1/* $OpenBSD: bcopy.S,v 1.4 2004/10/08 14:42:09 pefo Exp $ */ 2/*- 3 * Copyright (c) 1991, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * This code is derived from software contributed to Berkeley by 7 * Ralph Campbell. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34#include "DEFS.h" 35 36 37/* 38 * memcpy(to, from, len) 39 * {ov}bcopy(from, to, len) 40 */ 41LEAF(memcpy, 0) 42 .set noreorder 43 move v0, a0 # swap from and to 44 move a0, a1 45 move a1, v0 46ALEAF(bcopy) 47ALEAF(ovbcopy) 48 .set noreorder 49 PTR_ADDU t0, a0, a2 # t0 = end of s1 region 50 sltu t1, a1, t0 51 sltu t2, a0, a1 52 and t1, t1, t2 # t1 = true if from < to < (from+len) 53 beq t1, zero, forward # non overlapping, do forward copy 54 slt t2, a2, 12 # check for small copy 55 56 ble a2, zero, 2f 57 PTR_ADDU t1, a1, a2 # t1 = end of to region 581: 59 lb v1, -1(t0) # copy bytes backwards, 60 PTR_SUBU t0, t0, 1 # doesnt happen often so do slow way 61 PTR_SUBU t1, t1, 1 62 bne t0, a0, 1b 63 sb v1, 0(t1) 642: 65 j ra 66 nop 67forward: 68 bne t2, zero, smallcpy # do a small bcopy 69 xor v1, a0, a1 # compare low two bits of addresses 70 and v1, v1, 3 71 PTR_SUBU a3, zero, a1 # compute # bytes to word align address 72 beq v1, zero, aligned # addresses can be word aligned 73 and a3, a3, 3 74 75 beq a3, zero, 1f 76 PTR_SUBU a2, a2, a3 # subtract from remaining count 77 LWHI v1, 0(a0) # get next 4 bytes (unaligned) 78 LWLO v1, 3(a0) 79 PTR_ADDU a0, a0, a3 80 SWHI v1, 0(a1) # store 1, 2, or 3 bytes to align a1 81 PTR_ADDU a1, a1, a3 821: 83 and v1, a2, 3 # compute number of words left 84 PTR_SUBU a3, a2, v1 85 move a2, v1 86 PTR_ADDU a3, a3, a0 # compute ending address 872: 88 LWHI v1, 0(a0) # copy words a0 unaligned, a1 aligned 89 LWLO v1, 3(a0) 90 PTR_ADDU a0, a0, 4 91 sw v1, 0(a1) 92 PTR_ADDU a1, a1, 4 93 bne a0, a3, 2b 94 nop # We have to do this mmu-bug. 95 b smallcpy 96 nop 97aligned: 98 beq a3, zero, 1f 99 PTR_SUBU a2, a2, a3 # subtract from remaining count 100 LWHI v1, 0(a0) # copy 1, 2, or 3 bytes to align 101 PTR_ADDU a0, a0, a3 102 SWHI v1, 0(a1) 103 PTR_ADDU a1, a1, a3 1041: 105 and v1, a2, 3 # compute number of whole words left 106 PTR_SUBU a3, a2, v1 107 move a2, v1 108 PTR_ADDU a3, a3, a0 # compute ending address 1092: 110 lw v1, 0(a0) # copy words 111 PTR_ADDU a0, a0, 4 112 sw v1, 0(a1) 113 bne a0, a3, 2b 114 PTR_ADDU a1, a1, 4 115smallcpy: 116 ble a2, zero, 2f 117 PTR_ADDU a3, a2, a0 # compute ending address 1181: 119 lbu v1, 0(a0) # copy bytes 120 PTR_ADDU a0, a0, 1 121 sb v1, 0(a1) 122 bne a0, a3, 1b 123 PTR_ADDU a1, a1, 1 # MMU BUG ? can not do -1(a1) at 0x80000000!! 1242: 125 j ra 126 nop 127END(memcpy) 128