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gcc/libdecnumber/decPacked.c
Jakub Jelinek 99dee82307 Update copyright years.
2021-01-04 10:26:59 +01:00

231 lines
8.5 KiB
C
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/* Packed decimal conversion module for the decNumber C Library.
Copyright (C) 2007-2021 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 3, 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.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
/* ------------------------------------------------------------------ */
/* 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 */
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