/* ------------------------------------------------------------------ */ /* 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 // 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