/* ------------------------------------------------------------------ */ /* Decimal 64-bit format module */ /* ------------------------------------------------------------------ */ /* Copyright (c) IBM Corporation, 2000, 2009. 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 decimal64 format numbers. */ /* Conversions are supplied to and from decNumber and String. */ /* */ /* This is used when decNumber provides operations, either for all */ /* operations or as a proxy between decNumber and decSingle. */ /* */ /* Error handling is the same as decNumber (qv.). */ /* ------------------------------------------------------------------ */ #include // [for memset/memcpy] #include // [for printf] #define DECNUMDIGITS 16 // make decNumbers with space for 16 #include "decNumber/decNumber.h" // base number library #include "decNumber/decNumberLocal.h" // decNumber local types, etc. #include "decNumber/decimal64.h" // our primary include /* Utility routines and tables [in decimal64.c]; externs for C++ */ // DPD2BIN and the reverse are renamed to prevent link-time conflict // if decQuad is also built in the same executable #define DPD2BIN DPD2BINx #define BIN2DPD BIN2DPDx extern const uInt COMBEXP[32], COMBMSD[32]; extern const uShort DPD2BIN[1024]; extern const uShort BIN2DPD[1000]; extern const uByte BIN2CHAR[4001]; extern void decDigitsFromDPD(decNumber *, const uInt *, Int); extern void decDigitsToDPD(const decNumber *, uInt *, Int); #if DECTRACE || DECCHECK void decimal64Show(const decimal64 *); // for debug extern void decNumberShow(const decNumber *); // .. #endif /* Useful macro */ // Clear a structure (e.g., a decNumber) #define DEC_clear(d) memset(d, 0, sizeof(*d)) /* define and include the tables to use for conversions */ #define DEC_BIN2CHAR 1 #define DEC_DPD2BIN 1 #define DEC_BIN2DPD 1 // used for all sizes #include "decNumber/decDPD.h" // lookup tables /* ------------------------------------------------------------------ */ /* decimal64FromNumber -- convert decNumber to decimal64 */ /* */ /* ds is the target decimal64 */ /* dn is the source number (assumed valid) */ /* set is the context, used only for reporting errors */ /* */ /* The set argument is used only for status reporting and for the */ /* rounding mode (used if the coefficient is more than DECIMAL64_Pmax */ /* digits or an overflow is detected). If the exponent is out of the */ /* valid range then Overflow or Underflow will be raised. */ /* After Underflow a subnormal result is possible. */ /* */ /* DEC_Clamped is set if the number has to be 'folded down' to fit, */ /* by reducing its exponent and multiplying the coefficient by a */ /* power of ten, or if the exponent on a zero had to be clamped. */ /* ------------------------------------------------------------------ */ decimal64 * decimal64FromNumber(decimal64 *d64, const decNumber *dn, decContext *set) { uInt status=0; // status accumulator Int ae; // adjusted exponent decNumber dw; // work decContext dc; // .. uInt comb, exp; // .. uInt uiwork; // for macros uInt targar[2]={0, 0}; // target 64-bit #define targhi targar[1] // name the word with the sign #define targlo targar[0] // and the other // If the number has too many digits, or the exponent could be // out of range then reduce the number under the appropriate // constraints. This could push the number to Infinity or zero, // so this check and rounding must be done before generating the // decimal64] ae=dn->exponent+dn->digits-1; // [0 if special] if (dn->digits>DECIMAL64_Pmax // too many digits || ae>DECIMAL64_Emax // likely overflow || aeround; // use supplied rounding decNumberPlus(&dw, dn, &dc); // (round and check) // [this changes -0 to 0, so enforce the sign...] dw.bits|=dn->bits&DECNEG; status=dc.status; // save status dn=&dw; // use the work number } // maybe out of range if (dn->bits&DECSPECIAL) { // a special value if (dn->bits&DECINF) targhi=DECIMAL_Inf<<24; else { // sNaN or qNaN if ((*dn->lsu!