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9e329b544a
soft-fp should round floating pointer numbers according to the current
rounding mode. However, in the current code of lrint() and llrint(),
there are if statements before the actual rounding computation
if(j0 < -1)
return 0;
Where j0 is the exponent of the floating point number.
It means any number having a exponent less than -1
(i.e. interval (-0.5, 0.5)) will be rounded to 0 regardeless of the
rounding mode.
The bug already fixed in glibc in 2006 by moving the check afterwards
the rounding computation, but still persists in newlib.
This patch fixed it in a similar way to glibc
Ref Commit in glibc: 6624dbc07b5a9fb316ed188ef01f65b8eea8b47c
100 lines
2.3 KiB
C
100 lines
2.3 KiB
C
/* lrintf adapted to be llrintf for Newlib, 2009 by Craig Howland. */
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/* @(#)sf_lrint.c 5.1 93/09/24 */
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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/*
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* llrintf(x)
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* Return x rounded to integral value according to the prevailing
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* rounding mode.
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* Method:
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* Using floating addition.
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* Exception:
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* Inexact flag raised if x not equal to llrintf(x).
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*/
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#include "fdlibm.h"
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#ifdef __STDC__
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static const float
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#else
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static float
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#endif
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/* Adding a float, x, to 2^23 will cause the result to be rounded based on
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the fractional part of x, according to the implementation's current rounding
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mode. 2^23 is the smallest float that can be represented using all 23 significant
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digits. */
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TWO23[2]={
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8.3886080000e+06, /* 0x4b000000 */
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-8.3886080000e+06, /* 0xcb000000 */
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};
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#ifdef __STDC__
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long long int llrintf(float x)
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#else
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long long int llrintf(x)
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float x;
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#endif
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{
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__int32_t j0,sx;
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__uint32_t i0;
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float t;
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volatile float w;
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long long int result;
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GET_FLOAT_WORD(i0,x);
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/* Extract sign bit. */
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sx = (i0 >> 31);
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/* Extract exponent field. */
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j0 = ((i0 & 0x7f800000) >> 23) - 127;
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if (j0 < (int)(sizeof (long long int) * 8) - 1)
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{
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if (j0 >= 23)
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result = (long long int) ((i0 & 0x7fffff) | 0x800000) << (j0 - 23);
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else
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{
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w = TWO23[sx] + x;
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t = w - TWO23[sx];
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GET_FLOAT_WORD (i0, t);
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/* Detect the all-zeros representation of plus and
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minus zero, which fails the calculation below. */
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if ((i0 & ~((__uint32_t)1 << 31)) == 0)
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return 0;
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j0 = ((i0 >> 23) & 0xff) - 0x7f;
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i0 &= 0x7fffff;
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i0 |= 0x800000;
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result = (j0 < 0 ? 0 : i0 >> (23 - j0));
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}
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}
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else
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{
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return (long long int) x;
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}
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return sx ? -result : result;
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}
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#ifdef _DOUBLE_IS_32BITS
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#ifdef __STDC__
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long long int llrint(double x)
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#else
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long long int llrint(x)
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double x;
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#endif
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{
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return llrintf((float) x);
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}
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#endif /* defined(_DOUBLE_IS_32BITS) */
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