Remove __encodeDouble and __encodeFloat from the rts
[ghc.git] / rts / StgPrimFloat.c
1 /* -----------------------------------------------------------------------------
2 *
3 * (c) Lennart Augustsson
4 * (c) The GHC Team, 1998-2000
5 *
6 * Miscellaneous support for floating-point primitives
7 *
8 * ---------------------------------------------------------------------------*/
9
10 #include "PosixSource.h"
11 #include "Rts.h"
12
13 #include <math.h>
14
15 /*
16 * Encoding and decoding Doubles. Code based on the HBC code
17 * (lib/fltcode.c).
18 */
19
20 #ifdef _SHORT_LIMB
21 #define SIZEOF_LIMB_T SIZEOF_UNSIGNED_INT
22 #else
23 #ifdef _LONG_LONG_LIMB
24 #define SIZEOF_LIMB_T SIZEOF_UNSIGNED_LONG_LONG
25 #else
26 #define SIZEOF_LIMB_T SIZEOF_UNSIGNED_LONG
27 #endif
28 #endif
29
30 #if SIZEOF_LIMB_T == 4
31 #define GMP_BASE 4294967296.0
32 #elif SIZEOF_LIMB_T == 8
33 #define GMP_BASE 18446744073709551616.0
34 #else
35 #error Cannot cope with SIZEOF_LIMB_T -- please add definition of GMP_BASE
36 #endif
37
38 #define DNBIGIT ((SIZEOF_DOUBLE+SIZEOF_LIMB_T-1)/SIZEOF_LIMB_T)
39 #define FNBIGIT ((SIZEOF_FLOAT +SIZEOF_LIMB_T-1)/SIZEOF_LIMB_T)
40
41 #if IEEE_FLOATING_POINT
42 #define MY_DMINEXP ((DBL_MIN_EXP) - (DBL_MANT_DIG) - 1)
43 /* DMINEXP is defined in values.h on Linux (for example) */
44 #define DHIGHBIT 0x00100000
45 #define DMSBIT 0x80000000
46
47 #define MY_FMINEXP ((FLT_MIN_EXP) - (FLT_MANT_DIG) - 1)
48 #define FHIGHBIT 0x00800000
49 #define FMSBIT 0x80000000
50 #endif
51
52 #if defined(WORDS_BIGENDIAN) || defined(FLOAT_WORDS_BIGENDIAN)
53 #define L 1
54 #define H 0
55 #else
56 #define L 0
57 #define H 1
58 #endif
59
60 #define __abs(a) (( (a) >= 0 ) ? (a) : (-(a)))
61
62 StgDouble
63 __2Int_encodeDouble (I_ j_high, I_ j_low, I_ e)
64 {
65 StgDouble r;
66
67 /* assuming 32 bit ints */
68 ASSERT(sizeof(int ) == 4 );
69
70 r = (StgDouble)((unsigned int)j_high);
71 r *= 4294967296.0; /* exp2f(32); */
72 r += (StgDouble)((unsigned int)j_low);
73
74 /* Now raise to the exponent */
75 if ( r != 0.0 ) /* Lennart suggests this avoids a bug in MIPS's ldexp */
76 r = ldexp(r, e);
77
78 /* sign is encoded in the size */
79 if (j_high < 0)
80 r = -r;
81
82 return r;
83 }
84
85 /* Special version for words */
86 StgDouble
87 __word_encodeDouble (W_ j, I_ e)
88 {
89 StgDouble r;
90
91 r = (StgDouble)j;
92
93 /* Now raise to the exponent */
94 if ( r != 0.0 ) /* Lennart suggests this avoids a bug in MIPS's ldexp */
95 r = ldexp(r, e);
96
97 return r;
98 }
99
100 /* Special version for small Integers */
101 StgDouble
102 __int_encodeDouble (I_ j, I_ e)
103 {
104 StgDouble r;
105
106 r = (StgDouble)__abs(j);
107
108 /* Now raise to the exponent */
109 if ( r != 0.0 ) /* Lennart suggests this avoids a bug in MIPS's ldexp */
110 r = ldexp(r, e);
111
112 /* sign is encoded in the size */
113 if (j < 0)
114 r = -r;
115
116 return r;
117 }
118
119 /* Special version for small Integers */
120 StgFloat
121 __int_encodeFloat (I_ j, I_ e)
122 {
123 StgFloat r;
124
125 r = (StgFloat)__abs(j);
126
127 /* Now raise to the exponent */
128 if ( r != 0.0 ) /* Lennart suggests this avoids a bug in MIPS's ldexp */
129 r = ldexp(r, e);
