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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 | ||
1da177e4 LT |
23 | static int compare(FPU_REG const *b, int tagb) |
24 | { | |
3d0d14f9 IM |
25 | int diff, exp0, expb; |
26 | u_char st0_tag; | |
27 | FPU_REG *st0_ptr; | |
28 | FPU_REG x, y; | |
29 | u_char st0_sign, signb = getsign(b); | |
30 | ||
31 | st0_ptr = &st(0); | |
32 | st0_tag = FPU_gettag0(); | |
33 | st0_sign = getsign(st0_ptr); | |
34 | ||
35 | if (tagb == TAG_Special) | |
36 | tagb = FPU_Special(b); | |
37 | if (st0_tag == TAG_Special) | |
38 | st0_tag = FPU_Special(st0_ptr); | |
39 | ||
40 | if (((st0_tag != TAG_Valid) && (st0_tag != TW_Denormal)) | |
41 | || ((tagb != TAG_Valid) && (tagb != TW_Denormal))) { | |
42 | if (st0_tag == TAG_Zero) { | |
43 | if (tagb == TAG_Zero) | |
44 | return COMP_A_eq_B; | |
45 | if (tagb == TAG_Valid) | |
46 | return ((signb == | |
47 | SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B); | |
48 | if (tagb == TW_Denormal) | |
49 | return ((signb == | |
50 | SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B) | |
51 | | COMP_Denormal; | |
52 | } else if (tagb == TAG_Zero) { | |
53 | if (st0_tag == TAG_Valid) | |
54 | return ((st0_sign == | |
55 | SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B); | |
56 | if (st0_tag == TW_Denormal) | |
57 | return ((st0_sign == | |
58 | SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B) | |
59 | | COMP_Denormal; | |
60 | } | |
61 | ||
62 | if (st0_tag == TW_Infinity) { | |
63 | if ((tagb == TAG_Valid) || (tagb == TAG_Zero)) | |
64 | return ((st0_sign == | |
65 | SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B); | |
66 | else if (tagb == TW_Denormal) | |
67 | return ((st0_sign == | |
68 | SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B) | |
69 | | COMP_Denormal; | |
70 | else if (tagb == TW_Infinity) { | |
71 | /* The 80486 book says that infinities can be equal! */ | |
72 | return (st0_sign == signb) ? COMP_A_eq_B : | |
73 | ((st0_sign == | |
74 | SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B); | |
75 | } | |
76 | /* Fall through to the NaN code */ | |
77 | } else if (tagb == TW_Infinity) { | |
78 | if ((st0_tag == TAG_Valid) || (st0_tag == TAG_Zero)) | |
79 | return ((signb == | |
80 | SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B); | |
81 | if (st0_tag == TW_Denormal) | |
82 | return ((signb == | |
83 | SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B) | |
84 | | COMP_Denormal; | |
85 | /* Fall through to the NaN code */ | |
86 | } | |
87 | ||
88 | /* The only possibility now should be that one of the arguments | |
89 | is a NaN */ | |
90 | if ((st0_tag == TW_NaN) || (tagb == TW_NaN)) { | |
91 | int signalling = 0, unsupported = 0; | |
92 | if (st0_tag == TW_NaN) { | |
93 | signalling = | |
94 | (st0_ptr->sigh & 0xc0000000) == 0x80000000; | |
95 | unsupported = !((exponent(st0_ptr) == EXP_OVER) | |
96 | && (st0_ptr-> | |
97 | sigh & 0x80000000)); | |
98 | } | |
99 | if (tagb == TW_NaN) { | |
100 | signalling |= | |
101 | (b->sigh & 0xc0000000) == 0x80000000; | |
102 | unsupported |= !((exponent(b) == EXP_OVER) | |
103 | && (b->sigh & 0x80000000)); | |
104 | } | |
105 | if (signalling || unsupported) | |
106 | return COMP_No_Comp | COMP_SNaN | COMP_NaN; | |
107 | else | |
108 | /* Neither is a signaling NaN */ | |
109 | return COMP_No_Comp | COMP_NaN; | |
110 | } | |
111 | ||
112 | EXCEPTION(EX_Invalid); | |
1da177e4 LT |
