/*
 * Copyright (c) 2014 Clément Bœsch
 *
 * This file is part of FFmpeg.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, 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.
 */

/**
 * @file
 * hqx magnification filters (hq2x, hq3x, hq4x)
 *
 * Originally designed by Maxim Stephin.
 *
 * @see http://en.wikipedia.org/wiki/Hqx
 * @see http://web.archive.org/web/20131114143602/http://www.hiend3d.com/hq3x.html
 * @see http://blog.pkh.me/p/19-butchering-hqx-scaling-filters.html
 */

 /* Modified to 16-bit R5G6B5 for Snes9x */

#include <cstdlib>
#include <cstdint>

static uint32_t yuvtable[65536];

static void init()
{
    static bool initialized = false;
    if (initialized)
        return;
    initialized = true;

    // YUV table generation public domain from nall by near
    for (unsigned i = 0; i < 65536; i++)
    {
        uint8_t R = (i >> 0) & 31;
        uint8_t G = (i >> 5) & 31;
        uint8_t B = (i >> 11) & 31;

        // bgr565->bgr888
        double r = (R << 3) | (R >> 2);
        double g = (G << 2) | (G >> 4);
        double b = (B << 3) | (B >> 2);

        // bgr888->yuv888
        double y = (r + g + b) * (0.25f * (63.5f / 48.0f));
        double u = ((r - b) * 0.25f + 128.0f) * (7.5f / 7.0f);
        double v = ((g * 2.0f - r - b) * 0.125f + 128.0f) * (7.5f / 6.0f);

        yuvtable[i] = ((unsigned)y << 16) + ((unsigned)u << 8) + ((unsigned)v);
    }
}

static inline uint32_t rgb2yuv(const uint32_t *table, uint16_t color)
{
    return (table[color]);
}

static inline int yuv_diff(uint32_t yuv1, uint32_t yuv2)
{
#define YMASK 0xff0000
#define UMASK 0x00ff00
#define VMASK 0x0000ff
#define ABSDIFF(a, b) (abs((int)(a) - (int)(b)))

    return ABSDIFF(yuv1 & YMASK, yuv2 & YMASK) > (48 << 16) ||
           ABSDIFF(yuv1 & UMASK, yuv2 & UMASK) > (7 << 8) ||
           ABSDIFF(yuv1 & VMASK, yuv2 & VMASK) > (6 << 0);
}

static inline uint32_t interp_2px(uint16_t c1, int w1, uint16_t c2, int w2, int s)
{
    return (((((c1 & 0x07e0) >> 5) * w1 + ((c2 & 0x07e0) >> 5) * w2) << (5 - s)) & 0x07e0) |
           (((((c1 & 0xf81f)) * w1 + ((c2 & 0xf81f)) * w2) >> s) & 0xf81f);
}

static inline uint32_t interp_3px(uint16_t c1, int w1, uint16_t c2, int w2, uint16_t c3, int w3, int s)
{
    return (((((c1 & 0x07e0) >> 5) * w1 + ((c2 & 0x07e0) >> 5) * w2 + ((c3 & 0x07e0) >> 5) * w3) << (5 - s)) & 0x07e0) |
           (((((c1 & 0xf81f)) * w1 + ((c2 & 0xf81f)) * w2 + ((c3 & 0xf81f)) * w3) >> s) & 0xf81f);
}

/* m is the mask of diff with the center pixel that matters in the pattern, and
 * r is the expected result (bit set to 1 if there is difference with the
 * center, 0 otherwise) */
#define P(m, r) ((k_shuffled & (m)) == (r))

/* adjust 012345678 to 01235678: the mask doesn't contain the (null) diff
 * between the center/current pixel and itself */
#define DROP4(z) ((z) > 4 ? (z)-1 : (z))

/* shuffle the input mask: move bit n (4-adjusted) to position stored in p<n> */
#define SHF(x, rot, n) (((x) >> ((rot) ? 7 - DROP4(n) : DROP4(n)) & 1) << DROP4(p##n))

