237 lines
6.4 KiB
C
237 lines
6.4 KiB
C
/****************************************************************
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The author of this software (_dtoa, strtod) is David M. Gay.
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Please send bug reports to
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David M. Gay
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Bell Laboratories, Room 2C-463
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600 Mountain Avenue
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Murray Hill, NJ 07974-2070
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U.S.A.
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dmg@research.bell-labs.com
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*/
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#include <stdlib.h>
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#include <string.h>
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#define _RESEARCH_SOURCE
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#include <errno.h>
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#include <float.h>
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#include <math.h>
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#define CONST const
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/*
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* #define IEEE_8087 for IEEE-arithmetic machines where the least
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* significant byte has the lowest address.
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* #define IEEE_MC68k for IEEE-arithmetic machines where the most
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* significant byte has the lowest address.
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* #define Sudden_Underflow for IEEE-format machines without gradual
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* underflow (i.e., that flush to zero on underflow).
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* #define IBM for IBM mainframe-style floating-point arithmetic.
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* #define VAX for VAX-style floating-point arithmetic.
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* #define Unsigned_Shifts if >> does treats its left operand as unsigned.
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* #define No_leftright to omit left-right logic in fast floating-point
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* computation of dtoa.
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* #define Check_FLT_ROUNDS if FLT_ROUNDS can assume the values 2 or 3.
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* #define RND_PRODQUOT to use rnd_prod and rnd_quot (assembly routines
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* that use extended-precision instructions to compute rounded
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* products and quotients) with IBM.
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* #define ROUND_BIASED for IEEE-format with biased rounding.
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* #define Inaccurate_Divide for IEEE-format with correctly rounded
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* products but inaccurate quotients, e.g., for Intel i860.
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* #define Just_16 to store 16 bits per 32-bit long when doing high-precision
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* integer arithmetic. Whether this speeds things up or slows things
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* down depends on the machine and the number being converted.
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*/
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#if defined(IEEE_8087) + defined(IEEE_MC68k) + defined(VAX) + defined(IBM) != 1
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Exactly one of IEEE_8087, IEEE_MC68k, VAX, or IBM should be defined.
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#endif
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typedef union {
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double d;
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unsigned long ul[2];
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} Dul;
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#ifdef IEEE_8087
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#define word0(x) ((x).ul[1])
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#define word1(x) ((x).ul[0])
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#else
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#define word0(x) ((x).ul[0])
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#define word1(x) ((x).ul[1])
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#endif
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#ifdef Unsigned_Shifts
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#define Sign_Extend(a,b) if (b < 0) a |= 0xffff0000;
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#else
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#define Sign_Extend(a,b) /*no-op*/
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#endif
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/* The following definition of Storeinc is appropriate for MIPS processors.
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* An alternative that might be better on some machines is
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* #define Storeinc(a,b,c) (*a++ = b << 16 | c & 0xffff)
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*/
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#if defined(IEEE_8087) + defined(VAX)
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#define Storeinc(a,b,c) (((unsigned short *)a)[1] = (unsigned short)b, \
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((unsigned short *)a)[0] = (unsigned short)c, a++)
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#else
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#define Storeinc(a,b,c) (((unsigned short *)a)[0] = (unsigned short)b, \
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((unsigned short *)a)[1] = (unsigned short)c, a++)
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#endif
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/* #define P DBL_MANT_DIG */
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/* Ten_pmax = floor(P*log(2)/log(5)) */
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/* Bletch = (highest power of 2 < DBL_MAX_10_EXP) / 16 */
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/* Quick_max = floor((P-1)*log(FLT_RADIX)/log(10) - 1) */
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/* Int_max = floor(P*log(FLT_RADIX)/log(10) - 1) */
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#if defined(IEEE_8087) + defined(IEEE_MC68k)
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#define Exp_shift 20
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#define Exp_shift1 20
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#define Exp_msk1 0x100000
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#define Exp_msk11 0x100000
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#define Exp_mask 0x7ff00000
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#define P 53
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#define Bias 1023
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#define IEEE_Arith
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#define Emin (-1022)
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#define Exp_1 0x3ff00000
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#define Exp_11 0x3ff00000
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#define Ebits 11
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#define Frac_mask 0xfffff
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#define Frac_mask1 0xfffff
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#define Ten_pmax 22
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#define Bletch 0x10
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#define Bndry_mask 0xfffff
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#define Bndry_mask1 0xfffff
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#define LSB 1
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#define Sign_bit 0x80000000
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#define Log2P 1
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#define Tiny0 0
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#define Tiny1 1
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#define Quick_max 14
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#define Int_max 14
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#define Infinite(x) (word0(x) == 0x7ff00000) /* sufficient test for here */