113 | } |
114 | ||
3d0d14f9 IM |
115 | if (st0_sign != signb) { |
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); | |
1da177e4 LT |
119 | } |
120 | ||
3d0d14f9 IM |
121 | if ((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) { |
122 | FPU_to_exp16(st0_ptr, &x); | |
123 | FPU_to_exp16(b, &y); | |
124 | st0_ptr = &x; | |
125 | b = &y; | |
126 | exp0 = exponent16(st0_ptr); | |
127 | expb = exponent16(b); | |
128 | } else { | |
129 | exp0 = exponent(st0_ptr); | |
130 | expb = exponent(b); | |
1da177e4 | 131 | } |
1da177e4 LT |
132 | |
133 | #ifdef PARANOID | |
3d0d14f9 IM |
134 | if (!(st0_ptr->sigh & 0x80000000)) |
135 | EXCEPTION(EX_Invalid); | |
136 | if (!(b->sigh & 0x80000000)) | |
137 | EXCEPTION(EX_Invalid); | |
1da177e4 LT |
138 | #endif /* PARANOID */ |
139 | ||
3d0d14f9 IM |
140 | diff = exp0 - expb; |
141 | if (diff == 0) { | |
142 | diff = st0_ptr->sigh - b->sigh; /* Works only if ms bits are | |
143 | identical */ | |
144 | if (diff == 0) { | |
145 | diff = st0_ptr->sigl > b->sigl; | |
146 | if (diff == 0) | |
147 | diff = -(st0_ptr->sigl < b->sigl); | |
148 | } | |
1da177e4 | 149 | } |
1da177e4 | 150 | |
3d0d14f9 IM |
151 | if (diff > 0) { |
152 | return ((st0_sign == SIGN_POS) ? COMP_A_gt_B : COMP_A_lt_B) | |
153 | | (((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) ? | |
154 | COMP_Denormal : 0); | |
155 | } | |
156 | if (diff < 0) { | |
157 | return ((st0_sign == SIGN_POS) ? COMP_A_lt_B : COMP_A_gt_B) | |
158 | | (((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) ? | |
159 | COMP_Denormal : 0); | |
160 | } | |
1da177e4 | 161 | |
3d0d14f9 IM |
162 | return COMP_A_eq_B |
163 | | (((st0_tag == TW_Denormal) || (tagb == TW_Denormal)) ? | |
164 | COMP_Denormal : 0); | |
165 | ||
166 | } | |
1da177e4 LT |
167 | |
168 | /* This function requires that st(0) is not empty */ | |
169 | int FPU_compare_st_data(FPU_REG const *loaded_data, u_char loaded_tag) | |
170 | { | |
3d0d14f9 IM |
171 | int f = 0, c; |
172 | ||
173 | c = compare(loaded_data, loaded_tag); | |
174 | ||
175 | if (c & COMP_NaN) { | |
176 | EXCEPTION(EX_Invalid); | |
177 | f = SW_C3 | SW_C2 | SW_C0; | |
178 | } else | |
179 | switch (c & 7) { | |
180 | case COMP_A_lt_B: | |
181 | f = SW_C0; | |
182 | break; | |
183 | case COMP_A_eq_B: | |
184 | f = SW_C3; | |
185 | break; | |
186 | case COMP_A_gt_B: | |
187 | f = 0; | |
188 | break; | |
189 | case COMP_No_Comp: | |
190 | f = SW_C3 | SW_C2 | SW_C0; | |
191 | break; | |
1da177e4 | 192 | #ifdef PARANOID |
3d0d14f9 IM |
193 | default: |
194 | EXCEPTION(EX_INTERNAL | 0x121); | |
195 | f = SW_C3 | SW_C2 | SW_C0; | |
196 | break; | |
1da177e4 | 197 | #endif /* PARANOID */ |
3d0d14f9 IM |
198 | } |
199 | setcc(f); | |
200 | if (c & COMP_Denormal) { | |
201 | return denormal_operand() < 0; | |
202 | } | |
203 | return 0; | |
1da177e4 LT |
204 | } |
205 | ||
1da177e4 LT |
206 | static int compare_st_st(int nr) |
207 | { | |
3d0d14f9 IM |
208 | int f = 0, c; |
209 | FPU_REG *st_ptr; | |
210 | ||
211 | if (!NOT_EMPTY(0) || !NOT_EMPTY(nr)) { | |
212 | setcc(SW_C3 | SW_C2 | SW_C0); | |
213 | /* Stack fault */ | |
214 | EXCEPTION(EX_StackUnder); | |
215 | return !(control_word & CW_Invalid); | |
216 | } | |
217 | ||
218 | st_ptr = &st(nr); | |
219 | c = compare(st_ptr, FPU_gettagi(nr)); | |
220 | if (c & COMP_NaN) { | |
221 | setcc(SW_C3 | SW_C2 | SW_C0); | |
222 | EXCEPTION(EX_Invalid); | |
223 | return !(control_word & CW_Invalid); | |
