/*	$NetBSD: memcpy.S,v 1.3 1997/11/22 03:27:12 mark 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the NetBSD
 *	Foundation, Inc. and its contributors.
 * 4. Neither the name of The NetBSD Foundation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * 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.
 */
/* This was modified by Jay Monkman <jmonkman@smoothsmoothie.com> to
 *   save and restore r12. This is necessary for RTEMS.
 */
/* #include <machine/asm.h>*/
#define ENTRY(_LABEL) \
  .global _LABEL; _LABEL:
/*
.globl memcpy
memcpy:
*/
ENTRY(memcpy)
	stmfd	sp!, {r0, r12, lr}
	bl	_memcpy
	ldmfd	sp!, {r0, r12, pc}
/*
.globl memove
memmove:
*/
ENTRY(memmove)
	stmfd	sp!, {r0, r12, lr}
	bl	_memcpy
	ldmfd	sp!, {r0, r12, pc}
	
/*
 * 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()
 * memmove() and bcopy().
 *
 * 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;-)
 */
/*
_memcpy:
*/
ENTRY(_memcpy)
	/* Determine copy direction */
	cmp	r1, r0
	bcc	Lmemcpy_backwards
	moveq	r0, #0  	/* Quick abort for len=0 */
	moveq	pc, lr
	stmdb	sp!, {r0, lr}  /* memcpy() returns dest addr */
	subs	r2, r2, #4
	blt	Lmemcpy_fl4  /* less than 4 bytes */
	ands	r12, r0, #3
	bne	Lmemcpy_fdestul  /* oh unaligned destination addr */
	ands	r12, r1, #3
	bne	Lmemcpy_fsrcul  /* oh unaligned source addr */
Lmemcpy_ft8:
	/* We have aligned source and destination */
	subs	r2, r2, #8
	blt	Lmemcpy_fl12  /* less than 12 bytes (4 from above) */
	subs	r2, r2, #0x14         
	blt	Lmemcpy_fl32  /* 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_floop32:	
	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_floop32
	cmn	r2, #0x10
	ldmgeia	r1!, {r3, r4, r12, lr}	/* blat a remaining 16 bytes */
	stmgeia	r0!, {r3, r4, r12, lr}
	subge	r2, r2, #0x10         
	ldmia	sp!, {r4}  /* return r4 */
Lmemcpy_fl32:
	adds	r2, r2, #0x14         
	/* blat 12 bytes at a time */
Lmemcpy_floop12:
	ldmgeia	r1!, {r3, r12, lr}
	stmgeia	r0!, {r3, r12, lr}
	subges	r2, r2, #0x0c         
	bge	Lmemcpy_floop12
Lmemcpy_fl12:
	adds	r2, r2, #8
	blt	Lmemcpy_fl4
	subs	r2, r2, #4
	ldrlt	r3, [r1], #4
	strlt	r3, [r0], #4
	ldmgeia	r1!, {r3, r12}
	stmgeia	r0!, {r3, r12}
	subge	r2, r2, #4
Lmemcpy_fl4:
	/* less than 4 bytes to go */
	adds	r2, r2, #4
	ldmeqia	sp!, {r0, pc}  /* done */
	/* copy the crud byte at a time */
	cmp	r2, #2
	ldrb	r3, [r1], #1
	strb	r3, [r0], #1
	ldrgeb	r3, [r1], #1
	strgeb	r3, [r0], #1
	ldrgtb	r3, [r1], #1
	strgtb	r3, [r0], #1
	ldmia	sp!, {r0, pc}
	/* erg - unaligned destination */
Lmemcpy_fdestul:
	rsb	r12, r12, #4
	cmp	r12, #2
	/* align destination with byte copies */
	ldrb	r3, [r1], #1
	strb	r3, [r0], #1
	ldrgeb	r3, [r1], #1
	strgeb	r3, [r0], #1
	ldrgtb	r3, [r1], #1
	strgtb	r3, [r0], #1
	subs	r2, r2, r12
	blt	Lmemcpy_fl4  /* less the 4 bytes */
	ands	r12, r1, #3
	beq	Lmemcpy_ft8  /* we have an aligned source */
	/* erg - unaligned source */
	/* This is where it gets nasty ... */
Lmemcpy_fsrcul:
	bic	r1, r1, #3
	ldr	lr, [r1], #4
	cmp	r12, #2
	bgt	Lmemcpy_fsrcul3
	beq	Lmemcpy_fsrcul2
	cmp	r2, #0x0c            
	blt	Lmemcpy_fsrcul1loop4
	sub	r2, r2, #0x0c         
	stmdb	sp!, {r4, r5}
Lmemcpy_fsrcul1loop16:
	mov	r3, lr, lsr #8
	ldmia	r1!, {r4, r5, r12, lr}
