/*

 * Copyright © 2000 Keith Packard, member of The XFree86 Project, Inc.

 *             2005 Lars Knoll & Zack Rusin, Trolltech

 *

 * 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 Keith Packard not be used in

 * advertising or publicity pertaining to distribution of the software without

 * specific, written prior permission.  Keith Packard 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.

 */

#ifdef HAVE_CONFIG_H

#include <config.h>

#endif

#include <math.h>

#include <string.h>

#include "pixman-private.h"

#include "pixman-combine32.h"

/* component alpha helper functions */

static void

combine_mask_ca (uint32_t *src, uint32_t *mask)

{

    uint32_t a = *mask;

    uint32_t x;

    uint16_t xa;

    if (!a)

    {

	*(src) = 0;

	return;

    }

    x = *(src);

    if (a == ~0)

    {

	x = x >> A_SHIFT;

	x |= x << G_SHIFT;

	x |= x << R_SHIFT;

	*(mask) = x;

	return;

    }

    xa = x >> A_SHIFT;

    UN8x4_MUL_UN8x4 (x, a);

    *(src) = x;

    UN8x4_MUL_UN8 (a, xa);

    *(mask) = a;

}

static void

combine_mask_value_ca (uint32_t *src, const uint32_t *mask)

{

    uint32_t a = *mask;

    uint32_t x;

    if (!a)

    {

	*(src) = 0;

	return;

    }

    if (a == ~0)

	return;

    x = *(src);

    UN8x4_MUL_UN8x4 (x, a);

    *(src) = x;

}

static void

combine_mask_alpha_ca (const uint32_t *src, uint32_t *mask)

{

    uint32_t a = *(mask);

    uint32_t x;

    if (!a)

	return;

    x = *(src) >> A_SHIFT;

    if (x == MASK)

	return;

    if (a == ~0)

    {

	x |= x << G_SHIFT;

	x |= x << R_SHIFT;

	*(mask) = x;

	return;

    }

    UN8x4_MUL_UN8 (a, x);

    *(mask) = a;

}

/*

 * There are two ways of handling alpha -- either as a single unified value or

 * a separate value for each component, hence each macro must have two

 * versions.  The unified alpha version has a 'u' at the end of the name,

 * the component version has a 'ca'.  Similarly, functions which deal with

 * this difference will have two versions using the same convention.

 */

static force_inline uint32_t

combine_mask (const uint32_t *src, const uint32_t *mask, int i)

{

    uint32_t s, m;

    if (mask)

    {

	m = *(mask + i) >> A_SHIFT;

	if (!m)

	    return 0;

    }

    s = *(src + i);

    if (mask)

	UN8x4_MUL_UN8 (s, m);

    return s;

}

static void

combine_clear (pixman_implementation_t *imp,

               pixman_op_t              op,

               uint32_t *               dest,

               const uint32_t *         src,

               const uint32_t *         mask,

               int                      width)

{

    memset (dest, 0, width * sizeof (uint32_t));

}

static void

combine_dst (pixman_implementation_t *imp,

	     pixman_op_t	      op,

	     uint32_t *		      dest,

	     const uint32_t *	      src,

	     const uint32_t *         mask,

	     int		      width)

{

    return;

}

static void

combine_src_u (pixman_implementation_t *imp,

               pixman_op_t              op,

               uint32_t *               dest,

               const uint32_t *         src,

               const uint32_t *         mask,

               int                      width)

{

    int i;

    if (!mask)

    {

	memcpy (dest, src, width * sizeof (uint32_t));

    }

    else

    {

	for (i = 0; i < width; ++i)

	{

	    uint32_t s = combine_mask (src, mask, i);

	    *(dest + i) = s;

	}

    }

}

static void

combine_over_u (pixman_implementation_t *imp,

                pixman_op_t              op,

                uint32_t *               dest,

                const uint32_t *         src,

                const uint32_t *         mask,

                int                      width)

{

    int i;

    if (!mask)

    {

	for (i = 0; i < width; ++i)

	{

	    uint32_t s = *(src + i);

	    uint32_t a = ALPHA_8 (s);

	    if (a == 0xFF)

	    {

		*(dest + i) = s;

	    }

	    else if (s)

