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Diffstat (limited to 'sysdeps/alpha/rshift.S')
-rw-r--r-- | sysdeps/alpha/rshift.S | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/sysdeps/alpha/rshift.S b/sysdeps/alpha/rshift.S new file mode 100644 index 0000000..b458795 --- /dev/null +++ b/sysdeps/alpha/rshift.S @@ -0,0 +1,105 @@ + # Alpha 21064 __mpn_rshift -- + + # Copyright (C) 1994-2014 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 + # cnt r19 + + # This code runs at 4.8 cycles/limb on the 21064. With infinite unrolling, + # it would take 4 cycles/limb. It should be possible to get down to 3 + # cycles/limb since both ldq and stq can be paired with the other used + # instructions. But there are many restrictions in the 21064 pipeline that + # makes it hard, if not impossible, to get down to 3 cycles/limb: + + # 1. ldq has a 3 cycle delay, srl and sll have a 2 cycle delay. + # 2. Only aligned instruction pairs can be paired. + # 3. The store buffer or silo might not be able to deal with the bandwidth. + + .set noreorder + .set noat +.text + .align 3 + .globl __mpn_rshift + .ent __mpn_rshift +__mpn_rshift: + .frame $30,0,$26,0 + + ldq $4,0($17) # load first limb + addq $17,8,$17 + subq $31,$19,$7 + subq $18,1,$18 + and $18,4-1,$20 # number of limbs in first loop + sll $4,$7,$0 # compute function result + + beq $20,.L0 + subq $18,$20,$18 + + .align 3 +.Loop0: + ldq $3,0($17) + addq $16,8,$16 + addq $17,8,$17 + subq $20,1,$20 + srl $4,$19,$5 + sll $3,$7,$6 + bis $3,$3,$4 + bis $5,$6,$8 + stq $8,-8($16) + bne $20,.Loop0 + +.L0: beq $18,.Lend + + .align 3 +.Loop: ldq $3,0($17) + addq $16,32,$16 + subq $18,4,$18 + srl $4,$19,$5 + sll $3,$7,$6 + + ldq $4,8($17) + srl $3,$19,$1 + bis $5,$6,$8 + stq $8,-32($16) + sll $4,$7,$2 + + ldq $3,16($17) + srl $4,$19,$5 + bis $1,$2,$8 + stq $8,-24($16) + sll $3,$7,$6 + + ldq $4,24($17) + srl $3,$19,$1 + bis $5,$6,$8 + stq $8,-16($16) + sll $4,$7,$2 + + addq $17,32,$17 + bis $1,$2,$8 + stq $8,-8($16) + + bgt $18,.Loop + +.Lend: srl $4,$19,$8 + stq $8,0($16) + ret $31,($26),1 + .end __mpn_rshift |