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Diffstat (limited to 'libdecnumber/decPacked.c')
| -rw-r--r-- | libdecnumber/decPacked.c | 235 |
1 files changed, 235 insertions, 0 deletions
diff --git a/libdecnumber/decPacked.c b/libdecnumber/decPacked.c new file mode 100644 index 0000000..2b912fe --- /dev/null +++ b/libdecnumber/decPacked.c @@ -0,0 +1,235 @@ +/* Packed decimal conversion module for the decNumber C Library. + Copyright (C) 2007 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. + + In addition to the permissions in the GNU General Public License, + the Free Software Foundation gives you unlimited permission to link + the compiled version of this file into combinations with other + programs, and to distribute those combinations without any + restriction coming from the use of this file. (The General Public + License restrictions do apply in other respects; for example, they + cover modification of the file, and distribution when not linked + into a combine executable.) + + 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. */ + +/* ------------------------------------------------------------------ */ +/* Packed Decimal conversion module */ +/* ------------------------------------------------------------------ */ +/* This module comprises the routines for Packed Decimal format */ +/* numbers. Conversions are supplied to and from decNumber, which in */ +/* turn supports: */ +/* conversions to and from string */ +/* arithmetic routines */ +/* utilities. */ +/* Conversions from decNumber to and from densely packed decimal */ +/* formats are provided by the decimal32 through decimal128 modules. */ +/* ------------------------------------------------------------------ */ + +#include <string.h> /* for NULL */ +#include "decNumber.h" /* base number library */ +#include "decPacked.h" /* packed decimal */ +#include "decNumberLocal.h" /* decNumber local types, etc. */ + +/* ------------------------------------------------------------------ */ +/* decPackedFromNumber -- convert decNumber to BCD Packed Decimal */ +/* */ +/* bcd is the BCD bytes */ +/* length is the length of the BCD array */ +/* scale is the scale result */ +/* dn is the decNumber */ +/* returns bcd, or NULL if error */ +/* */ +/* The number is converted to a BCD packed decimal byte array, */ +/* right aligned in the bcd array, whose length is indicated by the */ +/* second parameter. The final 4-bit nibble in the array will be a */ +/* sign nibble, C (1100) for + and D (1101) for -. Unused bytes and */ +/* nibbles to the left of the number are set to 0. */ +/* */ +/* scale is set to the scale of the number (this is the exponent, */ +/* negated). To force the number to a specified scale, first use the */ +/* decNumberRescale routine, which will round and change the exponent */ +/* as necessary. */ +/* */ +/* If there is an error (that is, the decNumber has too many digits */ +/* to fit in length bytes, or it is a NaN or Infinity), NULL is */ +/* returned and the bcd and scale results are unchanged. Otherwise */ +/* bcd is returned. */ +/* ------------------------------------------------------------------ */ +uByte * decPackedFromNumber(uByte *bcd, Int length, Int *scale, + const decNumber *dn) { + const Unit *up=dn->lsu; /* Unit array pointer */ + uByte obyte, *out; /* current output byte, and where it goes */ + Int indigs=dn->digits; /* digits processed */ + uInt cut=DECDPUN; /* downcounter per Unit */ + uInt u=*up; /* work */ + uInt nib; /* .. */ + #if DECDPUN<=4 + uInt temp; /* .. */ + #endif + + if (dn->digits>length*2-1 /* too long .. */ + ||(dn->bits & DECSPECIAL)) return NULL; /* .. or special -- hopeless */ + + if (dn->bits&DECNEG) obyte=DECPMINUS; /* set the sign .. */ + else obyte=DECPPLUS; + *scale=-dn->exponent; /* .. and scale */ + + /* loop from lowest (rightmost) byte */ + out=bcd+length-1; /* -> final byte */ + for (; out>=bcd; out--) { + if (indigs>0) { + if (cut==0) { + up++; + u=*up; + cut=DECDPUN; + } + #if DECDPUN<=4 + temp=(u*6554)>>16; /* fast /10 */ + nib=u-X10(temp); + u=temp; + #else + nib=u%10; /* cannot use *6554 trick :-( */ + u=u/10; + #endif + obyte|=(nib<<4); + indigs--; + cut--; + } + *out=obyte; + obyte=0; /* assume 0 */ + if (indigs>0) { + if (cut==0) { + up++; + u=*up; + cut=DECDPUN; + } + #if DECDPUN<=4 + temp=(u*6554)>>16; /* as above */ + obyte=(uByte)(u-X10(temp)); + u=temp; + #else + obyte=(uByte)(u%10); + u=u/10; + #endif + indigs--; + cut--; + } + } /* loop */ + + return bcd; + } /* decPackedFromNumber */ + +/* ------------------------------------------------------------------ */ +/* decPackedToNumber -- convert BCD Packed Decimal to a decNumber */ +/* */ +/* bcd is the BCD bytes */ +/* length is the length of the BCD array */ +/* scale is the scale associated with the BCD integer */ +/* dn is the decNumber [with space for length*2 digits] */ +/* returns dn, or NULL if error */ +/* */ +/* The BCD packed decimal byte array, together with an associated */ +/* scale, is converted to a decNumber. The BCD array is assumed full */ +/* of digits, and must be ended by a 4-bit sign nibble in the least */ +/* significant four bits of the final byte. */ +/* */ +/* The scale is used (negated) as the exponent of the decNumber. */ +/* Note that zeros may have a sign and/or a scale. */ +/* */ +/* The decNumber structure is assumed to have sufficient space to */ +/* hold the converted number (that is, up to length*2-1 digits), so */ +/* no error is possible unless the adjusted exponent is out of range, */ +/* no sign nibble was found, or a sign nibble was found before the */ +/* final nibble. In these error cases, NULL is returned and the */ +/* decNumber will be 0. */ +/* ------------------------------------------------------------------ */ +decNumber * decPackedToNumber(const uByte *bcd, Int length, + const Int *scale, decNumber *dn) { + const uByte *last=bcd+length-1; /* -> last byte */ + const uByte *first; /* -> first non-zero byte */ + uInt nib; /* work nibble */ + Unit *up=dn->lsu; /* output pointer */ + Int digits; /* digits count */ + Int cut=0; /* phase of output */ + + decNumberZero(dn); /* default result */ + last=&bcd[length-1]; + nib=*last & 0x0f; /* get the sign */ + if (nib==DECPMINUS || nib==DECPMINUSALT) dn->bits=DECNEG; + else if (nib<=9) return NULL; /* not a sign nibble */ + + /* skip leading zero bytes [final byte is always non-zero, due to sign] */ + for (first=bcd; *first==0;) first++; + digits=(last-first)*2+1; /* calculate digits .. */ + if ((*first & 0xf0)==0) digits--; /* adjust for leading zero nibble */ + if (digits!=0) dn->digits=digits; /* count of actual digits [if 0, */ + /* leave as 1] */ + + /* check the adjusted exponent; note that scale could be unbounded */ + dn->exponent=-*scale; /* set the exponent */ + if (*scale>=0) { /* usual case */ + if ((dn->digits-*scale-1)<-DECNUMMAXE) { /* underflow */ + decNumberZero(dn); + return NULL;} + } + else { /* -ve scale; +ve exponent */ + /* need to be careful to avoid wrap, here, also BADINT case */ + if ((*scale<-DECNUMMAXE) /* overflow even without digits */ + || ((dn->digits-*scale-1)>DECNUMMAXE)) { /* overflow */ + decNumberZero(dn); + return NULL;} + } + if (digits==0) return dn; /* result was zero */ + + /* copy the digits to the number's units, starting at the lsu */ + /* [unrolled] */ + for (;;) { /* forever */ + /* left nibble first */ + nib=(unsigned)(*last & 0xf0)>>4; + /* got a digit, in nib */ + if (nib>9) {decNumberZero(dn); return NULL;} + + if (cut==0) *up=(Unit)nib; + else *up=(Unit)(*up+nib*DECPOWERS[cut]); + digits--; + if (digits==0) break; /* got them all */ + cut++; + if (cut==DECDPUN) { + up++; + cut=0; + } + last--; /* ready for next */ + nib=*last & 0x0f; /* get right nibble */ + if (nib>9) {decNumberZero(dn); return NULL;} + + /* got a digit, in nib */ + if (cut==0) *up=(Unit)nib; + else *up=(Unit)(*up+nib*DECPOWERS[cut]); + digits--; + if (digits==0) break; /* got them all */ + cut++; + if (cut==DECDPUN) { + up++; + cut=0; + } + } /* forever */ + + return dn; + } /* decPackedToNumber */ + |