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Added basic indexed mode handling
author lost
date Fri, 02 Jan 2009 04:22:39 +0000
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children 74a3fef7c8d0
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31:674ee393426c 32:9bd0fbfe7405
1 /*
2 insn_indexed.c
3 Copyright © 2008 William Astle
4
5 This file is part of LWASM.
6
7 LWASM is free software: you can redistribute it and/or modify it under the
8 terms of the GNU General Public License as published by the Free Software
9 Foundation, either version 3 of the License, or (at your option) any later
10 version.
11
12 This program is distributed in the hope that it will be useful, but WITHOUT
13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
15 more details.
16
17 You should have received a copy of the GNU General Public License along with
18 this program. If not, see <http://www.gnu.org/licenses/>.
19 */
20
21 /*
22 for handling indexed mode instructions
23 */
24
25 #define __insn_indexed_c_seen__
26
27 #include <ctype.h>
28 #include <string.h>
29
30 #include "lwasm.h"
31 #include "instab.h"
32 #include "expr.h"
33
34 void insn_indexed_aux(asmstate_t *as, lwasm_line_t *l, const char **p, int *b1, int *b2, int *b3)
35 {
36 static const char *regs = "X Y U S W PCRPC ";
37 static const struct { char *opstr; int pb; } simpleindex[] =
38 {
39 {",x", 0x84}, {",y", 0xa4}, {",u", 0xc4}, {",s", 0xe4},
40 {",x+", 0x80}, {",y+", 0xa0}, {",u+", 0xc0}, {",s+", 0xe0},
41 {",x++", 0x81}, {",y++", 0xa1}, {",u++", 0xc1}, {",s++", 0xe1},
42 {",-x", 0x82}, {",-y", 0xa2}, {",-u", 0xc2}, {",-s", 0xe2},
43 {",--x", 0x83}, {",--y", 0xa3}, {",--u", 0xc3}, {",--s", 0xe3},
44 {"a,x", 0x86}, {"a,y", 0xa6}, {"a,u", 0xc6}, {"a,s", 0xe6},
45 {"b,x", 0x85}, {"b,y", 0xa5}, {"b,u", 0xc5}, {"b,s", 0xe5},
46 {"e,x", 0x87}, {"e,y", 0xa7}, {"e,u", 0xc7}, {"e,s", 0xe7},
47 {"f,x", 0x8a}, {"f,y", 0xaa}, {"f,u", 0xca}, {"f,s", 0xea},
48 {"d,x", 0x8b}, {"d,y", 0xab}, {"d,u", 0xcb}, {"d,s", 0xed},
49 {"w,x", 0x8e}, {"w,y", 0xae}, {"w,u", 0xce}, {"w,s", 0xee},
50 {",w", 0x8f}, {",w++", 0xcf}, {",--w", 0xef},
51
52 {"[,x]", 0x94}, {"[,y]", 0xb4}, {"[,u", 0xd4}, {"[,s]", 0xf4},
53 {"[,x++]", 0x91}, {"[,y++]", 0xb1}, {"[,u++]", 0xd1}, {"[,s++]", 0xf1},
54 {"[,--x]", 0x93}, {"[,--y]", 0xb3}, {"[,--u]", 0xd3}, {"[,--s]", 0xf3},
55 {"[a,x]", 0x96}, {"[a,y]", 0xb6}, {"[a,u]", 0xd6}, {"[a,s]", 0xf6},
56 {"[b,x]", 0x95}, {"[b,y]", 0xb5}, {"[b,u]", 0xd5}, {"[b,s]", 0xf5},
57 {"[e,x]", 0x97}, {"[e,y]", 0xb7}, {"[e,u]", 0xd7}, {"[e,s]", 0xf7},
58 {"[f,x]", 0x9a}, {"[f,y]", 0xba}, {"[f,u]", 0xda}, {"[f,s]", 0xfa},
59 {"[d,x]", 0x9b}, {"[d,y]", 0xbb}, {"[d,u]", 0xdb}, {"[d,s]", 0xfd},
60 {"[w,x]", 0x9e}, {"[w,y]", 0xbe}, {"[w,u]", 0xde}, {"[w,s]", 0xfe},
