1 /* Decimal 32-bit format module for the decNumber C Library.
2 Copyright (C) 2005-2013 Free Software Foundation, Inc.
3 Contributed by IBM Corporation. Author Mike Cowlishaw.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 Under Section 7 of GPL version 3, you are granted additional
18 permissions described in the GCC Runtime Library Exception, version
19 3.1, as published by the Free Software Foundation.
21 You should have received a copy of the GNU General Public License and
22 a copy of the GCC Runtime Library Exception along with this program;
23 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24 <http://www.gnu.org/licenses/>. */
26 /* ------------------------------------------------------------------ */
27 /* Decimal 32-bit format module */
28 /* ------------------------------------------------------------------ */
29 /* This module comprises the routines for decimal32 format numbers. */
30 /* Conversions are supplied to and from decNumber and String. */
32 /* This is used when decNumber provides operations, either for all */
33 /* operations or as a proxy between decNumber and decSingle. */
35 /* Error handling is the same as decNumber (qv.). */
36 /* ------------------------------------------------------------------ */
37 #include <string.h> /* [for memset/memcpy] */
38 #include <stdio.h> /* [for printf] */
40 #include "dconfig.h" /* GCC definitions */
41 #define DECNUMDIGITS 7 /* make decNumbers with space for 7 */
42 #include "decNumber.h" /* base number library */
43 #include "decNumberLocal.h" /* decNumber local types, etc. */
44 #include "decimal32.h" /* our primary include */
46 /* Utility tables and routines [in decimal64.c] */
47 extern const uInt COMBEXP
[32], COMBMSD
[32];
48 extern const uShort DPD2BIN
[1024];
49 extern const uShort BIN2DPD
[1000];
50 extern const uByte BIN2CHAR
[4001];
52 extern void decDigitsToDPD(const decNumber
*, uInt
*, Int
);
53 extern void decDigitsFromDPD(decNumber
*, const uInt
*, Int
);
55 #if DECTRACE || DECCHECK
56 void decimal32Show(const decimal32
*); /* for debug */
57 extern void decNumberShow(const decNumber
*); /* .. */
61 /* Clear a structure (e.g., a decNumber) */
62 #define DEC_clear(d) memset(d, 0, sizeof(*d))
64 /* ------------------------------------------------------------------ */
65 /* decimal32FromNumber -- convert decNumber to decimal32 */
67 /* ds is the target decimal32 */
68 /* dn is the source number (assumed valid) */
69 /* set is the context, used only for reporting errors */
71 /* The set argument is used only for status reporting and for the */
72 /* rounding mode (used if the coefficient is more than DECIMAL32_Pmax */
73 /* digits or an overflow is detected). If the exponent is out of the */
74 /* valid range then Overflow or Underflow will be raised. */
75 /* After Underflow a subnormal result is possible. */
77 /* DEC_Clamped is set if the number has to be 'folded down' to fit, */
78 /* by reducing its exponent and multiplying the coefficient by a */
79 /* power of ten, or if the exponent on a zero had to be clamped. */
80 /* ------------------------------------------------------------------ */
81 decimal32
* decimal32FromNumber(decimal32
*d32
, const decNumber
*dn
,
83 uInt status
=0; /* status accumulator */
84 Int ae
; /* adjusted exponent */
85 decNumber dw
; /* work */
86 decContext dc
; /* .. */
87 uInt comb
, exp
; /* .. */
88 uInt uiwork
; /* for macros */
89 uInt targ
=0; /* target 32-bit */
91 /* If the number has too many digits, or the exponent could be */
