100) {
181: sprintf(sp, "%d", insk);
182: while (*sp)
183: sp++;
184: } else {
185: sp = conaddr(sp, 0,
186: (long)(unsigned)insk, I);
187: }
188: }
189: cp = indmtab[insn&0x7];
190: goto copy;
191: case 'n':
192: if (getb(s, b, sizeof(b)) == 0)
193: return (NULL);
194: insn = b[0];
195: goto next;
196: case 'o':
197: insk += add;
198: goto next;
199: case 'p':
200: sp = conaddr(sp, segm==1?1:0, (long)(unsigned)insk, I);
201: continue;
202: case 'q':
203: sp = conaddr(sp, 1, (long)(unsigned)insk, I);
204: continue;
205: case 'r':
206: regn:
207: cp = (t?regwtab:regbtab)[(insn>>n)&07];
208: *sp++ = *cp++;
209: *sp++ = *cp++;
210: continue;
211: case 's':
212: *sp++ = "ecsd"[(insn>>n)&03];
213: *sp++ = 's';
214: continue;
215: case 't':
216: if ((t=insn&m) == 0)
217: *sp++ = 'b';
218: continue;
219: case 'u':
220: if (getb(s, b, sizeof(b)) == 0)
221: return (NULL);
222: insk = b[0];
223: goto next;
224: case 'v':
225: if ((ins0&m) == 0) {
226: *sp++ = '$';
227: *sp++ = '1';
228: } else {
229: *sp++ = 'c';
230: *sp++ = 'l';
231: }
232: continue;
233: case 'w':
234: if (getb(s, &insk, sizeof(insk)) == 0)
235: return (NULL);
236: goto next;
237: case 'x':
238: *sp++ = 'a';
239: *sp++ = t ? 'x' : 'l';
240: continue;
241: case 'y':
242: if ((insk&0x80) != 0
243: && (n=insk&0x7F) < NMICALL
244: && (cp=sysitab[n]) != NULL)
245: sprintf(sp, "sys\t%s", cp);
246: else
247: sprintf(sp, "int\t0x%x", insk);
248: goto skip;
249: case 'z':
250: if ((insn&m) != 0)
251: return (NULL);
252: goto next;
253:
254: case 'F': /* 8087 codes */
255: if (getb(s, b, sizeof(b)) == 0)
256: return (NULL);
257: insk = ((insn&0x7)<<8) | b[0];
258: insn = b[0];
259: for (ip = fpinstab; ip->i_name!=NULL; ip++) {
260: if ((insk&ip->i_mask) != ip->i_code)
261: continue;
262: sp = putifmt(sp, s, ip->i_name, b[0], segm, t);
263: goto skip;
264: }
265: return (NULL);
266:
267: case 'P': /* Long pointers */
268: if (getb(s, &insn, sizeof (insn)) == 0)
269: return (NULL);
270: sprintf(sp, "0x%04x:0x%04x", insn, insk);
271: goto skip;
272: }
273: copy:
274: while (*cp)
275: *sp++ = *cp++;
276: continue;
277: skip:
278: while (*sp)
279: sp++;
280: continue;
281: }
282: return (sp);
283: }
284:
285: /*
286: * Given a size character, `t1', and a type, `t2', return the appropriate
287: * format string.
288: */
289: char *
290: getform(t1, t2)
291: register int t1;
292: register int t2;
293: {
294: register char *cp;
295: register char *sp;
296:
297: if (t1=='f' || t1=='F')
298: return ("%g");
299: if (t1 == 'h')
300: t1 = 'w';
301: if ((cp=index(sp="bwlv", t1)) == NULL)
302: return ("?");
303: t1 = cp-sp;
304: if ((cp=index(sp="duox", t2)) == NULL)
305: return ("?");
306: t2 = cp-sp;
307: return (formtab[t1][t2]);
308: }
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