/* used to check if there is YUV difference between 2 pixels */
#define WDIFF(c1, c2) yuv_diff(rgb2yuv(r2y, c1), rgb2yuv(r2y, c2))

/* bootstrap template for every interpolation code. It defines the shuffled
 * masks and surrounding pixels. The rot flag is used to indicate if it's a
 * rotation; its basic effect is to shuffle k using p8..p0 instead of p0..p8 */
#define INTERP_BOOTSTRAP(rot)                                                                                                                                         \
    const int k_shuffled = SHF(k, rot, 0) | SHF(k, rot, 1) | SHF(k, rot, 2) | SHF(k, rot, 3) | 0 | SHF(k, rot, 5) | SHF(k, rot, 6) | SHF(k, rot, 7) | SHF(k, rot, 8); \
                                                                                                                                                                      \
    const uint32_t w0 = w[p0], w1 = w[p1],                                                                                                                            \
                   w3 = w[p3], w4 = w[p4], w5 = w[p5],                                                                                                                \
                   w7 = w[p7]

/* Assuming p0..p8 is mapped to pixels 0..8, this function interpolates the
 * top-left pixel in the total of the 2x2 pixels to interpolates. The function
 * is also used for the 3 other pixels */
static inline uint32_t hq2x_interp_1x1(const uint32_t *r2y, int k,
                                       const uint16_t *w,
                                       int p0, int p1, int p2,
                                       int p3, int p4, int p5,
                                       int p6, int p7, int p8)
{
    INTERP_BOOTSTRAP(0);

    if ((P(0xbf, 0x37) || P(0xdb, 0x13)) && WDIFF(w1, w5))
        return interp_2px(w4, 3, w3, 1, 2);
    if ((P(0xdb, 0x49) || P(0xef, 0x6d)) && WDIFF(w7, w3))
        return interp_2px(w4, 3, w1, 1, 2);
    if ((P(0x0b, 0x0b) || P(0xfe, 0x4a) || P(0xfe, 0x1a)) && WDIFF(w3, w1))
        return w4;
    if ((P(0x6f, 0x2a) || P(0x5b, 0x0a) || P(0xbf, 0x3a) || P(0xdf, 0x5a) ||
         P(0x9f, 0x8a) || P(0xcf, 0x8a) || P(0xef, 0x4e) || P(0x3f, 0x0e) ||
         P(0xfb, 0x5a) || P(0xbb, 0x8a) || P(0x7f, 0x5a) || P(0xaf, 0x8a) ||
         P(0xeb, 0x8a)) &&
        WDIFF(w3, w1))
        return interp_2px(w4, 3, w0, 1, 2);
    if (P(0x0b, 0x08))
        return interp_3px(w4, 2, w0, 1, w1, 1, 2);
    if (P(0x0b, 0x02))
        return interp_3px(w4, 2, w0, 1, w3, 1, 2);
    if (P(0x2f, 0x2f))
        return interp_3px(w4, 14, w3, 1, w1, 1, 4);
    if (P(0xbf, 0x37) || P(0xdb, 0x13))
        return interp_3px(w4, 5, w1, 2, w3, 1, 3);
    if (P(0xdb, 0x49) || P(0xef, 0x6d))
        return interp_3px(w4, 5, w3, 2, w1, 1, 3);
    if (P(0x1b, 0x03) || P(0x4f, 0x43) || P(0x8b, 0x83) || P(0x6b, 0x43))
        return interp_2px(w4, 3, w3, 1, 2);
    if (P(0x4b, 0x09) || P(0x8b, 0x89) || P(0x1f, 0x19) || P(0x3b, 0x19))
        return interp_2px(w4, 3, w1, 1, 2);
    if (P(0x7e, 0x2a) || P(0xef, 0xab) || P(0xbf, 0x8f) || P(0x7e, 0x0e))
        return interp_3px(w4, 2, w3, 3, w1, 3, 3);
    if (P(0xfb, 0x6a) || P(0x6f, 0x6e) || P(0x3f, 0x3e) || P(0xfb, 0xfa) ||
        P(0xdf, 0xde) || P(0xdf, 0x1e))
        return interp_2px(w4, 3, w0, 1, 2);
    if (P(0x0a, 0x00) || P(0x4f, 0x4b) || P(0x9f, 0x1b) || P(0x2f, 0x0b) ||
        P(0xbe, 0x0a) || P(0xee, 0x0a) || P(0x7e, 0x0a) || P(0xeb, 0x4b) ||
        P(0x3b, 0x1b))
        return interp_3px(w4, 2, w3, 1, w1, 1, 2);
    return interp_3px(w4, 6, w3, 1, w1, 1, 3);
}