=0 || dn->digits>1) // non-zero coefficient && (dn->digitsbits&DECNAN) targhi|=DECIMAL_NaN<<24; else targhi|=DECIMAL_sNaN<<24; } // a NaN } // special else { // is finite if (decNumberIsZero(dn)) { // is a zero // set and clamp exponent if (dn->exponent<-DECIMAL64_Bias) { exp=0; // low clamp status|=DEC_Clamped; } else { exp=dn->exponent+DECIMAL64_Bias; // bias exponent if (exp>DECIMAL64_Ehigh) { // top clamp exp=DECIMAL64_Ehigh; status|=DEC_Clamped; } } comb=(exp>>5) & 0x18; // msd=0, exp top 2 bits .. } else { // non-zero finite number uInt msd; // work Int pad=0; // coefficient pad digits // the dn is known to fit, but it may need to be padded exp=(uInt)(dn->exponent+DECIMAL64_Bias); // bias exponent if (exp>DECIMAL64_Ehigh) { // fold-down case pad=exp-DECIMAL64_Ehigh; exp=DECIMAL64_Ehigh; // [to maximum] status|=DEC_Clamped; } // fastpath common case if (DECDPUN==3 && pad==0) { uInt dpd[6]={0,0,0,0,0,0}; uInt i; Int d=dn->digits; for (i=0; d>0; i++, d-=3) dpd[i]=BIN2DPD[dn->lsu[i]]; targlo =dpd[0]; targlo|=dpd[1]<<10; targlo|=dpd[2]<<20; if (dn->digits>6) { targlo|=dpd[3]<<30; targhi =dpd[3]>>2; targhi|=dpd[4]<<8; } msd=dpd[5]; // [did not really need conversion] } else { // general case decDigitsToDPD(dn, targar, pad); // save and clear the top digit msd=targhi>>18; targhi&=0x0003ffff; } // create the combination field if (msd>=8) comb=0x18 | ((exp>>7) & 0x06) | (msd & 0x01); else comb=((exp>>5) & 0x18) | msd; } targhi|=comb<<26; // add combination field .. targhi|=(exp&0xff)<<18; // .. and exponent continuation } // finite if (dn->bits&DECNEG) targhi|=0x80000000; // add sign bit // now write to storage; this is now always endian if (DECLITEND) { // lo int then hi UBFROMUI(d64->bytes, targar[0]); UBFROMUI(d64->bytes+4, targar[1]); } else { // hi int then lo UBFROMUI(d64->bytes, targar[1]); UBFROMUI(d64->bytes+4, targar[0]); } if (status!=0) decContextSetStatus(set, status); // pass on status // decimal64Show(d64); return d64; } // decimal64FromNumber /* ------------------------------------------------------------------ */ /* decimal64ToNumber -- convert decimal64 to decNumber */ /* d64 is the source decimal64 */ /* dn is the target number, with appropriate space */ /* No error is possible. */ /* ------------------------------------------------------------------ */ decNumber * decimal64ToNumber(const decimal64 *d64, decNumber *dn) { uInt msd; // coefficient MSD uInt exp; // exponent top two bits uInt comb; // combination field Int need; // work uInt uiwork; // for macros uInt sourar[2]; // source 64-bit #define sourhi sourar[1] // name the word with the sign #define sourlo sourar[0] // and the lower word // load source from storage; this is endian if (DECLITEND) { sourlo=UBTOUI(d64->bytes ); // directly load the low int sourhi=UBTOUI(d64->bytes+4); // then the high int } else { sourhi=UBTOUI(d64->bytes ); // directly load the high int sourlo=UBTOUI(d64->bytes+4); // then the low int } comb=(sourhi>>26)&0x1f; // combination field decNumberZero(dn); // clean number if (sourhi&0x80000000) dn->bits=DECNEG; // set sign if negative msd=COMBMSD[comb]; // decode the combination field exp=COMBEXP[comb]; // .. if (exp==3) { // is a special if (msd==0) { dn->bits|=DECINF; return dn; // no coefficient needed } else if (sourhi&0x02000000) dn->bits|=DECSNAN; else dn->bits|=DECNAN; msd=0; // no top digit } else { // is a finite number dn->exponent=(exp<<8)+((sourhi>>18)&0xff)-DECIMAL64_Bias; // unbiased } // get the coefficient sourhi&=0x0003ffff; // clean coefficient continuation if (msd) { // non-zero msd sourhi|=msd<<18; // prefix to coefficient need=6; // process 6 declets } else { // msd=0 if (!sourhi) { // top word 0 if (!sourlo) return dn; // easy: coefficient is 0 need=3; // process at least 3 declets if (sourlo&0xc0000000) need++; // process 4 declets // [could reduce some more, here] } else { // some bits in top word, msd=0 need=4; // process at least 4 declets if (sourhi&0x0003ff00) need++; // top declet!