224 | } else | |
225 | switch (c & 7) { | |
226 | case COMP_A_lt_B: | |
227 | f = SW_C0; | |
228 | break; | |
229 | case COMP_A_eq_B: | |
230 | f = SW_C3; | |
231 | break; | |
232 | case COMP_A_gt_B: | |
233 | f = 0; | |
234 | break; | |
235 | case COMP_No_Comp: | |
236 | f = SW_C3 | SW_C2 | SW_C0; | |
237 | break; | |
1da177e4 | 238 | #ifdef PARANOID |
3d0d14f9 IM |
239 | default: |
240 | EXCEPTION(EX_INTERNAL | 0x122); | |
241 | f = SW_C3 | SW_C2 | SW_C0; | |
242 | break; | |
1da177e4 | 243 | #endif /* PARANOID */ |
3d0d14f9 IM |
244 | } |
245 | setcc(f); | |
246 | if (c & COMP_Denormal) { | |
247 | return denormal_operand() < 0; | |
248 | } | |
249 | return 0; | |
1da177e4 LT |
250 | } |
251 | ||
1da177e4 LT |
252 | static int compare_u_st_st(int nr) |
253 | { | |
3d0d14f9 IM |
254 | int f = 0, c; |
255 | FPU_REG *st_ptr; | |
256 | ||
257 | if (!NOT_EMPTY(0) || !NOT_EMPTY(nr)) { | |
258 | setcc(SW_C3 | SW_C2 | SW_C0); | |
259 | /* Stack fault */ | |
260 | EXCEPTION(EX_StackUnder); | |
261 | return !(control_word & CW_Invalid); | |
1da177e4 | 262 | } |
3d0d14f9 IM |
263 | |
264 | st_ptr = &st(nr); | |
265 | c = compare(st_ptr, FPU_gettagi(nr)); | |
266 | if (c & COMP_NaN) { | |
267 | setcc(SW_C3 | SW_C2 | SW_C0); | |
268 | if (c & COMP_SNaN) { /* This is the only difference between | |
269 | un-ordered and ordinary comparisons */ | |
270 | EXCEPTION(EX_Invalid); | |
271 | return !(control_word & CW_Invalid); | |
272 | } | |
273 | return 0; | |
274 | } else | |
275 | switch (c & 7) { | |
276 | case COMP_A_lt_B: | |
277 | f = SW_C0; | |
278 | break; | |
279 | case COMP_A_eq_B: | |
280 | f = SW_C3; | |
281 | break; | |
282 | case COMP_A_gt_B: | |
283 | f = 0; | |
284 | break; | |
285 | case COMP_No_Comp: | |
286 | f = SW_C3 | SW_C2 | SW_C0; | |
287 | break; | |
1da177e4 | 288 | #ifdef PARANOID |
3d0d14f9 IM |
289 | default: |
290 | EXCEPTION(EX_INTERNAL | 0x123); | |
291 | f = SW_C3 | SW_C2 | SW_C0; | |
292 | break; | |
293 | #endif /* PARANOID */ | |
294 | } | |
295 | setcc(f); | |
296 | if (c & COMP_Denormal) { | |
297 | return denormal_operand() < 0; | |
298 | } | |
299 | return 0; | |
1da177e4 LT |
300 | } |
301 | ||
302 | /*---------------------------------------------------------------------------*/ | |
303 | ||
304 | void fcom_st(void) | |
305 | { | |
3d0d14f9 IM |
306 | /* fcom st(i) */ |
307 | compare_st_st(FPU_rm); | |
1da177e4 LT |
308 | } |
309 | ||
1da177e4 LT |
310 | void fcompst(void) |
311 | { | |
3d0d14f9 IM |
312 | /* fcomp st(i) */ |
313 | if (!compare_st_st(FPU_rm)) | |
314 | FPU_pop(); | |
1da177e4 LT |
315 | } |
316 | ||
1da177e4 LT |
317 | void fcompp(void) |
318 | { | |
3d0d14f9 IM |
319 | /* fcompp */ |
320 | if (FPU_rm != 1) { | |
321 | FPU_illegal(); | |
322 | return; | |
323 | } | |
324 | if (!compare_st_st(1)) | |
325 | poppop(); | |
1da177e4 LT |
326 | } |
327 | ||
1da177e4 LT |
328 | void fucom_(void) |
329 | { | |
3d0d14f9 IM |
330 | /* fucom st(i) */ |
331 | compare_u_st_st(FPU_rm); | |
1da177e4 LT |
332 | |
333 | } | |
334 | ||
1da177e4 LT |
335 | void fucomp(void) |
336 | { | |
3d0d14f9 IM |
337 | /* fucomp st(i) */ |
338 | if (!compare_u_st_st(FPU_rm)) | |
339 | FPU_pop(); | |
1da177e4 LT |
340 | } |
341 | ||
1da177e4 LT |
342 | void fucompp(void) |
343 | { | |
3d0d14f9 IM |
344 | /* fucompp */ |
345 | if (FPU_rm == 1) { | |
346 | if (!compare_u_st_st(1)) | |
347 | poppop(); | |
348 | } else | |
349 | FPU_illegal(); | |
1da177e4 | 350 | } |