61 {"[,w]", 0x90}, {"[,w++]", 0xd0}, {"[,--w]", 0xf0},
62
63 { "", -1 }
64 };
65 char stbuf[25];
66 int i;
67 int f8 = 0, f16 = 0;
68 int rn;
69 int indir = 0;
70 int rval;
71 int f0 = 0;
72 const char *p2;
73 lwasm_expr_stack_t *s;
74
75 *b1 = *b2 = *b3 = -1;
76
77 for (i = 0; i < 24; i++)
78 {
79 if (*((*p) + i) && !isspace(*((*p) + i)))
80 stbuf[i] = *((*p) + i);
81 else
82 break;
83 }
84 stbuf[i] = '\0';
85 if (!*((*p) + i) || isspace(*((*p) + i)))
86 {
87 int j;
88 // do simple lookup
89 for (j = 0; simpleindex[j].opstr[0]; j++)
90 {
91 if (!strcasecmp(stbuf, simpleindex[j].opstr))
92 break;
93 }
94 if (simpleindex[j].opstr[0])
95 {
96 *b1 = simpleindex[j].pb;
97 (*p) += i;
98 return;
99 }
100 }
101
102 // now we have the hard ones to work out here
103
104 // if we've previously forced the sizes, make a note of it
105 if (l -> fsize == 1)
106 f8 = 1;
107 else if (l -> fsize == 2)
108 f16 = 1;
109
110 if (**p == '[')
111 {
112 indir = 1;
113 (*p)++;
114 }
115
116 rn = 0;
117 for (i = 0; (*p)[i] && !isspace((*p)[i]); i++)
118 {
119 if ((*p)[i] == ',')
120 {
121 rn = 1;
122 break;
123 }
124 }
125
126 if (!rn && indir)
127 {
128 // extended indir
129 *b1 = 0x9f;
130 *b2 = 0;
131 *b3 = 0;
132 s = lwasm_expr_eval(*p, &p2);
133 if (!s)
134 {
135 register_error(as, l, 1, "Bad expression");
136 return;
137 }
138 *p = p2;
139 if (**p != ']')
140 {
141 register_error(as, l, 1, "Bad operand");
142 return;
143 }
144 (*p)++;
145 if (!lwasm_expr_is_constant(s))
146 {
147 register_error(as, l, 2, "Incomplete reference");
148 }
149 rn = lwasm_expr_get_value(s);
150 lwasm_expr_stack_free(s);
151 *b2 = (rn >> 8) & 0xff;
152 *b3 = rn & 0xff;
153 return;
154 }
155
156 if (**p == '<')
157 {
158 f8 = 1;
159 (*p)++;
160 }
161 else if (**p == '>')
162 {
163 f16 = 1;
164 (*p)++;
165 }
166
167 if (**p == '0' && *(*p+1) == ',')
168 {
169 f0 = 1;
170 }
171
172 // now we have to evaluate the expression
173 s = lwasm_expr_eval(*p, &p2);
174 *p = p2;
175 if (!s)
176 {
177 register_error(as, l, 1, "Bad expression");
178 return;
179 }
180 if (!lwasm_expr_is_constant(s))
181 {
182 register_error(as, l, 2, "Incomplete reference");
183 if (!f8 && !f0)
184 {
185 f16 = 1;
186 l -> fsize = 2;
187 }
188 }
189 rval = lwasm_expr_get_value(s);
190 lwasm_expr_stack_free(s);
191
192 // now look for a comma; if not present, explode
193 if (*(*p)++ != ',')
194 {
195 // syntax error; force 0 bit
196 *b1 = 00;
197 return;
198 }
199
200 // now get the register
201 rn = lwasm_lookupreg3(regs, p);
202 if (rn < 0)
203 goto reterr;
204
205 if (indir)
206 {
207 if (**p != ']')
208 goto reterr;
209 else
210 (*p)++;
211 }
212
213 // nnnn,W is only 16 bit
214 if (rn == 4)
215 {
216 if (f8)
217 goto reterr;
218 if (!f16 && !f0 && !(as -> pragmas & PRAGMA_NOINDEX0TONONE) && rval == 0)