	    {

		uint32_t d = *(dest + i);

		uint32_t ia = a ^ 0xFF;

		UN8x4_MUL_UN8_ADD_UN8x4 (d, ia, s);

		*(dest + i) = d;

	    }

	}

    }

    else

    {

	for (i = 0; i < width; ++i)

	{

	    uint32_t m = ALPHA_8 (*(mask + i));

	    if (m == 0xFF)

	    {

		uint32_t s = *(src + i);

		uint32_t a = ALPHA_8 (s);

		if (a == 0xFF)

		{

		    *(dest + i) = s;

		}

		else if (s)

		{

		    uint32_t d = *(dest + i);

		    uint32_t ia = a ^ 0xFF;

		    UN8x4_MUL_UN8_ADD_UN8x4 (d, ia, s);

		    *(dest + i) = d;

		}

	    }

	    else if (m)

	    {

		uint32_t s = *(src + i);

		if (s)

		{

		    uint32_t d = *(dest + i);

		    UN8x4_MUL_UN8 (s, m);

		    UN8x4_MUL_UN8_ADD_UN8x4 (d, ALPHA_8 (~s), s);

		    *(dest + i) = d;

		}

	    }

	}

    }

}

static void

combine_over_reverse_u (pixman_implementation_t *imp,

                        pixman_op_t              op,

                        uint32_t *               dest,

                        const uint32_t *         src,

                        const uint32_t *         mask,

                        int                      width)

{

    int i;

    for (i = 0; i < width; ++i)

    {

	uint32_t s = combine_mask (src, mask, i);

	uint32_t d = *(dest + i);

	uint32_t ia = ALPHA_8 (~*(dest + i));

	UN8x4_MUL_UN8_ADD_UN8x4 (s, ia, d);

	*(dest + i) = s;

    }

}

static void

combine_in_u (pixman_implementation_t *imp,

              pixman_op_t              op,

              uint32_t *               dest,

              const uint32_t *         src,

              const uint32_t *         mask,

              int                      width)

{

    int i;

    for (i = 0; i < width; ++i)

    {

	uint32_t s = combine_mask (src, mask, i);

	uint32_t a = ALPHA_8 (*(dest + i));

	UN8x4_MUL_UN8 (s, a);

	*(dest + i) = s;

    }

}

static void

combine_in_reverse_u (pixman_implementation_t *imp,

                      pixman_op_t              op,

                      uint32_t *               dest,

                      const uint32_t *         src,

                      const uint32_t *         mask,

                      int                      width)

{

    int i;

    for (i = 0; i < width; ++i)

    {

	uint32_t s = combine_mask (src, mask, i);

	uint32_t d = *(dest + i);

	uint32_t a = ALPHA_8 (s);

	UN8x4_MUL_UN8 (d, a);

	*(dest + i) = d;

    }

}

static void

combine_out_u (pixman_implementation_t *imp,

               pixman_op_t              op,

               uint32_t *               dest,

               const uint32_t *         src,

               const uint32_t *         mask,

               int                      width)

{

    int i;

    for (i = 0; i < width; ++i)

    {

	uint32_t s = combine_mask (src, mask, i);

	uint32_t a = ALPHA_8 (~*(dest + i));

	UN8x4_MUL_UN8 (s, a);

	*(dest + i) = s;

    }

}

static void

combine_out_reverse_u (pixman_implementation_t *imp,

                       pixman_op_t              op,

                       uint32_t *               dest,

                       const uint32_t *         src,

                       const uint32_t *         mask,

                       int                      width)

{

    int i;

    for (i = 0; i < width; ++i)

    {

	uint32_t s = combine_mask (src, mask, i);

	uint32_t d = *(dest + i);

	uint32_t a = ALPHA_8 (~s);

	UN8x4_MUL_UN8 (d, a);

	*(dest + i) = d;

    }

}

static void

combine_atop_u (pixman_implementation_t *imp,

                pixman_op_t              op,

                uint32_t *               dest,

                const uint32_t *         src,

                const uint32_t *         mask,

                int                      width)

{

    int i;

    for (i = 0; i < width; ++i)

    {

	uint32_t s = combine_mask (src, mask, i);

	uint32_t d = *(dest + i);

	uint32_t dest_a = ALPHA_8 (d);

	uint32_t src_ia = ALPHA_8 (~s);

