1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | NetWinder Floating Point Emulator |
4 | (c) Rebel.COM, 1998,1999 |
5 | (c) Philip Blundell, 1999, 2001 |
6 | |
7 | Direct questions, comments to Scott Bambrough <scottb@netwinder.org> |
8 | |
9 | */ |
10 | |
11 | #include "fpa11.h" |
12 | #include "fpopcode.h" |
13 | #include "fpa11.inl" |
14 | #include "fpmodule.h" |
15 | #include "fpmodule.inl" |
16 | #include "softfloat.h" |
17 | |
18 | unsigned int PerformFLT(const unsigned int opcode); |
19 | unsigned int PerformFIX(const unsigned int opcode); |
20 | |
21 | static unsigned int PerformComparison(const unsigned int opcode); |
22 | |
23 | unsigned int EmulateCPRT(const unsigned int opcode) |
24 | { |
25 | |
26 | if (opcode & 0x800000) { |
27 | /* This is some variant of a comparison (PerformComparison |
28 | will sort out which one). Since most of the other CPRT |
29 | instructions are oddball cases of some sort or other it |
30 | makes sense to pull this out into a fast path. */ |
31 | return PerformComparison(opcode); |
32 | } |
33 | |
34 | /* Hint to GCC that we'd like a jump table rather than a load of CMPs */ |
35 | switch ((opcode & 0x700000) >> 20) { |
36 | case FLT_CODE >> 20: |
37 | return PerformFLT(opcode); |
38 | break; |
39 | case FIX_CODE >> 20: |
40 | return PerformFIX(opcode); |
41 | break; |
42 | |
43 | case WFS_CODE >> 20: |
44 | writeFPSR(reg: readRegister(getRd(opcode))); |
45 | break; |
46 | case RFS_CODE >> 20: |
47 | writeRegister(getRd(opcode), val: readFPSR()); |
48 | break; |
49 | |
50 | default: |
51 | return 0; |
52 | } |
53 | |
54 | return 1; |
55 | } |
56 | |
57 | unsigned int PerformFLT(const unsigned int opcode) |
58 | { |
59 | FPA11 *fpa11 = GET_FPA11(); |
60 | struct roundingData roundData; |
61 | |
62 | roundData.mode = SetRoundingMode(opcode); |
63 | roundData.precision = SetRoundingPrecision(opcode); |
64 | roundData.exception = 0; |
65 | |
66 | switch (opcode & MASK_ROUNDING_PRECISION) { |
67 | case ROUND_SINGLE: |
68 | { |
69 | fpa11->fType[getFn(opcode)] = typeSingle; |
70 | fpa11->fpreg[getFn(opcode)].fSingle = int32_to_float32(&roundData, readRegister(getRd(opcode))); |
71 | } |
72 | break; |
73 | |
74 | case ROUND_DOUBLE: |
75 | { |
76 | fpa11->fType[getFn(opcode)] = typeDouble; |
77 | fpa11->fpreg[getFn(opcode)].fDouble = int32_to_float64(readRegister(getRd(opcode))); |
78 | } |
79 | break; |
80 | |
81 | #ifdef CONFIG_FPE_NWFPE_XP |
82 | case ROUND_EXTENDED: |
83 | { |
84 | fpa11->fType[getFn(opcode)] = typeExtended; |
85 | fpa11->fpreg[getFn(opcode)].fExtended = int32_to_floatx80(readRegister(getRd(opcode))); |
86 | } |
87 | break; |
88 | #endif |
89 | |
90 | default: |
91 | return 0; |
92 | } |
93 | |
94 | if (roundData.exception) |
95 | float_raise(roundData.exception); |
96 | |
97 | return 1; |
98 | } |
99 | |
100 | unsigned int PerformFIX(const unsigned int opcode) |
101 | { |
102 | FPA11 *fpa11 = GET_FPA11(); |
103 | unsigned int Fn = getFm(opcode); |
104 | struct roundingData roundData; |
105 | |
106 | roundData.mode = SetRoundingMode(opcode); |
107 | roundData.precision = SetRoundingPrecision(opcode); |
108 | roundData.exception = 0; |
109 | |
110 | switch (fpa11->fType[Fn]) { |
111 | case typeSingle: |
112 | { |
113 | writeRegister(getRd(opcode), val: float32_to_int32(&roundData, fpa11->fpreg[Fn].fSingle)); |
114 | } |
115 | break; |
116 | |
117 | case typeDouble: |
118 | { |
119 | writeRegister(getRd(opcode), val: float64_to_int32(&roundData, fpa11->fpreg[Fn].fDouble)); |
120 | } |
121 | break; |
122 | |
123 | #ifdef CONFIG_FPE_NWFPE_XP |
124 | case typeExtended: |
125 | { |
