1 /* Utility functions for decimal floating point support via decNumber.
2 Copyright (C) 2005 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 2, 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 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
22 #include "decNumber.h" /* base number library */
23 #include "decNumberLocal.h" /* decNumber local types, etc. */
24 #include "decUtility.h" /* utility routines */
27 #include "coretypes.h"
30 /* ================================================================== */
31 /* Shared utility routines */
32 /* ================================================================== */
34 /* define and include the conversion tables to use */
35 #define DEC_BIN2DPD 1 /* used for all sizes */
41 #include "decDPD.h" /* lookup tables */
43 /* The maximum number of decNumberUnits we need for a working copy of */
44 /* the units array is the ceiling of digits/DECDPUN, where digits is */
45 /* the maximum number of digits in any of the formats for which this */
46 /* is used. We do not want to include decimal128.h, so, as a very */
47 /* special case, that number is defined here. */
49 #define DECMAXUNITS ((DECMAX754+DECDPUN-1)/DECDPUN)
51 /* ------------------------------------------------------------------ */
52 /* decDensePackCoeff -- densely pack coefficient into DPD form */
54 /* dn is the source number (assumed valid, max DECMAX754 digits) */
55 /* bytes is the target's byte array */
56 /* len is length of target format's byte array */
57 /* shift is the number of 0 digits to add on the right (normally 0) */
59 /* The coefficient must be known small enough to fit, and is filled */
60 /* in from the right (least significant first). Note that the full */
61 /* coefficient is copied, including the leading 'odd' digit. This */
62 /* digit is retrieved and packed into the combination field by the */
65 /* shift is used for 'fold-down' padding. */
67 /* No error is possible. */
68 /* ------------------------------------------------------------------ */
70 decDensePackCoeff (decNumber * dn, uByte * bytes, Int len, Int shift)
73 Int n; /* output bunch counter */
74 Int digits = dn->digits; /* digit countdown */
75 uInt dpd; /* densely packed decimal value */
76 uInt bin; /* binary value 0-999 */
77 uByte *bout; /* -> current output byte */
78 Unit *inu = dn->lsu; /* -> current input unit */
79 Unit uar[DECMAXUNITS]; /* working copy of units, iff shifted */
80 #if DECDPUN!=3 /* not fast path */
81 Unit in; /* current input unit */
85 { /* shift towards most significant required */
86 /* shift the units array to the left by pad digits and copy */
87 /* [this code is a special case of decShiftToMost, which could */
88 /* be used instead if exposed and the array were copied first] */
89 Unit *target, *source, *first; /* work */
90 uInt next = 0; /* work */
92 source = dn->lsu + D2U (digits) - 1; /* where msu comes from */
93 first = uar + D2U (digits + shift) - 1; /* where msu will end up */
94 target = uar + D2U (digits) - 1 + D2U (shift); /* where upper part of first cut goes */
96 cut = (DECDPUN - shift % DECDPUN) % DECDPUN;
97 for (; source >= dn->lsu; source--, target--)
99 /* split the source Unit and accumulate remainder for next */
100 uInt rem = *source % powers[cut];
101 next += *source / powers[cut];
103 *target = (Unit) next; /* write to target iff valid */
104 next = rem * powers[DECDPUN - cut]; /* save remainder for next Unit */
106 /* propagate remainder to one below and clear the rest */
107 for (; target >= uar; target--)
109 *target = (Unit) next;
112 digits += shift; /* add count (shift) of zeros added */
113 inu = uar; /* use units in working array */
116 /* densely pack the coefficient into the byte array, starting from
117 the right (optionally padded) */
118 bout = &bytes[len - 1]; /* rightmost result byte for phase */
120 #if DECDPUN!=3 /* not fast path */
