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Annotation of OpenXM_contrib/gmp/mpn/alpha/rshift.s, Revision 1.1.1.1

1.1       maekawa     1:  # Alpha 21064 __mpn_rshift --
                      2:
                      3:  # Copyright (C) 1994, 1995 Free Software Foundation, Inc.
                      4:
                      5:  # This file is part of the GNU MP Library.
                      6:
                      7:  # The GNU MP Library is free software; you can redistribute it and/or modify
                      8:  # it under the terms of the GNU Library General Public License as published by
                      9:  # the Free Software Foundation; either version 2 of the License, or (at your
                     10:  # option) any later version.
                     11:
                     12:  # The GNU MP Library is distributed in the hope that it will be useful, but
                     13:  # WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
                     14:  # or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
                     15:  # License for more details.
                     16:
                     17:  # You should have received a copy of the GNU Library General Public License
                     18:  # along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
                     19:  # the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
                     20:  # MA 02111-1307, USA.
                     21:
                     22:
                     23:  # INPUT PARAMETERS
                     24:  # res_ptr     r16
                     25:  # s1_ptr      r17
                     26:  # size                r18
                     27:  # cnt         r19
                     28:
                     29:  # This code runs at 4.8 cycles/limb on the 21064.  With infinite unrolling,
                     30:  # it would take 4 cycles/limb.  It should be possible to get down to 3
                     31:  # cycles/limb since both ldq and stq can be paired with the other used
                     32:  # instructions.  But there are many restrictions in the 21064 pipeline that
                     33:  # makes it hard, if not impossible, to get down to 3 cycles/limb:
                     34:
                     35:  # 1. ldq has a 3 cycle delay, srl and sll have a 2 cycle delay.
                     36:  # 2. Only aligned instruction pairs can be paired.
                     37:  # 3. The store buffer or silo might not be able to deal with the bandwidth.
                     38:
                     39:        .set    noreorder
                     40:        .set    noat
                     41: .text
                     42:        .align  3
                     43:        .globl  __mpn_rshift
                     44:        .ent    __mpn_rshift
                     45: __mpn_rshift:
                     46:        .frame  $30,0,$26,0
                     47:
                     48:        ldq     $4,0($17)       # load first limb
                     49:        addq    $17,8,$17
                     50:        subq    $31,$19,$7
                     51:        subq    $18,1,$18
                     52:        and     $18,4-1,$20     # number of limbs in first loop
                     53:        sll     $4,$7,$0        # compute function result
                     54:
                     55:        beq     $20,.L0
                     56:        subq    $18,$20,$18
                     57:
                     58:        .align  3
                     59: .Loop0:
                     60:        ldq     $3,0($17)
                     61:        addq    $16,8,$16
                     62:        addq    $17,8,$17
                     63:        subq    $20,1,$20
                     64:        srl     $4,$19,$5
                     65:        sll     $3,$7,$6
                     66:        bis     $3,$3,$4
                     67:        bis     $5,$6,$8
                     68:        stq     $8,-8($16)
                     69:        bne     $20,.Loop0
                     70:
                     71: .L0:   beq     $18,.Lend
                     72:
                     73:        .align  3
                     74: .Loop: ldq     $3,0($17)
                     75:        addq    $16,32,$16
                     76:        subq    $18,4,$18
                     77:        srl     $4,$19,$5
                     78:        sll     $3,$7,$6
                     79:
                     80:        ldq     $4,8($17)
                     81:        srl     $3,$19,$1
                     82:        bis     $5,$6,$8
                     83:        stq     $8,-32($16)
                     84:        sll     $4,$7,$2
                     85:
                     86:        ldq     $3,16($17)
                     87:        srl     $4,$19,$5
                     88:        bis     $1,$2,$8
                     89:        stq     $8,-24($16)
                     90:        sll     $3,$7,$6
                     91:
                     92:        ldq     $4,24($17)
                     93:        srl     $3,$19,$1
                     94:        bis     $5,$6,$8
                     95:        stq     $8,-16($16)
                     96:        sll     $4,$7,$2
                     97:
                     98:        addq    $17,32,$17
                     99:        bis     $1,$2,$8
                    100:        stq     $8,-8($16)
                    101:
                    102:        bgt     $18,.Loop
                    103:
                    104: .Lend: srl     $4,$19,$8
                    105:        stq     $8,0($16)
                    106:        ret     $31,($26),1
                    107:        .end    __mpn_rshift