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/* $NetBSD: memcpy_arm.S,v 1.1 2003/10/14 07:51:45 scw Exp $ */
/*-
* Copyright (c) 1997 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Neil A. Carson and Mark Brinicombe
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <machine/asm.h>
__FBSDID("$FreeBSD$");
.syntax unified
/*
* This is one fun bit of code ...
* Some easy listening music is suggested while trying to understand this
* code e.g. Iron Maiden
*
* For anyone attempting to understand it :
*
* The core code is implemented here with simple stubs for memcpy().
*
* All local labels are prefixed with Lmemcpy_
* Following the prefix a label starting f is used in the forward copy code
* while a label using b is used in the backwards copy code
* The source and destination addresses determine whether a forward or
* backward copy is performed.
* Separate bits of code are used to deal with the following situations
* for both the forward and backwards copy.
* unaligned source address
* unaligned destination address
* Separate copy routines are used to produce an optimised result for each
* of these cases.
* The copy code will use LDM/STM instructions to copy up to 32 bytes at
* a time where possible.
*
* Note: r12 (aka ip) can be trashed during the function along with
* r0-r3 although r0-r2 have defined uses i.e. src, dest, len through out.
* Additional registers are preserved prior to use i.e. r4, r5 & lr
*
* Apologies for the state of the comments ;-)
*/
/* LINTSTUB: Func: void *memcpy(void *dst, const void *src, size_t len) */
ENTRY(memcpy)
/* save leaf functions having to store this away */
stmdb sp!, {r0, lr} /* memcpy() returns dest addr */
subs r2, r2, #4
blt .Lmemcpy_l4 /* less than 4 bytes */
ands r12, r0, #3
bne .Lmemcpy_destul /* oh unaligned destination addr */
ands r12, r1, #3
bne .Lmemcpy_srcul /* oh unaligned source addr */
.Lmemcpy_t8:
/* We have aligned source and destination */
subs r2, r2, #8
blt .Lmemcpy_l12 /* less than 12 bytes (4 from above) */
subs r2, r2, #0x14
blt .Lmemcpy_l32 /* less than 32 bytes (12 from above) */
stmdb sp!, {r4} /* borrow r4 */
/* blat 32 bytes at a time */
/* XXX for really big copies perhaps we should use more registers */
.Lmemcpy_loop32:
ldmia r1!, {r3, r4, r12, lr}
stmia r0!, {r3, r4, r12, lr}
ldmia r1!, {r3, r4, r12, lr}
stmia r0!, {r3, r4, r12, lr}
subs r2, r2, #0x20
bge .Lmemcpy_loop32
cmn r2, #0x10
ldmiage r1!, {r3, r4, r12, lr} /* blat a remaining 16 bytes */
stmiage r0!, {r3, r4, r12, lr}
subge r2, r2, #0x10
ldmia sp!, {r4} /* return r4 */
.Lmemcpy_l32:
adds r2, r2, #0x14
/* blat 12 bytes at a time */
.Lmemcpy_loop12:
ldmiage r1!, {r3, r12, lr}
stmiage r0!, {r3, r12, lr}
subsge r2, r2, #0x0c
bge .Lmemcpy_loop12
.Lmemcpy_l12:
adds r2, r2, #8
blt .Lmemcpy_l4
subs r2, r2, #4
ldrlt r3, [r1], #4
strlt r3, [r0], #4
ldmiage r1!, {r3, r12}
stmiage r0!, {r3, r12}
subge r2, r2, #4
.Lmemcpy_l4:
/* less than 4 bytes to go */
adds r2, r2, #4
#ifdef __APCS_26_
ldmiaeq sp!, {r0, pc}^ /* done */
#else
ldmiaeq sp!, {r0, pc} /* done */
#endif
/* copy the crud byte at a time */
cmp r2, #2
ldrb r3, [r1], #1
strb r3, [r0], #1
ldrbge r3, [r1], #1
strbge r3, [r0], #1
ldrbgt r3, [r1], #1
strbgt r3, [r0], #1
ldmia sp!, {r0, pc}
/* erg - unaligned destination */
.Lmemcpy_destul:
rsb r12, r12, #4
cmp r12, #2
/* align destination with byte copies */
ldrb r3, [r1], #1
