/*

 * Copyright © 2008 Mozilla Corporation

 * Copyright © 2010 Nokia Corporation

 *

 * Permission to use, copy, modify, distribute, and sell this software and its

 * documentation for any purpose is hereby granted without fee, provided that

 * the above copyright notice appear in all copies and that both that

 * copyright notice and this permission notice appear in supporting

 * documentation, and that the name of Mozilla Corporation not be used in

 * advertising or publicity pertaining to distribution of the software without

 * specific, written prior permission.  Mozilla Corporation makes no

 * representations about the suitability of this software for any purpose.  It

 * is provided "as is" without express or implied warranty.

 *

 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS

 * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND

 * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY

 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES

 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN

 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING

 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS

 * SOFTWARE.

 *

 * Author:  Jeff Muizelaar (jeff@infidigm.net)

 *

 */

/* Prevent the stack from becoming executable */

#if defined(__linux__) && defined(__ELF__)

.section .note.GNU-stack,"",%progbits

#endif

	.text

	.arch armv6

	.object_arch armv4

	.arm

	.altmacro

	.p2align 2

#include "pixman-arm-asm.h"

/*

 * Note: This code is only using armv5te instructions (not even armv6),

 *       but is scheduled for ARM Cortex-A8 pipeline. So it might need to

 *       be split into a few variants, tuned for each microarchitecture.

 *

 * TODO: In order to get good performance on ARM9/ARM11 cores (which don't

 * have efficient write combining), it needs to be changed to use 16-byte

 * aligned writes using STM instruction.

 *

 * Nearest scanline scaler macro template uses the following arguments:

 *  fname                     - name of the function to generate

 *  bpp_shift                 - (1 << bpp_shift) is the size of pixel in bytes

 *  t                         - type suffix for LDR/STR instructions

 *  prefetch_distance         - prefetch in the source image by that many

 *                              pixels ahead

 *  prefetch_braking_distance - stop prefetching when that many pixels are

 *                              remaining before the end of scanline

 */

.macro generate_nearest_scanline_func fname, bpp_shift, t,      \

                                      prefetch_distance,        \

                                      prefetch_braking_distance

pixman_asm_function fname

	W		.req	r0

	DST		.req	r1

	SRC		.req	r2

	VX		.req	r3

	UNIT_X		.req	ip

	TMP1		.req	r4

	TMP2		.req	r5

	VXMASK		.req	r6

	PF_OFFS		.req	r7

	SRC_WIDTH_FIXED	.req	r8

	ldr	UNIT_X, [sp]

	push	{r4, r5, r6, r7, r8, r10}

	mvn	VXMASK, #((1 << bpp_shift) - 1)

	ldr	SRC_WIDTH_FIXED, [sp, #28]

	/* define helper macro */

	.macro	scale_2_pixels

		ldr&t	TMP1, [SRC, TMP1]

		and	TMP2, VXMASK, VX, asr #(16 - bpp_shift)

		adds	VX, VX, UNIT_X

		str&t	TMP1, [DST], #(1 << bpp_shift)

9:		subpls	VX, VX, SRC_WIDTH_FIXED

		bpl	9b

		ldr&t	TMP2, [SRC, TMP2]

		and	TMP1, VXMASK, VX, asr #(16 - bpp_shift)

		adds	VX, VX, UNIT_X

		str&t	TMP2, [DST], #(1 << bpp_shift)

9:		subpls	VX, VX, SRC_WIDTH_FIXED

		bpl	9b

	.endm

	/* now do the scaling */

	and	TMP1, VXMASK, VX, asr #(16 - bpp_shift)

	adds	VX, VX, UNIT_X

9:	subpls	VX, VX, SRC_WIDTH_FIXED

	bpl	9b

	subs	W, W, #(8 + prefetch_braking_distance)

	blt	2f

	/* calculate prefetch offset */

	mov	PF_OFFS, #prefetch_distance

	mla	PF_OFFS, UNIT_X, PF_OFFS, VX

1:	/* main loop, process 8 pixels per iteration with prefetch */

	pld	[SRC, PF_OFFS, asr #(16 - bpp_shift)]

	add	PF_OFFS, UNIT_X, lsl #3

	scale_2_pixels

	scale_2_pixels

	scale_2_pixels

	scale_2_pixels

	subs	W, W, #8

	bge	1b

2:

	subs	W, W, #(4 - 8 - prefetch_braking_distance)

	blt	2f

1:	/* process the remaining pixels */

	scale_2_pixels

	scale_2_pixels

	subs	W, W, #4

	bge	1b

2:

	tst	W, #2

	beq	2f

	scale_2_pixels

2:

	tst	W, #1

	ldrne&t	TMP1, [SRC, TMP1]

	strne&t	TMP1, [DST]

	/* cleanup helper macro */

	.purgem	scale_2_pixels

	.unreq	DST

	.unreq	SRC

	.unreq	W

	.unreq	VX

	.unreq	UNIT_X

	.unreq	TMP1

	.unreq	TMP2

	.unreq	VXMASK

	.unreq	PF_OFFS

	.unreq  SRC_WIDTH_FIXED

	/* return */

	pop	{r4, r5, r6, r7, r8, r10}

	bx	lr

.endfunc

.endm

generate_nearest_scanline_func \

    pixman_scaled_nearest_scanline_0565_0565_SRC_asm_armv6, 1, h, 80, 32

generate_nearest_scanline_func \

    pixman_scaled_nearest_scanline_8888_8888_SRC_asm_armv6, 2,  , 48, 32