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1da177e4 LT |
1 | /*---------------------------------------------------------------------------+ |
2 | | reg_compare.c | | |
3 | | | | |
4 | | Compare two floating point registers | | |
5 | | | | |
6 | | Copyright (C) 1992,1993,1994,1997 | | |
7 | | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia | | |
8 | | E-mail billm@suburbia.net | | |
9 | | | | |
10 | | | | |
11 | +---------------------------------------------------------------------------*/ | |
12 | ||
13 | /*---------------------------------------------------------------------------+ | |
14 | | compare() is the core FPU_REG comparison function | | |
15 | +---------------------------------------------------------------------------*/ | |
16 | ||
17 | #include "fpu_system.h" | |
18 | #include "exception.h" | |
19 | #include "fpu_emu.h" | |
20 | #include "control_w.h" | |
21 | #include "status_w.h" | |
22 | ||
23 | ||
24 | static int compare(FPU_REG const *b, int tagb) | |
25 | { | |
26 | int diff, exp0, expb; | |
27 | u_char st0_tag; | |
28 | FPU_REG *st0_ptr; | |
29 | FPU_REG x, y; | |
30 | u_char st0_sign, signb = getsign(b); | |
31 | ||
32 | st0_ptr = &st(0); | |
33 | st0_tag = FPU_gettag0(); | |
34 | st0_sign = getsign(st0_ptr); | |
35 | ||
36 | if ( tagb == TAG_Special ) | |
37 | tagb = FPU_Special(b); | |
38 | if ( st0_tag == TAG_Special ) | |
39 | st0_tag = FPU_Special(st0_ptr); | |
40 | ||
41 | if ( ((st0_tag != TAG_Valid) && (st0_tag != TW_Denormal)) | |
42 | || ((tagb != TAG_Valid) && (tagb != TW_Denormal)) ) | |
43 | { | |
44 | if ( st0_tag == TAG_Zero ) | |
45 | { | |
46 | if ( tagb == TAG_Zero ) return COMP_A_eq_B; | |
47 | if ( tagb == TAG_Valid ) | |
48 | return ((signb == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B); | |
49 | if ( tagb == TW_Denormal ) | |
50 | return ((signb == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B) | |
51 | | COMP_Denormal; | |
52 | } | |
53 | else if ( tagb == TAG_Zero ) | |
54 | { | |
55 | if ( st0_tag == TAG_Valid ) | |
56 | return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B); | |
57 | if ( st0_tag == TW_Denormal ) | |
58 | return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B) | |
59 | | COMP_Denormal; | |
60 | } | |
61 | ||
62 | if ( st0_tag == TW_Infinity ) | |
63 | { | |
64 | if ( (tagb == TAG_Valid) || (tagb == TAG_Zero) ) | |
65 | return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B); | |
66 | else if ( tagb == TW_Denormal ) | |
67 | return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B) | |
68 | | COMP_Denormal; | |
69 | else if ( tagb == TW_Infinity ) | |
70 | { | |
71 | /* The 80486 book says that infinities can be equal! */ | |
72 | return (st0_sign == signb) ? COMP_A_eq_B : | |
73 | ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B); | |
74 | } | |
75 | /* Fall through to the NaN code */ | |
76 | } | |
77 | else if ( tagb == TW_Infinity ) | |
78 | { | |
79 | if ( (st0_tag == TAG_Valid) || (st0_tag == TAG_Zero) ) | |
80 | return ((signb == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B); | |
81 | if ( st0_tag == TW_Denormal ) | |
82 | return ((signb == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B) | |
83 | | COMP_Denormal; | |
84 | /* Fall through to the NaN code */ | |
85 | } | |
86 | ||
87 | /* The only possibility now should be that one of the arguments | |
88 | is a NaN */ | |
89 | if ( (st0_tag == TW_NaN) || (tagb == TW_NaN) ) | |
90 | { | |
91 | int signalling = 0, unsupported = 0; | |
92 | if ( st0_tag == TW_NaN ) | |
93 | { | |
94 | signalling = (st0_ptr->sigh & 0xc0000000) == 0x80000000; | |
95 | unsupported = !((exponent(st0_ptr) == EXP_OVER) | |