strb r3, [r0], #1
ldrbge r3, [r1], #1
strbge r3, [r0], #1
ldrbgt r3, [r1], #1
strbgt r3, [r0], #1
subs r2, r2, r12
blt .Lmemcpy_l4 /* less the 4 bytes */
ands r12, r1, #3
beq .Lmemcpy_t8 /* we have an aligned source */
/* erg - unaligned source */
/* This is where it gets nasty ... */
.Lmemcpy_srcul:
bic r1, r1, #3
ldr lr, [r1], #4
cmp r12, #2
bgt .Lmemcpy_srcul3
beq .Lmemcpy_srcul2
cmp r2, #0x0c
blt .Lmemcpy_srcul1loop4
sub r2, r2, #0x0c
stmdb sp!, {r4, r5}
.Lmemcpy_srcul1loop16:
#ifdef __ARMEB__
mov r3, lr, lsl #8
#else
mov r3, lr, lsr #8
#endif
ldmia r1!, {r4, r5, r12, lr}
#ifdef __ARMEB__
orr r3, r3, r4, lsr #24
mov r4, r4, lsl #8
orr r4, r4, r5, lsr #24
mov r5, r5, lsl #8
orr r5, r5, r12, lsr #24
mov r12, r12, lsl #8
orr r12, r12, lr, lsr #24
#else
orr r3, r3, r4, lsl #24
mov r4, r4, lsr #8
orr r4, r4, r5, lsl #24
mov r5, r5, lsr #8
orr r5, r5, r12, lsl #24
mov r12, r12, lsr #8
orr r12, r12, lr, lsl #24
#endif
stmia r0!, {r3-r5, r12}
subs r2, r2, #0x10
bge .Lmemcpy_srcul1loop16
ldmia sp!, {r4, r5}
adds r2, r2, #0x0c
blt .Lmemcpy_srcul1l4
.Lmemcpy_srcul1loop4:
#ifdef __ARMEB__
mov r12, lr, lsl #8
#else
mov r12, lr, lsr #8
#endif
ldr lr, [r1], #4
#ifdef __ARMEB__
orr r12, r12, lr, lsr #24
#else
orr r12, r12, lr, lsl #24
#endif
str r12, [r0], #4
subs r2, r2, #4
bge .Lmemcpy_srcul1loop4
.Lmemcpy_srcul1l4:
sub r1, r1, #3
b .Lmemcpy_l4
.Lmemcpy_srcul2:
cmp r2, #0x0c
blt .Lmemcpy_srcul2loop4
sub r2, r2, #0x0c
stmdb sp!, {r4, r5}
.Lmemcpy_srcul2loop16:
#ifdef __ARMEB__
mov r3, lr, lsl #16
#else
mov r3, lr, lsr #16
#endif
ldmia r1!, {r4, r5, r12, lr}
#ifdef __ARMEB__
orr r3, r3, r4, lsr #16
mov r4, r4, lsl #16
orr r4, r4, r5, lsr #16
mov r5, r5, lsl #16
orr r5, r5, r12, lsr #16
mov r12, r12, lsl #16
orr r12, r12, lr, lsr #16
#else
orr r3, r3, r4, lsl #16
mov r4, r4, lsr #16
orr r4, r4, r5, lsl #16
mov r5, r5, lsr #16
orr r5, r5, r12, lsl #16
mov r12, r12, lsr #16
orr r12, r12, lr, lsl #16
#endif
stmia r0!, {r3-r5, r12}
subs r2, r2, #0x10
bge .Lmemcpy_srcul2loop16
ldmia sp!, {r4, r5}
adds r2, r2, #0x0c
blt .Lmemcpy_srcul2l4
.Lmemcpy_srcul2loop4:
#ifdef __ARMEB__
mov r12, lr, lsl #16
#else
mov r12, lr, lsr #16
#endif
ldr lr, [r1], #4
#ifdef __ARMEB__
orr r12, r12, lr, lsr #16
#else
orr r12, r12, lr, lsl #16
#endif
str r12, [r0], #4
subs r2, r2, #4
bge .Lmemcpy_srcul2loop4
.Lmemcpy_srcul2l4:
sub r1, r1, #2
b .Lmemcpy_l4
.Lmemcpy_srcul3:
cmp r2, #0x0c
blt .Lmemcpy_srcul3loop4
sub r2, r2, #0x0c
stmdb sp!, {r4, r5}
.Lmemcpy_srcul3loop16:
#ifdef __ARMEB__
mov r3, lr, lsl #24
#else
mov r3, lr, lsr #24
#endif
ldmia r1!, {r4, r5, r12, lr}
#ifdef __ARMEB__
orr r3, r3, r4, lsr #8
mov r4, r4, lsl #24
orr r4, r4, r5, lsr #8
mov r5, r5, lsl #24
orr r5, r5, r12, lsr #8
mov r12, r12, lsl #24
orr r12, r12, lr, lsr #8
#else
orr r3, r3, r4, lsl #8
mov r4, r4, lsr #24
orr r4, r4, r5, lsl #8
mov r5, r5, lsr #24
orr r5, r5, r12, lsl #8
mov r12, r12, lsr #24
orr r12, r12, lr, lsl #8
#endif
stmia r0!, {r3-r5, r12}
subs r2, r2, #0x10
bge .Lmemcpy_srcul3loop16
ldmia sp!, {r4, r5}
adds r2, r2, #0x0c
blt .Lmemcpy_srcul3l4
.Lmemcpy_srcul3loop4:
#ifdef __ARMEB__
mov r12, lr, lsl #24
#else
mov r12, lr, lsr #24
#endif
ldr lr, [r1], #4
#ifdef __ARMEB__
orr r12, r12, lr, lsr #8
#else
orr r12, r12, lr, lsl #8
#endif
str r12, [r0], #4
subs r2, r2, #4
bge .Lmemcpy_srcul3loop4
.Lmemcpy_srcul3l4:
sub r1, r1, #1
b .Lmemcpy_l4
END(memcpy)
|
