memmove.S

/*
 * memmove.S
 */
	.text

    .global memmove
    .type memmove, %function
    .align 4

memmove:
	/* 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 */
.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 */
.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

	/* 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