	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
	stmia	r0!, {r3-r5, r12}
	subs	r2, r2, #0x10         
	bge	Lmemcpy_fsrcul1loop16
	ldmia	sp!, {r4, r5}
	adds	r2, r2, #0x0c         
	blt	Lmemcpy_fsrcul1l4
Lmemcpy_fsrcul1loop4:
	mov	r12, lr, lsr #8
	ldr	lr, [r1], #4
	orr	r12, r12, lr, lsl #24
	str	r12, [r0], #4
	subs	r2, r2, #4
	bge	Lmemcpy_fsrcul1loop4
Lmemcpy_fsrcul1l4:
	sub	r1, r1, #3
	b	Lmemcpy_fl4
Lmemcpy_fsrcul2:
	cmp	r2, #0x0c            
	blt	Lmemcpy_fsrcul2loop4
	sub	r2, r2, #0x0c         
	stmdb	sp!, {r4, r5}
Lmemcpy_fsrcul2loop16:
	mov	r3, lr, lsr #16
	ldmia	r1!, {r4, r5, r12, lr}
	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
	stmia	r0!, {r3-r5, r12}
	subs	r2, r2, #0x10         
	bge	Lmemcpy_fsrcul2loop16
	ldmia	sp!, {r4, r5}
	adds	r2, r2, #0x0c         
	blt	Lmemcpy_fsrcul2l4
Lmemcpy_fsrcul2loop4:
	mov	r12, lr, lsr #16
	ldr	lr, [r1], #4
	orr	r12, r12, lr, lsl #16
	str	r12, [r0], #4
	subs	r2, r2, #4
	bge	Lmemcpy_fsrcul2loop4
Lmemcpy_fsrcul2l4:
	sub	r1, r1, #2
	b	Lmemcpy_fl4
Lmemcpy_fsrcul3:
	cmp	r2, #0x0c            
	blt	Lmemcpy_fsrcul3loop4
	sub	r2, r2, #0x0c         
	stmdb	sp!, {r4, r5}
Lmemcpy_fsrcul3loop16:
	mov	r3, lr, lsr #24
	ldmia	r1!, {r4, r5, r12, lr}
	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
	stmia	r0!, {r3-r5, r12}
	subs	r2, r2, #0x10         
	bge	Lmemcpy_fsrcul3loop16
	ldmia	sp!, {r4, r5}
	adds	r2, r2, #0x0c         
	blt	Lmemcpy_fsrcul3l4
Lmemcpy_fsrcul3loop4:
	mov	r12, lr, lsr #24
	ldr	lr, [r1], #4
	orr	r12, r12, lr, lsl #8
	str	r12, [r0], #4
	subs	r2, r2, #4
	bge	Lmemcpy_fsrcul3loop4
Lmemcpy_fsrcul3l4:
	sub	r1, r1, #1
	b	Lmemcpy_fl4
Lmemcpy_backwards:
	add	r1, r1, r2
	add	r0, r0, r2
	subs	r2, r2, #4
	blt	Lmemcpy_bl4  /* less than 4 bytes */
	ands	r12, r0, #3
	bne	Lmemcpy_bdestul  /* oh unaligned destination addr */
	ands	r12, r1, #3
	bne	Lmemcpy_bsrcul  /* oh unaligned source addr */
Lmemcpy_bt8:
	/* We have aligned source and destination */
	subs	r2, r2, #8
	blt	Lmemcpy_bl12  /* less than 12 bytes (4 from above) */
	stmdb	sp!, {r4, lr}
	subs	r2, r2, #0x14  /* less than 32 bytes (12 from above) */
	blt	Lmemcpy_bl32
	/* blat 32 bytes at a time */
	/* XXX for really big copies perhaps we should use more registers */
Lmemcpy_bloop32:
	ldmdb	r1!, {r3, r4, r12, lr}
	stmdb	r0!, {r3, r4, r12, lr}
	ldmdb	r1!, {r3, r4, r12, lr}
	stmdb	r0!, {r3, r4, r12, lr}
	subs	r2, r2, #0x20         
	bge	Lmemcpy_bloop32
Lmemcpy_bl32:
	cmn	r2, #0x10            
	ldmgedb	r1!, {r3, r4, r12, lr}	/* blat a remaining 16 bytes */
	stmgedb	r0!, {r3, r4, r12, lr}
	subge	r2, r2, #0x10         
	adds	r2, r2, #0x14         
	ldmgedb	r1!, {r3, r12, lr}	/* blat a remaining 12 bytes */
	stmgedb	r0!, {r3, r12, lr}
	subge	r2, r2, #0x0c         
	ldmia	sp!, {r4, lr}
Lmemcpy_bl12:
	adds	r2, r2, #8
	blt	Lmemcpy_bl4
	subs	r2, r2, #4
	ldrlt	r3, [r1, #-4]!
	strlt	r3, [r0, #-4]!
	ldmgedb	r1!, {r3, r12}
	stmgedb	r0!, {r3, r12}
	subge	r2, r2, #4
Lmemcpy_bl4:
	/* less than 4 bytes to go */
	adds	r2, r2, #4
	moveq	pc, lr  	/* done */
	/* copy the crud byte at a time */
	cmp	r2, #2
	ldrb	r3, [r1, #-1]!
	strb	r3, [r0, #-1]!
	ldrgeb	r3, [r1, #-1]!
	strgeb	r3, [r0, #-1]!
	ldrgtb	r3, [r1, #-1]!
	strgtb	r3, [r0, #-1]!
