1/* IBM POWER sub_n -- Subtract two limb vectors of equal, non-zero length. 2 * 3 * Copyright (C) 1992, 1994, 1995, 1996, 1999, 4 * 2002 Free Software Foundation, Inc. 5 * 6 * This file is part of Libgcrypt. 7 * 8 * Libgcrypt is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU Lesser General Public License as 10 * published by the Free Software Foundation; either version 2.1 of 11 * the License, or (at your option) any later version. 12 * 13 * Libgcrypt is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU Lesser General Public License for more details. 17 * 18 * You should have received a copy of the GNU Lesser General Public 19 * License along with this program; if not, write to the Free Software 20 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA 21 */ 22 23#include "sysdep.h" 24#include "asm-syntax.h" 25 26/* 27# INPUT PARAMETERS 28# res_ptr r3 29# s1_ptr r4 30# s2_ptr r5 31# size r6 32 */ 33 34 .toc 35 .extern _gcry_mpih_sub_n[DS] 36 .extern ._gcry_mpih_sub_n 37.csect [PR] 38 .align 2 39 .globl _gcry_mpih_sub_n 40 .globl ._gcry_mpih_sub_n 41 .csect _gcry_mpih_sub_n[DS] 42_gcry_mpih_sub_n: 43 .long ._gcry_mpih_sub_n, TOC[tc0], 0 44 .csect [PR] 45._gcry_mpih_sub_n: 46 andil. 10,6,1 # odd or even number of limbs? 47 l 8,0(4) # load least significant s1 limb 48 l 0,0(5) # load least significant s2 limb 49 cal 3,-4(3) # offset res_ptr, it's updated before it's used 50 sri 10,6,1 # count for unrolled loop 51 sf 7,0,8 # subtract least significant limbs, set cy 52 mtctr 10 # copy count into CTR 53 beq 0,Leven # branch if even # of limbs (# of limbs >= 2) 54 55# We have an odd # of limbs. Add the first limbs separately. 56 cmpi 1,10,0 # is count for unrolled loop zero? 57 bne 1,L1 # branch if not 58 st 7,4(3) 59 sfe 3,0,0 # load !cy into ... 60 sfi 3,3,0 # ... return value register 61 br # return 62 63# We added least significant limbs. Now reload the next limbs to enter loop. 64L1: lu 8,4(4) # load s1 limb and update s1_ptr 65 lu 0,4(5) # load s2 limb and update s2_ptr 66 stu 7,4(3) 67 sfe 7,0,8 # subtract limbs, set cy 68Leven: lu 9,4(4) # load s1 limb and update s1_ptr 69 lu 10,4(5) # load s2 limb and update s2_ptr 70 bdz Lend # If done, skip loop 71 72Loop: lu 8,4(4) # load s1 limb and update s1_ptr 73 lu 0,4(5) # load s2 limb and update s2_ptr 74 sfe 11,10,9 # subtract previous limbs with cy, set cy 75 stu 7,4(3) # 76 lu 9,4(4) # load s1 limb and update s1_ptr 77 lu 10,4(5) # load s2 limb and update s2_ptr 78 sfe 7,0,8 # subtract previous limbs with cy, set cy 79 stu 11,4(3) # 80 bdn Loop # decrement CTR and loop back 81 82Lend: sfe 11,10,9 # subtract limbs with cy, set cy 83 st 7,4(3) # 84 st 11,8(3) # 85 sfe 3,0,0 # load !cy into ... 86 sfi 3,3,0 # ... return value register 87 br 88 89