1/* 2 * File: arch/blackfin/lib/memcmp.S 3 * Based on: 4 * Author: 5 * 6 * Created: 7 * Description: 8 * 9 * Modified: 10 * Copyright 2004-2006 Analog Devices Inc. 11 * 12 * Bugs: Enter bugs at http://blackfin.uclinux.org/ 13 * 14 * This program is free software; you can redistribute it and/or modify 15 * it under the terms of the GNU General Public License as published by 16 * the Free Software Foundation; either version 2 of the License, or 17 * (at your option) any later version. 18 * 19 * This program is distributed in the hope that it will be useful, 20 * but WITHOUT ANY WARRANTY; without even the implied warranty of 21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 22 * GNU General Public License for more details. 23 * 24 * You should have received a copy of the GNU General Public License 25 * along with this program; if not, see the file COPYING, or write 26 * to the Free Software Foundation, Inc., 27 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 28 */ 29 30#include <linux/linkage.h> 31 32/* int memcmp(const void *s1, const void *s2, size_t n); 33 * R0 = First Address (s1) 34 * R1 = Second Address (s2) 35 * R2 = count (n) 36 * 37 * Favours word aligned data. 38 */ 39 40.text 41 42.align 2 43 44ENTRY(_memcmp) 45 I1 = P3; 46 P0 = R0; /* P0 = s1 address */ 47 P3 = R1; /* P3 = s2 Address */ 48 P2 = R2 ; /* P2 = count */ 49 CC = R2 <= 7(IU); 50 IF CC JUMP .Ltoo_small; 51 I0 = R1; /* s2 */ 52 R1 = R1 | R0; /* OR addresses together */ 53 R1 <<= 30; /* check bottom two bits */ 54 CC = AZ; /* AZ set if zero. */ 55 IF !CC JUMP .Lbytes ; /* Jump if addrs not aligned. */ 56 57 P1 = P2 >> 2; /* count = n/4 */ 58 R3 = 3; 59 R2 = R2 & R3; /* remainder */ 60 P2 = R2; /* set remainder */ 61 62 LSETUP (.Lquad_loop_s, .Lquad_loop_e) LC0=P1; 63.Lquad_loop_s: 64#if ANOMALY_05000202 65 R0 = [P0++]; 66 R1 = [I0++]; 67#else 68 MNOP || R0 = [P0++] || R1 = [I0++]; 69#endif 70 CC = R0 == R1; 71 IF !CC JUMP .Lquad_different; 72.Lquad_loop_e: 73 NOP; 74 75 P3 = I0; /* s2 */ 76.Ltoo_small: 77 CC = P2 == 0; /* Check zero count*/ 78 IF CC JUMP .Lfinished; /* very unlikely*/ 79 80.Lbytes: 81 LSETUP (.Lbyte_loop_s, .Lbyte_loop_e) LC0=P2; 82.Lbyte_loop_s: 83 R1 = B[P3++](Z); /* *s2 */ 84 R0 = B[P0++](Z); /* *s1 */ 85 CC = R0 == R1; 86 IF !CC JUMP .Ldifferent; 87.Lbyte_loop_e: 88 NOP; 89 90.Ldifferent: 91 R0 = R0 - R1; 92 P3 = I1; 93 RTS; 94 95.Lquad_different: 96 /* We've read two quads which don't match. 97 * Can't just compare them, because we're 98 * a little-endian machine, so the MSBs of 99 * the regs occur at later addresses in the 100 * string. 101 * Arrange to re-read those two quads again, 102 * byte-by-byte. 103 */ 104 P0 += -4; /* back up to the start of the */ 105 P3 = I0; /* quads, and increase the*/ 106 P2 += 4; /* remainder count*/ 107 P3 += -4; 108 JUMP .Lbytes; 109 110.Lfinished: 111 R0 = 0; 112 P3 = I1; 113 RTS; 114 115ENDPROC(_memcmp) 116