/* Assuming p0..p8 is mapped to pixels 0..8, this function interpolates the
 * top-left and top-center pixel in the total of the 3x3 pixels to
 * interpolates. The function is also used for the 3 other couples of pixels
 * defining the outline. The center pixel is not defined through this function,
 * since it's just the same as the original value. */
static inline void hq3x_interp_2x1(uint16_t *dst, int dst_linesize,
                                   const uint32_t *r2y, int k,
                                   const uint16_t *w,
                                   int pos00, int pos01,
                                   int p0, int p1, int p2,
                                   int p3, int p4, int p5,
                                   int p6, int p7, int p8,
                                   int rotate)
{
    INTERP_BOOTSTRAP(rotate);

    uint16_t *dst00 = &dst[dst_linesize * (pos00 >> 1) + (pos00 & 1)];
    uint16_t *dst01 = &dst[dst_linesize * (pos01 >> 1) + (pos01 & 1)];

    if ((P(0xdb, 0x49) || P(0xef, 0x6d)) && WDIFF(w7, w3))
        *dst00 = interp_2px(w4, 3, w1, 1, 2);
    else if ((P(0xbf, 0x37) || P(0xdb, 0x13)) && WDIFF(w1, w5))
        *dst00 = interp_2px(w4, 3, w3, 1, 2);
    else if ((P(0x0b, 0x0b) || P(0xfe, 0x4a) || P(0xfe, 0x1a)) && WDIFF(w3, w1))
        *dst00 = w4;
    else if ((P(0x6f, 0x2a) || P(0x5b, 0x0a) || P(0xbf, 0x3a) || P(0xdf, 0x5a) ||
              P(0x9f, 0x8a) || P(0xcf, 0x8a) || P(0xef, 0x4e) || P(0x3f, 0x0e) ||
              P(0xfb, 0x5a) || P(0xbb, 0x8a) || P(0x7f, 0x5a) || P(0xaf, 0x8a) ||
              P(0xeb, 0x8a)) &&
             WDIFF(w3, w1))
        *dst00 = interp_2px(w4, 3, w0, 1, 2);
    else if (P(0x4b, 0x09) || P(0x8b, 0x89) || P(0x1f, 0x19) || P(0x3b, 0x19))
        *dst00 = interp_2px(w4, 3, w1, 1, 2);
    else if (P(0x1b, 0x03) || P(0x4f, 0x43) || P(0x8b, 0x83) || P(0x6b, 0x43))
        *dst00 = interp_2px(w4, 3, w3, 1, 2);
    else if (P(0x7e, 0x2a) || P(0xef, 0xab) || P(0xbf, 0x8f) || P(0x7e, 0x0e))
        *dst00 = interp_2px(w3, 1, w1, 1, 1);
    else if (P(0x4f, 0x4b) || P(0x9f, 0x1b) || P(0x2f, 0x0b) || P(0xbe, 0x0a) ||
             P(0xee, 0x0a) || P(0x7e, 0x0a) || P(0xeb, 0x4b) || P(0x3b, 0x1b))
        *dst00 = interp_3px(w4, 2, w3, 7, w1, 7, 4);
    else if (P(0x0b, 0x08) || P(0xf9, 0x68) || P(0xf3, 0x62) || P(0x6d, 0x6c) ||
             P(0x67, 0x66) || P(0x3d, 0x3c) || P(0x37, 0x36) || P(0xf9, 0xf8) ||
             P(0xdd, 0xdc) || P(0xf3, 0xf2) || P(0xd7, 0xd6) || P(0xdd, 0x1c) ||
             P(0xd7, 0x16) || P(0x0b, 0x02))
        *dst00 = interp_2px(w4, 3, w0, 1, 2);
    else
        *dst00 = interp_3px(w4, 2, w3, 1, w1, 1, 2);