=0, process 5 } } //msd=0 decDigitsFromDPD(dn, sourar, need); // process declets return dn; } // decimal64ToNumber /* ------------------------------------------------------------------ */ /* to-scientific-string -- conversion to numeric string */ /* to-engineering-string -- conversion to numeric string */ /* */ /* decimal64ToString(d64, string); */ /* decimal64ToEngString(d64, string); */ /* */ /* d64 is the decimal64 format number to convert */ /* string is the string where the result will be laid out */ /* */ /* string must be at least 24 characters */ /* */ /* No error is possible, and no status can be set. */ /* ------------------------------------------------------------------ */ char * decimal64ToEngString(const decimal64 *d64, char *string){ decNumber dn; // work decimal64ToNumber(d64, &dn); decNumberToEngString(&dn, string); return string; } // decimal64ToEngString char * decimal64ToString(const decimal64 *d64, char *string){ uInt msd; // coefficient MSD Int exp; // exponent top two bits or full uInt comb; // combination field char *cstart; // coefficient start char *c; // output pointer in string const uByte *u; // work char *s, *t; // .. (source, target) Int dpd; // .. Int pre, e; // .. uInt uiwork; // for macros uInt sourar[2]; // source 64-bit #define sourhi sourar[1] // name the word with the sign #define sourlo sourar[0] // and the lower word // load source from storage; this is endian if (DECLITEND) { sourlo=UBTOUI(d64->bytes ); // directly load the low int sourhi=UBTOUI(d64->bytes+4); // then the high int } else { sourhi=UBTOUI(d64->bytes ); // directly load the high int sourlo=UBTOUI(d64->bytes+4); // then the low int } c=string; // where result will go if (((Int)sourhi)<0) *c++='-'; // handle sign comb=(sourhi>>26)&0x1f; // combination field msd=COMBMSD[comb]; // decode the combination field exp=COMBEXP[comb]; // .. if (exp==3) { if (msd==0) { // infinity strcpy(c, "Inf"); strcpy(c+3, "inity"); return string; // easy } if (sourhi&0x02000000) *c++='s'; // sNaN strcpy(c, "NaN"); // complete word c+=3; // step past if (sourlo==0 && (sourhi&0x0003ffff)==0) return string; // zero payload // otherwise drop through to add integer; set correct exp exp=0; msd=0; // setup for following code } else exp=(exp<<8)+((sourhi>>18)&0xff)-DECIMAL64_Bias; // convert 16 digits of significand to characters cstart=c; // save start of coefficient if (msd) *c++='0'+(char)msd; // non-zero most significant digit // Now decode the declets. After extracting each one, it is // decoded to binary and then to a 4-char sequence by table lookup; // the 4-chars are a 1-char length (significant digits, except 000 // has length 0). This allows us to left-align the first declet // with non-zero content, then remaining ones are full 3-char // length. We use fixed-length memcpys because variable-length // causes a subroutine call in GCC. (These are length 4 for speed // and are safe because the array has an extra terminator byte.) #define dpd2char u=&BIN2CHAR[DPD2BIN[dpd]*4]; \ if (c!=cstart) {memcpy(c, u+1, 4); c+=3;} \ else if (*u) {memcpy(c, u+4-*u, 4); c+=*u;} dpd=(sourhi>>8)&0x3ff; // declet 1 dpd2char; dpd=((sourhi&0xff)<<2) | (sourlo>>30); // declet 2 dpd2char; dpd=(sourlo>>20)&0x3ff; // declet 3 dpd2char; dpd=(sourlo>>10)&0x3ff; // declet 4 dpd2char; dpd=(sourlo)&0x3ff; // declet 5 dpd2char; if (c==cstart) *c++='0'; // all zeros -- make 0 if (exp==0) { // integer or NaN case -- easy *c='\0'; // terminate return string; } /* non-0 exponent */ e=0; // assume no E pre=c-cstart+exp; // [here, pre-exp is the digits count (==1 for zero)] if (exp>0 || pre<-5) { // need exponential form e=pre-1; // calculate E value pre=1; // assume one digit before '.' } // exponential form /* modify the coefficient, adding 0s, '.', and E+nn as needed */ s=c-1; // source (LSD) if (pre>0) { // ddd.ddd (plain), perhaps with E char *dotat=cstart+pre; if (dotat=dotat; s--, t--) *t=*s; // open the gap; leave t at gap *t='.'; // insert the dot c++; // length increased by one } // finally add the E-part, if needed; it will never be 0, and has // a maximum length of 3 digits if (e!