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jeremybenn |
/* Packed decimal conversion module for the decNumber C Library.
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Copyright (C) 2007 Free Software Foundation, Inc.
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Contributed by IBM Corporation. Author Mike Cowlishaw.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 2, or (at your option) any later
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version.
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In addition to the permissions in the GNU General Public License,
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the Free Software Foundation gives you unlimited permission to link
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the compiled version of this file into combinations with other
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programs, and to distribute those combinations without any
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restriction coming from the use of this file. (The General Public
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License restrictions do apply in other respects; for example, they
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cover modification of the file, and distribution when not linked
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into a combine executable.)
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING. If not, write to the Free
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Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301, USA. */
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/* ------------------------------------------------------------------ */
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/* Packed Decimal conversion module */
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/* ------------------------------------------------------------------ */
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/* This module comprises the routines for Packed Decimal format */
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/* numbers. Conversions are supplied to and from decNumber, which in */
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/* turn supports: */
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/* conversions to and from string */
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/* arithmetic routines */
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/* utilities. */
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/* Conversions from decNumber to and from densely packed decimal */
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/* formats are provided by the decimal32 through decimal128 modules. */
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/* ------------------------------------------------------------------ */
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#include <string.h> /* for NULL */
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#include "decNumber.h" /* base number library */
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#include "decPacked.h" /* packed decimal */
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#include "decNumberLocal.h" /* decNumber local types, etc. */
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/* ------------------------------------------------------------------ */
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/* decPackedFromNumber -- convert decNumber to BCD Packed Decimal */
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/* */
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/* bcd is the BCD bytes */
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/* length is the length of the BCD array */
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/* scale is the scale result */
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/* dn is the decNumber */
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/* returns bcd, or NULL if error */
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/* */
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/* The number is converted to a BCD packed decimal byte array, */
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/* right aligned in the bcd array, whose length is indicated by the */
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/* second parameter. The final 4-bit nibble in the array will be a */
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/* sign nibble, C (1100) for + and D (1101) for -. Unused bytes and */
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/* nibbles to the left of the number are set to 0. */
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/* */
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/* scale is set to the scale of the number (this is the exponent, */
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/* negated). To force the number to a specified scale, first use the */
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/* decNumberRescale routine, which will round and change the exponent */
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/* as necessary. */
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/* */
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/* If there is an error (that is, the decNumber has too many digits */
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/* to fit in length bytes, or it is a NaN or Infinity), NULL is */
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/* returned and the bcd and scale results are unchanged. Otherwise */
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/* bcd is returned. */
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/* ------------------------------------------------------------------ */
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uByte * decPackedFromNumber(uByte *bcd, Int length, Int *scale,
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const decNumber *dn) {
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const Unit *up=dn->lsu; /* Unit array pointer */
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uByte obyte, *out; /* current output byte, and where it goes */
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Int indigs=dn->digits; /* digits processed */
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uInt cut=DECDPUN; /* downcounter per Unit */
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uInt u=*up; /* work */
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uInt nib; /* .. */
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#if DECDPUN<=4
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uInt temp; /* .. */
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#endif
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if (dn->digits>length*2-1 /* too long .. */
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||(dn->bits & DECSPECIAL)) return NULL; /* .. or special -- hopeless */
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if (dn->bits&DECNEG) obyte=DECPMINUS; /* set the sign .. */
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else obyte=DECPPLUS;
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*scale=-dn->exponent; /* .. and scale */
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/* loop from lowest (rightmost) byte */
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out=bcd+length-1; /* -> final byte */
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for (; out>=bcd; out--) {
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if (indigs>0) {
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if (cut==0) {
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up++;
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u=*up;
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cut=DECDPUN;
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}
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#if DECDPUN<=4
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temp=(u*6554)>>16; /* fast /10 */
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nib=u-X10(temp);
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u=temp;
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#else
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nib=u%10; /* cannot use *6554 trick :-( */
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u=u/10;
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#endif
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obyte|=(nib<<4);
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indigs--;
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cut--;
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}
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*out=obyte;
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obyte=0; /* assume 0 */
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if (indigs>0) {
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if (cut==0) {
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up++;
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u=*up;
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cut=DECDPUN;