    if ((P(0xfe, 0xde) || P(0x9e, 0x16) || P(0xda, 0x12) || P(0x17, 0x16) ||
         P(0x5b, 0x12) || P(0xbb, 0x12)) &&
        WDIFF(w1, w5))
        *dst01 = w4;
    else if ((P(0x0f, 0x0b) || P(0x5e, 0x0a) || P(0xfb, 0x7b) || P(0x3b, 0x0b) ||
              P(0xbe, 0x0a) || P(0x7a, 0x0a)) &&
             WDIFF(w3, w1))
        *dst01 = w4;
    else if (P(0xbf, 0x8f) || P(0x7e, 0x0e) || P(0xbf, 0x37) || P(0xdb, 0x13))
        *dst01 = interp_2px(w1, 3, w4, 1, 2);
    else if (P(0x02, 0x00) || P(0x7c, 0x28) || P(0xed, 0xa9) || P(0xf5, 0xb4) ||
             P(0xd9, 0x90))
        *dst01 = interp_2px(w4, 3, w1, 1, 2);
    else if (P(0x4f, 0x4b) || P(0xfb, 0x7b) || P(0xfe, 0x7e) || P(0x9f, 0x1b) ||
             P(0x2f, 0x0b) || P(0xbe, 0x0a) || P(0x7e, 0x0a) || P(0xfb, 0x4b) ||
             P(0xfb, 0xdb) || P(0xfe, 0xde) || P(0xfe, 0x56) || P(0x57, 0x56) ||
             P(0x97, 0x16) || P(0x3f, 0x1e) || P(0xdb, 0x12) || P(0xbb, 0x12))
        *dst01 = interp_2px(w4, 7, w1, 1, 3);
    else
        *dst01 = w4;
}

/* Assuming p0..p8 is mapped to pixels 0..8, this function interpolates the
 * top-left block of 2x2 pixels in the total of the 4x4 pixels (or 4 blocks) to
 * interpolates. The function is also used for the 3 other blocks of 2x2
 * pixels. */
static inline void hq4x_interp_2x2(uint16_t *dst, int dst_linesize,
                                   const uint32_t *r2y, int k,
                                   const uint16_t *w,
                                   int pos00, int pos01,
                                   int pos10, int pos11,
                                   int p0, int p1, int p2,
                                   int p3, int p4, int p5,
                                   int p6, int p7, int p8)
{
    INTERP_BOOTSTRAP(0);

    uint16_t *dst00 = &dst[dst_linesize * (pos00 >> 1) + (pos00 & 1)];
    uint16_t *dst01 = &dst[dst_linesize * (pos01 >> 1) + (pos01 & 1)];
    uint16_t *dst10 = &dst[dst_linesize * (pos10 >> 1) + (pos10 & 1)];
    uint16_t *dst11 = &dst[dst_linesize * (pos11 >> 1) + (pos11 & 1)];