121 in = *inu; /* prime */
122 cut = 0; /* at lowest digit */
123 bin = 0; /* [keep compiler quiet] */
126 for (n = 0; digits > 0; n++)
127 { /* each output bunch */
128 #if DECDPUN==3 /* fast path, 3-at-a-time */
129 bin = *inu; /* 3 ready for convert */
130 digits -= 3; /* [may go negative] */
131 inu++; /* may need another */
133 #else /* must collect digit-by-digit */
134 Unit dig; /* current digit */
135 Int j; /* digit-in-bunch count */
136 for (j = 0; j < 3; j++)
139 Unit temp = (Unit) ((uInt) (in * 6554) >> 16);
140 dig = (Unit) (in - X10 (temp));
156 break; /* [also protects *inu below] */
166 /* here we have 3 digits in bin, or have used all input digits */
170 /* write bunch (bcd) to byte array */
174 *bout = (uByte) dpd; /* [top 2 bits truncated] */
176 *bout = (uByte) (dpd >> 8);
179 *bout |= (uByte) (dpd << 2);
181 *bout = (uByte) (dpd >> 6);
184 *bout |= (uByte) (dpd << 4);
186 *bout = (uByte) (dpd >> 4);
189 *bout |= (uByte) (dpd << 6);
191 *bout = (uByte) (dpd >> 2);
199 /* ------------------------------------------------------------------ */
200 /* decDenseUnpackCoeff -- unpack a format's coefficient */
202 /* byte is the source's byte array */
203 /* len is length of the source's byte array */
204 /* dn is the target number, with 7, 16, or 34-digit space. */
205 /* bunches is the count of DPD groups in the decNumber (2, 5, or 11)*/
206 /* odd is 1 if there is a non-zero leading 10-bit group containing */
207 /* a single digit, 0 otherwise */
209 /* (This routine works on a copy of the number, if necessary, where */
210 /* an extra 10-bit group is prefixed to the coefficient continuation */
211 /* to hold the most significant digit if the latter is non-0.) */
213 /* dn->digits is set, but not the sign or exponent. */
214 /* No error is possible [the redundant 888 codes are allowed]. */
215 /* ------------------------------------------------------------------ */
217 decDenseUnpackCoeff (uByte * bytes, Int len, decNumber * dn,
218 Int bunches, Int odd)
220 uInt dpd = 0; /* collector for 10 bits */
222 uByte *bin; /* -> current input byte */
223 Unit *uout = dn->lsu; /* -> current output unit */
224 Unit out = 0; /* accumulator */
225 Int cut = 0; /* power of ten in current unit */
226 Unit *last = uout; /* will be unit containing msd */
228 uInt bcd; /* BCD result */
229 uInt nibble; /* work */
232 /* Expand the densely-packed integer, right to left */
233 bin = &bytes[len - 1]; /* next input byte to use */
234 for (n = 0; n < bunches + odd; n++)
235 { /* N bunches of 10 bits */
236 /* assemble the 10 bits */
242 dpd |= (*bin & 0x03) << 8;
245 dpd = (unsigned) *bin >> 2;
247 dpd |= (*bin & 0x0F) << 6;
250 dpd = (unsigned) *bin >> 4;
252 dpd |= (*bin & 0x3F) << 4;
255 dpd = (unsigned) *bin >> 6;
267 *uout = DPD2BIN[dpd]; /* convert 10 bits to binary 0-999 */
268 last = uout; /* record most significant unit */
272 #else /* DECDPUN!=3 */
274 { /* fastpath [e.g., leading zeros] */
276 for (; cut >= DECDPUN;)
285 bcd = DPD2BCD[dpd]; /* convert 10 bits to 12 bits BCD */
286 /* now split the 3 BCD nibbles into bytes, and accumulate into units */
287 /* If this is the last bunch and it is an odd one, we only have one */
288 /* nibble to handle [extras could overflow a Unit] */
289 nibble = bcd & 0x000f;
293 out = (Unit) (out + nibble * powers[cut]);
305 nibble = bcd & 0x00f0;
310 out = (Unit) (out + nibble * powers[cut]);
320 nibble = bcd & 0x0f00;
325 out = (Unit) (out + nibble * powers[cut]);
339 *uout = out; /* write out final unit */
341 /* here, last points to the most significant unit with digits */
342 /* we need to inspect it to get final digits count */
343 dn->digits = (last - dn->lsu) * DECDPUN; /* floor of digits */
344 for (cut = 0; cut < DECDPUN; cut++)
346 if (*last < powers[cut])
351 dn->digits++; /* zero has one digit */
356 __dec_byte_swap (unsigned long in)
359 unsigned char *p = (unsigned char *) &out;