67 lines
2.0 KiB
ArmAsm
67 lines
2.0 KiB
ArmAsm
/* $NetBSD: frexp.S,v 1.2 1997/05/08 13:38:38 matthias Exp $ */
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/*
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* Copyright (c) 1992 Helsinki University of Technology
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* All Rights Reserved.
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*
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* Permission to use, copy, modify and distribute this software and its
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* documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* HELSINKI UNIVERSITY OF TECHNOLOGY ALLOWS FREE USE OF THIS SOFTWARE IN
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* ITS "AS IS" CONDITION. HELSINKI UNIVERSITY OF TECHNOLOGY DISCLAIMS ANY
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* LIABILITY OF ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE
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* USE OF THIS SOFTWARE.
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*/
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/*
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* HISTORY
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* 29-Apr-92 Tero Kivinen (kivinen) at Helsinki University of Technology
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* Created.
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*/
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/*
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* double frexp(value, eptr)
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* double value;
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* int *eptr;
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*
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* The frexp subroutine returns the mantissa of a double value
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* as a double quantity, x, of magnitude less than one and
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* greater than or equal to 0.5 (0.5 <= |x| < 1) and stores an
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* integer n such that value = x*2**n indirectly through eptr.
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*
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* One exception: if the given value is 0, then x and *eptr are made
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* zero.
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*/
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#include <machine/asm.h>
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#if defined(LIBC_SCCS)
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RCSID("$NetBSD: frexp.S,v 1.2 1997/05/08 13:38:38 matthias Exp $")
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#endif
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ENTRY(frexp)
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enter [],8
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movd 12(fp),r1 /* value, high 32 bit */
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cmpd 0,r1 /* check if 0 */
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beq 0f /* we do not support denormalized values */
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movd r1,r2
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bicd 0x7ff00000,r2 /* clear exponent */
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ord 0x3fe00000,r2 /* set it to 1024 == exponent -11 == .5-1 */
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lshd -20,r1 /* extract exponent */
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andd 0x7ff,r1 /* 11 lower bits */
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subd 1022,r1 /* unbias exponent */
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movd r1,0(16(fp))
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movd 8(fp),-8(fp) /* value, low 32 bit */
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movd r2,-4(fp) /* value without exponent, high 32 bit */
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movl -8(fp),f0 /* load return value */
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exit []
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ret 0
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0: movqd 0,0(16(fp)) /* return exp = 0, mantissa = 9 */
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movdl 0,f0
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exit []
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ret 0
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