    const int cond00 = (P(0xbf, 0x37) || P(0xdb, 0x13)) && WDIFF(w1, w5);
    const int cond01 = (P(0xdb, 0x49) || P(0xef, 0x6d)) && WDIFF(w7, w3);
    const int cond02 = (P(0x6f, 0x2a) || P(0x5b, 0x0a) || P(0xbf, 0x3a) ||
                        P(0xdf, 0x5a) || P(0x9f, 0x8a) || P(0xcf, 0x8a) ||
                        P(0xef, 0x4e) || P(0x3f, 0x0e) || P(0xfb, 0x5a) ||
                        P(0xbb, 0x8a) || P(0x7f, 0x5a) || P(0xaf, 0x8a) ||
                        P(0xeb, 0x8a)) &&
                       WDIFF(w3, w1);
    const int cond03 = P(0xdb, 0x49) || P(0xef, 0x6d);
    const int cond04 = P(0xbf, 0x37) || P(0xdb, 0x13);
    const int cond05 = P(0x1b, 0x03) || P(0x4f, 0x43) || P(0x8b, 0x83) ||
                       P(0x6b, 0x43);
    const int cond06 = P(0x4b, 0x09) || P(0x8b, 0x89) || P(0x1f, 0x19) ||
                       P(0x3b, 0x19);
    const int cond07 = P(0x0b, 0x08) || P(0xf9, 0x68) || P(0xf3, 0x62) ||
                       P(0x6d, 0x6c) || P(0x67, 0x66) || P(0x3d, 0x3c) ||
                       P(0x37, 0x36) || P(0xf9, 0xf8) || P(0xdd, 0xdc) ||
                       P(0xf3, 0xf2) || P(0xd7, 0xd6) || P(0xdd, 0x1c) ||
                       P(0xd7, 0x16) || P(0x0b, 0x02);
    const int cond08 = (P(0x0f, 0x0b) || P(0x2b, 0x0b) || P(0xfe, 0x4a) ||
                        P(0xfe, 0x1a)) &&
                       WDIFF(w3, w1);
    const int cond09 = P(0x2f, 0x2f);
    const int cond10 = P(0x0a, 0x00);
    const int cond11 = P(0x0b, 0x09);
    const int cond12 = P(0x7e, 0x2a) || P(0xef, 0xab);
    const int cond13 = P(0xbf, 0x8f) || P(0x7e, 0x0e);
    const int cond14 = P(0x4f, 0x4b) || P(0x9f, 0x1b) || P(0x2f, 0x0b) ||
                       P(0xbe, 0x0a) || P(0xee, 0x0a) || P(0x7e, 0x0a) ||
                       P(0xeb, 0x4b) || P(0x3b, 0x1b);
    const int cond15 = P(0x0b, 0x03);

    if (cond00)
        *dst00 = interp_2px(w4, 5, w3, 3, 3);
    else if (cond01)
        *dst00 = interp_2px(w4, 5, w1, 3, 3);
    else if ((P(0x0b, 0x0b) || P(0xfe, 0x4a) || P(0xfe, 0x1a)) && WDIFF(w3, w1))
        *dst00 = w4;
    else if (cond02)
        *dst00 = interp_2px(w4, 5, w0, 3, 3);
    else if (cond03)
        *dst00 = interp_2px(w4, 3, w3, 1, 2);
    else if (cond04)
        *dst00 = interp_2px(w4, 3, w1, 1, 2);
    else if (cond05)
        *dst00 = interp_2px(w4, 5, w3, 3, 3);
    else if (cond06)
        *dst00 = interp_2px(w4, 5, w1, 3, 3);
    else if (P(0x0f, 0x0b) || P(0x5e, 0x0a) || P(0x2b, 0x0b) || P(0xbe, 0x0a) ||
             P(0x7a, 0x0a) || P(0xee, 0x0a))
        *dst00 = interp_2px(w1, 1, w3, 1, 1);
    else if (cond07)
        *dst00 = interp_2px(w4, 5, w0, 3, 3);
    else
        *dst00 = interp_3px(w4, 2, w1, 1, w3, 1, 2);