	UN8x4_MUL_UN8_ADD_UN8x4_MUL_UN8 (s, dest_a, d, src_ia);

	*(dest + i) = s;

    }

}

static void

combine_atop_reverse_u (pixman_implementation_t *imp,

                        pixman_op_t              op,

                        uint32_t *               dest,

                        const uint32_t *         src,

                        const uint32_t *         mask,

                        int                      width)

{

    int i;

    for (i = 0; i < width; ++i)

    {

	uint32_t s = combine_mask (src, mask, i);

	uint32_t d = *(dest + i);

	uint32_t src_a = ALPHA_8 (s);

	uint32_t dest_ia = ALPHA_8 (~d);

	UN8x4_MUL_UN8_ADD_UN8x4_MUL_UN8 (s, dest_ia, d, src_a);

	*(dest + i) = s;

    }

}

static void

combine_xor_u (pixman_implementation_t *imp,

               pixman_op_t              op,

               uint32_t *               dest,

               const uint32_t *         src,

               const uint32_t *         mask,

               int                      width)

{

    int i;

    for (i = 0; i < width; ++i)

    {

	uint32_t s = combine_mask (src, mask, i);

	uint32_t d = *(dest + i);

	uint32_t src_ia = ALPHA_8 (~s);

	uint32_t dest_ia = ALPHA_8 (~d);

	UN8x4_MUL_UN8_ADD_UN8x4_MUL_UN8 (s, dest_ia, d, src_ia);

	*(dest + i) = s;

    }

}

static void

combine_add_u (pixman_implementation_t *imp,

               pixman_op_t              op,

               uint32_t *               dest,

               const uint32_t *         src,

               const uint32_t *         mask,

               int                      width)

{

    int i;

    for (i = 0; i < width; ++i)

    {

	uint32_t s = combine_mask (src, mask, i);

	uint32_t d = *(dest + i);

	UN8x4_ADD_UN8x4 (d, s);

	*(dest + i) = d;

    }

}

/*

 * PDF blend modes:

 *

 * The following blend modes have been taken from the PDF ISO 32000

 * specification, which at this point in time is available from

 *

 *     http://www.adobe.com/devnet/pdf/pdf_reference.html

 *

 * The specific documents of interest are the PDF spec itself:

 *

 *     http://wwwimages.adobe.com/www.adobe.com/content/dam/Adobe/en/devnet/pdf/pdfs/PDF32000_2008.pdf

 *

 * chapters 11.3.5 and 11.3.6 and a later supplement for Adobe Acrobat

 * 9.1 and Reader 9.1:

 *

 *     http://wwwimages.adobe.com/www.adobe.com/content/dam/Adobe/en/devnet/pdf/pdfs/adobe_supplement_iso32000_1.pdf

 *

 * that clarifies the specifications for blend modes ColorDodge and

 * ColorBurn.

 *

 * The formula for computing the final pixel color given in 11.3.6 is:

 *

 *     αr × Cr = (1 – αs) × αb × Cb + (1 – αb) × αs × Cs + αb × αs × B(Cb, Cs)

 *

 * with B() is the blend function. When B(Cb, Cs) = Cs, this formula

 * reduces to the regular OVER operator.

 *

 * Cs and Cb are not premultiplied, so in our implementation we instead

 * use:

 *

 *     cr = (1 – αs) × cb  +  (1 – αb) × cs  +  αb × αs × B (cb/αb, cs/αs)

 *

 * where cr, cs, and cb are premultiplied colors, and where the

 *

 *     αb × αs × B(cb/αb, cs/αs)

 *

 * part is first arithmetically simplified under the assumption that αb

 * and αs are not 0, and then updated to produce a meaningful result when

 * they are.

