1 /* ------------------------------------------------------------------ */
2 /* Packed Decimal conversion module */
3 /* ------------------------------------------------------------------ */
4 /* Copyright (c) IBM Corporation, 2000, 2002. All rights reserved. */
5 /* */
6 /* This software is made available under the terms of the */
7 /* ICU License -- ICU 1.8.1 and later. */
8 /* */
9 /* The description and User's Guide ("The decNumber C Library") for */
10 /* this software is called decNumber.pdf. This document is */
11 /* available, together with arithmetic and format specifications, */
12 /* testcases, and Web links, at: http://www2.hursley.ibm.com/decimal */
13 /* */
14 /* Please send comments, suggestions, and corrections to the author: */
15 /* mfc@uk.ibm.com */
16 /* Mike Cowlishaw, IBM Fellow */
17 /* IBM UK, PO Box 31, Birmingham Road, Warwick CV34 5JL, UK */
18 /* ------------------------------------------------------------------ */
19 /* This module comprises the routines for Packed Decimal format */
20 /* numbers. Conversions are supplied to and from decNumber, which in */
21 /* turn supports: */
22 /* conversions to and from string */
23 /* arithmetic routines */
24 /* utilities. */
25 /* Conversions from decNumber to and from densely packed decimal */
26 /* formats are provided by the decimal32 through decimal128 modules. */
27 /* ------------------------------------------------------------------ */
28
29 #include <string.h> // for NULL
30 #if defined(_MSVC_)
31 #pragma warning(disable:4244) // [for win64]
32 #endif /*defined(_MSVC_)*/
33 #include "decNumber.h" // base number library
34 #include "decPacked.h" // packed decimal
35 #include "decNumberLocal.h" // decNumber local types, etc.
36
37 /* ------------------------------------------------------------------ */
38 /* decPackedFromNumber -- convert decNumber to BCD Packed Decimal */
39 /* */
40 /* bcd is the BCD bytes */
41 /* length is the length of the BCD array */
42 /* scale is the scale result */
43 /* dn is the decNumber */
44 /* returns bcd, or NULL if error */
45 /* */
46 /* The number is converted to a BCD packed decimal byte array, */
47 /* right aligned in the bcd array, whose length is indicated by the */
48 /* second parameter. The final 4-bit nibble in the array will be a */
49 /* sign nibble, C (1100) for + and D (1101) for -. Unused bytes and */
50 /* nibbles to the left of the number are set to 0. */
51 /* */
52 /* scale is set to the scale of the number (this is the exponent, */
53 /* negated). To force the number to a specified scale, first use the */
54 /* decNumberRescale routine, which will round and change the exponent */
55 /* as necessary. */
56 /* */
57 /* If there is an error (that is, the decNumber has too many digits */
58 /* to fit in length bytes, or it is a NaN or Infinity), NULL is */
59 /* returned and the bcd and scale results are unchanged. Otherwise */
60 /* bcd is returned. */
61 /* ------------------------------------------------------------------ */
decPackedFromNumber(uByte * bcd,Int length,Int * scale,const decNumber * dn)62 uByte * decPackedFromNumber(uByte *bcd, Int length, Int *scale,
63 const decNumber *dn) {
64 const Unit *up=dn->lsu; // Unit array pointer
65 uByte obyte, *out; // current output byte, and where it goes
66 Int indigs=dn->digits; // digits processed
67 uInt cut=DECDPUN; // downcounter per Unit
68 uInt u=*up; // work
69 uInt nib; // ..
70 #if DECDPUN<=4
71 uInt temp; // ..
72 #endif
73
74 if (dn->digits>length*2-1 // too long ..
75 ||(dn->bits & DECSPECIAL)) return NULL; // .. or special -- hopeless
76
77 if (dn->bits&DECNEG) obyte=DECPMINUS; // set the sign ..
