Current File : //glibc-2.29/sysdeps/x86_64/fpu/e_ilogbl.S
/*
* Written by J.T. Conklin <jtc@netbsd.org>.
* Changes for long double by Ulrich Drepper <drepper@cygnus.com>
* Adapted for x86-64 by Andreas Jaeger <aj@suse.de>.
* Public domain.
*/
#include <machine/asm.h>
ENTRY(__ieee754_ilogbl)
fldt 8(%rsp)
/* I added the following ugly construct because ilogb(+-Inf) is
required to return INT_MAX in ISO C99.
-- jakub@redhat.com. */
fxam /* Is NaN or +-Inf? */
fstsw %ax
movb $0x45, %dh
andb %ah, %dh
cmpb $0x05, %dh
je 1f /* Is +-Inf, jump. */
cmpb $0x40, %dh
je 2f /* Is +-Inf, jump. */
fxtract
fstp %st
fistpl -4(%rsp)
fwait
movl -4(%rsp),%eax
ret
1: fstp %st
movl $0x7fffffff, %eax
ret
2: fstp %st
movl $0x80000000, %eax /* FP_ILOGB0 */
ret
END (__ieee754_ilogbl)
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