 *

 * For all the blend mode operators, the alpha channel is given by

 *

 *     αr = αs + αb + αb × αs

 */

/*

 * Multiply

 *

 *      ad * as * B(d / ad, s / as)

 *    = ad * as * d/ad * s/as

 *    = d * s

 *

 */

static void

combine_multiply_u (pixman_implementation_t *imp,

                    pixman_op_t              op,

                    uint32_t *               dest,

                    const uint32_t *         src,

                    const uint32_t *         mask,

                    int                      width)

{

    int i;

    for (i = 0; i < width; ++i)

    {

	uint32_t s = combine_mask (src, mask, i);

	uint32_t d = *(dest + i);

	uint32_t ss = s;

	uint32_t src_ia = ALPHA_8 (~s);

	uint32_t dest_ia = ALPHA_8 (~d);

	UN8x4_MUL_UN8_ADD_UN8x4_MUL_UN8 (ss, dest_ia, d, src_ia);

	UN8x4_MUL_UN8x4 (d, s);

	UN8x4_ADD_UN8x4 (d, ss);

	*(dest + i) = d;

    }

}

static void

combine_multiply_ca (pixman_implementation_t *imp,

                     pixman_op_t              op,

                     uint32_t *               dest,

                     const uint32_t *         src,

                     const uint32_t *         mask,

                     int                      width)

{

    int i;

    for (i = 0; i < width; ++i)

    {

	uint32_t m = *(mask + i);

	uint32_t s = *(src + i);

	uint32_t d = *(dest + i);

	uint32_t r = d;

	uint32_t dest_ia = ALPHA_8 (~d);

	combine_mask_ca (&s, &m);

	UN8x4_MUL_UN8x4_ADD_UN8x4_MUL_UN8 (r, ~m, s, dest_ia);

	UN8x4_MUL_UN8x4 (d, s);

	UN8x4_ADD_UN8x4 (r, d);

	*(dest + i) = r;

    }

}

#define CLAMP(v, low, high)						\

    do									\

    {									\

	if (v < (low))							\

	    v = (low);							\

	if (v > (high))							\

	    v = (high);							\

    } while (0)

