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/*

 *  Fast C2P (Chunky-to-Planar) Conversion

 *

 *  Copyright (C) 2003 Geert Uytterhoeven

 *

 *  NOTES:

 *    - This code was inspired by Scout's C2P tutorial

 *    - It assumes to run on a big endian system

 *

 *  This file is subject to the terms and conditions of the GNU General Public

 *  License. See the file COPYING in the main directory of this archive

 *  for more details.

 */

#include <linux/string.h>

#include "c2p.h"

    /*

     *  Basic transpose step

     */

#define _transp(d, i1, i2, shift, mask)                 \

    do {                                                \

        u32 t = (d[i1] ^ (d[i2] >> shift)) & mask;      \

        d[i1] ^= t;                                     \

        d[i2] ^= t << shift;                            \

    } while (0)

static inline u32 get_mask(int n)

{

    switch (n) {

        case 1:

            return 0x55555555;

            break;

        case 2:

            return 0x33333333;

            break;

        case 4:

            return 0x0f0f0f0f;

            break;

        case 8:

            return 0x00ff00ff;

            break;

        case 16:

            return 0x0000ffff;

            break;

    }

    return 0;

}

#define transp_nx1(d, n)                                \

    do {                                                \

        u32 mask = get_mask(n);                         \

        /* First block */                               \

        _transp(d, 0, 1, n, mask);                       \

        /* Second block */                              \

        _transp(d, 2, 3, n, mask);                      \

        /* Third block */                               \

        _transp(d, 4, 5, n, mask);                      \

        /* Fourth block */                              \

        _transp(d, 6, 7, n, mask);                      \

    } while (0)

#define transp_nx2(d, n)                                \

    do {                                                \

        u32 mask = get_mask(n);                         \

        /* First block */                               \

        _transp(d, 0, 2, n, mask);                       \

        _transp(d, 1, 3, n, mask);                      \

        /* Second block */                              \

        _transp(d, 4, 6, n, mask);                      \

        _transp(d, 5, 7, n, mask);                      \

    } while (0)

#define transp_nx4(d, n)                                \

    do {                                                \

        u32 mask = get_mask(n);                         \

        _transp(d, 0, 4, n, mask);                       \

        _transp(d, 1, 5, n, mask);                      \

        _transp(d, 2, 6, n, mask);                      \

        _transp(d, 3, 7, n, mask);                      \

    } while (0)

#define transp(d, n, m) transp_nx ## m(d, n)

    /*

     *  Perform a full C2P step on 32 8-bit pixels, stored in 8 32-bit words

     *  containing

     *    - 32 8-bit chunky pixels on input

     *    - permuted planar data on output

     */

static void c2p_8bpp(u32 d[8])

{

    transp(d, 16, 4);

    transp(d, 8, 2);

    transp(d, 4, 1);

    transp(d, 2, 4);

    transp(d, 1, 2);

}

    /*

     *  Array containing the permution indices of the planar data after c2p

     */

static const int perm_c2p_8bpp[8] = { 7, 5, 3, 1, 6, 4, 2, 0 };

    /*

     *  Compose two values, using a bitmask as decision value

     *  This is equivalent to (a & mask) | (b & ~mask)

     */

static inline unsigned long comp(unsigned long a, unsigned long b,

                                 unsigned long mask)

{

        return ((a ^ b) & mask) ^ b;

}

    /*

     *  Store a full block of planar data after c2p conversion

     */

static inline void store_planar(char *dst, u32 dst_inc, u32 bpp, u32 d[8])

{

    int i;

    for (i = 0; i < bpp; i++, dst += dst_inc)

        *(u32 *)dst = d[perm_c2p_8bpp[i]];

}

    /*

     *  Store a partial block of planar data after c2p conversion

     */

static inline void store_planar_masked(char *dst, u32 dst_inc, u32 bpp,

                                       u32 d[8], u32 mask)

{

    int i;

    for (i = 0; i < bpp; i++, dst += dst_inc)

        *(u32 *)dst = comp(d[perm_c2p_8bpp[i]], *(u32 *)dst, mask);

}

    /*

     *  c2p - Copy 8-bit chunky image data to a planar frame buffer

     *  @dst: Starting address of the planar frame buffer

     *  @dx: Horizontal destination offset (in pixels)

     *  @dy: Vertical destination offset (in pixels)

     *  @width: Image width (in pixels)

     *  @height: Image height (in pixels)

     *  @dst_nextline: Frame buffer offset to the next line (in bytes)

     *  @dst_nextplane: Frame buffer offset to the next plane (in bytes)

     *  @src_nextline: Image offset to the next line (in bytes)

     *  @bpp: Bits per pixel of the planar frame buffer (1-8)

     */

void c2p(u8 *dst, const u8 *src, u32 dx, u32 dy, u32 width, u32 height,

         u32 dst_nextline, u32 dst_nextplane, u32 src_nextline, u32 bpp)

{

    int dst_idx;

    u32 d[8], first, last, w;

    const u8 *c;

    u8 *p;

    dst += dy*dst_nextline+(dx & ~31);

    dst_idx = dx % 32;

    first = ~0UL >> dst_idx;

    last = ~(~0UL >> ((dst_idx+width) % 32));

    while (height--) {

        c = src;

        p = dst;

        w = width;

        if (dst_idx+width <= 32) {

            /* Single destination word */

            first &= last;

            memset(d, 0, sizeof(d));

            memcpy((u8 *)d+dst_idx, c, width);

            c += width;

            c2p_8bpp(d);

            store_planar_masked(p, dst_nextplane, bpp, d, first);

            p += 4;

        } else {

            /* Multiple destination words */

            w = width;

            /* Leading bits */

            if (dst_idx) {

                w = 32 - dst_idx;

                memset(d, 0, dst_idx);

                memcpy((u8 *)d+dst_idx, c, w);

                c += w;

                c2p_8bpp(d);

                store_planar_masked(p, dst_nextplane, bpp, d, first);

                p += 4;

                w = width-w;

            }

            /* Main chunk */

            while (w >= 32) {

                memcpy(d, c, 32);

                c += 32;

                c2p_8bpp(d);

                store_planar(p, dst_nextplane, bpp, d);

                p += 4;

                w -= 32;

            }

            /* Trailing bits */

            w %= 32;

            if (w > 0) {

                memcpy(d, c, w);

                memset((u8 *)d+w, 0, 32-w);

                c2p_8bpp(d);

                store_planar_masked(p, dst_nextplane, bpp, d, last);

            }

        }

        src += src_nextline;

        dst += dst_nextline;

    }

}