freebsd-skq/contrib/compiler-rt/lib/floattisf.c
dim fb422e6d31 MFC r262613:
Merge the projects/clang-sparc64 branch back to head.  This brings in
several updates from the llvm and clang trunks to make the sparc64
backend fully functional.

Apart from one patch to sys/sparc64/include/pcpu.h which is still under
discussion, this makes it possible to let clang fully build world and
kernel for sparc64.

Any assistance with testing this on actual sparc64 hardware is greatly
appreciated, as there will unavoidably be bugs left.

Many thanks go to Roman Divacky for his upstream work on getting the
sparc64 backend into shape.

MFC r262985:

Repair a few minor mismerges from r262261 in the clang-sparc64 project
branch.  This is also to minimize differences with upstream.
2014-03-26 07:31:57 +00:00

85 lines
2.6 KiB
C

/* ===-- floattisf.c - Implement __floattisf -------------------------------===
*
* The LLVM Compiler Infrastructure
*
* This file is dual licensed under the MIT and the University of Illinois Open
* Source Licenses. See LICENSE.TXT for details.
*
* ===----------------------------------------------------------------------===
*
* This file implements __floattisf for the compiler_rt library.
*
* ===----------------------------------------------------------------------===
*/
#include "int_lib.h"
#ifdef CRT_HAS_128BIT
/* Returns: convert a to a float, rounding toward even. */
/* Assumption: float is a IEEE 32 bit floating point type
* ti_int is a 128 bit integral type
*/
/* seee eeee emmm mmmm mmmm mmmm mmmm mmmm */
si_int __clzti2(ti_int a);
float
__floattisf(ti_int a)
{
if (a == 0)
return 0.0F;
const unsigned N = sizeof(ti_int) * CHAR_BIT;
const ti_int s = a >> (N-1);
a = (a ^ s) - s;
int sd = N - __clzti2(a); /* number of significant digits */
int e = sd - 1; /* exponent */
if (sd > FLT_MANT_DIG)
{
/* start: 0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx
* finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR
* 12345678901234567890123456
* 1 = msb 1 bit
* P = bit FLT_MANT_DIG-1 bits to the right of 1
* Q = bit FLT_MANT_DIG bits to the right of 1
* R = "or" of all bits to the right of Q
*/
switch (sd)
{
case FLT_MANT_DIG + 1:
a <<= 1;
break;
case FLT_MANT_DIG + 2:
break;
default:
a = ((tu_int)a >> (sd - (FLT_MANT_DIG+2))) |
((a & ((tu_int)(-1) >> ((N + FLT_MANT_DIG+2) - sd))) != 0);
};
/* finish: */
a |= (a & 4) != 0; /* Or P into R */
++a; /* round - this step may add a significant bit */
a >>= 2; /* dump Q and R */
/* a is now rounded to FLT_MANT_DIG or FLT_MANT_DIG+1 bits */
if (a & ((tu_int)1 << FLT_MANT_DIG))
{
a >>= 1;
++e;
}
/* a is now rounded to FLT_MANT_DIG bits */
}
else
{
a <<= (FLT_MANT_DIG - sd);
/* a is now rounded to FLT_MANT_DIG bits */
}
float_bits fb;
fb.u = ((su_int)s & 0x80000000) | /* sign */
((e + 127) << 23) | /* exponent */
((su_int)a & 0x007FFFFF); /* mantissa */
return fb.f;
}
#endif /* CRT_HAS_128BIT */