1/* alpha - left shift 2 * 3 * Copyright (C) 1994, 1995, 1998, 2001, 4 * 2002 Free Software Foundation, Inc. 5 * 6 * 7 * This file is part of Libgcrypt. 8 * 9 * Libgcrypt is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU Lesser General Public License as 11 * published by the Free Software Foundation; either version 2.1 of 12 * the License, or (at your option) any later version. 13 * 14 * Libgcrypt is distributed in the hope that it will be useful, 15 * but WITHOUT ANY WARRANTY; without even the implied warranty of 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17 * GNU Lesser General Public License for more details. 18 * 19 * You should have received a copy of the GNU Lesser General Public 20 * License along with this program; if not, write to the Free Software 21 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA 22 * 23 * Note: This code is heavily based on the GNU MP Library. 24 * Actually it's the same code with only minor changes in the 25 * way the data is stored; this is to support the abstraction 26 * of an optional secure memory allocation which may be used 27 * to avoid revealing of sensitive data due to paging etc. 28 */ 29 30 31 32/******************* 33 * mpi_limb_t 34 * _gcry_mpih_lshift( mpi_ptr_t wp, (r16) 35 * mpi_ptr_t up, (r17) 36 * mpi_size_t usize, (r18) 37 * unsigned cnt) (r19) 38 * 39 * This code runs at 4.8 cycles/limb on the 21064. With infinite unrolling, 40 * it would take 4 cycles/limb. It should be possible to get down to 3 41 * cycles/limb since both ldq and stq can be paired with the other used 42 * instructions. But there are many restrictions in the 21064 pipeline that 43 * makes it hard, if not impossible, to get down to 3 cycles/limb: 44 * 45 * 1. ldq has a 3 cycle delay, srl and sll have a 2 cycle delay. 46 * 2. Only aligned instruction pairs can be paired. 47 * 3. The store buffer or silo might not be able to deal with the bandwidth. 48 */ 49 50 .set noreorder 51 .set noat 52.text 53 .align 3 54 .globl _gcry_mpih_lshift 55 .ent _gcry_mpih_lshift 56_gcry_mpih_lshift: 57 .frame $30,0,$26,0 58 59 s8addq $18,$17,$17 # make r17 point at end of s1 60 ldq $4,-8($17) # load first limb 61 subq $17,8,$17 62 subq $31,$19,$7 63 s8addq $18,$16,$16 # make r16 point at end of RES 64 subq $18,1,$18 65 and $18,4-1,$20 # number of limbs in first loop 66 srl $4,$7,$0 # compute function result 67 68 beq $20,.L0 69 subq $18,$20,$18 70 71 .align 3 72.Loop0: 73 ldq $3,-8($17) 74 subq $16,8,$16 75 subq $17,8,$17 76 subq $20,1,$20 77 sll $4,$19,$5 78 srl $3,$7,$6 79 bis $3,$3,$4 80 bis $5,$6,$8 81 stq $8,0($16) 82 bne $20,.Loop0 83 84.L0: beq $18,.Lend 85 86 .align 3 87.Loop: ldq $3,-8($17) 88 subq $16,32,$16 89 subq $18,4,$18 90 sll $4,$19,$5 91 srl $3,$7,$6 92 93 ldq $4,-16($17) 94 sll $3,$19,$1 95 bis $5,$6,$8 96 stq $8,24($16) 97 srl $4,$7,$2 98 99 ldq $3,-24($17) 100 sll $4,$19,$5 101 bis $1,$2,$8 102 stq $8,16($16) 103 srl $3,$7,$6 104 105 ldq $4,-32($17) 106 sll $3,$19,$1 107 bis $5,$6,$8 108 stq $8,8($16) 109 srl $4,$7,$2 110 111 subq $17,32,$17 112 bis $1,$2,$8 113 stq $8,0($16) 114 115 bgt $18,.Loop 116 117.Lend: sll $4,$19,$8 118 stq $8,-8($16) 119 ret $31,($26),1 120 .end _gcry_mpih_lshift 121 122 123