1/* 2 * File: memcmp.S 3 * 4 * Copyright 2004-2007 Analog Devices Inc. 5 * Enter bugs at http://blackfin.uclinux.org/ 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License as published by 9 * the Free Software Foundation; either version 2 of the License, or 10 * (at your option) any later version. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 * 17 * You should have received a copy of the GNU General Public License 18 * along with this program; if not, see the file COPYING, or write 19 * to the Free Software Foundation, Inc., 20 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 21 */ 22 23.align 2 24 25/* 26 * C Library function MEMCMP 27 * R0 = First Address 28 * R1 = Second Address 29 * R2 = count 30 * Favours word aligned data. 31 */ 32 33.globl _memcmp; 34.type _memcmp, STT_FUNC; 35_memcmp: 36 I1 = P3; 37 P0 = R0; /* P0 = s1 address */ 38 P3 = R1; /* P3 = s2 Address */ 39 P2 = R2 ; /* P2 = count */ 40 CC = R2 <= 7(IU); 41 IF CC JUMP .Ltoo_small; 42 I0 = R1; /* s2 */ 43 R1 = R1 | R0; /* OR addresses together */ 44 R1 <<= 30; /* check bottom two bits */ 45 CC = AZ; /* AZ set if zero. */ 46 IF !CC JUMP .Lbytes ; /* Jump if addrs not aligned. */ 47 48 P1 = P2 >> 2; /* count = n/4 */ 49 R3 = 3; 50 R2 = R2 & R3; /* remainder */ 51 P2 = R2; /* set remainder */ 52 53 LSETUP (.Lquad_loop_s , .Lquad_loop_e) LC0=P1; 54.Lquad_loop_s: 55 NOP; 56 R0 = [P0++]; 57 R1 = [I0++]; 58 CC = R0 == R1; 59 IF !CC JUMP .Lquad_different; 60.Lquad_loop_e: 61 NOP; 62 63 P3 = I0; /* s2 */ 64.Ltoo_small: 65 CC = P2 == 0; /* Check zero count*/ 66 IF CC JUMP .Lfinished; /* very unlikely*/ 67 68.Lbytes: 69 LSETUP (.Lbyte_loop_s , .Lbyte_loop_e) LC0=P2; 70.Lbyte_loop_s: 71 R1 = B[P3++](Z); /* *s2 */ 72 R0 = B[P0++](Z); /* *s1 */ 73 CC = R0 == R1; 74 IF !CC JUMP .Ldifferent; 75.Lbyte_loop_e: 76 NOP; 77 78.Ldifferent: 79 R0 = R0 - R1; 80 P3 = I1; 81 RTS; 82 83.Lquad_different: 84/* We've read two quads which don't match. 85 * Can't just compare them, because we're 86 * a little-endian machine, so the MSBs of 87 * the regs occur at later addresses in the 88 * string. 89 * Arrange to re-read those two quads again, 90 * byte-by-byte. 91 */ 92 P0 += -4; /* back up to the start of the */ 93 P3 = I0; /* quads, and increase the*/ 94 P2 += 4; /* remainder count*/ 95 P3 += -4; 96 JUMP .Lbytes; 97 98.Lfinished: 99 R0 = 0; 100 P3 = I1; 101 RTS; 102 103.size _memcmp, .-_memcmp 104