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/* IBM POWER submul_1 -- Multiply a limb vector with a limb and subtract
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* the result from a second limb vector.
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* Copyright (C) 1992, 1994, 1999 Free Software Foundation, Inc.
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* This file is part of GnuPG.
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* GnuPG is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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* GnuPG is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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#include "asm-syntax.h"
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# The RS/6000 has no unsigned 32x32->64 bit multiplication instruction. To
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# obtain that operation, we have to use the 32x32->64 signed multiplication
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# instruction, and add the appropriate compensation to the high limb of the
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# result. We add the multiplicand if the multiplier has its most significant
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# bit set, and we add the multiplier if the multiplicand has its most
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# significant bit set. We need to preserve the carry flag between each
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# iteration, so we have to compute the compensation carefully (the natural,
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# srai+and doesn't work). Since the POWER architecture has a branch unit
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# we can branch in zero cycles, so that's how we perform the additions.
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.csect .mpihelp_submul_1[PR]
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.globl mpihelp_submul_1
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.globl .mpihelp_submul_1
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.csect mpihelp_submul_1[DS]
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.long .mpihelp_submul_1[PR], TOC[tc0], 0
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.csect .mpihelp_submul_1[PR]
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sf 8,11,7 # add res_limb
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a 11,8,11 # invert cy (r11 is junk)
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ae 11,0,9 # low limb + old_cy_limb + old cy
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aze 10,10 # propagate cy to new cy_limb
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sf 8,11,7 # add res_limb
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a 11,8,11 # invert cy (r11 is junk)
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cax 10,10,6 # adjust high limb for negative limb from s1
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a 11,8,11 # invert cy (r11 is junk)
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cax 9,9,6 # adjust high limb for negative limb from s1
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ae 10,10,0 # propagate cy to new cy_limb
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sf 8,11,7 # add res_limb
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a 11,8,11 # invert cy (r11 is junk)
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cax 10,10,6 # adjust high limb for negative limb from s1
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ae 9,9,0 # propagate cy to new cy_limb
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sf 8,11,7 # add res_limb
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a 11,8,11 # invert cy (r11 is junk)
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cax 9,9,6 # adjust high limb for negative limb from s1
added
removed
mpi/power/mpih-mul3.S