130
131 /* sign is encoded in the size */
132 if (j < 0)
133 r = -r;
134
135 return r;
136 }
137
138 /* Special version for small positive Integers */
139 StgFloat
140 __word_encodeFloat (W_ j, I_ e)
141 {
142 StgFloat r;
143
144 r = (StgFloat)j;
145
146 /* Now raise to the exponent */
147 if ( r != 0.0 ) /* Lennart suggests this avoids a bug in MIPS's ldexp */
148 r = ldexp(r, e);
149
150 return r;
151 }
152
153 /* This only supports IEEE floating point */
154
155 void
156 __decodeDouble (MP_INT *man, I_ *exp, StgDouble dbl)
157 {
158 /* Do some bit fiddling on IEEE */
159 unsigned int low, high; /* assuming 32 bit ints */
160 int sign, iexp;
161 union { double d; unsigned int i[2]; } u; /* assuming 32 bit ints, 64 bit double */
162
163 ASSERT(sizeof(unsigned int ) == 4 );
164 ASSERT(sizeof(dbl ) == SIZEOF_DOUBLE);
165 ASSERT(sizeof(man->_mp_d[0]) == SIZEOF_LIMB_T);
166 ASSERT(DNBIGIT*SIZEOF_LIMB_T >= SIZEOF_DOUBLE);
167
168 u.d = dbl; /* grab chunks of the double */
169 low = u.i[L];
170 high = u.i[H];
171
172 /* we know the MP_INT* passed in has size zero, so we realloc
173 no matter what.
174 */
175 man->_mp_alloc = DNBIGIT;
176
177 if (low == 0 && (high & ~DMSBIT) == 0) {
178 man->_mp_size = 0;
179 *exp = 0L;
180 } else {
181 man->_mp_size = DNBIGIT;
182 iexp = ((high >> 20) & 0x7ff) + MY_DMINEXP;
183 sign = high;
184
185 high &= DHIGHBIT-1;
186 if (iexp != MY_DMINEXP) /* don't add hidden bit to denorms */
187 high |= DHIGHBIT;
188 else {
189 iexp++;
190 /* A denorm, normalize the mantissa */
191 while (! (high & DHIGHBIT)) {
192 high <<= 1;
193 if (low & DMSBIT)
194 high++;
195 low <<= 1;
196 iexp--;
197 }
198 }
199 *exp = (I_) iexp;
200 #if DNBIGIT == 2
201 man->_mp_d[0] = (mp_limb_t)low;
202 man->_mp_d[1] = (mp_limb_t)high;
203 #else
204 #if DNBIGIT == 1
205 man->_mp_d[0] = ((mp_limb_t)high) << 32 | (mp_limb_t)low;
206 #else
207 #error Cannot cope with DNBIGIT
208 #endif
209 #endif
210 if (sign < 0)
211 man->_mp_size = -man->_mp_size;
212 }
213 }
214
215 void
216 __decodeDouble_2Int (I_ *man_sign, W_ *man_high, W_ *man_low, I_ *exp, StgDouble dbl)
217 {
218 /* Do some bit fiddling on IEEE */
219 unsigned int low, high; /* assuming 32 bit ints */
220 int sign, iexp;
221 union { double d; unsigned int i[2]; } u; /* assuming 32 bit ints, 64 bit double */
222
223 ASSERT(sizeof(unsigned int ) == 4 );
224 ASSERT(sizeof(dbl ) == 8 );
225 ASSERT(sizeof(dbl ) == SIZEOF_DOUBLE);
226
227 u.d = dbl; /* grab chunks of the double */
228 low = u.i[L];
229 high = u.i[H];
230
231 if (low == 0 && (high & ~DMSBIT) == 0) {
232 *man_low = 0;
233 *man_high = 0;
234 *exp = 0L;
235 } else {
236 iexp = ((high >> 20) & 0x7ff) + MY_DMINEXP;
237 sign = high;
238
239 high &= DHIGHBIT-1;
240 if (iexp != MY_DMINEXP) /* don't add hidden bit to denorms */
241 high |= DHIGHBIT;
242 else {
243 iexp++;
244 /* A denorm, normalize the mantissa */
245 while (! (high & DHIGHBIT)) {
246 high <<= 1;
247 if (low & DMSBIT)
248 high++;
249 low <<= 1;
250 iexp--;
251 }
252 }
253 *exp = (I_) iexp;
254 *man_low = low;
255 *man_high = high;
256 *man_sign = (sign < 0) ? -1 : 1;
257 }
258 }
259
260 /* Convenient union types for checking the layout of IEEE 754 types -
