diff options
Diffstat (limited to 'libc/sysdeps/i386/fpu/e_ilogb.S')
| -rw-r--r-- | libc/sysdeps/i386/fpu/e_ilogb.S | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/libc/sysdeps/i386/fpu/e_ilogb.S b/libc/sysdeps/i386/fpu/e_ilogb.S new file mode 100644 index 000000000..29ef2214e --- /dev/null +++ b/libc/sysdeps/i386/fpu/e_ilogb.S @@ -0,0 +1,42 @@ +/* + * Written by J.T. Conklin <jtc@netbsd.org>. + * Public domain. + */ + +#include <machine/asm.h> + +RCSID("$NetBSD: s_ilogb.S,v 1.5 1995/10/12 15:53:09 jtc Exp $") + +ENTRY(__ieee754_ilogb) + fldl 4(%esp) +/* 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 +-0, jump. */ + + fxtract + pushl %eax + cfi_adjust_cfa_offset (4) + fstp %st + + fistpl (%esp) + fwait + popl %eax + cfi_adjust_cfa_offset (-4) + + ret + +1: fstp %st + movl $0x7fffffff, %eax + ret +2: fstp %st + movl $0x80000000, %eax /* FP_ILOGB0 */ + ret +END (__ieee754_ilogb) |