=0) { *c++='E'; // starts with E *c++='+'; // assume positive if (e<0) { *(c-1)='-'; // oops, need '-' e=-e; // uInt, please } u=&BIN2CHAR[e*4]; // -> length byte memcpy(c, u+4-*u, 4); // copy fixed 4 characters [is safe] c+=*u; // bump pointer appropriately } *c='\0'; // add terminator //printf("res %s\n", string); return string; } // pre>0 /* -5<=pre<=0: here for plain 0.ddd or 0.000ddd forms (can never have E) */ t=c+1-pre; *(t+1)='\0'; // can add terminator now for (; s>=cstart; s--, t--) *t=*s; // shift whole coefficient right c=cstart; *c++='0'; // always starts with 0. *c++='.'; for (; pre<0; pre++) *c++='0'; // add any 0's after '.' //printf("res %s\n", string); return string; } // decimal64ToString /* ------------------------------------------------------------------ */ /* to-number -- conversion from numeric string */ /* */ /* decimal64FromString(result, string, set); */ /* */ /* result is the decimal64 format number which gets the result of */ /* the conversion */ /* *string is the character string which should contain a valid */ /* number (which may be a special value) */ /* set is the context */ /* */ /* The context is supplied to this routine is used for error handling */ /* (setting of status and traps) and for the rounding mode, only. */ /* If an error occurs, the result will be a valid decimal64 NaN. */ /* ------------------------------------------------------------------ */ decimal64 * decimal64FromString(decimal64 *result, const char *string, decContext *set) { decContext dc; // work decNumber dn; // .. decContextDefault(&dc, DEC_INIT_DECIMAL64); // no traps, please dc.round=set->round; // use supplied rounding decNumberFromString(&dn, string, &dc); // will round if needed decimal64FromNumber(result, &dn, &dc); if (dc.status!=0) { // something happened decContextSetStatus(set, dc.status); // .. pass it on } return result; } // decimal64FromString /* ------------------------------------------------------------------ */ /* decimal64IsCanonical -- test whether encoding is canonical */ /* d64 is the source decimal64 */ /* returns 1 if the encoding of d64 is canonical, 0 otherwise */ /* No error is possible. */ /* ------------------------------------------------------------------ */ uInt decimal64IsCanonical(const decimal64 *d64) { decNumber dn; // work decimal64 canon; // .. decContext dc; // .. decContextDefault(&dc, DEC_INIT_DECIMAL64); decimal64ToNumber(d64, &dn); decimal64FromNumber(&canon, &dn, &dc);// canon will now be canonical return memcmp(d64, &canon, DECIMAL64_Bytes)==0; } // decimal64IsCanonical /* ------------------------------------------------------------------ */ /* decimal64Canonical -- copy an encoding, ensuring it is canonical */ /* d64 is the source decimal64 */ /* result is the target (may be the same decimal64) */ /* returns result */ /* No error is possible. */ /* ------------------------------------------------------------------ */ decimal64 * decimal64Canonical(decimal64 *result, const decimal64 *d64) { decNumber dn; // work decContext dc; // .. decContextDefault(&dc, DEC_INIT_DECIMAL64); decimal64ToNumber(d64, &dn); decimal64FromNumber(result, &dn, &dc);// result will now be canonical return result; } // decimal64Canonical #if DECTRACE || DECCHECK /* Macros for accessing decimal64 fields. These