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Diffstat (limited to 'libdecnumber/decimal128.c')
| -rw-r--r-- | libdecnumber/decimal128.c | 337 |
1 files changed, 337 insertions, 0 deletions
diff --git a/libdecnumber/decimal128.c b/libdecnumber/decimal128.c new file mode 100644 index 0000000..214dba0 --- /dev/null +++ b/libdecnumber/decimal128.c @@ -0,0 +1,337 @@ +/* Decimal 128-bit format module from the decNumber C Library. + Copyright (C) 2005 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 2, 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. + + You should have received a copy of the GNU General Public License + along with GCC; see the file COPYING. If not, write to the Free + Software Foundation, 59 Temple Place - Suite 330, Boston, MA + 02111-1307, USA. */ + +/* ------------------------------------------------------------------ */ +/* This module comprises the routines for decimal128 format numbers. */ +/* Conversions are supplied to and from decNumber and String. */ +/* */ +/* No arithmetic routines are included; decNumber provides these. */ +/* */ +/* Error handling is the same as decNumber (qv.). */ +/* ------------------------------------------------------------------ */ +#include <string.h> /* [for memset/memcpy] */ +#include <stdio.h> /* [for printf] */ + +#define DECNUMDIGITS 34 /* we need decNumbers with space for 34 */ +#include "decNumber.h" /* base number library */ +#include "decNumberLocal.h" /* decNumber local types, etc. */ +#include "decimal128.h" /* our primary include */ +#include "decUtility.h" /* utility routines */ + +#if DECTRACE || DECCHECK +void decimal128Show (decimal128 *); /* for debug */ +void decNumberShow (decNumber *); /* .. */ +#endif + +/* Useful macro */ +/* Clear a structure (e.g., a decNumber) */ +#define DEC_clear(d) memset(d, 0, sizeof(*d)) + +/* ------------------------------------------------------------------ */ +/* decimal128FromNumber -- convert decNumber to decimal128 */ +/* */ +/* ds is the target decimal128 */ +/* 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 DECIMAL128_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. */ +/* ------------------------------------------------------------------ */ +decimal128 * +decimal128FromNumber (decimal128 * d128, decNumber * dn, decContext * set) +{ + uInt status = 0; /* status accumulator */ + Int pad = 0; /* coefficient pad digits */ + decNumber dw; /* work */ + decContext dc; /* .. */ + uByte isneg = dn->bits & DECNEG; /* non-0 if original sign set */ + uInt comb, exp; /* work */ + + /* If the number is finite, and has too many digits, or the exponent */ + /* could be out of range then we reduce the number under the */ + /* appropriate constraints */ + if (!(dn->bits & DECSPECIAL)) + { /* not a special value */ + Int ae = dn->exponent + dn->digits - 1; /* adjusted exponent */ + if (dn->digits > DECIMAL128_Pmax /* too many digits */ + || ae > DECIMAL128_Emax /* likely overflow */ + || ae < DECIMAL128_Emin) + { /* likely underflow */ + decContextDefault (&dc, DEC_INIT_DECIMAL128); /* [no traps] */ + dc.round = set->round; /* use supplied rounding */ + decNumberPlus (&dw, dn, &dc); /* (round and check) */ + /* [this changes -0 to 0, but it will be restored below] */ + status |= dc.status; /* save status */ + dn = &dw; /* use the work number */ + } + /* [this could have pushed number to Infinity or zero, so this */ + /* rounding must be done before we generate the decimal128] */ + } + + DEC_clear (d128); /* clean the target */ + if (dn->bits & DECSPECIAL) + { /* a special value */ + uByte top; /* work */ + if (dn->bits & DECINF) + top = DECIMAL_Inf; + else + { /* sNaN or qNaN */ + if ((*dn->lsu != 0 || dn->digits > 1) /* non-zero coefficient */ + && (dn->digits < DECIMAL128_Pmax)) + { /* coefficient fits */ + decDensePackCoeff (dn, d128->bytes, sizeof (d128->bytes), 0); + } + if (dn->bits & DECNAN) + top = DECIMAL_NaN; + else + top = DECIMAL_sNaN; + } + d128->bytes[0] = top; + } + else if (decNumberIsZero (dn)) + { /* a zero */ + /* set and clamp exponent */ + if (dn->exponent < -DECIMAL128_Bias) + { + exp = 0; + status |= DEC_Clamped; + } + else + { + exp = dn->exponent + DECIMAL128_Bias; /* bias exponent */ + if (exp > DECIMAL128_Ehigh) + { /* top clamp */ + exp = DECIMAL128_Ehigh; + status |= DEC_Clamped; + } + } + comb = (exp >> 9) & 0x18; /* combination field */ + d128->bytes[0] = (uByte) (comb << 2); + exp &= 0xfff; /* remaining exponent bits */ + decimal128SetExpCon (d128, exp); + } + else + { /* non-zero finite number */ + uInt msd; /* work */ + + /* we have a dn that fits, but it may need to be padded */ + exp = (uInt) (dn->exponent + DECIMAL128_Bias); /* bias exponent */ + + if (exp > DECIMAL128_Ehigh) + { /* fold-down case */ + pad = exp - DECIMAL128_Ehigh; + exp = DECIMAL128_Ehigh; /* [to maximum] */ + status |= DEC_Clamped; + } + + decDensePackCoeff (dn, d128->bytes, sizeof (d128->bytes), pad); + + /* save and clear the top digit */ + msd = ((unsigned) d128->bytes[1] << 2) & 