2017-12-07 Vladimir Makarov <vmakarov@redhat.com>
[official-gcc.git] / libdecnumber / decPacked.c
blobbe1221ada2dbd71ee2aef3dade000459c9797d7b
1 /* Packed decimal conversion module for the decNumber C Library.
2 Copyright (C) 2007-2017 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
10 version.
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
15 for more details.
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 /* Packed Decimal conversion module */
28 /* ------------------------------------------------------------------ */
29 /* This module comprises the routines for Packed Decimal format */
30 /* numbers. Conversions are supplied to and from decNumber, which in */
31 /* turn supports: */
32 /* conversions to and from string */
33 /* arithmetic routines */
34 /* utilities. */
35 /* Conversions from decNumber to and from densely packed decimal */
36 /* formats are provided by the decimal32 through decimal128 modules. */
37 /* ------------------------------------------------------------------ */
39 #include <string.h> /* for NULL */
40 #include "decNumber.h" /* base number library */
41 #include "decPacked.h" /* packed decimal */
42 #include "decNumberLocal.h" /* decNumber local types, etc. */
44 /* ------------------------------------------------------------------ */
45 /* decPackedFromNumber -- convert decNumber to BCD Packed Decimal */
46 /* */
47 /* bcd is the BCD bytes */
48 /* length is the length of the BCD array */
49 /* scale is the scale result */
50 /* dn is the decNumber */
51 /* returns bcd, or NULL if error */
52 /* */
53 /* The number is converted to a BCD packed decimal byte array, */
54 /* right aligned in the bcd array, whose length is indicated by the */
55 /* second parameter. The final 4-bit nibble in the array will be a */
56 /* sign nibble, C (1100) for + and D (1101) for -. Unused bytes and */
57 /* nibbles to the left of the number are set to 0. */
58 /* */
59 /* scale is set to the scale of the number (this is the exponent, */
60 /* negated). To force the number to a specified scale, first use the */
61 /* decNumberRescale routine, which will round and change the exponent */
62 /* as necessary. */
63 /* */
64 /* If there is an error (that is, the decNumber has too many digits */
65 /* to fit in length bytes, or it is a NaN or Infinity), NULL is */
66 /* returned and the bcd and scale results are unchanged. Otherwise */
67 /* bcd is returned. */
68 /* ------------------------------------------------------------------ */
69 uByte * decPackedFromNumber(uByte *bcd, Int length, Int *scale,
70 const decNumber *dn) {
71 const Unit *up=dn->lsu; /* Unit array pointer */
72 uByte obyte, *out; /* current output byte, and where it goes */
73 Int indigs=dn->digits; /* digits processed */
74 uInt cut=DECDPUN; /* downcounter per Unit */
75 uInt u=*up; /* work */
76 uInt nib; /* .. */
77 #if DECDPUN<=4
78 uInt temp; /* .. */
79 #endif
81 if (dn->digits>length*2-1 /* too long .. */
82 ||(dn->bits & DECSPECIAL)) return NULL; /* .. or special -- hopeless */
84 if (dn->bits&DECNEG) obyte=DECPMINUS; /* set the sign .. */
85 else obyte=DECPPLUS;
86 *scale=-dn->exponent; /* .. and scale */
88 /* loop from lowest (rightmost) byte */
89 out=bcd+length-1; /* -> final byte */
90 for (; out>=bcd; out--) {
91 if (indigs>0) {
92 if (cut==0) {
93 up++;
94 u=*up;
95 cut=DECDPUN;
97 #if DECDPUN<=4
98 temp=(u*6554)>>16; /* fast /10 */
99 nib=u-X10(temp);
100 u=temp;
101 #else
102 nib=u%10; /* cannot use *6554 trick :-( */
103 u=u/10;
104 #endif
105 obyte|=(nib<<4);
106 indigs--;
107 cut--;
109 *out=obyte;
110 obyte=0; /* assume 0 */
111 if (indigs>0) {
112 if (cut==0) {
113 up++;
114 u=*up;
115 cut=DECDPUN;
117 #if DECDPUN<=4
118 temp=(u*6554)>>16; /* as above */
119 obyte=(uByte)(u-X10(temp));
120 u=temp;
121 #else
122 obyte=(uByte)(u%10);
