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PowerPC floating point little-endian [10 of 15]

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http://sourceware.org/ml/libc-alpha/2013-07/msg00201.html

These two functions oddly test x+1>0 when a double x is >= 0.0, and
similarly when x is negative.  I don't see the point of that since the
test should always be true.  I also don't see any need to convert x+1
to integer rather than simply using xr+1.  Note that the standard
allows these functions to return any value when the input is outside
the range of long long, but it's not too hard to prevent xr+1
overflowing so that's what I've done.

(With rounding mode FE_UPWARD, x+1 can be a lot more than what you
might naively expect, but perhaps that situation was covered by the
x - xrf < 1.0 test.)

	* sysdeps/powerpc/fpu/s_llround.c (__llround): Rewrite.
	* sysdeps/powerpc/fpu/s_llroundf.c (__llroundf): Rewrite.
This commit is contained in:
Alan Modra 2013-08-17 18:30:23 +09:30
parent 603e84104c
commit da13146da1
3 changed files with 37 additions and 34 deletions
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5
ChangeLog
View File

@ -1,3 +1,8 @@
2013-10-04 Alan Modra <amodra@gmail.com>
* sysdeps/powerpc/fpu/s_llround.c (__llround): Rewrite.
* sysdeps/powerpc/fpu/s_llroundf.c (__llroundf): Rewrite.
2013-10-04 Alan Modra <amodra@gmail.com>
* sysdeps/powerpc/fpu/s_float_bitwise.h (__float_and_test28): Don't

33
sysdeps/powerpc/fpu/s_llround.c
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@ -19,29 +19,28 @@
#include <math.h>
#include <math_ldbl_opt.h>
/* I think that what this routine is supposed to do is round a value
to the nearest integer, with values exactly on the boundary rounded
away from zero. */
/* This routine relies on (long long)x, when x is out of range of a long long,
clipping to MAX_LLONG or MIN_LLONG. */
/* Round to the nearest integer, with values exactly on a 0.5 boundary
rounded away from zero, regardless of the current rounding mode.
If (long long)x, when x is out of range of a long long, clips at
LLONG_MAX or LLONG_MIN, then this implementation also clips. */
long long int
__llround (double x)
{
double xrf;
long long int xr;
xr = (long long int) x;
xrf = (double) xr;
long long xr = (long long) x;
double xrf = (double) xr;
if (x >= 0.0)
if (x - xrf >= 0.5 && x - xrf < 1.0 && x+1 > 0)
return x+1;
else
return x;
{
if (x - xrf >= 0.5)
xr += (long long) ((unsigned long long) xr + 1) > 0;
}
else
if (xrf - x >= 0.5 && xrf - x < 1.0 && x-1 < 0)
return x-1;
else
return x;
{
if (xrf - x >= 0.5)
xr -= (long long) ((unsigned long long) xr - 1) < 0;
}
return xr;
}
weak_alias (__llround, llround)
#ifdef NO_LONG_DOUBLE

33
sysdeps/powerpc/fpu/s_llroundf.c
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@ -18,28 +18,27 @@
#include <math.h>
/* I think that what this routine is supposed to do is round a value
to the nearest integer, with values exactly on the boundary rounded
away from zero. */
/* This routine relies on (long long)x, when x is out of range of a long long,
clipping to MAX_LLONG or MIN_LLONG. */
/* Round to the nearest integer, with values exactly on a 0.5 boundary
rounded away from zero, regardless of the current rounding mode.
If (long long)x, when x is out of range of a long long, clips at
LLONG_MAX or LLONG_MIN, then this implementation also clips. */
long long int
__llroundf (float x)
{
float xrf;
long long int xr;
xr = (long long int) x;
xrf = (float) xr;
long long xr = (long long) x;
float xrf = (float) xr;
if (x >= 0.0)
if (x - xrf >= 0.5 && x - xrf < 1.0 && x+1 > 0)
return x+1;
else
return x;
{
if (x - xrf >= 0.5)
xr += (long long) ((unsigned long long) xr + 1) > 0;
}
else
if (xrf - x >= 0.5 && xrf - x < 1.0 && x-1 < 0)
return x-1;
else
return x;
{
if (xrf - x >= 0.5)
xr -= (long long) ((unsigned long long) xr - 1) < 0;
}
return xr;
}
weak_alias (__llroundf, llroundf)