78 else obyte=DECPPLUS;
79 *scale=-dn->exponent; // .. and scale
80
81 // loop from lowest (rightmost) byte
82 out=bcd+length-1; // -> final byte
83 for (; out>=bcd; out--) {
84 if (indigs>0) {
85 if (cut==0) {
86 up++;
87 u=*up;
88 cut=DECDPUN;
89 }
90 #if DECDPUN<=4
91 temp=(u*6554)>>16; // fast /10
92 nib=u-X10(temp);
93 u=temp;
94 #else
95 nib=u%10; // cannot use *6554 trick :-(
96 u=u/10;
97 #endif
98 obyte|=(nib<<4);
99 indigs--;
100 cut--;
101 }
102 *out=obyte;
103 obyte=0; // assume 0
104 if (indigs>0) {
105 if (cut==0) {
106 up++;
107 u=*up;
108 cut=DECDPUN;
109 }
110 #if DECDPUN<=4
111 temp=(u*6554)>>16; // as above
112 obyte=(uByte)(u-X10(temp));
113 u=temp;
114 #else
115 obyte=(uByte)(u%10);
116 u=u/10;
117 #endif
118 indigs--;
119 cut--;
120 }
121 } // loop
122
123 return bcd;
124 } // decPackedFromNumber
125
126 /* ------------------------------------------------------------------ */
127 /* decPackedToNumber -- convert BCD Packed Decimal to a decNumber */
128 /* */
129 /* bcd is the BCD bytes */
130 /* length is the length of the BCD array */
131 /* scale is the scale associated with the BCD integer */
132 /* dn is the decNumber [with space for length*2 digits] */
133 /* returns dn, or NULL if error */
134 /* */
135 /* The BCD packed decimal byte array, together with an associated */
136 /* scale, is converted to a decNumber. The BCD array is assumed full */
137 /* of digits, and must be ended by a 4-bit sign nibble in the least */
138 /* significant four bits of the final byte. */
139 /* */
140 /* The scale is used (negated) as the exponent of the decNumber. */
141 /* Note that zeros may have a sign and/or a scale. */
142 /* */
143 /* The decNumber structure is assumed to have sufficient space to */
144 /* hold the converted number (that is, up to length*2-1 digits), so */
145 /* no error is possible unless the adjusted exponent is out of range, */
146 /* no sign nibble was found, or a sign nibble was found before the */
147 /* final nibble. In these error cases, NULL is returned and the */
148 /* decNumber will be 0. */
149 /* ------------------------------------------------------------------ */
decPackedToNumber(const uByte * bcd,Int length,const Int * scale,decNumber * dn)150 decNumber * decPackedToNumber(const uByte *bcd, Int length,
151 const Int *scale, decNumber *dn) {
152 const uByte *last=bcd+length-1; // -> last byte
153 const uByte *first; // -> first non-zero byte
154 uInt nib; // work nibble
155 Unit *up=dn->lsu; // output pointer
156 Int digits; // digits count
157 Int cut=0; // phase of output
158
159 decNumberZero(dn); // default result
160 last=&bcd[length-1];
161 nib=*last & 0x0f; // get the sign
162 if (nib==DECPMINUS || nib==DECPMINUSALT) dn->bits=DECNEG;
163 else if (nib<=9) return NULL; // not a sign nibble
164
165 // skip leading zero bytes [final byte is always non-zero, due to sign]
166 for (first=bcd; *first==0;) first++;
167 digits=(last-first)*2+1; // calculate digits ..
168 if ((*first & 0xf0)==0) digits--; // adjust for leading zero nibble
169 if (digits!=0) dn->digits=digits; // count of actual digits [if 0,
170 // leave as 1]
171
172 // check the adjusted exponent; note that scale could be unbounded
173 dn->exponent=-*scale; // set the exponent
174 if (*scale>=0) { // usual case
175 if ((dn->digits-*scale-1)<-DECNUMMAXE) { // underflow
176 decNumberZero(dn);
177 return NULL;}
178 }
179 else { // -ve scale; +ve exponent
180 // need to be careful to avoid wrap, here, also BADINT case
181 if ((*scale<-DECNUMMAXE) // overflow even without digits
182 || ((dn->digits-*scale-1)>DECNUMMAXE)) { // overflow
183 decNumberZero(dn);
184 return NULL;}
185 }
186 if (digits==0) return dn; // result was zero
187
188 // copy the digits to the number's units, starting at the lsu
189 // [unrolled]
190 for (;;) { // forever
191 // left nibble first
192 nib=(unsigned)(*last & 0xf0)>>4;
193 // got a digit, in nib
194 if (nib>9) {decNumberZero(dn); return NULL;}
195
196 if (cut==0) *up=(Unit)nib;
197 else *up=(Unit)(*up+nib*powers[cut]);
198 digits--;
199 if (digits==0) break; // got them all
200 cut++;
201 if (cut==DECDPUN) {
202 up++;
203 cut=0;
204 }
205 last--; // ready for next
206 nib=*last & 0x0f; // get right nibble
207 if (nib>9) {decNumberZero(dn); return NULL;}
208
209 // got a digit, in nib
210 if (cut==0) *up=(Unit)nib;
211 else *up=(Unit)(*up+nib*powers[cut]);
212 digits--;
213 if (digits==0) break; // got them all
214 cut++;
215 if (cut==DECDPUN) {
216 up++;
217 cut=0;
218 }
219 } // forever
220
221 return dn;
222 } // decPackedToNumber
223
224