126 | writeRegister(getRd(opcode), floatx80_to_int32(&roundData, fpa11->fpreg[Fn].fExtended)); |
127 | } |
128 | break; |
129 | #endif |
130 | |
131 | default: |
132 | return 0; |
133 | } |
134 | |
135 | if (roundData.exception) |
136 | float_raise(roundData.exception); |
137 | |
138 | return 1; |
139 | } |
140 | |
141 | /* This instruction sets the flags N, Z, C, V in the FPSR. */ |
142 | static unsigned int PerformComparison(const unsigned int opcode) |
143 | { |
144 | FPA11 *fpa11 = GET_FPA11(); |
145 | unsigned int Fn = getFn(opcode), Fm = getFm(opcode); |
146 | int e_flag = opcode & 0x400000; /* 1 if CxFE */ |
147 | int n_flag = opcode & 0x200000; /* 1 if CNxx */ |
148 | unsigned int flags = 0; |
149 | |
150 | #ifdef CONFIG_FPE_NWFPE_XP |
151 | floatx80 rFn, rFm; |
152 | |
153 | /* Check for unordered condition and convert all operands to 80-bit |
154 | format. |
155 | ?? Might be some mileage in avoiding this conversion if possible. |
156 | Eg, if both operands are 32-bit, detect this and do a 32-bit |
157 | comparison (cheaper than an 80-bit one). */ |
158 | switch (fpa11->fType[Fn]) { |
159 | case typeSingle: |
160 | //printk("single.\n"); |
161 | if (float32_is_nan(fpa11->fpreg[Fn].fSingle)) |
162 | goto unordered; |
163 | rFn = float32_to_floatx80(fpa11->fpreg[Fn].fSingle); |
164 | break; |
165 | |
166 | case typeDouble: |
167 | //printk("double.\n"); |
168 | if (float64_is_nan(fpa11->fpreg[Fn].fDouble)) |
169 | goto unordered; |
170 | rFn = float64_to_floatx80(fpa11->fpreg[Fn].fDouble); |
171 | break; |
172 | |
173 | case typeExtended: |
174 | //printk("extended.\n"); |
175 | if (floatx80_is_nan(fpa11->fpreg[Fn].fExtended)) |
176 | goto unordered; |
177 | rFn = fpa11->fpreg[Fn].fExtended; |
178 | break; |
179 | |
180 | default: |
181 | return 0; |
182 | } |
183 | |
184 | if (CONSTANT_FM(opcode)) { |
185 | //printk("Fm is a constant: #%d.\n",Fm); |
186 | rFm = getExtendedConstant(Fm); |
187 | if (floatx80_is_nan(rFm)) |
188 | goto unordered; |
189 | } else { |
190 | //printk("Fm = r%d which contains a ",Fm); |
191 | switch (fpa11->fType[Fm]) { |
192 | case typeSingle: |
193 | //printk("single.\n"); |
194 | if (float32_is_nan(fpa11->fpreg[Fm].fSingle)) |
195 | goto unordered; |
196 | rFm = float32_to_floatx80(fpa11->fpreg[Fm].fSingle); |
197 | break; |
198 | |
199 | case typeDouble: |
200 | //printk("double.\n"); |
201 | if (float64_is_nan(fpa11->fpreg[Fm].fDouble)) |
202 | goto unordered; |
203 | rFm = float64_to_floatx80(fpa11->fpreg[Fm].fDouble); |
204 | break; |
205 | |
206 | case typeExtended: |
207 | //printk("extended.\n"); |
208 | if (floatx80_is_nan(fpa11->fpreg[Fm].fExtended)) |
209 | goto unordered; |
210 | rFm = fpa11->fpreg[Fm].fExtended; |
211 | break; |
212 | |
213 | default: |
214 | return 0; |
215 | } |
216 | } |
217 | |
218 | if (n_flag) |
219 | rFm.high ^= 0x8000; |
220 | |
221 | /* test for less than condition */ |
222 | if (floatx80_lt(rFn, rFm)) |
223 | flags |= CC_NEGATIVE; |
224 | |
225 | /* test for equal condition */ |
226 | if (floatx80_eq(rFn, rFm)) |
227 | flags |= CC_ZERO; |
228 | |
229 | /* test for greater than or equal condition */ |
230 | if (floatx80_lt(rFm, rFn)) |
231 | flags |= CC_CARRY; |
232 | |
233 | #else |
234 | if (CONSTANT_FM(opcode)) { |
235 | /* Fm is a constant. Do the comparison in whatever precision |
236 | Fn happens to be stored in. */ |
237 | if (fpa11->fType[Fn] == typeSingle) { |
238 | float32 rFm = getSingleConstant(nIndex: Fm); |
239 | float32 rFn = fpa11->fpreg[Fn].fSingle; |
240 | |
241 | if (float32_is_nan(a: rFn)) |
242 | goto unordered; |
243 | |
244 | if (n_flag) |
