sysdeps/m88k/m88100/sub_n.s

   1 ; mc88100 __mpn_sub -- Subtract two limb vectors of the same length > 0 and
   2 ; store difference in a third limb vector.
   3
   4 ; Copyright (C) 1992, 1994 Free Software Foundation, Inc.
   5
   6 ; This file is part of the GNU MP Library.
   7
   8 ; The GNU MP Library is free software; you can redistribute it and/or modify
   9 ; it under the terms of the GNU Lesser General Public License as published by
  10 ; the Free Software Foundation; either version 2.1 of the License, or (at your
  11 ; option) any later version.
  12
  13 ; The GNU MP Library is distributed in the hope that it will be useful, but
  14 ; WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  15 ; or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  16 ; License for more details.
  17
  18 ; You should have received a copy of the GNU Lesser General Public License
  19 ; along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
  20 ; the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21
  22
  23 ; INPUT PARAMETERS
  24 ; res_ptr       r2
  25 ; s1_ptr        r3
  26 ; s2_ptr        r4
  27 ; size          r5
  28
  29 ; This code has been optimized to run one instruction per clock, avoiding
  30 ; load stalls and writeback contention.  As a result, the instruction
  31 ; order is not always natural.
  32
  33 ; The speed is about 4.6 clocks/limb + 18 clocks/limb-vector on an 88100,
  34 ; but on the 88110, it seems to run much slower, 6.6 clocks/limb.
  35
  36         text
  37         align    16
  38         global   ___mpn_sub_n
  39 ___mpn_sub_n:
  40         ld      r6,r3,0                 ; read first limb from s1_ptr
  41         extu    r10,r5,3
  42         ld      r7,r4,0                 ; read first limb from s2_ptr
  43
  44         subu.co r5,r0,r5                ; (clear carry as side effect)
  45         mak     r5,r5,3<4>
  46         bcnd    eq0,r5,Lzero
  47
  48         or      r12,r0,lo16(Lbase)
  49         or.u    r12,r12,hi16(Lbase)
  50         addu    r12,r12,r5              ; r12 is address for entering in loop
  51
  52         extu    r5,r5,2                 ; divide by 4
  53         subu    r2,r2,r5                ; adjust res_ptr
  54         subu    r3,r3,r5                ; adjust s1_ptr
  55         subu    r4,r4,r5                ; adjust s2_ptr
  56
  57         or      r8,r6,r0
  58
  59         jmp.n   r12
  60          or     r9,r7,r0
  61
  62 Loop:   addu    r3,r3,32
  63         st      r8,r2,28
  64         addu    r4,r4,32
  65         ld      r6,r3,0
  66         addu    r2,r2,32
  67         ld      r7,r4,0
  68 Lzero:  subu    r10,r10,1               ; subtract 0 + 8r limbs (adj loop cnt)
  69 Lbase:  ld      r8,r3,4
  70         subu.cio r6,r6,r7
  71         ld      r9,r4,4
  72         st      r6,r2,0
  73         ld      r6,r3,8                 ; subtract 7 + 8r limbs
  74         subu.cio r8,r8,r9
  75         ld      r7,r4,8
  76         st      r8,r2,4
  77         ld      r8,r3,12                ; subtract 6 + 8r limbs
  78         subu.cio r6,r6,r7
  79         ld      r9,r4,12
  80         st      r6,r2,8
  81         ld      r6,r3,16                ; subtract 5 + 8r limbs
  82         subu.cio r8,r8,r9
  83         ld      r7,r4,16
  84         st      r8,r2,12
  85         ld      r8,r3,20                ; subtract 4 + 8r limbs
  86         subu.cio r6,r6,r7
  87         ld      r9,r4,20
  88         st      r6,r2,16
  89         ld      r6,r3,24                ; subtract 3 + 8r limbs
  90         subu.cio r8,r8,r9
  91         ld      r7,r4,24
  92         st      r8,r2,20
  93         ld      r8,r3,28                ; subtract 2 + 8r limbs
  94         subu.cio r6,r6,r7
  95         ld      r9,r4,28
  96         st      r6,r2,24
  97         bcnd.n  ne0,r10,Loop            ; subtract 1 + 8r limbs
  98          subu.cio r8,r8,r9
  99
 100         st      r8,r2,28                ; store most significant limb
 101
 102         addu.ci r2,r0,r0                ; return carry-out from most sign. limb
 103         jmp.n    r1
 104          xor    r2,r2,1