#define PDF_SEPARABLE_BLEND_MODE(name)					\

    static void								\

    combine_ ## name ## _u (pixman_implementation_t *imp,		\

			    pixman_op_t              op,		\

                            uint32_t *               dest,		\

			    const uint32_t *         src,		\

			    const uint32_t *         mask,		\

			    int                      width)		\

    {									\

	int i;								\

	for (i = 0; i < width; ++i)					\

	{								\

	    uint32_t s = combine_mask (src, mask, i);			\

	    uint32_t d = *(dest + i);					\

	    uint8_t sa = ALPHA_8 (s);					\

	    uint8_t isa = ~sa;						\

	    uint8_t da = ALPHA_8 (d);					\

	    uint8_t ida = ~da;						\

	    int32_t ra, rr, rg, rb;					\

	    								\

	    ra = da * 0xff + sa * 0xff - sa * da;			\

	    rr = isa * RED_8 (d) + ida * RED_8 (s);			\

	    rg = isa * GREEN_8 (d) + ida * GREEN_8 (s);			\

	    rb = isa * BLUE_8 (d) + ida * BLUE_8 (s);			\

									\

	    rr += blend_ ## name (RED_8 (d), da, RED_8 (s), sa);	\

	    rg += blend_ ## name (GREEN_8 (d), da, GREEN_8 (s), sa);    \

	    rb += blend_ ## name (BLUE_8 (d), da, BLUE_8 (s), sa);	\

                                                                        \

	    CLAMP (ra, 0, 255 * 255);				        \

	    CLAMP (rr, 0, 255 * 255);				        \

	    CLAMP (rg, 0, 255 * 255);				        \

	    CLAMP (rb, 0, 255 * 255);				        \

									\

	    ra = DIV_ONE_UN8 (ra);					\

	    rr = DIV_ONE_UN8 (rr);					\

	    rg = DIV_ONE_UN8 (rg);					\

	    rb = DIV_ONE_UN8 (rb);					\

									\

	    *(dest + i) = ra << 24 | rr << 16 | rg << 8 | rb;		\

	}								\

    }									\

    									\

    static void								\

    combine_ ## name ## _ca (pixman_implementation_t *imp,		\

			     pixman_op_t              op,		\

                             uint32_t *               dest,		\

			     const uint32_t *         src,		\

			     const uint32_t *         mask,		\

			     int                      width)		\

    {									\

	int i;								\

	for (i = 0; i < width; ++i)					\

	{								\

	    uint32_t m = *(mask + i);					\

	    uint32_t s = *(src + i);					\

	    uint32_t d = *(dest + i);					\

	    uint8_t da = ALPHA_8 (d);					\

	    uint8_t ida = ~da;						\

	    int32_t ra, rr, rg, rb;					\

	    uint8_t ira, iga, iba;					\

	    								\

	    combine_mask_ca (&s, &m);					\

	    								\

	    ira = ~RED_8 (m);						\

	    iga = ~GREEN_8 (m);						\

	    iba = ~BLUE_8 (m);						\

									\

	    ra = da * 0xff + ALPHA_8 (s) * 0xff - ALPHA_8 (s) * da;	\

	    rr = ira * RED_8 (d) + ida * RED_8 (s);			\

	    rg = iga * GREEN_8 (d) + ida * GREEN_8 (s);			\

	    rb = iba * BLUE_8 (d) + ida * BLUE_8 (s);			\

									\

	    rr += blend_ ## name (RED_8 (d), da, RED_8 (s), RED_8 (m));	\

	    rg += blend_ ## name (GREEN_8 (d), da, GREEN_8 (s), GREEN_8 (m)); \

	    rb += blend_ ## name (BLUE_8 (d), da, BLUE_8 (s), BLUE_8 (m)); \

									\

	    CLAMP (ra, 0, 255 * 255);				        \

	    CLAMP (rr, 0, 255 * 255);				        \

	    CLAMP (rg, 0, 255 * 255);				        \

	    CLAMP (rb, 0, 255 * 255);				        \

									\

	    ra = DIV_ONE_UN8 (ra);					\

	    rr = DIV_ONE_UN8 (rr);					\

	    rg = DIV_ONE_UN8 (rg);					\

	    rb = DIV_ONE_UN8 (rb);					\

									\

	    *(dest + i) = ra << 24 | rr << 16 | rg << 8 | rb;		\

	}								\

    }

/*

 * Screen

 *

 *      ad * as * B(d/ad, s/as)

 *    = ad * as * (d/ad + s/as - s/as * d/ad)

 *    = ad * s + as * d - s * d

 */

static inline int32_t

blend_screen (int32_t d, int32_t ad, int32_t s, int32_t as)

{

    return s * ad + d * as - s * d;

}

PDF_SEPARABLE_BLEND_MODE (screen)

/*

 * Overlay

 *

 *     ad * as * B(d/ad, s/as)

 *   = ad * as * Hardlight (s, d)

 *   = if (d / ad < 0.5)

 *         as * ad * Multiply (s/as, 2 * d/ad)

 *     else

 *         as * ad * Screen (s/as, 2 * d / ad - 1)

 *   = if (d < 0.5 * ad)

 *         as * ad * s/as * 2 * d /ad

 *     else

 *         as * ad * (s/as + 2 * d / ad - 1 - s / as * (2 * d / ad - 1))

 *   = if (2 * d < ad)

 *         2 * s * d

 *     else

 *         ad * s + 2 * as * d - as * ad - ad * s * (2 * d / ad - 1)

 *   = if (2 * d < ad)

 *         2 * s * d

 *     else

 *         as * ad - 2 * (ad - d) * (as - s)

 */

static inline int32_t

blend_overlay (int32_t d, int32_t ad, int32_t s, int32_t as)

{

    uint32_t r;

    if (2 * d < ad)

	r = 2 * s * d;

    else

	r = as * ad - 2 * (ad - d) * (as - s);

    return r;

}

PDF_SEPARABLE_BLEND_MODE (overlay)

/*

 * Darken

 *

 *     ad * as * B(d/ad, s/as)

 *   = ad * as * MIN(d/ad, s/as)

 *   = MIN (as * d, ad * s)

 */

static inline int32_t

blend_darken (int32_t d, int32_t ad, int32_t s, int32_t as)

{

    s = ad * s;

    d = as * d;

    return s > d ? d : s;

}

PDF_SEPARABLE_BLEND_MODE (darken)

/*

 * Lighten

 *

 *     ad * as * B(d/ad, s/as)

 *   = ad * as * MAX(d/ad, s/as)

 *   = MAX (as * d, ad * s)

