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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "runtime.h"
static uint64 uvnan = 0x7FF0000000000001ULL;
static uint64 uvinf = 0x7FF0000000000000ULL;
static uint64 uvneginf = 0xFFF0000000000000ULL;
uint32
float32tobits(float32 f)
{
// The obvious cast-and-pointer code is technically
// not valid, and gcc miscompiles it. Use a union instead.
union {
float32 f;
uint32 i;
} u;
u.f = f;
return u.i;
}
uint64
float64tobits(float64 f)
{
// The obvious cast-and-pointer code is technically
// not valid, and gcc miscompiles it. Use a union instead.
union {
float64 f;
uint64 i;
} u;
u.f = f;
return u.i;
}
float64
float64frombits(uint64 i)
{
// The obvious cast-and-pointer code is technically
// not valid, and gcc miscompiles it. Use a union instead.
union {
float64 f;
uint64 i;
} u;
u.i = i;
return u.f;
}
float32
float32frombits(uint32 i)
{
// The obvious cast-and-pointer code is technically
// not valid, and gcc miscompiles it. Use a union instead.
union {
float32 f;
uint32 i;
} u;
u.i = i;
return u.f;
}
bool
isInf(float64 f, int32 sign)
{
uint64 x;
x = float64tobits(f);
if(sign == 0)
return x == uvinf || x == uvneginf;
if(sign > 0)
return x == uvinf;
return x == uvneginf;
}
float64
NaN(void)
{
return float64frombits(uvnan);
}
bool
isNaN(float64 f)
{
uint64 x;
x = float64tobits(f);
return ((uint32)(x>>52) & 0x7FF) == 0x7FF && !isInf(f, 0);
}
float64
Inf(int32 sign)
{
if(sign >= 0)
return float64frombits(uvinf);
else
return float64frombits(uvneginf);
}
enum
{
MASK = 0x7ffL,
SHIFT = 64-11-1,
BIAS = 1022L,
};
float64
frexp(float64 d, int32 *ep)
{
uint64 x;
if(d == 0) {
*ep = 0;
return 0;
}
x = float64tobits(d);
*ep = (int32)((x >> SHIFT) & MASK) - BIAS;
x &= ~((uint64)MASK << SHIFT);
x |= (uint64)BIAS << SHIFT;
return float64frombits(x);
}
float64
ldexp(float64 d, int32 e)
{
uint64 x;
if(d == 0)
return 0;
x = float64tobits(d);
e += (int32)(x >> SHIFT) & MASK;
if(e <= 0)
return 0; /* underflow */
if(e >= MASK){ /* overflow */
if(d < 0)
return Inf(-1);
return Inf(1);
}
x &= ~((uint64)MASK << SHIFT);
x |= (uint64)e << SHIFT;
return float64frombits(x);
}
float64
modf(float64 d, float64 *ip)
{
float64 dd;
uint64 x;
int32 e;
if(d < 1) {
if(d < 0) {
d = modf(-d, ip);
*ip = -*ip;
return -d;
}
*ip = 0;
return d;
}
x = float64tobits(d);
e = (int32)((x >> SHIFT) & MASK) - BIAS;
/*
* Keep the top 11+e bits; clear the rest.
*/
if(e <= 64-11)
x &= ~(((uint64)1 << (64LL-11LL-e))-1);
dd = float64frombits(x);
*ip = dd;
return d - dd;
}
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