d19fdc056d
nan64.c was part of change #1 in this repository and did not have a notice at that point (September 2003). An earlier copy of libfmt, dated January 14-15, 2003, makes it clear that nan64.c was extracted from fltfmt.c and strtod.c, so use the same notice they use.
79 lines
1.2 KiB
C
79 lines
1.2 KiB
C
/* Copyright (c) 2002-2006 Lucent Technologies; see LICENSE */
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/*
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* 64-bit IEEE not-a-number routines.
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* This is big/little-endian portable assuming that
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* the 64-bit doubles and 64-bit integers have the
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* same byte ordering.
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*/
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#include "plan9.h"
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#include <assert.h>
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#include "fmt.h"
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#include "fmtdef.h"
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static uvlong uvnan = ((uvlong)0x7FF00000<<32)|0x00000001;
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static uvlong uvinf = ((uvlong)0x7FF00000<<32)|0x00000000;
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static uvlong uvneginf = ((uvlong)0xFFF00000<<32)|0x00000000;
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/* gcc sees through the obvious casts. */
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static uvlong
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d2u(double d)
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{
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union {
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uvlong v;
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double d;
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} u;
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assert(sizeof(u.d) == sizeof(u.v));
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u.d = d;
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return u.v;
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}
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static double
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u2d(uvlong v)
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{
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union {
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uvlong v;
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double d;
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} u;
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assert(sizeof(u.d) == sizeof(u.v));
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u.v = v;
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return u.d;
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}
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double
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__NaN(void)
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{
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return u2d(uvnan);
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}
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int
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__isNaN(double d)
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{
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uvlong x;
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x = d2u(d);
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/* IEEE 754: exponent bits 0x7FF and non-zero mantissa */
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return (x&uvinf) == uvinf && (x&~uvneginf) != 0;
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}
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double
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__Inf(int sign)
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{
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return u2d(sign < 0 ? uvneginf : uvinf);
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}
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int
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__isInf(double d, int sign)
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{
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uvlong x;
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x = d2u(d);
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if(sign == 0)
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return x==uvinf || x==uvneginf;
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else if(sign > 0)
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return x==uvinf;
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else
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return x==uvneginf;
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}
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