	mov	pc, lr
	/* erg - unaligned destination */
Lmemcpy_bdestul:
	cmp	r12, #2
	/* align destination with byte copies */
	ldrb	r3, [r1, #-1]!
	strb	r3, [r0, #-1]!
	ldrgeb	r3, [r1, #-1]!
	strgeb	r3, [r0, #-1]!
	ldrgtb	r3, [r1, #-1]!
	strgtb	r3, [r0, #-1]!
	subs	r2, r2, r12
	blt	Lmemcpy_bl4  /* less than 4 bytes to go */
	ands	r12, r1, #3
	beq	Lmemcpy_bt8  /* we have an aligned source */
	/* erg - unaligned source */
	/* This is where it gets nasty ... */
Lmemcpy_bsrcul:
	bic	r1, r1, #3
	ldr	r3, [r1, #0]
	cmp	r12, #2
	blt	Lmemcpy_bsrcul1
	beq	Lmemcpy_bsrcul2
	cmp	r2, #0x0c            
	blt	Lmemcpy_bsrcul3loop4
	sub	r2, r2, #0x0c         
	stmdb	sp!, {r4, r5, lr}
Lmemcpy_bsrcul3loop16:
	mov	lr, r3, lsl #8
	ldmdb	r1!, {r3-r5, r12}
	orr	lr, lr, r12, lsr #24
	mov	r12, r12, lsl #8
	orr	r12, r12, r5, lsr #24
	mov	r5, r5, lsl #8
	orr	r5, r5, r4, lsr #24
	mov	r4, r4, lsl #8
	orr	r4, r4, r3, lsr #24
	stmdb	r0!, {r4, r5, r12, lr}
	subs	r2, r2, #0x10         
	bge	Lmemcpy_bsrcul3loop16
	ldmia	sp!, {r4, r5, lr}
	adds	r2, r2, #0x0c         
	blt	Lmemcpy_bsrcul3l4
Lmemcpy_bsrcul3loop4:
	mov	r12, r3, lsl #8
	ldr	r3, [r1, #-4]!
	orr	r12, r12, r3, lsr #24
	str	r12, [r0, #-4]!
	subs	r2, r2, #4
	bge	Lmemcpy_bsrcul3loop4
Lmemcpy_bsrcul3l4:
	add	r1, r1, #3
	b	Lmemcpy_bl4
Lmemcpy_bsrcul2:
	cmp	r2, #0x0c            
	blt	Lmemcpy_bsrcul2loop4
	sub	r2, r2, #0x0c         
	stmdb	sp!, {r4, r5, lr}
Lmemcpy_bsrcul2loop16:
	mov	lr, r3, lsl #16
	ldmdb	r1!, {r3-r5, r12}
	orr	lr, lr, r12, lsr #16
	mov	r12, r12, lsl #16
	orr	r12, r12, r5, lsr #16
	mov	r5, r5, lsl #16
	orr	r5, r5, r4, lsr #16
	mov	r4, r4, lsl #16
	orr	r4, r4, r3, lsr #16
	stmdb	r0!, {r4, r5, r12, lr}
	subs	r2, r2, #0x10         
	bge	Lmemcpy_bsrcul2loop16
	ldmia	sp!, {r4, r5, lr}
	adds	r2, r2, #0x0c         
	blt	Lmemcpy_bsrcul2l4
Lmemcpy_bsrcul2loop4:
	mov	r12, r3, lsl #16
	ldr	r3, [r1, #-4]!
	orr	r12, r12, r3, lsr #16
	str	r12, [r0, #-4]!
	subs	r2, r2, #4
	bge	Lmemcpy_bsrcul2loop4
Lmemcpy_bsrcul2l4:
	add	r1, r1, #2
	b	Lmemcpy_bl4
Lmemcpy_bsrcul1:
	cmp	r2, #0x0c            
	blt	Lmemcpy_bsrcul1loop4
	sub	r2, r2, #0x0c         
	stmdb	sp!, {r4, r5, lr}
Lmemcpy_bsrcul1loop32:
	mov	lr, r3, lsl #24
	ldmdb	r1!, {r3-r5, r12}
	orr	lr, lr, r12, lsr #8
	mov	r12, r12, lsl #24
	orr	r12, r12, r5, lsr #8
	mov	r5, r5, lsl #24
	orr	r5, r5, r4, lsr #8
	mov	r4, r4, lsl #24
	orr	r4, r4, r3, lsr #8
	stmdb	r0!, {r4, r5, r12, lr}
	subs	r2, r2, #0x10         
	bge	Lmemcpy_bsrcul1loop32
	ldmia	sp!, {r4, r5, lr}
	adds	r2, r2, #0x0c         
	blt	Lmemcpy_bsrcul1l4
Lmemcpy_bsrcul1loop4:
	mov	r12, r3, lsl #24
	ldr	r3, [r1, #-4]!
	orr	r12, r12, r3, lsr #8
	str	r12, [r0, #-4]!
	subs	r2, r2, #4
	bge	Lmemcpy_bsrcul1loop4
Lmemcpy_bsrcul1l4:
	add	r1, r1, #1
	b	Lmemcpy_bl4