261 based on defs in GNU libc <ieee754.h>
262 */
263
264 void
265 __decodeFloat_Int (I_ *man, I_ *exp, StgFloat flt)
266 {
267 /* Do some bit fiddling on IEEE */
268 int high, sign; /* assuming 32 bit ints */
269 union { float f; int i; } u; /* assuming 32 bit float and int */
270
271 ASSERT(sizeof(int ) == 4 );
272 ASSERT(sizeof(flt ) == 4 );
273 ASSERT(sizeof(flt ) == SIZEOF_FLOAT );
274
275 u.f = flt; /* grab the float */
276 high = u.i;
277
278 if ((high & ~FMSBIT) == 0) {
279 *man = 0;
280 *exp = 0;
281 } else {
282 *exp = ((high >> 23) & 0xff) + MY_FMINEXP;
283 sign = high;
284
285 high &= FHIGHBIT-1;
286 if (*exp != MY_FMINEXP) /* don't add hidden bit to denorms */
287 high |= FHIGHBIT;
288 else {
289 (*exp)++;
290 /* A denorm, normalize the mantissa */
291 while (! (high & FHIGHBIT)) {
292 high <<= 1;
293 (*exp)--;
294 }
295 }
296 *man = high;
297 if (sign < 0)
298 *man = - *man;
299 }
300 }
301
302 union stg_ieee754_flt
303 {
304 float f;
305 struct {
306
307 #if WORDS_BIGENDIAN
308 unsigned int negative:1;
309 unsigned int exponent:8;
310 unsigned int mantissa:23;
311 #else
312 unsigned int mantissa:23;
313 unsigned int exponent:8;
314 unsigned int negative:1;
315 #endif
316 } ieee;
317 struct {
318
319 #if WORDS_BIGENDIAN
320 unsigned int negative:1;
321 unsigned int exponent:8;
322 unsigned int quiet_nan:1;
323 unsigned int mantissa:22;
324 #else
325 unsigned int mantissa:22;
326 unsigned int quiet_nan:1;
327 unsigned int exponent:8;
328 unsigned int negative:1;
329 #endif
330 } ieee_nan;
331 };
332
333 /*
334
335 To recap, here's the representation of a double precision
336 IEEE floating point number:
337
338 sign 63 sign bit (0==positive, 1==negative)
339 exponent 62-52 exponent (biased by 1023)
340 fraction 51-0 fraction (bits to right of binary point)
341 */
342
343 union stg_ieee754_dbl
344 {
345 double d;
346 struct {
347
348 #if WORDS_BIGENDIAN
349 unsigned int negative:1;
350 unsigned int exponent:11;
351 unsigned int mantissa0:20;
352 unsigned int mantissa1:32;
353 #else
354 #if FLOAT_WORDS_BIGENDIAN
355 unsigned int mantissa0:20;
356 unsigned int exponent:11;
357 unsigned int negative:1;
358 unsigned int mantissa1:32;
359 #else
360 unsigned int mantissa1:32;
361 unsigned int mantissa0:20;
362 unsigned int exponent:11;
363 unsigned int negative:1;
364 #endif
365 #endif
366 } ieee;
367 /* This format makes it easier to see if a NaN is a signalling NaN. */
368 struct {
369
370 #if WORDS_BIGENDIAN
371 unsigned int negative:1;
372 unsigned int exponent:11;
373 unsigned int quiet_nan:1;
374 unsigned int mantissa0:19;
375 unsigned int mantissa1:32;
376 #else
377 #if FLOAT_WORDS_BIGENDIAN
378 unsigned int mantissa0:19;
379 unsigned int quiet_nan:1;
380 unsigned int exponent:11;
381 unsigned int negative:1;
382 unsigned int mantissa1:32;
383 #else
384 unsigned int mantissa1:32;
385 unsigned int mantissa0:19;
386 unsigned int quiet_nan:1;
387 unsigned int exponent:11;
388 unsigned int negative:1;
389 #endif
390 #endif
391 } ieee_nan;
392 };
393
394 /*
395 * Predicates for testing for extreme IEEE fp values. Used
396 * by the bytecode evaluator and the Prelude.