assume the argument is a reference (pointer) to the decimal64 structure, and the decimal64 is in network byte order (big-endian) */ // Get sign #define decimal64Sign(d) ((unsigned)(d)->bytes[0]>>7) // Get combination field #define decimal64Comb(d) (((d)->bytes[0] & 0x7c)>>2) // Get exponent continuation [does not remove bias] #define decimal64ExpCon(d) ((((d)->bytes[0] & 0x03)<<6) \ | ((unsigned)(d)->bytes[1]>>2)) // Set sign [this assumes sign previously 0] #define decimal64SetSign(d, b) { \ (d)->bytes[0]|=((unsigned)(b)<<7);} // Set exponent continuation [does not apply bias] // This assumes range has been checked and exponent previously 0; // type of exponent must be unsigned #define decimal64SetExpCon(d, e) { \ (d)->bytes[0]|=(uByte)((e)>>6); \ (d)->bytes[1]|=(uByte)(((e)&0x3F)<<2);} /* ------------------------------------------------------------------ */ /* decimal64Show -- display a decimal64 in hexadecimal [debug aid] */ /* d64 -- the number to show */ /* ------------------------------------------------------------------ */ // Also shows sign/cob/expconfields extracted void decimal64Show(const decimal64 *d64) { char buf[DECIMAL64_Bytes*2+1]; Int i, j=0; if (DECLITEND) { for (i=0; ibytes[7-i]); } printf(" D64> %s [S:%d Cb:%02x Ec:%02x] LittleEndian\n", buf, d64->bytes[7]>>7, (d64->bytes[7]>>2)&0x1f, ((d64->bytes[7]&0x3)<<6)| (d64->bytes[6]>>2)); } else { // big-endian for (i=0; ibytes[i]); } printf(" D64> %s [S:%d Cb:%02x Ec:%02x] BigEndian\n", buf, decimal64Sign(d64), decimal64Comb(d64), decimal64ExpCon(d64)); } } // decimal64Show #endif /* ================================================================== */ /* Shared utility routines and tables */ /* ================================================================== */ // define and include the conversion tables to use for shared code #if DECDPUN==3 #define DEC_DPD2BIN 1 #else #define DEC_DPD2BCD 1 #endif #include "decNumber/decDPD.h" // lookup tables // The maximum number of decNumberUnits needed for a working copy of // the units array is the ceiling of digits/DECDPUN, where digits is // the maximum number of digits in any of the formats for which this // is used. decimal128.h must not be included in this module, so, as // a very special case, that number is defined as a literal here. #define DECMAX754 34 #define DECMAXUNITS ((DECMAX754+DECDPUN-1)/DECDPUN) /* ------------------------------------------------------------------ */ /* Combination field lookup tables (uInts to save measurable work) */ /* */ /* COMBEXP - 2-bit most-significant-bits of exponent */ /* [11 if an Infinity or NaN] */ /* COMBMSD - 4-bit most-significant-digit */ /* [0=Infinity, 1=NaN if COMBEXP=11] */ /* */ /* Both are indexed by the 5-bit combination field (0-31) */ /* ------------------------------------------------------------------ */ const uInt COMBEXP[32]={0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 0, 0, 1, 1, 2, 2, 3, 3}; const uInt COMBMSD[32]={0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 8, 9, 8, 9, 0, 1}; /* ------------------------------------------------------------------ */ /* decDigitsToDPD -- pack coefficient into DPD form */ /* */ /* dn is the source number (assumed valid, max DECMAX754 digits) */ /* targ is 1, 2, or 4-element uInt array, which the caller must */ /* have cleared to zeros */ /* shift is the number of 0 digits to add on the right (normally 0) */ /* */ /* The coefficient must be known small enough to fit. The full */ /* coefficient is copied, including the leading 'odd' digit. This */ /* digit is retrieved and packed into the combination field by the */ /* caller. */ /* */ /* The target uInts are altered only as necessary to receive the */ /* digits of the decNumber. When more than one uInt is needed, they */ /* are filled from left to right (that is, the uInt at offset 0 