1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
|
/* Decimal 128-bit format module from the decNumber C Library.
Copyright (C) 2005 Free Software Foundation, Inc.
Contributed by IBM Corporation. Author Mike Cowlishaw.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING. If not, write to the Free
Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301, USA. */
/* ------------------------------------------------------------------ */
/* This module comprises the routines for decimal128 format numbers. */
/* Conversions are supplied to and from decNumber and String. */
/* */
/* No arithmetic routines are included; decNumber provides these. */
/* */
/* Error handling is the same as decNumber (qv.). */
/* ------------------------------------------------------------------ */
#include <string.h> /* [for memset/memcpy] */
#include <stdio.h> /* [for printf] */
#define DECNUMDIGITS 34 /* we need decNumbers with space for 34 */
#include "config.h"
#include "decNumber.h" /* base number library */
#include "decNumberLocal.h" /* decNumber local types, etc. */
#include "decimal128.h" /* our primary include */
#include "decUtility.h" /* utility routines */
#if DECTRACE || DECCHECK
void decimal128Show (const decimal128 *); /* for debug */
void decNumberShow (const decNumber *); /* .. */
#endif
/* Useful macro */
/* Clear a structure (e.g., a decNumber) */
#define DEC_clear(d) memset(d, 0, sizeof(*d))
/* ------------------------------------------------------------------ */
/* decimal128FromNumber -- convert decNumber to decimal128 */
/* */
/* ds is the target decimal128 */
/* dn is the source number (assumed valid) */
/* set is the context, used only for reporting errors */
/* */
/* The set argument is used only for status reporting and for the */
/* rounding mode (used if the coefficient is more than DECIMAL128_Pmax*/
/* digits or an overflow is detected). If the exponent is out of the */
/* valid range then Overflow or Underflow will be raised. */
/* After Underflow a subnormal result is possible. */
/* */
/* DEC_Clamped is set if the number has to be 'folded down' to fit, */
/* by reducing its exponent and multiplying the coefficient by a */
/* power of ten, or if the exponent on a zero had to be clamped. */
/* ------------------------------------------------------------------ */
decimal128 *
decimal128FromNumber (decimal128 * d128, const decNumber * dn, decContext * set)
{
uInt status = 0; /* status accumulator */
Int pad = 0; /* coefficient pad digits */
decNumber dw; /* work */
decContext dc; /* .. */
uByte isneg = dn->bits & DECNEG; /* non-0 if original sign set */
uInt comb, exp; /* work */
/* If the number is finite, and has too many digits, or the exponent */
/* could be out of range then we reduce the number under the */
/* appropriate constraints */
if (!(dn->bits & DECSPECIAL))
{ /* not a special value */
Int ae = dn->exponent + dn->digits - 1; /* adjusted exponent */
if (dn->digits > DECIMAL128_Pmax /* too many digits */
|| ae > DECIMAL128_Emax /* likely overflow */
|| ae < DECIMAL128_Emin)
{ /* likely underflow */
decContextDefault (&dc, DEC_INIT_DECIMAL128); /* [no traps] */
dc.round = set->round; /* use supplied rounding */
decNumberPlus (&dw, dn, &dc); /* (round and check) */
/* [this changes -0 to 0, but it will be restored below] */
status |= dc.status; /* save status */
dn = &dw; /* use the work number */
}
/* [this could have pushed number to Infinity or zero, so this */
/* rounding must be done before we generate the decimal128] */
}
DEC_clear (d128); /* clean the target */
if (dn->bits & DECSPECIAL)
{ /* a special value */
uByte top; /* work */
if (dn->bits & DECINF)
top = DECIMAL_Inf;
else
{ /* sNaN or qNaN */
if ((*dn->lsu != 0 || dn->digits > 1) /* non-zero coefficient */
&& (dn->digits < DECIMAL128_Pmax))
{ /* coefficient fits */
decDensePackCoeff (dn, d128->bytes, sizeof (d128->bytes), 0);
}
if (dn->bits & DECNAN)
top = DECIMAL_NaN;
else
top = DECIMAL_sNaN;
}
d128->bytes[0] = top;
}
else if (decNumberIsZero (dn))
{ /* a zero */
/* set and clamp exponent */
if (dn->exponent < -DECIMAL128_Bias)
{
exp = 0;
status |= DEC_Clamped;
}
else
{
exp = dn->exponent + DECIMAL128_Bias; /* bias exponent */
if (exp > DECIMAL128_Ehigh)
{ /* top clamp */
exp = DECIMAL128_Ehigh;
status |= DEC_Clamped;
}
}
comb = (exp >> 9) & 0x18; /* combination field */
d128->bytes[0] = (uByte) (comb << 2);
exp &= 0xfff; /* remaining exponent bits */
decimal128SetExpCon (d128, exp);
}
else
{ /* non-zero finite number */
uInt msd; /* work */
/* we have a dn that fits, but it may need to be padded */
exp = (uInt) (dn->exponent + DECIMAL128_Bias); /* bias exponent */
if (exp > DECIMAL128_Ehigh)
{ /* fold-down case */
pad = exp - DECIMAL128_Ehigh;
exp = DECIMAL128_Ehigh; /* [to maximum] */
status |= DEC_Clamped;
}
decDensePackCoeff (dn, d128->bytes, sizeof (d128->bytes), pad);
/* save and clear the top digit */
msd = ((unsigned) d128->bytes[1] << 2) & 0x0c; /* top 2 bits */
msd |= ((unsigned) d128->bytes[2] >> 6); /* low 2 bits */
d128->bytes[1] &= 0xfc;
d128->bytes[2] &= 0x3f;
/* create the combination field */
if (msd >= 8)
