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| author | Ulrich Drepper <drepper@redhat.com> | 1999-07-14 00:54:57 +0000 |
|---|---|---|
| committer | Ulrich Drepper <drepper@redhat.com> | 1999-07-14 00:54:57 +0000 |
| commit | abfbdde177c3a7155070dda1b2cdc8292054cc26 (patch) | |
| tree | e021306b596381fbf8311d2b7eb294e918ff17c8 /sysdeps/i386/fpu/s_log2.S | |
| parent | 86421aa57ecfd70963ae66848bd6a6dd3b8e0fe6 (diff) | |
| download | glibc-abfbdde177c3a7155070dda1b2cdc8292054cc26.tar.gz glibc-abfbdde177c3a7155070dda1b2cdc8292054cc26.tar.xz glibc-abfbdde177c3a7155070dda1b2cdc8292054cc26.zip | |
Update.
Diffstat (limited to 'sysdeps/i386/fpu/s_log2.S')
| -rw-r--r-- | sysdeps/i386/fpu/s_log2.S | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/sysdeps/i386/fpu/s_log2.S b/sysdeps/i386/fpu/s_log2.S new file mode 100644 index 0000000000..4632c96f67 --- /dev/null +++ b/sysdeps/i386/fpu/s_log2.S @@ -0,0 +1,59 @@ +/* + * Written by J.T. Conklin <jtc@netbsd.org>. + * Adapted for use as log2 by Ulrich Drepper <drepper@cygnus.com>. + * Public domain. + * + * Changed to use fyl2xp1 for values near 1, <drepper@cygnus.com>. + */ + +#include <machine/asm.h> + +#ifdef __ELF__ + .section .rodata +#else + .text +#endif + .align ALIGNARG(4) + ASM_TYPE_DIRECTIVE(one,@object) +one: .double 1.0 + ASM_SIZE_DIRECTIVE(one) + /* It is not important that this constant is precise. It is only + a value which is known to be on the safe side for using the + fyl2xp1 instruction. */ + ASM_TYPE_DIRECTIVE(limit,@object) +limit: .double 0.29 + ASM_SIZE_DIRECTIVE(limit) + + +#ifdef PIC +#define MO(op) op##@GOTOFF(%edx) +#else +#define MO(op) op +#endif + + .text +ENTRY(__log2) +#ifdef PIC + call 1f +1: popl %edx + addl $_GLOBAL_OFFSET_TABLE_+[.-1b], %edx +#endif + fldl MO(one) + fldl 4(%esp) // x : 1 + fld %st // x : x : 1 + fsub %st(2), %st // x-1 : x : 1 + fld %st // x-1 : x-1 : x : 1 + fabs // |x-1| : x-1 : x : 1 + fcompl MO(limit) // x-1 : x : 1 + fnstsw // x-1 : x : 1 + andb $0x45, %ah + jz 2f + fstp %st(1) // x-1 : 1 + fyl2xp1 // log(x) + ret + +2: fstp %st(0) // x : 1 + fyl2x // log(x) + ret +END (__log2) +weak_alias (__log2, log2) |