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84 lines
2.6 KiB
ArmAsm
84 lines
2.6 KiB
ArmAsm
# Alpha 21064 __mpn_mul_1 -- Multiply a limb vector with a limb and store
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# the result in a second limb vector.
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# Copyright (C) 1992-2024 Free Software Foundation, Inc.
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# This file is part of the GNU MP Library.
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# The GNU MP Library is free software; you can redistribute it and/or modify
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# it under the terms of the GNU Lesser General Public License as published by
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# the Free Software Foundation; either version 2.1 of the License, or (at your
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# option) any later version.
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# The GNU MP Library is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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# License for more details.
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# You should have received a copy of the GNU Lesser General Public License
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# along with the GNU MP Library. If not, see <https://www.gnu.org/licenses/>.
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# INPUT PARAMETERS
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# res_ptr r16
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# s1_ptr r17
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# size r18
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# s2_limb r19
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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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# 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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.set noreorder
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.set noat
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.text
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.align 3
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.globl __mpn_mul_1
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.ent __mpn_mul_1 2
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__mpn_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 __mpn_mul_1
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