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5980be9b3c
This work is based in part on code from NetBSD libm, libc and kernel. The library is partly public domain and partly BSD-style licensed.
108 lines
3.5 KiB
ArmAsm
108 lines
3.5 KiB
ArmAsm
/* $NetBSD: e_exp.S,v 1.14 2008/06/23 10:24:13 drochner Exp $ */
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/*
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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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#include "abi.h"
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RCSID("$NetBSD: e_exp.S,v 1.14 2008/06/23 10:24:13 drochner Exp $")
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#if 0
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RCSID("$FreeBSD: src/lib/msun/i387/e_exp.S,v 1.8.2.1 2000/07/10 09:16:28 obrien Exp $")
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#endif
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/* e^x = 2^(x * log2(e)) */
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ENTRY(__ieee754_exp)
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XMM_ONE_ARG_DOUBLE_PROLOGUE
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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 ARG_DOUBLE_ONE_MSW, %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 ARG_DOUBLE_ONE
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/*
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* Ensure that the rounding mode is to nearest (to give the smallest
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* possible fraction) and that the precision is as high as possible.
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* We may as well mask interrupts if we switch the mode.
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*/
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#define CWSTORE_SAV ARG_DOUBLE_ONE_LSW /* XXX overwrites the argument */
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#define CWSTORE_TMP ARG_DOUBLE_ONE_MSW
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fstcw CWSTORE_SAV
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movl CWSTORE_SAV, %eax
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andl $0x0f00, %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, CWSTORE_TMP
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fldcw CWSTORE_TMP
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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 CWSTORE_SAV
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1:
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XMM_DOUBLE_EPILOGUE
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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, although the
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* C version would return (x + x) (Real Indefinite) if x is a NaN.
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*/
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cmpl $0xfff00000, ARG_DOUBLE_ONE_MSW
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jne x_not_minus_Inf
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cmpl $0, ARG_DOUBLE_ONE_LSW
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jne x_not_minus_Inf
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fldz
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XMM_DOUBLE_EPILOGUE
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ret
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x_not_minus_Inf:
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fldl ARG_DOUBLE_ONE
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XMM_DOUBLE_EPILOGUE
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ret
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