245 | rFm ^= 0x80000000; |
246 | |
247 | /* test for less than condition */ |
248 | if (float32_lt_nocheck(a: rFn, b: rFm)) |
249 | flags |= CC_NEGATIVE; |
250 | |
251 | /* test for equal condition */ |
252 | if (float32_eq_nocheck(a: rFn, b: rFm)) |
253 | flags |= CC_ZERO; |
254 | |
255 | /* test for greater than or equal condition */ |
256 | if (float32_lt_nocheck(a: rFm, b: rFn)) |
257 | flags |= CC_CARRY; |
258 | } else { |
259 | float64 rFm = getDoubleConstant(nIndex: Fm); |
260 | float64 rFn = fpa11->fpreg[Fn].fDouble; |
261 | |
262 | if (float64_is_nan(a: rFn)) |
263 | goto unordered; |
264 | |
265 | if (n_flag) |
266 | rFm ^= 0x8000000000000000ULL; |
267 | |
268 | /* test for less than condition */ |
269 | if (float64_lt_nocheck(a: rFn, b: rFm)) |
270 | flags |= CC_NEGATIVE; |
271 | |
272 | /* test for equal condition */ |
273 | if (float64_eq_nocheck(a: rFn, b: rFm)) |
274 | flags |= CC_ZERO; |
275 | |
276 | /* test for greater than or equal condition */ |
277 | if (float64_lt_nocheck(a: rFm, b: rFn)) |
278 | flags |= CC_CARRY; |
279 | } |
280 | } else { |
281 | /* Both operands are in registers. */ |
282 | if (fpa11->fType[Fn] == typeSingle |
283 | && fpa11->fType[Fm] == typeSingle) { |
284 | float32 rFm = fpa11->fpreg[Fm].fSingle; |
285 | float32 rFn = fpa11->fpreg[Fn].fSingle; |
286 | |
287 | if (float32_is_nan(a: rFn) |
288 | || float32_is_nan(a: rFm)) |
289 | goto unordered; |
290 | |
291 | if (n_flag) |
292 | rFm ^= 0x80000000; |
293 | |
294 | /* test for less than condition */ |
295 | if (float32_lt_nocheck(a: rFn, b: rFm)) |
296 | flags |= CC_NEGATIVE; |
297 | |
298 | /* test for equal condition */ |
299 | if (float32_eq_nocheck(a: rFn, b: rFm)) |
300 | flags |= CC_ZERO; |
301 | |
302 | /* test for greater than or equal condition */ |
303 | if (float32_lt_nocheck(a: rFm, b: rFn)) |
304 | flags |= CC_CARRY; |
305 | } else { |
306 | /* Promote 32-bit operand to 64 bits. */ |
307 | float64 rFm, rFn; |
308 | |
309 | rFm = (fpa11->fType[Fm] == typeSingle) ? |
310 | float32_to_float64(fpa11->fpreg[Fm].fSingle) |
311 | : fpa11->fpreg[Fm].fDouble; |
312 | |
313 | rFn = (fpa11->fType[Fn] == typeSingle) ? |
314 | float32_to_float64(fpa11->fpreg[Fn].fSingle) |
315 | : fpa11->fpreg[Fn].fDouble; |
316 | |
317 | if (float64_is_nan(a: rFn) |
318 | || float64_is_nan(a: rFm)) |
319 | goto unordered; |
320 | |
321 | if (n_flag) |
322 | rFm ^= 0x8000000000000000ULL; |
323 | |
324 | /* test for less than condition */ |
325 | if (float64_lt_nocheck(a: rFn, b: rFm)) |
326 | flags |= CC_NEGATIVE; |
327 | |
328 | /* test for equal condition */ |
329 | if (float64_eq_nocheck(a: rFn, b: rFm)) |
330 | flags |= CC_ZERO; |
331 | |
332 | /* test for greater than or equal condition */ |
333 | if (float64_lt_nocheck(a: rFm, b: rFn)) |
334 | flags |= CC_CARRY; |
335 | } |
336 | } |
337 | |
338 | #endif |
339 | |
340 | writeConditionCodes(val: flags); |
341 | |
342 | return 1; |
343 | |
344 | unordered: |
345 | /* ?? The FPA data sheet is pretty vague about this, in particular |
346 | about whether the non-E comparisons can ever raise exceptions. |
347 | This implementation is based on a combination of what it says in |
348 | the data sheet, observation of how the Acorn emulator actually |
349 | behaves (and how programs expect it to) and guesswork. */ |
350 | flags |= CC_OVERFLOW; |
351 | flags &= ~(CC_ZERO | CC_NEGATIVE); |
352 | |
353 | if (BIT_AC & readFPSR()) |
354 | flags |= CC_CARRY; |
355 | |
356 | if (e_flag) |
357 | float_raise(float_flag_invalid); |
358 | |
359 | writeConditionCodes(val: flags); |
360 | return 1; |
361 | } |
362 | |