will */ /* end up with the least-significant digits). */ /* */ /* shift is used for 'fold-down' padding. */ /* */ /* No error is possible. */ /* ------------------------------------------------------------------ */ #if DECDPUN<=4 // Constant multipliers for divide-by-power-of five using reciprocal // multiply, after removing powers of 2 by shifting, and final shift // of 17 [we only need up to **4] static const uInt multies[]={131073, 26215, 5243, 1049, 210}; // QUOT10 -- macro to return the quotient of unit u divided by 10**n #define QUOT10(u, n) ((((uInt)(u)>>(n))*multies[n])>>17) #endif void decDigitsToDPD(const decNumber *dn, uInt *targ, Int shift) { Int cut; // work Int n; // output bunch counter Int digits=dn->digits; // digit countdown uInt dpd; // densely packed decimal value uInt bin; // binary value 0-999 uInt *uout=targ; // -> current output uInt uInt uoff=0; // -> current output offset [from right] const Unit *inu=dn->lsu; // -> current input unit Unit uar[DECMAXUNITS]; // working copy of units, iff shifted #if DECDPUN!=3 // not fast path Unit in; // current unit #endif if (shift!=0) { // shift towards most significant required // shift the units array to the left by pad digits and copy // [this code is a special case of decShiftToMost, which could // be used instead if exposed and the array were copied first] const Unit *source; // .. Unit *target, *first; // .. uInt next=0; // work source=dn->lsu+D2U(digits)-1; // where msu comes from target=uar+D2U(digits)-1+D2U(shift);// where upper part of first cut goes cut=DECDPUN-MSUDIGITS(shift); // where to slice if (cut==0) { // unit-boundary case for (; source>=dn->lsu; source--, target--) *target=*source; } else { first=uar+D2U(digits+shift)-1; // where msu will end up for (; source>=dn->lsu; source--, target--) { // split the source Unit and accumulate remainder for next #if DECDPUN<=4 uInt quot=QUOT10(*source, cut); uInt rem=*source-quot*DECPOWERS[cut]; next+=quot; #else uInt rem=*source%DECPOWERS[cut]; next+=*source/DECPOWERS[cut]; #endif if (target<=first) *target=(Unit)next; // write to target iff valid next=rem*DECPOWERS[DECDPUN-cut]; // save remainder for next Unit } } // shift-move // propagate remainder to one below and clear the rest for (; target>=uar; target--) { *target=(Unit)next; next=0; } digits+=shift; // add count (shift) of zeros added inu=uar; // use units in working array } /* now densely pack the coefficient into DPD declets */ #if DECDPUN!=3 // not fast path in=*inu; // current unit cut=0; // at lowest digit bin=0; // [keep compiler quiet] #endif for(n=0; digits>0; n++) { // each output bunch #if DECDPUN==3 // fast path, 3-at-a-time bin=*inu; // 3 digits ready for convert digits-=3; // [may go negative] inu++; // may need another #else // must collect digit-by-digit Unit dig; // current digit Int j; // digit-in-declet count for (j=0; j<3; j++) { #if DECDPUN<=4 Unit temp=(Unit)((uInt)(in*6554)>>16); dig=(Unit)(in-X10(temp)); in=temp; #else dig=in%10; in=in/10; #endif if (j==0) bin=dig; else if (j==1) bin+=X10(dig); else /* j==2 */ bin+=X100(dig); digits--; if (digits==0) break; // [also protects *inu below] cut++; if (cut==DECDPUN) {inu++; in=*inu; cut=0;} } #endif // here there are 3 digits in bin, or have used all input digits dpd=BIN2DPD[bin]; // write declet to uInt array *uout|=dpd<>(10-uoff); // collect top bits } // n declets return; } // decDigitsToDPD /* ------------------------------------------------------------------ */ /* decDigitsFromDPD -- unpack a format's coefficient */ /* */ /* dn is the target number, with 7, 16, or 34-digit space. */ /* sour is a 1, 2, or 4-element uInt array containing only declets */ /* declets is the number of (right-aligned) declets in sour to */ /* be processed. This may be 1 more than the obvious number in */ /* a format, as any top digit is