92 /* out of range then reduce the number under the appropriate */
93 /* constraints. This could push the number to Infinity or zero, */
94 /* so this check and rounding must be done before generating the */
96 ae
=dn
->exponent
+dn
->digits
-1; /* [0 if special] */
97 if (dn
->digits
>DECIMAL32_Pmax
/* too many digits */
98 || ae
>DECIMAL32_Emax
/* likely overflow */
99 || ae
<DECIMAL32_Emin
) { /* likely underflow */
100 decContextDefault(&dc
, DEC_INIT_DECIMAL32
); /* [no traps] */
101 dc
.round
=set
->round
; /* use supplied rounding */
102 decNumberPlus(&dw
, dn
, &dc
); /* (round and check) */
103 /* [this changes -0 to 0, so enforce the sign...] */
104 dw
.bits
|=dn
->bits
&DECNEG
;
105 status
=dc
.status
; /* save status */
106 dn
=&dw
; /* use the work number */
107 } /* maybe out of range */
109 if (dn
->bits
&DECSPECIAL
) { /* a special value */
110 if (dn
->bits
&DECINF
) targ
=DECIMAL_Inf
<<24;
111 else { /* sNaN or qNaN */
112 if ((*dn
->lsu
!=0 || dn
->digits
>1) /* non-zero coefficient */
113 && (dn
->digits
<DECIMAL32_Pmax
)) { /* coefficient fits */
114 decDigitsToDPD(dn
, &targ
, 0);
116 if (dn
->bits
&DECNAN
) targ
|=DECIMAL_NaN
<<24;
117 else targ
|=DECIMAL_sNaN
<<24;
121 else { /* is finite */
122 if (decNumberIsZero(dn
)) { /* is a zero */
123 /* set and clamp exponent */
124 if (dn
->exponent
<-DECIMAL32_Bias
) {
125 exp
=0; /* low clamp */
129 exp
=dn
->exponent
+DECIMAL32_Bias
; /* bias exponent */
130 if (exp
>DECIMAL32_Ehigh
) { /* top clamp */
135 comb
=(exp
>>3) & 0x18; /* msd=0, exp top 2 bits .. */
137 else { /* non-zero finite number */
139 Int pad
=0; /* coefficient pad digits */
141 /* the dn is known to fit, but it may need to be padded */
142 exp
=(uInt
)(dn
->exponent
+DECIMAL32_Bias
); /* bias exponent */
143 if (exp
>DECIMAL32_Ehigh
) { /* fold-down case */
144 pad
=exp
-DECIMAL32_Ehigh
;
145 exp
=DECIMAL32_Ehigh
; /* [to maximum] */
149 /* fastpath common case */
150 if (DECDPUN
==3 && pad
==0) {
151 targ
=BIN2DPD
[dn
->lsu
[0]];
152 if (dn
->digits
>3) targ
|=(uInt
)(BIN2DPD
[dn
->lsu
[1]])<<10;
153 msd
=(dn
->digits
==7 ? dn
->lsu
[2] : 0);
155 else { /* general case */
156 decDigitsToDPD(dn
, &targ
, pad
);
157 /* save and clear the top digit */
162 /* create the combination field */
163 if (msd
>=8) comb
=0x18 | ((exp
>>5) & 0x06) | (msd
& 0x01);
164 else comb
=((exp
>>3) & 0x18) | msd
;
166 targ
|=comb
<<26; /* add combination field .. */
167 targ
|=(exp
&0x3f)<<20; /* .. and exponent continuation */
170 if (dn
->bits
&DECNEG
) targ
|=0x80000000; /* add sign bit */
172 /* now write to storage; this is endian */
173 UBFROMUI(d32
->bytes
, targ
); /* directly store the int */
175 if (status
!=0) decContextSetStatus(set
, status
); /* pass on status */
176 /* decimal32Show(d32); */
178 } /* decimal32FromNumber */
180 /* ------------------------------------------------------------------ */
181 /* decimal32ToNumber -- convert decimal32 to decNumber */
182 /* d32 is the source decimal32 */
183 /* dn is the target number, with appropriate space */
184 /* No error is possible. */
185 /* ------------------------------------------------------------------ */
186 decNumber
* decimal32ToNumber(const decimal32
*d32
, decNumber
*dn
) {
187 uInt msd
; /* coefficient MSD */
188 uInt exp
; /* exponent top two bits */
189 uInt comb
; /* combination field */
190 uInt sour
; /* source 32-bit */
191 uInt uiwork
; /* for macros */
193 /* load source from storage; this is endian */
194 sour