96 | && (st0_ptr->sigh & 0x80000000)); | |
97 | } | |
98 | if ( tagb == TW_NaN ) | |
99 | { | |
100 | signalling |= (b->sigh & 0xc0000000) == 0x80000000; | |
101 | unsupported |= !((exponent(b) == EXP_OVER) | |
102 | && (b->sigh & 0x80000000)); | |
103 | } | |
104 | if ( signalling || unsupported ) | |
105 | return COMP_No_Comp | COMP_SNaN | COMP_NaN; | |
106 | else | |
107 | /* Neither is a signaling NaN */ | |
108 | return COMP_No_Comp | COMP_NaN; | |
109 | } | |
110 | ||
111 | EXCEPTION(EX_Invalid); | |
112 | } | |
113 | ||
114 | if (st0_sign != signb) | |
115 | { | |
116 | return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B) | |
117 | | ( ((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) ? | |
118 | COMP_Denormal : 0); | |
119 | } | |
120 | ||
121 | if ( (st0_tag == TW_Denormal) || (tagb == TW_Denormal) ) | |
122 | { | |
123 | FPU_to_exp16(st0_ptr, &x); | |
124 | FPU_to_exp16(b, &y); | |
125 | st0_ptr = &x; | |
126 | b = &y; | |
127 | exp0 = exponent16(st0_ptr); | |
128 | expb = exponent16(b); | |
129 | } | |
130 | else | |
131 | { | |
132 | exp0 = exponent(st0_ptr); | |
133 | expb = exponent(b); | |
134 | } | |
135 | ||
136 | #ifdef PARANOID | |
137 | if (!(st0_ptr->sigh & 0x80000000)) EXCEPTION(EX_Invalid); | |
138 | if (!(b->sigh & 0x80000000)) EXCEPTION(EX_Invalid); | |
139 | #endif /* PARANOID */ | |
140 | ||
141 | diff = exp0 - expb; | |
142 | if ( diff == 0 ) | |
143 | { | |
144 | diff = st0_ptr->sigh - b->sigh; /* Works only if ms bits are | |
145 | identical */ | |
146 | if ( diff == 0 ) | |
147 | { | |
148 | diff = st0_ptr->sigl > b->sigl; | |
149 | if ( diff == 0 ) | |
150 | diff = -(st0_ptr->sigl < b->sigl); | |
151 | } | |
152 | } | |
153 | ||
154 | if ( diff > 0 ) | |
155 | { | |
156 | return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B) | |
157 | | ( ((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) ? | |
158 | COMP_Denormal : 0); | |
159 | } | |
160 | if ( diff < 0 ) | |
161 | { | |
162 | return ((st0_sign == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B) | |
163 | | ( ((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) ? | |
164 | COMP_Denormal : 0); | |
165 | } | |
166 | ||
167 | return COMP_A_eq_B | |
168 | | ( ((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) ? | |
169 | COMP_Denormal : 0); | |
170 | ||
171 | } | |
172 | ||
173 | ||
174 | /* This function requires that st(0) is not empty */ | |
175 | int FPU_compare_st_data(FPU_REG const *loaded_data, u_char loaded_tag) | |
176 | { | |
177 | int f = 0, c; | |
178 | ||
179 | c = compare(loaded_data, loaded_tag); | |
180 | ||
181 | if (c & COMP_NaN) | |
182 | { | |
183 | EXCEPTION(EX_Invalid); | |
184 | f = SW_C3 | SW_C2 | SW_C0; | |
185 | } | |
186 | else | |
187 | switch (c & 7) | |
188 | { | |
189 | case COMP_A_lt_B: | |
190 | f = SW_C0; | |
191 | break; | |
192 | case COMP_A_eq_B: | |
193 | f = SW_C3; | |
194 | break; | |
195 | case COMP_A_gt_B: | |
196 | f = 0; | |
197 | break; | |
198 | case COMP_No_Comp: | |
199 | f = SW_C3 | SW_C2 | SW_C0; | |
200 | break; | |
201 | #ifdef PARANOID | |
202 | default: | |
203 | EXCEPTION(EX_INTERNAL|0x121); | |
204 | f = SW_C3 | SW_C2 | SW_C0; | |
205 | break; | |
206 | #endif /* PARANOID */ | |
207 | } | |
208 | setcc(f); | |
209 | if (c & COMP_Denormal) | |
210 | { | |
211 | return denormal_operand() < 0; | |
212 | } | |
213 | return 0; | |
214 | } | |
215 | ||
216 | ||
217 | static int compare_st_st(int nr) | |
218 | { | |
219 | int f = 0, c; | |
220 | FPU_REG *st_ptr; | |
221 | ||
222 | if ( !NOT_EMPTY(0) || !NOT_EMPTY(nr) ) | |
223 | { | |
224 | setcc(SW_C3 | SW_C2 | SW_C0); | |