123 u=u/10;
124 #endif
125 indigs--;
126 cut--;
128 } /* loop */
130 return bcd;
131 } /* decPackedFromNumber */
133 /* ------------------------------------------------------------------ */
134 /* decPackedToNumber -- convert BCD Packed Decimal to a decNumber */
135 /* */
136 /* bcd is the BCD bytes */
137 /* length is the length of the BCD array */
138 /* scale is the scale associated with the BCD integer */
139 /* dn is the decNumber [with space for length*2 digits] */
140 /* returns dn, or NULL if error */
141 /* */
142 /* The BCD packed decimal byte array, together with an associated */
143 /* scale, is converted to a decNumber. The BCD array is assumed full */
144 /* of digits, and must be ended by a 4-bit sign nibble in the least */
145 /* significant four bits of the final byte. */
146 /* */
147 /* The scale is used (negated) as the exponent of the decNumber. */
148 /* Note that zeros may have a sign and/or a scale. */
149 /* */
150 /* The decNumber structure is assumed to have sufficient space to */
151 /* hold the converted number (that is, up to length*2-1 digits), so */
152 /* no error is possible unless the adjusted exponent is out of range, */
153 /* no sign nibble was found, or a sign nibble was found before the */
154 /* final nibble. In these error cases, NULL is returned and the */
155 /* decNumber will be 0. */
156 /* ------------------------------------------------------------------ */
157 decNumber * decPackedToNumber(const uByte *bcd, Int length,
158 const Int *scale, decNumber *dn) {
159 const uByte *last=bcd+length-1; /* -> last byte */
160 const uByte *first; /* -> first non-zero byte */
161 uInt nib; /* work nibble */
162 Unit *up=dn->lsu; /* output pointer */
163 Int digits; /* digits count */
164 Int cut=0; /* phase of output */
166 decNumberZero(dn); /* default result */
167 last=&bcd[length-1];
168 nib=*last & 0x0f; /* get the sign */
169 if (nib==DECPMINUS || nib==DECPMINUSALT) dn->bits=DECNEG;
170 else if (nib<=9) return NULL; /* not a sign nibble */
172 /* skip leading zero bytes [final byte is always non-zero, due to sign] */
173 for (first=bcd; *first==0;) first++;
174 digits=(last-first)*2+1; /* calculate digits .. */
175 if ((*first & 0xf0)==0) digits--; /* adjust for leading zero nibble */
176 if (digits!=0) dn->digits=digits; /* count of actual digits [if 0, */
177 /* leave as 1] */
179 /* check the adjusted exponent; note that scale could be unbounded */
180 dn->exponent=-*scale; /* set the exponent */
181 if (*scale>=0) { /* usual case */
182 if ((dn->digits-*scale-1)<-DECNUMMAXE) { /* underflow */
183 decNumberZero(dn);
184 return NULL;}
186 else { /* -ve scale; +ve exponent */
187 /* need to be careful to avoid wrap, here, also BADINT case */
188 if ((*scale<-DECNUMMAXE) /* overflow even without digits */
189 || ((dn->digits-*scale-1)>DECNUMMAXE)) { /* overflow */
190 decNumberZero(dn);
191 return NULL;}
193 if (digits==0) return dn; /* result was zero */
195 /* copy the digits to the number's units, starting at the lsu */
196 /* [unrolled] */
197 for (;;) { /* forever */
198 /* left nibble first */
199 nib=(unsigned)(*last & 0xf0)>>4;
200 /* got a digit, in nib */
201 if (nib>9) {decNumberZero(dn); return NULL;}
203 if (cut==0) *up=(Unit)nib;
204 else *up=(Unit)(*up+nib*DECPOWERS[cut]);
205 digits--;
206 if (digits==0) break; /* got them all */
207 cut++;
208 if (cut==DECDPUN) {
209 up++;
210 cut=0;
212 last--; /* ready for next */
213 nib=*last & 0x0f; /* get right nibble */
214 if (nib>9) {decNumberZero(dn); return NULL;}
216 /* got a digit, in nib */
217 if (cut==0) *up=(Unit)nib;
218 else *up=(Unit)(*up+nib*DECPOWERS[cut]);
219 digits--;
220 if (digits==0) break; /* got them all */
221 cut++;
222 if (cut==DECDPUN) {
223 up++;
224 cut=0;
226 } /* forever */
228 return dn;
229 } /* decPackedToNumber */