=UBTOUI(d32
->bytes
); /* directly load the int */
196 comb
=(sour
>>26)&0x1f; /* combination field */
198 decNumberZero(dn
); /* clean number */
199 if (sour
&0x80000000) dn
->bits
=DECNEG
; /* set sign if negative */
201 msd
=COMBMSD
[comb
]; /* decode the combination field */
202 exp
=COMBEXP
[comb
]; /* .. */
204 if (exp
==3) { /* is a special */
207 return dn
; /* no coefficient needed */
209 else if (sour
&0x02000000) dn
->bits
|=DECSNAN
;
210 else dn
->bits
|=DECNAN
;
211 msd
=0; /* no top digit */
213 else { /* is a finite number */
214 dn
->exponent
=(exp
<<6)+((sour
>>20)&0x3f)-DECIMAL32_Bias
; /* unbiased */
217 /* get the coefficient */
218 sour
&=0x000fffff; /* clean coefficient continuation */
219 if (msd
) { /* non-zero msd */
220 sour
|=msd
<<20; /* prefix to coefficient */
221 decDigitsFromDPD(dn
, &sour
, 3); /* process 3 declets */
225 if (!sour
) return dn
; /* easy: coefficient is 0 */
226 if (sour
&0x000ffc00) /* need 2 declets? */
227 decDigitsFromDPD(dn
, &sour
, 2); /* process 2 declets */
229 decDigitsFromDPD(dn
, &sour
, 1); /* process 1 declet */
231 } /* decimal32ToNumber */
233 /* ------------------------------------------------------------------ */
234 /* to-scientific-string -- conversion to numeric string */
235 /* to-engineering-string -- conversion to numeric string */
237 /* decimal32ToString(d32, string); */
238 /* decimal32ToEngString(d32, string); */
240 /* d32 is the decimal32 format number to convert */
241 /* string is the string where the result will be laid out */
243 /* string must be at least 24 characters */
245 /* No error is possible, and no status can be set. */
246 /* ------------------------------------------------------------------ */
247 char * decimal32ToEngString(const decimal32
*d32
, char *string
){
248 decNumber dn
; /* work */
249 decimal32ToNumber(d32
, &dn
);
250 decNumberToEngString(&dn
, string
);
252 } /* decimal32ToEngString */
254 char * decimal32ToString(const decimal32
*d32
, char *string
){
255 uInt msd
; /* coefficient MSD */
256 Int exp
; /* exponent top two bits or full */
257 uInt comb
; /* combination field */
258 char *cstart
; /* coefficient start */
259 char *c
; /* output pointer in string */
260 const uByte
*u
; /* work */
261 char *s
, *t
; /* .. (source, target) */
264 uInt uiwork
; /* for macros */
265 uInt sour
; /* source 32-bit */
267 /* load source from storage; this is endian */
268 sour
=UBTOUI(d32
->bytes
); /* directly load the int */
270 c
=string
; /* where result will go */
271 if (((Int
)sour
)<0) *c
++='-'; /* handle sign */
273 comb
=(sour
>>26)&0x1f; /* combination field */
274 msd
=COMBMSD
[comb
]; /* decode the combination field */
275 exp
=COMBEXP
[comb
]; /* .. */
278 if (msd
==0) { /* infinity */
280 strcpy(c
+3, "inity");
281 return string
; /* easy */
283 if (sour
&0x02000000) *c
++='s'; /* sNaN */
284 strcpy(c
, "NaN"); /* complete word */
285 c
+=3; /* step past */
286 if ((sour
&0x000fffff)==0) return string
; /* zero payload */
287 /* otherwise drop through to add integer; set correct exp */
288 exp
=0; msd
=0; /* setup for following code */
290 else exp
=(exp
<<6)+((sour
>>20)&0x3f)-DECIMAL32_Bias
; /* unbiased */
292 /* convert 7 digits of significand to characters */
293 cstart
=c
; /* save start of coefficient */
294 if (msd
) *c
++='0'+(char)msd
; /* non-zero most significant digit */
296 /* Now decode the declets. After extracting each one, it is */
297 /* decoded to binary and then to a 4-char sequence by table lookup; */