prefixed to the coefficient */ /* continuation field. It also may be as small as 1, as the */ /* caller may pre-process leading zero declets. */ /* */ /* When doing the 'extra declet' case care is taken to avoid writing */ /* extra digits when there are leading zeros, as these could overflow */ /* the units array when DECDPUN is not 3. */ /* */ /* The target uInts are used only as necessary to process declets */ /* declets into the decNumber. When more than one uInt is needed, */ /* they are used from left to right (that is, the uInt at offset 0 */ /* provides the least-significant digits). */ /* */ /* dn->digits is set, but not the sign or exponent. */ /* No error is possible [the redundant 888 codes are allowed]. */ /* ------------------------------------------------------------------ */ void decDigitsFromDPD(decNumber *dn, const uInt *sour, Int declets) { uInt dpd; // collector for 10 bits Int n; // counter Unit *uout=dn->lsu; // -> current output unit Unit *last=uout; // will be unit containing msd const uInt *uin=sour; // -> current input uInt uInt uoff=0; // -> current input offset [from right] #if DECDPUN!=3 uInt bcd; // BCD result uInt nibble; // work Unit out=0; // accumulator Int cut=0; // power of ten in current unit #endif #if DECDPUN>4 uInt const *pow; // work #endif // Expand the densely-packed integer, right to left for (n=declets-1; n>=0; n--) { // count down declets of 10 bits dpd=*uin>>uoff; uoff+=10; if (uoff>32) { // crossed uInt boundary uin++; uoff-=32; // [if using this code for wider, check this] dpd|=*uin<<(10-uoff); // get waiting bits } dpd&=0x3ff; // clear uninteresting bits #if DECDPUN==3 if (dpd==0) *uout=0; else { *uout=DPD2BIN[dpd]; // convert 10 bits to binary 0-999 last=uout; // record most significant unit } uout++; } // n #else // DECDPUN!=3 if (dpd==0) { // fastpath [e.g., leading zeros] // write out three 0 digits (nibbles); out may have digit(s) cut++; if (cut==DECDPUN) {*uout=out; if (out) {last=uout; out=0;} uout++; cut=0;} if (n==0) break; // [as below, works even if MSD=0] cut++; if (cut==DECDPUN) {*uout=out; if (out) {last=uout; out=0;} uout++; cut=0;} cut++; if (cut==DECDPUN) {*uout=out; if (out) {last=uout; out=0;} uout++; cut=0;} continue; } bcd=DPD2BCD[dpd]; // convert 10 bits to 12 bits BCD // now accumulate the 3 BCD nibbles into units nibble=bcd & 0x00f; if (nibble) out=(Unit)(out+nibble*DECPOWERS[cut]); cut++; if (cut==DECDPUN) {*uout=out; if (out) {last=uout; out=0;} uout++; cut=0;} bcd>>=4; // if this is the last declet and the remaining nibbles in bcd // are 00 then process no more nibbles, because this could be // the 'odd' MSD declet and writing any more Units would then // overflow the unit array if (n==0 && !bcd) break; nibble=bcd & 0x00f; if (nibble) out=(Unit)(out+nibble*DECPOWERS[cut]); cut++; if (cut==DECDPUN) {*uout=out; if (out) {last=uout; out=0;} uout++; cut=0;} bcd>>=4; nibble=bcd & 0x00f; if (nibble) out=(Unit)(out+nibble*DECPOWERS[cut]); cut++; if (cut==DECDPUN) {*uout=out; if (out) {last=uout; out=0;} uout++; cut=0;} } // n if (cut!=0) { // some more left over *uout=out; // write out final unit if (out) last=uout; // and note if non-zero } #endif // here, last points to the most significant unit with digits; // inspect it to get the final digits count -- this is essentially // the same code as decGetDigits in decNumber.c dn->digits=(last-dn->lsu)*DECDPUN+1; // floor of digits, plus // must be at least 1 digit #if DECDPUN>1 if (*last<10) return; // common odd digit or 0 dn->digits++; // must be 2 at least #if DECDPUN>2 if (*last<100) return; // 10-99 dn->digits++; // must be 3 at least #if DECDPUN>3 if (*last<1000) return; // 100-999 dn->digits++; // must be 4 at least #if DECDPUN>4 for (pow=&DECPOWERS[4]; *last>=*pow; pow++) dn->digits++; #endif #endif #endif #endif return; } //decDigitsFromDPD