397 *
398 */
399
400 /* In case you don't suppport IEEE, you'll just get dummy defs.. */
401 #ifdef IEEE_FLOATING_POINT
402
403 StgInt
404 isDoubleNaN(StgDouble d)
405 {
406 union stg_ieee754_dbl u;
407
408 u.d = d;
409
410 return (
411 u.ieee.exponent == 2047 /* 2^11 - 1 */ && /* Is the exponent all ones? */
412 (u.ieee.mantissa0 != 0 || u.ieee.mantissa1 != 0)
413 /* and the mantissa non-zero? */
414 );
415 }
416
417 StgInt
418 isDoubleInfinite(StgDouble d)
419 {
420 union stg_ieee754_dbl u;
421
422 u.d = d;
423
424 /* Inf iff exponent is all ones, mantissa all zeros */
425 return (
426 u.ieee.exponent == 2047 /* 2^11 - 1 */ &&
427 u.ieee.mantissa0 == 0 &&
428 u.ieee.mantissa1 == 0
429 );
430 }
431
432 StgInt
433 isDoubleDenormalized(StgDouble d)
434 {
435 union stg_ieee754_dbl u;
436
437 u.d = d;
438
439 /* A (single/double/quad) precision floating point number
440 is denormalised iff:
441 - exponent is zero
442 - mantissa is non-zero.
443 - (don't care about setting of sign bit.)
444
445 */
446 return (
447 u.ieee.exponent == 0 &&
448 (u.ieee.mantissa0 != 0 ||
449 u.ieee.mantissa1 != 0)
450 );
451
452 }
453
454 StgInt
455 isDoubleNegativeZero(StgDouble d)
456 {
457 union stg_ieee754_dbl u;
458
459 u.d = d;
460 /* sign (bit 63) set (only) => negative zero */
461
462 return (
463 u.ieee.negative == 1 &&
464 u.ieee.exponent == 0 &&
465 u.ieee.mantissa0 == 0 &&
466 u.ieee.mantissa1 == 0);
467 }
468
469 /* Same tests, this time for StgFloats. */
470
471 /*
472 To recap, here's the representation of a single precision
473 IEEE floating point number:
474
475 sign 31 sign bit (0 == positive, 1 == negative)
476 exponent 30-23 exponent (biased by 127)
477 fraction 22-0 fraction (bits to right of binary point)
478 */
479
480
481 StgInt
482 isFloatNaN(StgFloat f)
483 {
484 union stg_ieee754_flt u;
485 u.f = f;
486
487 /* Floating point NaN iff exponent is all ones, mantissa is
488 non-zero (but see below.) */
489 return (
490 u.ieee.exponent == 255 /* 2^8 - 1 */ &&
491 u.ieee.mantissa != 0);
492 }
493
494 StgInt
495 isFloatInfinite(StgFloat f)
496 {
497 union stg_ieee754_flt u;
498 u.f = f;
499
500 /* A float is Inf iff exponent is max (all ones),
501 and mantissa is min(all zeros.) */
502 return (
503 u.ieee.exponent == 255 /* 2^8 - 1 */ &&
504 u.ieee.mantissa == 0);
505 }
506
507 StgInt
508 isFloatDenormalized(StgFloat f)
509 {
510 union stg_ieee754_flt u;
511 u.f = f;
512
513 /* A (single/double/quad) precision floating point number
514 is denormalised iff:
515 - exponent is zero
516 - mantissa is non-zero.
517 - (don't care about setting of sign bit.)
518
519 */
520 return (
521 u.ieee.exponent == 0 &&
522 u.ieee.mantissa != 0);
523 }
524
525 StgInt
526 isFloatNegativeZero(StgFloat f)
527 {
528 union stg_ieee754_flt u;
529 u.f = f;
530
531 /* sign (bit 31) set (only) => negative zero */
532 return (
533 u.ieee.negative &&
534 u.ieee.exponent == 0 &&
535 u.ieee.mantissa == 0);
536 }
537
538 #else /* ! IEEE_FLOATING_POINT */
539
540 /* Dummy definitions of predicates - they all return false */
541 StgInt isDoubleNaN(d) StgDouble d; { return 0; }
542 StgInt isDoubleInfinite(d) StgDouble d; { return 0; }
543 StgInt isDoubleDenormalized(d) StgDouble d; { return 0; }
544 StgInt isDoubleNegativeZero(d) StgDouble d; { return 0; }
545 StgInt isFloatNaN(f) StgFloat f; { return 0; }
546 StgInt isFloatInfinite(f) StgFloat f; { return 0; }
547 StgInt isFloatDenormalized(f) StgFloat f; { return 0; }
548 StgInt isFloatNegativeZero(f) StgFloat f; { return 0; }
549
550 #endif /* ! IEEE_FLOATING_POINT */