On Tue, Jan 12, 2010 at 10:32:23AM -0500, A. Craig West wrote: > I recently ran into a problem building ffmpeg on a uclibc system, > where ffmpeg appears to depend on the log2f function. A bit of > investigation led me to a section of code in libm/float_wrappers.c, > with #undef L_log2f, and the comment: > /* For the time being, do _NOT_ implement these functions > * that are defined by SuSv3 */ > > What is missing is any explanation of WHY these functions are left > unimplemented.
Attached patch enable those function to allow ffmpeg/x264/... to build. > There is the secondary issue of why ffmpeg requires > this function, but that isn't really pertinent to this list... Significant overall speed difference compared to the double version (on libc which actually implement a float version). Aurel
>From af843d0a18279725cedb51e00209457e8d0281c0 Mon Sep 17 00:00:00 2001 From: Aurelien Jacobs <au...@gnuage.org> Date: Fri, 15 Jan 2010 19:43:06 +0100 Subject: [PATCH] enable log2f and exp2f Signed-off-by: Aurelien Jacobs <au...@gnuage.org> --- libm/Makefile.in | 4 +++- libm/float_wrappers.c | 4 ++-- test/math/compile_test.c | 4 ++-- 3 files changed, 7 insertions(+), 5 deletions(-) diff --git a/libm/Makefile.in b/libm/Makefile.in index 56b2d76..6eb9358 100644 --- a/libm/Makefile.in +++ b/libm/Makefile.in @@ -75,7 +75,7 @@ libm_CSRC := \ s_remquo.c w_exp2.c # Not implemented [yet?], see comment in float_wrappers.c: -# exp2f.o fdimf.o fmaf.o fmaxf.o fminf.o log2f.o +# fdimf.o fmaf.o fmaxf.o fminf.o # nearbyintf.o remquof.o scalblnf.o tgammaf.o FL_MOBJ := \ acosf.o \ @@ -93,6 +93,7 @@ FL_MOBJ := \ coshf.o \ erfcf.o \ erff.o \ + exp2f.o \ expf.o \ expm1f.o \ fabsf.o \ @@ -108,6 +109,7 @@ FL_MOBJ := \ llroundf.o \ log10f.o \ log1pf.o \ + log2f.o \ logbf.o \ logf.o \ lrintf.o \ diff --git a/libm/float_wrappers.c b/libm/float_wrappers.c index 93d56c3..e1ab8b5 100644 --- a/libm/float_wrappers.c +++ b/libm/float_wrappers.c @@ -41,12 +41,10 @@ long long func##f (float x) \ /* For the time being, do _NOT_ implement these functions * that are defined by SuSv3 [why?] */ -#undef L_exp2f /*float exp2f(float);*/ #undef L_fdimf /*float fdimf(float, float);*/ #undef L_fmaf /*float fmaf(float, float, float);*/ #undef L_fmaxf /*float fmaxf(float, float);*/ #undef L_fminf /*float fminf(float, float);*/ -#undef L_log2f /*float log2f(float);*/ #undef L_nearbyintf /*float nearbyintf(float);*/ #undef L_nexttowardf /*float nexttowardf(float, long double);*/ #undef L_remquof /*float remquof(float, float, int *);*/ @@ -70,6 +68,7 @@ float cosf(float); float coshf(float); float erfcf(float); float erff(float); +float exp2f(float); float expf(float); float expm1f(float); float fabsf(float); @@ -83,6 +82,7 @@ float lgammaf(float); long long llroundf(float); float log10f(float); float log1pf(float); +float log2f(float); float logbf(float); float logf(float); long lroundf(float); diff --git a/test/math/compile_test.c b/test/math/compile_test.c index 6148885..ab8c40c 100644 --- a/test/math/compile_test.c +++ b/test/math/compile_test.c @@ -18,7 +18,7 @@ r += cosf(float_x); r += coshf(float_x); r += erfcf(float_x); r += erff(float_x); -/*r += exp2f(float_x); - uclibc does not have it (yet?) */ +r += exp2f(float_x); r += expf(float_x); r += expm1f(float_x); r += fabsf(float_x); @@ -38,7 +38,7 @@ r += llrintf(float_x); r += llroundf(float_x); r += log10f(float_x); r += log1pf(float_x); -/*r += log2f(float_x); - uclibc does not have it (yet?) */ +r += log2f(float_x); r += logbf(float_x); r += logf(float_x); r += lrintf(float_x); -- 1.6.0.4
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