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https://git.planet-casio.com/Lephenixnoir/OpenLibm.git
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100 lines
3.1 KiB
ArmAsm
100 lines
3.1 KiB
ArmAsm
/*
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* Copyright (c) 1993,94 Winning Strategies, Inc.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Winning Strategies, Inc.
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* 4. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Written by:
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* J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc.
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*/
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#include <machine/asm.h>
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//__FBSDID("$FreeBSD: src/lib/msun/i387/e_exp.S,v 1.14 2011/01/07 16:13:12 kib Exp $")
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/* e^x = 2^(x * log2(e)) */
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ENTRY(exp)
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/*
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* If x is +-Inf, then the subtraction would give Inf-Inf = NaN.
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* Avoid this. Also avoid it if x is NaN for convenience.
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*/
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movl 8(%esp),%eax
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andl $0x7fffffff,%eax
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cmpl $0x7ff00000,%eax
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jae x_Inf_or_NaN
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fldl 4(%esp)
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/*
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* Extended precision is needed to reduce the maximum error from
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* hundreds of ulps to less than 1 ulp. Switch to it if necessary.
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* We may as well set the rounding mode to to-nearest and mask traps
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* if we switch.
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*/
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fstcw 4(%esp)
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movl 4(%esp),%eax
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andl $0x0300,%eax
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cmpl $0x0300,%eax /* RC == 0 && PC == 3? */
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je 1f /* jump if mode is good */
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movl $0x137f,8(%esp)
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fldcw 8(%esp)
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1:
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fldl2e
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fmulp /* x * log2(e) */
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fst %st(1)
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frndint /* int(x * log2(e)) */
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fst %st(2)
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fsubrp /* fract(x * log2(e)) */
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f2xm1 /* 2^(fract(x * log2(e))) - 1 */
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fld1
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faddp /* 2^(fract(x * log2(e))) */
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fscale /* e^x */
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fstp %st(1)
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je 1f
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fldcw 4(%esp)
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1:
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ret
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x_Inf_or_NaN:
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/*
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* Return 0 if x is -Inf. Otherwise just return x; when x is Inf
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* this gives Inf, and when x is a NaN this gives the same result
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* as (x + x) (x quieted).
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*/
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cmpl $0xfff00000,8(%esp)
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jne x_not_minus_Inf
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cmpl $0,4(%esp)
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jne x_not_minus_Inf
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fldz
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ret
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x_not_minus_Inf:
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fldl 4(%esp)
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ret
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END(exp)
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.section .note.GNU-stack,"",%progbits
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