hanchenye-llvm-project/compiler-rt/lib/fixdfdi.c

42 lines
1.2 KiB
C

//===-- fixdfdi.c - Implement __fixdfdi -----------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements __fixdfdi for the compiler_rt library.
//
//===----------------------------------------------------------------------===//
#include "int_lib.h"
// Returns: convert a to a signed long long, rounding toward zero.
// Assumption: double is a IEEE 64 bit floating point type
// su_int is a 32 bit integral type
// value in double is representable in di_int (no range checking performed)
// seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm
di_int
__fixdfdi(double a)
{
double_bits fb;
fb.f = a;
int e = ((fb.u.high & 0x7FF00000) >> 20) - 1023;
if (e < 0)
return 0;
di_int s = (si_int)(fb.u.high & 0x80000000) >> 31;
dwords r;
r.high = (fb.u.high & 0x000FFFFF) | 0x00100000;
r.low = fb.u.low;
if (e > 52)
r.all <<= (e - 52);
else
r.all >>= (52 - e);
return (r.all ^ s) - s;
}