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#else
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#undef Sudden_Underflow
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#define Sudden_Underflow
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#ifdef IBM
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#define Exp_shift 24
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#define Exp_shift1 24
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#define Exp_msk1 0x1000000
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#define Exp_msk11 0x1000000
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#define Exp_mask 0x7f000000
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#define P 14
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#define Bias 65
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#define Exp_1 0x41000000
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#define Exp_11 0x41000000
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#define Ebits 8 /* exponent has 7 bits, but 8 is the right value in b2d */
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#define Frac_mask 0xffffff
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#define Frac_mask1 0xffffff
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#define Bletch 4
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#define Ten_pmax 22
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#define Bndry_mask 0xefffff
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#define Bndry_mask1 0xffffff
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#define LSB 1
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#define Sign_bit 0x80000000
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#define Log2P 4
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#define Tiny0 0x100000
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#define Tiny1 0
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#define Quick_max 14
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#define Int_max 15
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#else /* VAX */
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#define Exp_shift 23
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#define Exp_shift1 7
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#define Exp_msk1 0x80
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#define Exp_msk11 0x800000
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#define Exp_mask 0x7f80
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#define P 56
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#define Bias 129
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#define Exp_1 0x40800000
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#define Exp_11 0x4080
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#define Ebits 8
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#define Frac_mask 0x7fffff
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#define Frac_mask1 0xffff007f
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#define Ten_pmax 24
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#define Bletch 2
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#define Bndry_mask 0xffff007f
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#define Bndry_mask1 0xffff007f
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#define LSB 0x10000
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#define Sign_bit 0x8000
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#define Log2P 1
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#define Tiny0 0x80
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#define Tiny1 0
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#define Quick_max 15
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#define Int_max 15
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#endif
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#endif
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#ifndef IEEE_Arith
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#define ROUND_BIASED
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#endif
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#define Big0 (Frac_mask1 | Exp_msk1*(DBL_MAX_EXP+Bias-1))
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#define Big1 0xffffffff
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#ifndef Just_16
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/* When Pack_32 is not defined, we store 16 bits per 32-bit long.
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* This makes some inner loops simpler and sometimes saves work
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* during multiplications, but it often seems to make things slightly
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* slower. Hence the default is now to store 32 bits per long.
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*/
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#ifndef Pack_32
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#define Pack_32
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#endif
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#endif
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#define Kmax 15
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struct
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Bigint {
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struct Bigint *next;
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int k, maxwds, sign, wds;
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unsigned long x[1];
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};
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typedef struct Bigint Bigint;
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/* This routines shouldn't be visible externally */
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extern Bigint *_Balloc(int);
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extern void _Bfree(Bigint *);
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extern Bigint *_multadd(Bigint *, int, int);
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extern int _hi0bits(unsigned long);
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extern Bigint *_mult(Bigint *, Bigint *);
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extern Bigint *_pow5mult(Bigint *, int);
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extern Bigint *_lshift(Bigint *, int);
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extern int _cmp(Bigint *, Bigint *);
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extern Bigint *_diff(Bigint *, Bigint *);
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extern Bigint *_d2b(double, int *, int *);
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extern Bigint *_i2b(int);
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extern double _tens[], _bigtens[], _tinytens[];
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#ifdef IEEE_Arith
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#define n_bigtens 5
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#else
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#ifdef IBM
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#define n_bigtens 3
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#else
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#define n_bigtens 2
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#endif
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#endif
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#define Balloc(x) _Balloc(x)
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#define Bfree(x) _Bfree(x)
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#define Bcopy(x,y) memcpy((char *)&x->sign, (char *)&y->sign, \
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y->wds*sizeof(long) + 2*sizeof(int))
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#define multadd(x,y,z) _multadd(x,y,z)
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#define hi0bits(x) _hi0bits(x)
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#define i2b(x) _i2b(x)
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#define mult(x,y) _mult(x,y)
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#define pow5mult(x,y) _pow5mult(x,y)
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#define lshift(x,y) _lshift(x,y)
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#define cmp(x,y) _cmp(x,y)
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#define diff(x,y) _diff(x,y)
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#define d2b(x,y,z) _d2b(x,y,z)
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#define tens _tens
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#define bigtens _bigtens
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#define tinytens _tinytens
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