219 {
220 if (indir)
221 *b1 = 0x90;
222 else
223 *b1 = 0x8f;
224 return;
225 }
226 if (indir)
227 *b1 = 0xb0;
228 else
229 *b1 = 0xcf;
230 *b2 = (rval >> 8) & 0xff;
231 *b3 = rval & 0xff;
232 return;
233 }
234
235 if (indir) indir = 0x10;
236
237 // PCR? redo v1, v2 relative to current address
238 if (rn == 5)
239 {
240 rval -= as -> addr;
241
242 // we have a slight problem here
243 // PCR based on current insn loc is really
244 // -125 <= offset <= +130 (8 bit offset)
245 // NOTE: when we are called, we already have the opcode emitted
246 // so we only need to worry about the size of the operand
247 // hence the 2 and 3 magic numbers below instead of 3 and 4
248 // (and that also avoids errors with two byte opcodes, etc)
249 if (f8 || (!f16 && rval >= -125 && rval <= 130))
250 {
251 *b1 = indir | 0x8C;
252 rval -= 2;
253 if (rval < -128 || rval > 127)
254 register_error(as, l, 2, "Byte overflow");
255 *b2 = rval & 0xff;
256 return;
257 }
258
259 // anything else is 16 bit offset
260 // need 16 bit
261 *b1 = indir | 0x8D;
262 rval -= 3;
263 *b2 = (rval >> 8) & 0xff;
264 *b3 = rval & 0xff;
265 return;
266 }
267
268 // constant offset from PC
269 if (rn == 6)
270 {
271 if (f8 || (!f16 && rval >= -128 && rval <= 127))
272 {
273 *b1 = indir | 0x8C;
274 if (rval < -128 || rval > 127)
275 register_error(as, l, 2, "Byte overflow");
276 *b2 = rval & 0xff;
277 return;
278 }
279
280 // everything else must be 16 bit
281 // need 16 bit
282 *b1 = indir | 0x8D;
283 *b2 = (rval >> 8) & 0xff;
284 *b3 = rval & 0xff;
285 return;
286 }
287
288 // we only have to deal with x,y,u,s here
289 if (!f8 && !f16 && rval >= -16 && rval <= 15)
290 {
291 if (rval == 0 && !f0 && !(as -> pragmas & PRAGMA_NOINDEX0TONONE))
292 {
293 *b1 = rn << 5 | indir | 0x80 | 0x04;
294 return;
295 }
296 // we pick the smallest value here
297 if (indir)
298 {
299 f8 = 1;
300 goto no5bit;
301 }
302 *b1 = rn << 5 | (rval & 0x1F);
303 return;
304 }
305 no5bit:
306 if (f16 || (!f8 && (rval < -128 || rval > 127)))
307 {
308 // must be a 16 bit offset here
309 *b1 = rn << 5 | indir | 0x80 | 0x09;
310 *b2 = (rval >> 8) & 0xff;
311 *b3 = rval & 0xff;
312 return;
313 }
314
315 // if we're here, we have an 8 bit offset
316 *b1 = rn << 5 | indir | 0x80 | 0x08;
317 if (rval < -128 || rval > 127)
318 register_error(as, l, 2, "Byte overflow");
319 *b2 = rval & 0xff;
320 return;
321 reterr:
322 *b1 = 0;
323 return;
324 }
325
326 OPFUNC(insn_indexed)
327 {
328 int b1, b2, b3;
329
330 lwasm_emitop(as, l, instab[opnum].ops[0]);
331
332 insn_indexed_aux(as, l, (const char **)p, &b1, &b2, &b3);
333 if (b1 != -1)
334 lwasm_emit(as, l, b1);
335 if (b2 != -1)
336 lwasm_emit(as, l, b2);
337 if (b3 != -1)
338 lwasm_emit(as, l, b3);
339 }