225 | /* Stack fault */ | |
226 | EXCEPTION(EX_StackUnder); | |
227 | return !(control_word & CW_Invalid); | |
228 | } | |
229 | ||
230 | st_ptr = &st(nr); | |
231 | c = compare(st_ptr, FPU_gettagi(nr)); | |
232 | if (c & COMP_NaN) | |
233 | { | |
234 | setcc(SW_C3 | SW_C2 | SW_C0); | |
235 | EXCEPTION(EX_Invalid); | |
236 | return !(control_word & CW_Invalid); | |
237 | } | |
238 | else | |
239 | switch (c & 7) | |
240 | { | |
241 | case COMP_A_lt_B: | |
242 | f = SW_C0; | |
243 | break; | |
244 | case COMP_A_eq_B: | |
245 | f = SW_C3; | |
246 | break; | |
247 | case COMP_A_gt_B: | |
248 | f = 0; | |
249 | break; | |
250 | case COMP_No_Comp: | |
251 | f = SW_C3 | SW_C2 | SW_C0; | |
252 | break; | |
253 | #ifdef PARANOID | |
254 | default: | |
255 | EXCEPTION(EX_INTERNAL|0x122); | |
256 | f = SW_C3 | SW_C2 | SW_C0; | |
257 | break; | |
258 | #endif /* PARANOID */ | |
259 | } | |
260 | setcc(f); | |
261 | if (c & COMP_Denormal) | |
262 | { | |
263 | return denormal_operand() < 0; | |
264 | } | |
265 | return 0; | |
266 | } | |
267 | ||
268 | ||
269 | static int compare_u_st_st(int nr) | |
270 | { | |
271 | int f = 0, c; | |
272 | FPU_REG *st_ptr; | |
273 | ||
274 | if ( !NOT_EMPTY(0) || !NOT_EMPTY(nr) ) | |
275 | { | |
276 | setcc(SW_C3 | SW_C2 | SW_C0); | |
277 | /* Stack fault */ | |
278 | EXCEPTION(EX_StackUnder); | |
279 | return !(control_word & CW_Invalid); | |
280 | } | |
281 | ||
282 | st_ptr = &st(nr); | |
283 | c = compare(st_ptr, FPU_gettagi(nr)); | |
284 | if (c & COMP_NaN) | |
285 | { | |
286 | setcc(SW_C3 | SW_C2 | SW_C0); | |
287 | if (c & COMP_SNaN) /* This is the only difference between | |
288 | un-ordered and ordinary comparisons */ | |
289 | { | |
290 | EXCEPTION(EX_Invalid); | |
291 | return !(control_word & CW_Invalid); | |
292 | } | |
293 | return 0; | |
294 | } | |
295 | else | |
296 | switch (c & 7) | |
297 | { | |
298 | case COMP_A_lt_B: | |
299 | f = SW_C0; | |
300 | break; | |
301 | case COMP_A_eq_B: | |
302 | f = SW_C3; | |
303 | break; | |
304 | case COMP_A_gt_B: | |
305 | f = 0; | |
306 | break; | |
307 | case COMP_No_Comp: | |
308 | f = SW_C3 | SW_C2 | SW_C0; | |
309 | break; | |
310 | #ifdef PARANOID | |
311 | default: | |
312 | EXCEPTION(EX_INTERNAL|0x123); | |
313 | f = SW_C3 | SW_C2 | SW_C0; | |
314 | break; | |
315 | #endif /* PARANOID */ | |
316 | } | |
317 | setcc(f); | |
318 | if (c & COMP_Denormal) | |
319 | { | |
320 | return denormal_operand() < 0; | |
321 | } | |
322 | return 0; | |
323 | } | |
324 | ||
325 | /*---------------------------------------------------------------------------*/ | |
326 | ||
327 | void fcom_st(void) | |
328 | { | |
329 | /* fcom st(i) */ | |
330 | compare_st_st(FPU_rm); | |
331 | } | |
332 | ||
333 | ||
334 | void fcompst(void) | |
335 | { | |
336 | /* fcomp st(i) */ | |
337 | if ( !compare_st_st(FPU_rm) ) | |
338 | FPU_pop(); | |
339 | } | |
340 | ||
341 | ||
342 | void fcompp(void) | |
343 | { | |
344 | /* fcompp */ | |
345 | if (FPU_rm != 1) | |
346 | { | |
347 | FPU_illegal(); | |
348 | return; | |
349 | } | |
350 | if ( !compare_st_st(1) ) | |
351 | poppop(); | |
352 | } | |
353 | ||
354 | ||
355 | void fucom_(void) | |
356 | { | |
357 | /* fucom st(i) */ | |
358 | compare_u_st_st(FPU_rm); | |
359 | ||
360 | } | |
361 | ||
362 | ||
363 | void fucomp(void) | |
364 | { | |
365 | /* fucomp st(i) */ | |
366 | if ( !compare_u_st_st(FPU_rm) ) | |
367 | FPU_pop(); | |
368 | } | |
369 | ||
370 | ||
371 | void fucompp(void) | |
372 | { | |
373 | /* fucompp */ | |
374 | if (FPU_rm == 1) | |
375 | { | |
376 | if ( !compare_u_st_st(1) ) | |
377 | poppop(); | |
378 | } | |
379 | else | |
380 | FPU_illegal(); | |
381 | } |