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}
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#if DECDPUN<=4
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temp=(u*6554)>>16; /* as above */
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obyte=(uByte)(u-X10(temp));
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u=temp;
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#else
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obyte=(uByte)(u%10);
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u=u/10;
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#endif
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indigs--;
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cut--;
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}
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} /* loop */
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return bcd;
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} /* decPackedFromNumber */
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/* ------------------------------------------------------------------ */
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/* decPackedToNumber -- convert BCD Packed Decimal to a decNumber */
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/* */
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/* bcd is the BCD bytes */
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/* length is the length of the BCD array */
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/* scale is the scale associated with the BCD integer */
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/* dn is the decNumber [with space for length*2 digits] */
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/* returns dn, or NULL if error */
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/* */
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/* The BCD packed decimal byte array, together with an associated */
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/* scale, is converted to a decNumber. The BCD array is assumed full */
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/* of digits, and must be ended by a 4-bit sign nibble in the least */
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/* significant four bits of the final byte. */
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/* */
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/* The scale is used (negated) as the exponent of the decNumber. */
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/* Note that zeros may have a sign and/or a scale. */
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/* */
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/* The decNumber structure is assumed to have sufficient space to */
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/* hold the converted number (that is, up to length*2-1 digits), so */
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/* no error is possible unless the adjusted exponent is out of range, */
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/* no sign nibble was found, or a sign nibble was found before the */
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/* final nibble. In these error cases, NULL is returned and the */
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/* decNumber will be 0. */
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/* ------------------------------------------------------------------ */
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decNumber * decPackedToNumber(const uByte *bcd, Int length,
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const Int *scale, decNumber *dn) {
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const uByte *last=bcd+length-1; /* -> last byte */
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const uByte *first; /* -> first non-zero byte */
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uInt nib; /* work nibble */
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Unit *up=dn->lsu; /* output pointer */
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Int digits; /* digits count */
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Int cut=0; /* phase of output */
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decNumberZero(dn); /* default result */
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last=&bcd[length-1];
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nib=*last & 0x0f; /* get the sign */
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if (nib==DECPMINUS || nib==DECPMINUSALT) dn->bits=DECNEG;
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else if (nib<=9) return NULL; /* not a sign nibble */
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/* skip leading zero bytes [final byte is always non-zero, due to sign] */
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for (first=bcd; *first==0;) first++;
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digits=(last-first)*2+1; /* calculate digits .. */
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if ((*first & 0xf0)==0) digits--; /* adjust for leading zero nibble */
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if (digits!=0) dn->digits=digits; /* count of actual digits [if 0, */
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/* leave as 1] */
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/* check the adjusted exponent; note that scale could be unbounded */
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dn->exponent=-*scale; /* set the exponent */
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if (*scale>=0) { /* usual case */
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if ((dn->digits-*scale-1)<-DECNUMMAXE) { /* underflow */
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decNumberZero(dn);
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return NULL;}
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}
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else { /* -ve scale; +ve exponent */
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/* need to be careful to avoid wrap, here, also BADINT case */
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if ((*scale<-DECNUMMAXE) /* overflow even without digits */
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|| ((dn->digits-*scale-1)>DECNUMMAXE)) { /* overflow */
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decNumberZero(dn);
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return NULL;}
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}
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if (digits==0) return dn; /* result was zero */
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/* copy the digits to the number's units, starting at the lsu */
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/* [unrolled] */
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for (;;) { /* forever */
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/* left nibble first */
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nib=(unsigned)(*last & 0xf0)>>4;
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/* got a digit, in nib */
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if (nib>9) {decNumberZero(dn); return NULL;}
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if (cut==0) *up=(Unit)nib;
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else *up=(Unit)(*up+nib*DECPOWERS[cut]);
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digits--;
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if (digits==0) break; /* got them all */
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cut++;
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if (cut==DECDPUN) {
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up++;
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cut=0;
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}
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last--; /* ready for next */
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nib=*last & 0x0f; /* get right nibble */
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if (nib>9) {decNumberZero(dn); return NULL;}
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/* got a digit, in nib */
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if (cut==0) *up=(Unit)nib;
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else *up=(Unit)(*up+nib*DECPOWERS[cut]);
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digits--;
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if (digits==0) break; /* got them all */
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cut++;
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if (cut==DECDPUN) {
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up++;
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cut=0;
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}
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} /* forever */
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return dn;
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} /* decPackedToNumber */
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