298 /* the 4-chars are a 1-char length (significant digits, except 000 */
299 /* has length 0). This allows us to left-align the first declet */
300 /* with non-zero content, then remaining ones are full 3-char */
301 /* length. We use fixed-length memcpys because variable-length */
302 /* causes a subroutine call in GCC. (These are length 4 for speed */
303 /* and are safe because the array has an extra terminator byte.) */
304 #define dpd2char u=&BIN2CHAR[DPD2BIN[dpd]*4]; \
305 if (c!=cstart) {memcpy(c, u+1, 4); c+=3;} \
306 else if (*u) {memcpy(c, u+4-*u, 4); c+=*u;}
308 dpd
=(sour
>>10)&0x3ff; /* declet 1 */
310 dpd
=(sour
)&0x3ff; /* declet 2 */
313 if (c
==cstart
) *c
++='0'; /* all zeros -- make 0 */
315 if (exp
==0) { /* integer or NaN case -- easy */
316 *c
='\0'; /* terminate */
321 e
=0; /* assume no E */
323 /* [here, pre-exp is the digits count (==1 for zero)] */
324 if (exp
>0 || pre
<-5) { /* need exponential form */
325 e
=pre
-1; /* calculate E value */
326 pre
=1; /* assume one digit before '.' */
327 } /* exponential form */
329 /* modify the coefficient, adding 0s, '.', and E+nn as needed */
330 s
=c
-1; /* source (LSD) */
331 if (pre
>0) { /* ddd.ddd (plain), perhaps with E */
332 char *dotat
=cstart
+pre
;
333 if (dotat
<c
) { /* if embedded dot needed... */
335 for (; s
>=dotat
; s
--, t
--) *t
=*s
; /* open the gap; leave t at gap */
336 *t
='.'; /* insert the dot */
337 c
++; /* length increased by one */
340 /* finally add the E-part, if needed; it will never be 0, and has */
341 /* a maximum length of 3 digits (E-101 case) */
343 *c
++='E'; /* starts with E */
344 *c
++='+'; /* assume positive */
346 *(c
-1)='-'; /* oops, need '-' */
347 e
=-e
; /* uInt, please */
349 u
=&BIN2CHAR
[e
*4]; /* -> length byte */
350 memcpy(c
, u
+4-*u
, 4); /* copy fixed 4 characters [is safe] */
351 c
+=*u
; /* bump pointer appropriately */
353 *c
='\0'; /* add terminator */
354 /*printf("res %s\n", string); */
358 /* -5<=pre<=0: here for plain 0.ddd or 0.000ddd forms (can never have E) */
360 *(t
+1)='\0'; /* can add terminator now */
361 for (; s
>=cstart
; s
--, t
--) *t
=*s
; /* shift whole coefficient right */
363 *c
++='0'; /* always starts with 0. */
365 for (; pre
<0; pre
++) *c
++='0'; /* add any 0's after '.' */
366 /*printf("res %s\n", string); */
368 } /* decimal32ToString */
370 /* ------------------------------------------------------------------ */
371 /* to-number -- conversion from numeric string */
373 /* decimal32FromString(result, string, set); */
375 /* result is the decimal32 format number which gets the result of */
377 /* *string is the character string which should contain a valid */
378 /* number (which may be a special value) */
379 /* set is the context */
381 /* The context is supplied to this routine is used for error handling */
382 /* (setting of status and traps) and for the rounding mode, only. */
383 /* If an error occurs, the result will be a valid decimal32 NaN. */
384 /* ------------------------------------------------------------------ */
385 decimal32
* decimal32FromString(decimal32
*result
, const char *string
,
387 decContext dc
; /* work */
388 decNumber dn
; /* .. */
390 decContextDefault(&dc
, DEC_INIT_DECIMAL32
); /* no traps, please */
391 dc
.round
=set
->round
; /* use supplied rounding */
393 decNumberFromString(&dn
, string
, &dc
); /* will round if needed */
394 decimal32FromNumber(result
, &dn
, &dc
);
395 if (dc
.status
!=0) { /* something happened */
396 decContextSetStatus(set
