2002-06-29 16:15:02 +02:00
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/* Alpha 21064 mpih-mul1.S -- Multiply a limb vector with a limb and store
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* the result in a second limb vector.
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*
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* Copyright (C) 1992, 1994, 1995, 1998,
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2001 Free Software Foundation, Inc.
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*
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* This file is part of GnuPG.
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*
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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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*
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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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*
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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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2005-05-31 10:39:18 +02:00
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
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* USA.
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2002-06-29 16:15:02 +02:00
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*/
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/*******************
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* mpi_limb_t
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* mpihelp_mul_1( mpi_ptr_t res_ptr, (r16)
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* mpi_ptr_t s1_ptr, (r17)
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* mpi_size_t s1_size, (r18)
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* mpi_limb_t s2_limb) (r19)
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*
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* This code runs at 42 cycles/limb on the EV4 and 18 cycles/limb on the EV5.
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*
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* To improve performance for long multiplications, we would use
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* 'fetch' for S1 and 'fetch_m' for RES. It's not obvious how to use
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* these instructions without slowing down the general code: 1. We can
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* only have two prefetches in operation at any time in the Alpha
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* architecture. 2. There will seldom be any special alignment
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* between RES_PTR and S1_PTR. Maybe we can simply divide the current
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* loop into an inner and outer loop, having the inner loop handle
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* exactly one prefetch block?
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*/
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.set noreorder
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.set noat
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.text
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.align 3
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.globl mpihelp_mul_1
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.ent mpihelp_mul_1 2
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mpihelp_mul_1:
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.frame $30,0,$26
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ldq $2,0($17) # $2 = s1_limb
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subq $18,1,$18 # size--
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mulq $2,$19,$3 # $3 = prod_low
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bic $31,$31,$4 # clear cy_limb
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umulh $2,$19,$0 # $0 = prod_high
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beq $18,Lend1 # jump if size was == 1
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ldq $2,8($17) # $2 = s1_limb
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subq $18,1,$18 # size--
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stq $3,0($16)
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beq $18,Lend2 # jump if size was == 2
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.align 3
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Loop: mulq $2,$19,$3 # $3 = prod_low
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addq $4,$0,$0 # cy_limb = cy_limb + 'cy'
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subq $18,1,$18 # size--
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umulh $2,$19,$4 # $4 = cy_limb
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ldq $2,16($17) # $2 = s1_limb
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addq $17,8,$17 # s1_ptr++
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addq $3,$0,$3 # $3 = cy_limb + prod_low
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stq $3,8($16)
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cmpult $3,$0,$0 # $0 = carry from (cy_limb + prod_low)
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addq $16,8,$16 # res_ptr++
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bne $18,Loop
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Lend2: mulq $2,$19,$3 # $3 = prod_low
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addq $4,$0,$0 # cy_limb = cy_limb + 'cy'
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umulh $2,$19,$4 # $4 = cy_limb
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addq $3,$0,$3 # $3 = cy_limb + prod_low
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cmpult $3,$0,$0 # $0 = carry from (cy_limb + prod_low)
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stq $3,8($16)
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addq $4,$0,$0 # cy_limb = prod_high + cy
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ret $31,($26),1
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Lend1: stq $3,0($16)
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ret $31,($26),1
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.end mpihelp_mul_1
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