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| author | Joseph Myers <joseph@codesourcery.com> | 2012-03-14 11:53:32 +0000 |
|---|---|---|
| committer | Joseph Myers <joseph@codesourcery.com> | 2012-03-14 11:53:32 +0000 |
| commit | e456826d7a539fb322bb9719297bd386eded8e32 (patch) | |
| tree | 5a0b1e8979b004c88796e199fac827a0d8817207 /math/s_csqrtf.c | |
| parent | 6278569b6c1ee1b6e2b36af059e699233da0b88b (diff) | |
| download | glibc-e456826d7a539fb322bb9719297bd386eded8e32.tar.gz glibc-e456826d7a539fb322bb9719297bd386eded8e32.tar.xz glibc-e456826d7a539fb322bb9719297bd386eded8e32.zip | |
Fix csqrt overflow/underflow (bug 13841).
Diffstat (limited to 'math/s_csqrtf.c')
| -rw-r--r-- | math/s_csqrtf.c | 26 |
1 files changed, 24 insertions, 2 deletions
diff --git a/math/s_csqrtf.c b/math/s_csqrtf.c index d9949c685b..6539ba2249 100644 --- a/math/s_csqrtf.c +++ b/math/s_csqrtf.c @@ -1,5 +1,5 @@ /* Complex square root of float value. - Copyright (C) 1997, 1998, 2005, 2011 Free Software Foundation, Inc. + Copyright (C) 1997-2012 Free Software Foundation, Inc. This file is part of the GNU C Library. Based on an algorithm by Stephen L. Moshier <moshier@world.std.com>. Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997. @@ -21,7 +21,7 @@ #include <complex.h> #include <math.h> #include <math_private.h> - +#include <float.h> __complex__ float __csqrtf (__complex__ float x) @@ -83,6 +83,22 @@ __csqrtf (__complex__ float x) else { float d, r, s; + int scale = 0; + + if (fabsf (__real__ x) > FLT_MAX / 2.0f + || fabsf (__imag__ x) > FLT_MAX / 2.0f) + { + scale = 1; + __real__ x = __scalbnf (__real__ x, -2 * scale); + __imag__ x = __scalbnf (__imag__ x, -2 * scale); + } + else if (fabsf (__real__ x) < FLT_MIN + && fabsf (__imag__ x) < FLT_MIN) + { + scale = -(FLT_MANT_DIG / 2); + __real__ x = __scalbnf (__real__ x, -2 * scale); + __imag__ x = __scalbnf (__imag__ x, -2 * scale); + } d = __ieee754_hypotf (__real__ x, __imag__ x); /* Use the identity 2 Re res Im res = Im x @@ -98,6 +114,12 @@ __csqrtf (__complex__ float x) r = fabsf ((0.5f * __imag__ x) / s); } + if (scale) + { + r = __scalbnf (r, scale); + s = __scalbnf (s, scale); + } + __real__ res = r; __imag__ res = __copysignf (s, __imag__ x); } |