rockbox/firmware/target/arm/memcpy-arm.S

/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2006 Free Software Foundation, Inc.
 * This file was originally part of the GNU C Library
 * Contributed to glibc by MontaVista Software, Inc. (written by Nicolas Pitre)
 * Adapted for Rockbox by Daniel Ankers
 *
 * All files in this archive are subject to the GNU General Public License.
 * See the file COPYING in the source tree root for full license agreement.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/

#include "config.h"

/*
 * Endian independent macros for shifting bytes within registers.
 */
#ifndef __ARMEB__
#define pull            lsr
#define push            lsl
#else
#define pull            lsl
#define push            lsr
#endif

/* Prototype: void *memcpy(void *dest, const void *src, size_t n); */

    .section    .icode,"ax",%progbits

    .align      2
    .global     memcpy
    .type       memcpy,%function

memcpy:
		stmfd	sp!, {r0, r4, lr}

		subs	r2, r2, #4
		blt	8f
		ands	ip, r0, #3
		bne	9f
		ands	ip, r1, #3
		bne	10f

1:		subs	r2, r2, #(28)
		stmfd	sp!, {r5 - r8}
		blt	5f

2:
3:
4:		ldmia	r1!, {r3, r4, r5, r6, r7, r8, ip, lr}
		subs	r2, r2, #32
		stmia	r0!, {r3, r4, r5, r6, r7, r8, ip, lr}
		bge	3b

5:		ands	ip, r2, #28
		rsb	ip, ip, #32
		addne	pc, pc, ip		@ C is always clear here
		b	7f
6:		nop
		ldr	r3, [r1], #4
		ldr	r4, [r1], #4
		ldr	r5, [r1], #4
		ldr	r6, [r1], #4
		ldr	r7, [r1], #4
		ldr	r8, [r1], #4
		ldr	lr, [r1], #4

		add	pc, pc, ip
		nop
		nop
		str	r3, [r0], #4
		str	r4, [r0], #4
		str	r5, [r0], #4
		str	r6, [r0], #4
		str	r7, [r0], #4
		str	r8, [r0], #4
		str	lr, [r0], #4

7:		ldmfd	sp!, {r5 - r8}

8:		movs	r2, r2, lsl #31
		ldrneb	r3, [r1], #1
		ldrcsb	r4, [r1], #1
		ldrcsb	ip, [r1]
		strneb	r3, [r0], #1
		strcsb	r4, [r0], #1
		strcsb	ip, [r0]

		ldmfd	sp!, {r0, r4, pc}

9:		rsb	ip, ip, #4
		cmp	ip, #2
		ldrgtb	r3, [r1], #1
		ldrgeb	r4, [r1], #1
		ldrb	lr, [r1], #1
		strgtb	r3, [r0], #1
		strgeb	r4, [r0], #1
		subs	r2, r2, ip
		strb	lr, [r0], #1
		blt	8b
		ands	ip, r1, #3
		beq	1b

10:		bic	r1, r1, #3
		cmp	ip, #2
		ldr	lr, [r1], #4
		beq	17f
		bgt	18f


		.macro	forward_copy_shift pull push

		subs	r2, r2, #28
		blt	14f

11:		stmfd	sp!, {r5 - r9}

12:
13:		ldmia	r1!, {r4, r5, r6, r7}
		mov	r3, lr, pull #\pull
		subs	r2, r2, #32
		ldmia	r1!, {r8, r9, ip, lr}
		orr	r3, r3, r4, push #\push
		mov	r4, r4, pull #\pull
		orr	r4, r4, r5, push #\push
		mov	r5, r5, pull #\pull
		orr	r5, r5, r6, push #\push
		mov	r6, r6, pull #\pull
		orr	r6, r6, r7, push #\push
		mov	r7, r7, pull #\pull
		orr	r7, r7, r8, push #\push
		mov	r8, r8, pull #\pull
		orr	r8, r8, r9, push #\push
		mov	r9, r9, pull #\pull
		orr	r9, r9, ip, push #\push
		mov	ip, ip, pull #\pull
		orr	ip, ip, lr, push #\push
		stmia	r0!, {r3, r4, r5, r6, r7, r8, r9, ip}
		bge	12b

		ldmfd	sp!, {r5 - r9}

14:		ands	ip, r2, #28
		beq	16f

15:		mov	r3, lr, pull #\pull
		ldr	lr, [r1], #4
		subs	ip, ip, #4
		orr	r3, r3, lr, push #\push
		str	r3, [r0], #4
		bgt	15b

16:		sub	r1, r1, #(\push / 8)
		b	8b

		.endm


		forward_copy_shift	pull=8	push=24

17:		forward_copy_shift	pull=16	push=16

18:		forward_copy_shift	pull=24	push=8