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glibc/sysdeps/i386/fpu/e_scalb.S
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/* | |
* Written by J.T. Conklin <jtc@netbsd.org>. | |
* Public domain. | |
* | |
* Correct handling of y==-inf <drepper@gnu> | |
*/ | |
#include <machine/asm.h> | |
.section .rodata | |
.align ALIGNARG(4) | |
.type zero_nan,@object | |
zero_nan: | |
.double 0.0 | |
nan: .byte 0, 0, 0, 0, 0, 0, 0xff, 0x7f | |
.byte 0, 0, 0, 0, 0, 0, 0, 0x80 | |
.byte 0, 0, 0, 0, 0, 0, 0xff, 0x7f | |
ASM_SIZE_DIRECTIVE(zero_nan) | |
#ifdef PIC | |
# define MO(op) op##@GOTOFF(%ecx) | |
# define MOX(op,x,f) op##@GOTOFF(%ecx,x,f) | |
#else | |
# define MO(op) op | |
# define MOX(op,x,f) op(,x,f) | |
#endif | |
.text | |
ENTRY(__ieee754_scalb) | |
fldl 12(%esp) | |
fxam | |
fnstsw | |
fldl 4(%esp) | |
andl $0x4700, %eax | |
cmpl $0x0700, %eax | |
je 1f | |
andl $0x4500, %eax | |
cmpl $0x0100, %eax | |
je 2f | |
fxam | |
fnstsw | |
andl $0x4500, %eax | |
cmpl $0x0100, %eax | |
je 3f | |
fld %st(1) | |
frndint | |
fcomp %st(2) | |
fnstsw | |
sahf | |
jne 4f | |
fscale | |
fstp %st(1) | |
ret | |
/* y is -inf */ | |
1: fxam | |
#ifdef PIC | |
LOAD_PIC_REG (cx) | |
#endif | |
fnstsw | |
movl 8(%esp), %edx | |
shrl $5, %eax | |
fstp %st | |
fstp %st | |
andl $0x80000000, %edx | |
andl $0x0228, %eax | |
cmpl $0x0028, %eax | |
je 4f | |
andl $8, %eax | |
shrl $27, %edx | |
addl %edx, %eax | |
fldl MOX(zero_nan, %eax, 1) | |
ret | |
/* The result is NaN, but we must not raise an exception. | |
So use a variable. */ | |
2: fstp %st | |
fstp %st | |
#ifdef PIC | |
LOAD_PIC_REG (cx) | |
#endif | |
fldl MO(nan) | |
ret | |
/* The first parameter is a NaN. Return it. */ | |
3: fstp %st(1) | |
ret | |
/* Return NaN and raise the invalid exception. */ | |
4: fstp %st | |
fstp %st | |
fldz | |
fdiv %st | |
ret | |
END(__ieee754_scalb) | |
strong_alias (__ieee754_scalb, __scalb_finite) |