| /* IBM POWER sub_n -- Subtract two limb vectors of equal, non-zero length. |
| * |
| * Copyright (C) 1992, 1994, 1995, 1996, 1999, |
| * 2002 Free Software Foundation, Inc. |
| * |
| * This file is part of Libgcrypt. |
| * |
| * Libgcrypt 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. |
| * |
| * Libgcrypt 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 this program; if not, write to the Free Software |
| * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA |
| */ |
| |
| #include "sysdep.h" |
| #include "asm-syntax.h" |
| |
| /* |
| # INPUT PARAMETERS |
| # res_ptr r3 |
| # s1_ptr r4 |
| # s2_ptr r5 |
| # size r6 |
| */ |
| |
| .toc |
| .extern _gcry_mpih_sub_n[DS] |
| .extern ._gcry_mpih_sub_n |
| .csect [PR] |
| .align 2 |
| .globl _gcry_mpih_sub_n |
| .globl ._gcry_mpih_sub_n |
| .csect _gcry_mpih_sub_n[DS] |
| _gcry_mpih_sub_n: |
| .long ._gcry_mpih_sub_n, TOC[tc0], 0 |
| .csect [PR] |
| ._gcry_mpih_sub_n: |
| andil. 10,6,1 # odd or even number of limbs? |
| l 8,0(4) # load least significant s1 limb |
| l 0,0(5) # load least significant s2 limb |
| cal 3,-4(3) # offset res_ptr, it's updated before it's used |
| sri 10,6,1 # count for unrolled loop |
| sf 7,0,8 # subtract least significant limbs, set cy |
| mtctr 10 # copy count into CTR |
| beq 0,Leven # branch if even # of limbs (# of limbs >= 2) |
| |
| # We have an odd # of limbs. Add the first limbs separately. |
| cmpi 1,10,0 # is count for unrolled loop zero? |
| bne 1,L1 # branch if not |
| st 7,4(3) |
| sfe 3,0,0 # load !cy into ... |
| sfi 3,3,0 # ... return value register |
| br # return |
| |
| # We added least significant limbs. Now reload the next limbs to enter loop. |
| L1: lu 8,4(4) # load s1 limb and update s1_ptr |
| lu 0,4(5) # load s2 limb and update s2_ptr |
| stu 7,4(3) |
| sfe 7,0,8 # subtract limbs, set cy |
| Leven: lu 9,4(4) # load s1 limb and update s1_ptr |
| lu 10,4(5) # load s2 limb and update s2_ptr |
| bdz Lend # If done, skip loop |
| |
| Loop: lu 8,4(4) # load s1 limb and update s1_ptr |
| lu 0,4(5) # load s2 limb and update s2_ptr |
| sfe 11,10,9 # subtract previous limbs with cy, set cy |
| stu 7,4(3) # |
| lu 9,4(4) # load s1 limb and update s1_ptr |
| lu 10,4(5) # load s2 limb and update s2_ptr |
| sfe 7,0,8 # subtract previous limbs with cy, set cy |
| stu 11,4(3) # |
| bdn Loop # decrement CTR and loop back |
| |
| Lend: sfe 11,10,9 # subtract limbs with cy, set cy |
| st 7,4(3) # |
| st 11,8(3) # |
| sfe 3,0,0 # load !cy into ... |
| sfi 3,3,0 # ... return value register |
| br |
| |