0x0c; /* top 2 bits */ + msd |= ((unsigned) d128->bytes[2] >> 6); /* low 2 bits */ + d128->bytes[1] &= 0xfc; + d128->bytes[2] &= 0x3f; + + /* create the combination field */ + if (msd >= 8) + comb = 0x18 | (msd & 0x01) | ((exp >> 11) & 0x06); + else + comb = (msd & 0x07) | ((exp >> 9) & 0x18); + d128->bytes[0] = (uByte) (comb << 2); + exp &= 0xfff; /* remaining exponent bits */ + decimal128SetExpCon (d128, exp); + } + + if (isneg) + decimal128SetSign (d128, 1); + if (status != 0) + decContextSetStatus (set, status); /* pass on status */ + + /* decimal128Show(d128); */ + return d128; +} + +/* ------------------------------------------------------------------ */ +/* decimal128ToNumber -- convert decimal128 to decNumber */ +/* d128 is the source decimal128 */ +/* dn is the target number, with appropriate space */ +/* No error is possible. */ +/* ------------------------------------------------------------------ */ +decNumber * +decimal128ToNumber (decimal128 * d128, decNumber * dn) +{ + uInt msd; /* coefficient MSD */ + decimal128 wk; /* working copy, if needed */ + uInt top = d128->bytes[0] & 0x7f; /* top byte, less sign bit */ + decNumberZero (dn); /* clean target */ + /* set the sign if negative */ + if (decimal128Sign (d128)) + dn->bits = DECNEG; + + if (top >= 0x78) + { /* is a special */ + if ((top & 0x7c) == (DECIMAL_Inf & 0x7c)) + dn->bits |= DECINF; + else if ((top & 0x7e) == (DECIMAL_NaN & 0x7e)) + dn->bits |= DECNAN; + else + dn->bits |= DECSNAN; + msd = 0; /* no top digit */ + } + else + { /* have a finite number */ + uInt comb = top >> 2; /* combination field */ + uInt exp; /* exponent */ + + if (comb >= 0x18) + { + msd = 8 + (comb & 0x01); + exp = (comb & 0x06) << 11; /* MSBs */ + } + else + { + msd = comb & 0x07; + exp = (comb & 0x18) << 9; + } + dn->exponent = exp + decimal128ExpCon (d128) - DECIMAL128_Bias; /* remove bias */ + } + + /* get the coefficient, unless infinite */ + if (!(dn->bits & DECINF)) + { + Int bunches = DECIMAL128_Pmax / 3; /* coefficient full bunches to convert */ + Int odd = 0; /* assume MSD is 0 (no odd bunch) */ + if (msd != 0) + { /* coefficient has leading non-0 digit */ + /* make a copy of the decimal128, with an extra bunch which has */ + /* the top digit ready for conversion */ + wk = *d128; /* take a copy */ + wk.bytes[0] = 0; /* clear all but coecon */ + wk.bytes[1] = 0; /* .. */ + wk.bytes[2] &= 0x3f; /* .. */ + wk.bytes[1] |= (msd >> 2); /* and prefix MSD */ + wk.bytes[2] |= (msd << 6); /* .. */ + odd++; /* indicate the extra */ + d128 = &wk; /* use the work copy */ + } + decDenseUnpackCoeff (d128->bytes, sizeof (d128->bytes), dn, bunches, + odd); + } + + /* decNumberShow(dn); */ + return dn; +} + +/* ------------------------------------------------------------------ */ +/* to-scientific-string -- conversion to numeric string */ +/* to-engineering-string -- conversion to numeric string */ +/* */ +/* decimal128ToString(d128, string); */ +/* decimal128ToEngString(d128, string); */ +/* */ +/* d128 is the decimal128 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 * +decimal128ToString (decimal128 * d128, char *string) +{ + decNumber dn; /* work */ + decimal128ToNumber (d128, &dn); + decNumberToString (&dn, string); + return string; +} + +char * +decimal128ToEngString (decimal128 * d128, char *string) +{ + decNumber dn; /* work */ + decimal128ToNumber (d128, &dn); + decNumberToEngString (&dn, string); + return string; +} + +/* ------------------------------------------------------------------ */ +/* to-number -- conversion from numeric string */ +/* */ +/* decimal128FromString(result, string, set); */ +/* */ +/* result is the decimal128 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 decimal128 NaN. */ +/* ------------------------------------------------------------------ */ +decimal128 * +decimal128FromString (decimal128 * result, char *string, decContext * set) +{ + decContext dc; /* work */ + decNumber dn; /* .. */ + + decContextDefault (&dc, DEC_INIT_DECIMAL128); /* no traps, please */ + dc.round = set->round; /* use supplied rounding */ + + decNumberFromString (&dn, string, &dc); /* will round if needed */ + decimal128FromNumber (result, &dn, &dc); + if (dc.status != 0) + { /* something happened */ + decContextSetStatus (set, dc.status); /* .. pass it on */ + } + return result; +} + + +#if DECTRACE || DECCHECK +/* ------------------------------------------------------------------ */ +/* decimal128Show -- display a single in hexadecimal [debug aid] */ +/* d128 -- the number to show */ +/* ------------------------------------------------------------------ */ +/* Also shows sign/cob/expconfields extracted */ +void +decimal128Show (decimal128 * d128) +{ + char buf[DECIMAL128_Bytes * 2 + 1]; + Int i, j; + j = 0; + for (i = 0; i < DECIMAL128_Bytes; i++) + { + sprintf (&buf[j], "%02x", d128->bytes[i]); + j = j + 2; + } + printf (" D128> %s [S:%d Cb:%02x E:%d]\n", buf, + decimal128Sign (d128), decimal128Comb (d128), + decimal128ExpCon (d128)); +} +#endif |