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authorZack Weinberg <zackw@panix.com>2017-06-08 15:39:03 -0400
committerZack Weinberg <zackw@panix.com>2017-06-08 15:39:03 -0400
commit5046dbb4a7eba5eccfd258f92f4735c9ffc8d069 (patch)
tree4470480d904b65cf14ca524f96f79eca818c3eaf /REORG.TODO/sysdeps/alpha/mul_1.S
parent199fc19d3aaaf57944ef036e15904febe877fc93 (diff)
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All top-level files and directories are moved into a temporary storage directory, REORG.TODO, except for files that will certainly still exist in their current form at top level when we're done (COPYING, COPYING.LIB, LICENSES, NEWS, README), all old ChangeLog files (which are moved to the new directory OldChangeLogs, instead), and the generated file INSTALL (which is just deleted; in the new order, there will be no generated files checked into version control).
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+ # Alpha 21064 __mpn_mul_1 -- Multiply a limb vector with a limb and store
+ # the result in a second limb vector.
+
+ # Copyright (C) 1992-2017 Free Software Foundation, Inc.
+
+ # This file is part of the GNU MP Library.
+
+ # The GNU MP Library is free software; you can redistribute it and/or modify
+ # it under the terms of the GNU Lesser General Public License as published by
+ # the Free Software Foundation; either version 2.1 of the License, or (at your
+ # option) any later version.
+
+ # The GNU MP Library is distributed in the hope that it will be useful, but
+ # WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ # or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+ # License for more details.
+
+ # You should have received a copy of the GNU Lesser General Public License
+ # along with the GNU MP Library. If not, see <http://www.gnu.org/licenses/>.
+
+
+ # INPUT PARAMETERS
+ # res_ptr r16
+ # s1_ptr r17
+ # size r18
+ # s2_limb r19
+
+ # This code runs at 42 cycles/limb on the EV4 and 18 cycles/limb on the EV5.
+
+ # To improve performance for long multiplications, we would use
+ # 'fetch' for S1 and 'fetch_m' for RES. It's not obvious how to use
+ # these instructions without slowing down the general code: 1. We can
+ # only have two prefetches in operation at any time in the Alpha
+ # architecture. 2. There will seldom be any special alignment
+ # between RES_PTR and S1_PTR. Maybe we can simply divide the current
+ # loop into an inner and outer loop, having the inner loop handle
+ # exactly one prefetch block?
+
+ .set noreorder
+ .set noat
+.text
+ .align 3
+ .globl __mpn_mul_1
+ .ent __mpn_mul_1 2
+__mpn_mul_1:
+ .frame $30,0,$26
+
+ ldq $2,0($17) # $2 = s1_limb
+ subq $18,1,$18 # size--
+ mulq $2,$19,$3 # $3 = prod_low
+ bic $31,$31,$4 # clear cy_limb
+ umulh $2,$19,$0 # $0 = prod_high
+ beq $18,Lend1 # jump if size was == 1
+ ldq $2,8($17) # $2 = s1_limb
+ subq $18,1,$18 # size--
+ stq $3,0($16)
+ beq $18,Lend2 # jump if size was == 2
+
+ .align 3
+Loop: mulq $2,$19,$3 # $3 = prod_low
+ addq $4,$0,$0 # cy_limb = cy_limb + 'cy'
+ subq $18,1,$18 # size--
+ umulh $2,$19,$4 # $4 = cy_limb
+ ldq $2,16($17) # $2 = s1_limb
+ addq $17,8,$17 # s1_ptr++
+ addq $3,$0,$3 # $3 = cy_limb + prod_low
+ stq $3,8($16)
+ cmpult $3,$0,$0 # $0 = carry from (cy_limb + prod_low)
+ addq $16,8,$16 # res_ptr++
+ bne $18,Loop
+
+Lend2: mulq $2,$19,$3 # $3 = prod_low
+ addq $4,$0,$0 # cy_limb = cy_limb + 'cy'
+ umulh $2,$19,$4 # $4 = cy_limb
+ addq $3,$0,$3 # $3 = cy_limb + prod_low
+ cmpult $3,$0,$0 # $0 = carry from (cy_limb + prod_low)
+ stq $3,8($16)
+ addq $4,$0,$0 # cy_limb = prod_high + cy
+ ret $31,($26),1
+Lend1: stq $3,0($16)
+ ret $31,($26),1
+
+ .end __mpn_mul_1