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/* ------------------------------------------------------------------ */
/* Packed Decimal conversion module */
/* ------------------------------------------------------------------ */
/* Copyright (c) IBM Corporation, 2000, 2002. All rights reserved. */
/* */
/* This software is made available under the terms of the */
/* ICU License -- ICU 1.8.1 and later. */
/* */
/* The description and User's Guide ("The decNumber C Library") for */
/* this software is called decNumber.pdf. This document is */
/* available, together with arithmetic and format specifications, */
/* testcases, and Web links, on the General Decimal Arithmetic page. */
/* */
/* Please send comments, suggestions, and corrections to the author: */
/* mfc@uk.ibm.com */
/* Mike Cowlishaw, IBM Fellow */
/* IBM UK, PO Box 31, Birmingham Road, Warwick CV34 5JL, UK */
/* ------------------------------------------------------------------ */
/* 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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