comb = 0x18 | (msd & 0x01) | ((exp >> 11) & 0x06);
else
comb = (msd & 0x07) | ((exp >> 9) & 0x18);
d128->bytes[0] = (uByte) (comb << 2);
exp &= 0xfff; /* remaining exponent bits */
decimal128SetExpCon (d128, exp);
}
if (isneg)
decimal128SetSign (d128, 1);
if (status != 0)
decContextSetStatus (set, status); /* pass on status */
/* decimal128Show(d128); */
return d128;
}
/* ------------------------------------------------------------------ */
/* decimal128ToNumber -- convert decimal128 to decNumber */
/* d128 is the source decimal128 */
/* dn is the target number, with appropriate space */
/* No error is possible. */
/* ------------------------------------------------------------------ */
decNumber *
decimal128ToNumber (const decimal128 * d128, decNumber * dn)
{
uInt msd; /* coefficient MSD */
decimal128 wk; /* working copy, if needed */
uInt top = d128->bytes[0] & 0x7f; /* top byte, less sign bit */
decNumberZero (dn); /* clean target */
/* set the sign if negative */
if (decimal128Sign (d128))
dn->bits = DECNEG;
if (top >= 0x78)
{ /* is a special */
if ((top & 0x7c) == (DECIMAL_Inf & 0x7c))
dn->bits |= DECINF;
else if ((top & 0x7e) == (DECIMAL_NaN & 0x7e))
dn->bits |= DECNAN;
else
dn->bits |= DECSNAN;
msd = 0; /* no top digit */
}
else
{ /* have a finite number */
uInt comb = top >> 2; /* combination field */
uInt exp; /* exponent */
if (comb >= 0x18)
{
msd = 8 + (comb & 0x01);
exp = (comb & 0x06) << 11; /* MSBs */
}
else
{
msd = comb & 0x07;
exp = (comb & 0x18) << 9;
}
dn->exponent = exp + decimal128ExpCon (d128) - DECIMAL128_Bias; /* remove bias */
}
/* get the coefficient, unless infinite */
if (!(dn->bits & DECINF))
{
Int bunches = DECIMAL128_Pmax / 3; /* coefficient full bunches to convert */
Int odd = 0; /* assume MSD is 0 (no odd bunch) */
if (msd != 0)
{ /* coefficient has leading non-0 digit */
/* make a copy of the decimal128, with an extra bunch which has */
/* the top digit ready for conversion */
wk = *d128; /* take a copy */
wk.bytes[0] = 0; /* clear all but coecon */
wk.bytes[1] = 0; /* .. */
wk.bytes[2] &= 0x3f; /* .. */
wk.bytes[1] |= (msd >> 2); /* and prefix MSD */
wk.bytes[2] |= (msd << 6); /* .. */
odd++; /* indicate the extra */
d128 = &wk; /* use the work copy */
}
decDenseUnpackCoeff (d128->bytes, sizeof (d128->bytes), dn, bunches,
odd);
}
/* decNumberShow(dn); */
return dn;
}
/* ------------------------------------------------------------------ */
/* to-scientific-string -- conversion to numeric string */
/* to-engineering-string -- conversion to numeric string */
/* */
/* decimal128ToString(d128, string); */
/* decimal128ToEngString(d128, string); */
/* */
/* d128 is the decimal128 format number to convert */
/* string is the string where the result will be laid out */
/* */
/* string must be at least 24 characters */
/* */
/* No error is possible, and no status can be set. */
/* ------------------------------------------------------------------ */
char *
decimal128ToString (const decimal128 * d128, char *string)
{
decNumber dn; /* work */
decimal128ToNumber (d128, &dn);
decNumberToString (&dn, string);
return string;
}
char *
decimal128ToEngString (const decimal128 * d128, char *string)
{
decNumber dn; /* work */
decimal128ToNumber (d128, &dn);
decNumberToEngString (&dn, string);
return string;
}
/* ------------------------------------------------------------------ */
/* to-number -- conversion from numeric string */
/* */
/* decimal128FromString(result, string, set); */
/* */
/* result is the decimal128 format number which gets the result of */
/* the conversion */
/* *string is the character string which should contain a valid */
/* number (which may be a special value) */
/* set is the context */
/* */
/* The context is supplied to this routine is used for error handling */
/* (setting of status and traps) and for the rounding mode, only. */
/* If an error occurs, the result will be a valid decimal128 NaN. */
/* ------------------------------------------------------------------ */
decimal128 *
decimal128FromString (decimal128 * result, const char *string, decContext * set)
{
decContext dc; /* work */
decNumber dn; /* .. */
decContextDefault (&dc, DEC_INIT_DECIMAL128); /* no traps, please */
dc.round = set->round; /* use supplied rounding */
decNumberFromString (&dn, string, &dc); /* will round if needed */
decimal128FromNumber (result, &dn, &dc);
if (dc.status != 0)
{ /* something happened */
decContextSetStatus (set, dc.status); /* .. pass it on */
}
return result;
}
#if DECTRACE || DECCHECK
/* ------------------------------------------------------------------ */
/* decimal128Show -- display a single in hexadecimal [debug aid] */
/* d128 -- the number to show */
/* ------------------------------------------------------------------ */
/* Also shows sign/cob/expconfields extracted */
void
decimal128Show (const decimal128 * d128)
{
char buf[DECIMAL128_Bytes * 2 + 1];
Int i, j;
j = 0;
for (i = 0; i < DECIMAL128_Bytes; i++)
{
sprintf (&buf[j], "%02x", d128->bytes[i]);
j = j + 2;
}
printf (" D128> %s [S:%d Cb:%02x E:%d]\n", buf,
decimal128Sign (d128), decimal128Comb (d128),
decimal128ExpCon (d128));
}
#endif
|