, dc
.status
); /* .. pass it on */
399 } /* decimal32FromString */
401 /* ------------------------------------------------------------------ */
402 /* decimal32IsCanonical -- test whether encoding is canonical */
403 /* d32 is the source decimal32 */
404 /* returns 1 if the encoding of d32 is canonical, 0 otherwise */
405 /* No error is possible. */
406 /* ------------------------------------------------------------------ */
407 uInt
decimal32IsCanonical(const decimal32
*d32
) {
408 decNumber dn
; /* work */
409 decimal32 canon
; /* .. */
410 decContext dc
; /* .. */
411 decContextDefault(&dc
, DEC_INIT_DECIMAL32
);
412 decimal32ToNumber(d32
, &dn
);
413 decimal32FromNumber(&canon
, &dn
, &dc
);/* canon will now be canonical */
414 return memcmp(d32
, &canon
, DECIMAL32_Bytes
)==0;
415 } /* decimal32IsCanonical */
417 /* ------------------------------------------------------------------ */
418 /* decimal32Canonical -- copy an encoding, ensuring it is canonical */
419 /* d32 is the source decimal32 */
420 /* result is the target (may be the same decimal32) */
422 /* No error is possible. */
423 /* ------------------------------------------------------------------ */
424 decimal32
* decimal32Canonical(decimal32
*result
, const decimal32
*d32
) {
425 decNumber dn
; /* work */
426 decContext dc
; /* .. */
427 decContextDefault(&dc
, DEC_INIT_DECIMAL32
);
428 decimal32ToNumber(d32
, &dn
);
429 decimal32FromNumber(result
, &dn
, &dc
);/* result will now be canonical */
431 } /* decimal32Canonical */
433 #if DECTRACE || DECCHECK
434 /* Macros for accessing decimal32 fields. These assume the argument
435 is a reference (pointer) to the decimal32 structure, and the
436 decimal32 is in network byte order (big-endian) */
438 #define decimal32Sign(d) ((unsigned)(d)->bytes[0]>>7)
440 /* Get combination field */
441 #define decimal32Comb(d) (((d)->bytes[0] & 0x7c)>>2)
443 /* Get exponent continuation [does not remove bias] */
444 #define decimal32ExpCon(d) ((((d)->bytes[0] & 0x03)<<4) \
445 | ((unsigned)(d)->bytes[1]>>4))
447 /* Set sign [this assumes sign previously 0] */
448 #define decimal32SetSign(d, b) { \
449 (d)->bytes[0]|=((unsigned)(b)<<7);}
451 /* Set exponent continuation [does not apply bias] */
452 /* This assumes range has been checked and exponent previously 0; */
453 /* type of exponent must be unsigned */
454 #define decimal32SetExpCon(d, e) { \
455 (d)->bytes[0]|=(uByte)((e)>>4); \
456 (d)->bytes[1]|=(uByte)(((e)&0x0F)<<4);}
458 /* ------------------------------------------------------------------ */
459 /* decimal32Show -- display a decimal32 in hexadecimal [debug aid] */
460 /* d32 -- the number to show */
461 /* ------------------------------------------------------------------ */
462 /* Also shows sign/cob/expconfields extracted - valid bigendian only */
463 void decimal32Show(const decimal32
*d32
) {
464 char buf
[DECIMAL32_Bytes
*2+1];
468 for (i
=0; i
<DECIMAL32_Bytes
; i
++, j
+=2) {
469 sprintf(&buf
[j
], "%02x", d32
->bytes
[3-i
]);
471 printf(" D32> %s [S:%d Cb:%02x Ec:%02x] LittleEndian\n", buf
,
472 d32
->bytes
[3]>>7, (d32
->bytes
[3]>>2)&0x1f,
473 ((d32
->bytes
[3]&0x3)<<4)| (d32
->bytes
[2]>>4));
476 for (i
=0; i
<DECIMAL32_Bytes
; i
++, j
+=2) {
477 sprintf(&buf
[j
], "%02x", d32
->bytes
[i
]);
479 printf(" D32> %s [S:%d Cb:%02x Ec:%02x] BigEndian\n", buf
,
480 decimal32Sign(d32
), decimal32Comb(d32
), decimal32ExpCon(d32
));
482 } /* decimal32Show */
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