95 lines
3.2 KiB
ArmAsm
95 lines
3.2 KiB
ArmAsm
/* ffs.S - ARCv2 find first set assembly routines */
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/*
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* Copyright (c) 2014 Wind River Systems, Inc.
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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 are met:
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*
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* 1) Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* 2) Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* 3) Neither the name of Wind River Systems nor the names of its contributors
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* may be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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DESCRIPTION
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This library implements nanoFfsMsb() and nanoFfsLsb() which returns the
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most and least significant bit set respectively.
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*/
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#define _ASMLANGUAGE
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#include <toolchain.h>
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#include <sections.h>
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/* Exports */
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GTEXT(nanoFfsMsb)
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GTEXT(nanoFfsLsb)
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/*******************************************************************************
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*
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* nanoFfsMsb - find first set bit (searching from the most significant bit)
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*
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* This routine finds the first bit set in the argument passed it and
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* returns the index of that bit. Bits are numbered starting
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* at 1 from the least significant bit. A return value of zero indicates that
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* the value passed is zero.
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*
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* RETURNS: most significant bit set
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*/
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SECTION_FUNC(TEXT, nanoFfsMsb)
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/*
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* The FLS instruction returns the bit number (0-31), and 0 if the operand
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* is 0. So, the bit number must be incremented by 1 only in the case of
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* an operand value that is non-zero.
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*/
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fls.f r0, r0
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j_s.d [blink]
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add.nz r0, r0, 1
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/*******************************************************************************
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*
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* nanoFfsLsb - find first set bit (searching from the least significant bit)
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*
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* This routine finds the first bit set in the argument passed it and
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* returns the index of that bit. Bits are numbered starting
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* at 1 from the least significant bit. A return value of zero indicates that
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* the value passed is zero.
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*
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* RETURNS: least significant bit set
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*/
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SECTION_FUNC(TEXT, nanoFfsLsb)
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/*
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* The FFS instruction returns the bit number (0-31), and 31 if the operand
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* is 0. So, the bit number must be incremented by 1, or, in the case of an
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* operand value of 0, set to 0.
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*/
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ffs.f r0, r0
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add.nz r0, r0, 1
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j_s.d [blink]
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mov.z r0, 0
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