| Aubrey.Li | 3f0606a | 2007-03-09 13:38:44 +0800 | [diff] [blame^] | 1 | /* |
| 2 | * File: arch/blackfin/lib/memcmp.S |
| 3 | * Based on: |
| 4 | * Author: |
| 5 | * |
| 6 | * Created: |
| 7 | * Description: |
| 8 | * |
| 9 | * Rev: $Id: memcmp.S 2386 2006-11-01 04:57:26Z magicyang $ |
| 10 | * |
| 11 | * Modified: |
| 12 | * Copyright 2004-2006 Analog Devices Inc. |
| 13 | * |
| 14 | * Bugs: Enter bugs at http://blackfin.uclinux.org/ |
| 15 | * |
| 16 | * This program is free software; you can redistribute it and/or modify |
| 17 | * it under the terms of the GNU General Public License as published by |
| 18 | * the Free Software Foundation; either version 2 of the License, or |
| 19 | * (at your option) any later version. |
| 20 | * |
| 21 | * This program is distributed in the hope that it will be useful, |
| 22 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 23 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 24 | * GNU General Public License for more details. |
| 25 | * |
| 26 | * You should have received a copy of the GNU General Public License |
| 27 | * along with this program; if not, see the file COPYING, or write |
| 28 | * to the Free Software Foundation, Inc., |
| 29 | * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
| 30 | */ |
| 31 | |
| 32 | .align 2 |
| 33 | |
| 34 | /* |
| 35 | * C Library function MEMCMP |
| 36 | * R0 = First Address |
| 37 | * R1 = Second Address |
| 38 | * R2 = count |
| 39 | * Favours word aligned data. |
| 40 | */ |
| 41 | |
| 42 | .globl _memcmp; |
| 43 | _memcmp: |
| 44 | I1 = P3; |
| 45 | P0 = R0; /* P0 = s1 address */ |
| 46 | P3 = R1; /* P3 = s2 Address */ |
| 47 | P2 = R2 ; /* P2 = count */ |
| 48 | CC = R2 <= 7(IU); |
| 49 | IF CC JUMP .Ltoo_small; |
| 50 | I0 = R1; /* s2 */ |
| 51 | R1 = R1 | R0; /* OR addresses together */ |
| 52 | R1 <<= 30; /* check bottom two bits */ |
| 53 | CC = AZ; /* AZ set if zero. */ |
| 54 | IF !CC JUMP .Lbytes ; /* Jump if addrs not aligned. */ |
| 55 | |
| 56 | P1 = P2 >> 2; /* count = n/4 */ |
| 57 | R3 = 3; |
| 58 | R2 = R2 & R3; /* remainder */ |
| 59 | P2 = R2; /* set remainder */ |
| 60 | |
| 61 | LSETUP (.Lquad_loop_s , .Lquad_loop_e) LC0=P1; |
| 62 | .Lquad_loop_s: |
| 63 | NOP; |
| 64 | R0 = [P0++]; |
| 65 | R1 = [I0++]; |
| 66 | CC = R0 == R1; |
| 67 | IF !CC JUMP .Lquad_different; |
| 68 | .Lquad_loop_e: |
| 69 | NOP; |
| 70 | |
| 71 | P3 = I0; /* s2 */ |
| 72 | .Ltoo_small: |
| 73 | CC = P2 == 0; /* Check zero count*/ |
| 74 | IF CC JUMP .Lfinished; /* very unlikely*/ |
| 75 | |
| 76 | .Lbytes: |
| 77 | LSETUP (.Lbyte_loop_s , .Lbyte_loop_e) LC0=P2; |
| 78 | .Lbyte_loop_s: |
| 79 | R1 = B[P3++](Z); /* *s2 */ |
| 80 | R0 = B[P0++](Z); /* *s1 */ |
| 81 | CC = R0 == R1; |
| 82 | IF !CC JUMP .Ldifferent; |
| 83 | .Lbyte_loop_e: |
| 84 | NOP; |
| 85 | |
| 86 | .Ldifferent: |
| 87 | R0 = R0 - R1; |
| 88 | P3 = I1; |
| 89 | RTS; |
| 90 | |
| 91 | .Lquad_different: |
| 92 | /* We've read two quads which don't match. |
| 93 | * Can't just compare them, because we're |
| 94 | * a little-endian machine, so the MSBs of |
| 95 | * the regs occur at later addresses in the |
| 96 | * string. |
| 97 | * Arrange to re-read those two quads again, |
| 98 | * byte-by-byte. |
| 99 | */ |
| 100 | P0 += -4; /* back up to the start of the */ |
| 101 | P3 = I0; /* quads, and increase the*/ |
| 102 | P2 += 4; /* remainder count*/ |
| 103 | P3 += -4; |
| 104 | JUMP .Lbytes; |
| 105 | |
| 106 | .Lfinished: |
| 107 | R0 = 0; |
| 108 | P3 = I1; |
| 109 | RTS; |