 */

static inline int32_t

blend_lighten (int32_t d, int32_t ad, int32_t s, int32_t as)

{

    s = ad * s;

    d = as * d;

    return s > d ? s : d;

}

PDF_SEPARABLE_BLEND_MODE (lighten)

/*

 * Hard light

 *

 *     ad * as * B(d/ad, s/as)

 *   = if (s/as <= 0.5)

 *         ad * as * Multiply (d/ad, 2 * s/as)

 *     else

 *         ad * as * Screen (d/ad, 2 * s/as - 1)

 *   = if 2 * s <= as

 *         ad * as * d/ad * 2 * s / as

 *     else

 *         ad * as * (d/ad + (2 * s/as - 1) + d/ad * (2 * s/as - 1))

 *   = if 2 * s <= as

 *         2 * s * d

 *     else

 *         as * ad - 2 * (ad - d) * (as - s)

 */

static inline int32_t

blend_hard_light (int32_t d, int32_t ad, int32_t s, int32_t as)

{

    if (2 * s < as)

	return 2 * s * d;

    else

	return as * ad - 2 * (ad - d) * (as - s);

}

PDF_SEPARABLE_BLEND_MODE (hard_light)

/*

 * Difference

 *

 *     ad * as * B(s/as, d/ad)

 *   = ad * as * abs (s/as - d/ad)

 *   = if (s/as <= d/ad)

 *         ad * as * (d/ad - s/as)

 *     else

 *         ad * as * (s/as - d/ad)

 *   = if (ad * s <= as * d)

 *        as * d - ad * s

 *     else

 *        ad * s - as * d

 */

static inline int32_t

blend_difference (int32_t d, int32_t ad, int32_t s, int32_t as)

{

    int32_t das = d * as;

    int32_t sad = s * ad;

    if (sad < das)

	return das - sad;

    else

	return sad - das;

}

PDF_SEPARABLE_BLEND_MODE (difference)

/*

 * Exclusion

 *

 *     ad * as * B(s/as, d/ad)

 *   = ad * as * (d/ad + s/as - 2 * d/ad * s/as)

 *   = as * d + ad * s - 2 * s * d

 */

/* This can be made faster by writing it directly and not using

 * PDF_SEPARABLE_BLEND_MODE, but that's a performance optimization */

static inline int32_t

blend_exclusion (int32_t d, int32_t ad, int32_t s, int32_t as)

{

    return s * ad + d * as - 2 * d * s;

}

PDF_SEPARABLE_BLEND_MODE (exclusion)

#undef PDF_SEPARABLE_BLEND_MODE

/* Component alpha combiners */

static void

combine_clear_ca (pixman_implementation_t *imp,

                  pixman_op_t              op,

                  uint32_t *                dest,

                  const uint32_t *          src,

                  const uint32_t *          mask,

                  int                      width)

{

    memset (dest, 0, width * sizeof(uint32_t));

}

static void

combine_src_ca (pixman_implementation_t *imp,

                pixman_op_t              op,

                uint32_t *                dest,

                const uint32_t *          src,

                const uint32_t *          mask,

                int                      width)

{

    int i;

    for (i = 0; i < width; ++i)

    {

	uint32_t s = *(src + i);

	uint32_t m = *(mask + i);

	combine_mask_value_ca (&s, &m);

	*(dest + i) = s;

    }

}

static void

combine_over_ca (pixman_implementation_t *imp,

                 pixman_op_t              op,

                 uint32_t *                dest,

                 const uint32_t *          src,

                 const uint32_t *          mask,

                 int                      width)

{

    int i;

    for (i = 0; i < width; ++i)

    {

	uint32_t s = *(src + i);

	uint32_t m = *(mask + i);

	uint32_t a;

	combine_mask_ca (&s, &m);

	a = ~m;

	if (a)

	{

	    uint32_t d = *(dest + i);

	    UN8x4_MUL_UN8x4_ADD_UN8x4 (d, a, s);

	    s = d;

	}

	*(dest + i) = s;

    }

}

static void

combine_over_reverse_ca (pixman_implementation_t *imp,

                         pixman_op_t              op,

                         uint32_t *                dest,

                         const uint32_t *          src,

                         const uint32_t *          mask,

                         int                      width)

{