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Diffstat (limited to 'sysdeps/alpha/submul_1.s')
| -rw-r--r-- | sysdeps/alpha/submul_1.s | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/sysdeps/alpha/submul_1.s b/sysdeps/alpha/submul_1.s new file mode 100644 index 0000000000..acaa11c545 --- /dev/null +++ b/sysdeps/alpha/submul_1.s @@ -0,0 +1,100 @@ + # Alpha 21064 __mpn_submul_1 -- Multiply a limb vector with a limb and + # subtract the result from a second limb vector. + + # Copyright (C) 1992, 1994, 1995 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 Library General Public License as published by + # the Free Software Foundation; either version 2 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 Library General Public + # License for more details. + + # You should have received a copy of the GNU Library General Public License + # along with the GNU MP Library; see the file COPYING.LIB. If not, write to + # the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + + + # INPUT PARAMETERS + # res_ptr r16 + # s1_ptr r17 + # size r18 + # s2_limb r19 + + # This code runs at 42 cycles/limb on the 21064. + + # 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_submul_1 + .ent __mpn_submul_1 2 +__mpn_submul_1: + .frame $30,0,$26 + + ldq $2,0($17) # $2 = s1_limb + addq $17,8,$17 # s1_ptr++ + subq $18,1,$18 # size-- + mulq $2,$19,$3 # $3 = prod_low + ldq $5,0($16) # $5 = *res_ptr + umulh $2,$19,$0 # $0 = prod_high + beq $18,Lend1 # jump if size was == 1 + ldq $2,0($17) # $2 = s1_limb + addq $17,8,$17 # s1_ptr++ + subq $18,1,$18 # size-- + subq $5,$3,$3 + cmpult $5,$3,$4 + stq $3,0($16) + addq $16,8,$16 # res_ptr++ + beq $18,Lend2 # jump if size was == 2 + + .align 3 +Loop: mulq $2,$19,$3 # $3 = prod_low + ldq $5,0($16) # $5 = *res_ptr + addq $4,$0,$0 # cy_limb = cy_limb + 'cy' + subq $18,1,$18 # size-- + umulh $2,$19,$4 # $4 = cy_limb + ldq $2,0($17) # $2 = s1_limb + addq $17,8,$17 # s1_ptr++ + addq $3,$0,$3 # $3 = cy_limb + prod_low + cmpult $3,$0,$0 # $0 = carry from (cy_limb + prod_low) + subq $5,$3,$3 + cmpult $5,$3,$5 + stq $3,0($16) + addq $16,8,$16 # res_ptr++ + addq $5,$0,$0 # combine carries + bne $18,Loop + +Lend2: mulq $2,$19,$3 # $3 = prod_low + ldq $5,0($16) # $5 = *res_ptr + 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) + subq $5,$3,$3 + cmpult $5,$3,$5 + stq $3,0($16) + addq $5,$0,$0 # combine carries + addq $4,$0,$0 # cy_limb = prod_high + cy + ret $31,($26),1 +Lend1: subq $5,$3,$3 + cmpult $5,$3,$5 + stq $3,0($16) + addq $0,$5,$0 + ret $31,($26),1 + + .end __mpn_submul_1 |