Blame sysdeps/x86_64/fpu/s_log1pl.S
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/*
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* Written by J.T. Conklin <jtc@netbsd.org>.
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* Public domain.
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*
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* Adapted for `long double' by Ulrich Drepper <drepper@cygnus.com>.
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* Adapted for x86-64 by Andreas Jaeger <aj@suse.de>.
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*/
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#include <machine/asm.h>
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RCSID("$NetBSD: s_log1p.S,v 1.7 1995/05/09 00:10:58 jtc Exp $")
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.section .rodata
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.align ALIGNARG(4)
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/* The fyl2xp1 can only be used for values in
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-1 + sqrt(2) / 2 <= x <= 1 - sqrt(2) / 2
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0.29 is a safe value.
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*/
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limit: .tfloat 0.29
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/* Please note: we use a double value here. Since 1.0 has
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an exact representation this does not effect the accuracy
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but it helps to optimize the code. */
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one: .double 1.0
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/*
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* Use the fyl2xp1 function when the argument is in the range -0.29 to 0.29,
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* otherwise fyl2x with the needed extra computation.
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*/
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#ifdef PIC
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#define MO(op) op##(%rip)
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#else
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#define MO(op) op
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#endif
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.text
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ENTRY(__log1pl)
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fldln2
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fldt 8(%rsp)
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fxam
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fnstsw
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fld %st
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testb $1, %ah
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jnz 3f // in case x is NaN or ±Inf
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4:
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fabs
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fldt MO(limit)
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fcompp
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fnstsw
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andb $1,%ah
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jz 2f
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movzwl 8+8(%rsp), %eax
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xorb $0x80, %ah
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cmpl $0xc040, %eax
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jae 5f
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faddl MO(one)
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5: fyl2x
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ret
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2: fyl2xp1
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ret
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3: testb $4, %ah
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jnz 4b // in case x is ±Inf
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fstp %st(1)
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fstp %st(1)
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fadd %st(0)
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ret
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END (__log1pl)
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