    if (cond00)
        *dst01 = interp_2px(w4, 7, w3, 1, 3);
    else if (cond08)
        *dst01 = w4;
    else if (cond02)
        *dst01 = interp_2px(w4, 3, w0, 1, 2);
    else if (cond09)
        *dst01 = w4;
    else if (cond10)
        *dst01 = interp_3px(w4, 5, w1, 2, w3, 1, 3);
    else if (P(0x0b, 0x08))
        *dst01 = interp_3px(w4, 5, w1, 2, w0, 1, 3);
    else if (cond11)
        *dst01 = interp_2px(w4, 5, w1, 3, 3);
    else if (cond04)
        *dst01 = interp_2px(w1, 3, w4, 1, 2);
    else if (cond12)
        *dst01 = interp_3px(w1, 2, w4, 1, w3, 1, 2);
    else if (cond13)
        *dst01 = interp_2px(w1, 5, w3, 3, 3);
    else if (cond05)
        *dst01 = interp_2px(w4, 7, w3, 1, 3);
    else if (P(0xf3, 0x62) || P(0x67, 0x66) || P(0x37, 0x36) || P(0xf3, 0xf2) ||
             P(0xd7, 0xd6) || P(0xd7, 0x16) || P(0x0b, 0x02))
        *dst01 = interp_2px(w4, 3, w0, 1, 2);
    else if (cond14)
        *dst01 = interp_2px(w1, 1, w4, 1, 1);
    else
        *dst01 = interp_2px(w4, 3, w1, 1, 2);

    if (cond01)
        *dst10 = interp_2px(w4, 7, w1, 1, 3);
    else if (cond08)
        *dst10 = w4;
    else if (cond02)
        *dst10 = interp_2px(w4, 3, w0, 1, 2);
    else if (cond09)
        *dst10 = w4;
    else if (cond10)
        *dst10 = interp_3px(w4, 5, w3, 2, w1, 1, 3);
    else if (P(0x0b, 0x02))
        *dst10 = interp_3px(w4, 5, w3, 2, w0, 1, 3);
    else if (cond15)
        *dst10 = interp_2px(w4, 5, w3, 3, 3);
    else if (cond03)
        *dst10 = interp_2px(w3, 3, w4, 1, 2);
    else if (cond13)
        *dst10 = interp_3px(w3, 2, w4, 1, w1, 1, 2);
    else if (cond12)
        *dst10 = interp_2px(w3, 5, w1, 3, 3);
    else if (cond06)
        *dst10 = interp_2px(w4, 7, w1, 1, 3);
    else if (P(0x0b, 0x08) || P(0xf9, 0x68) || P(0x6d, 0x6c) || P(0x3d, 0x3c) ||
             P(0xf9, 0xf8) || P(0xdd, 0xdc) || P(0xdd, 0x1c))
        *dst10 = interp_2px(w4, 3, w0, 1, 2);
    else if (cond14)
        *dst10 = interp_2px(w3, 1, w4, 1, 1);
    else
        *dst10 = interp_2px(w4, 3, w3, 1, 2);

    if ((P(0x7f, 0x2b) || P(0xef, 0xab) || P(0xbf, 0x8f) || P(0x7f, 0x0f)) &&
        WDIFF(w3, w1))
        *dst11 = w4;
    else if (cond02)
        *dst11 = interp_2px(w4, 7, w0, 1, 3);
    else if (cond15)
        *dst11 = interp_2px(w4, 7, w3, 1, 3);
    else if (cond11)
        *dst11 = interp_2px(w4, 7, w1, 1, 3);
    else if (P(0x0a, 0x00) || P(0x7e, 0x2a) || P(0xef, 0xab) || P(0xbf, 0x8f) ||
             P(0x7e, 0x0e))
        *dst11 = interp_3px(w4, 6, w3, 1, w1, 1, 3);
    else if (cond07)
        *dst11 = interp_2px(w4, 7, w0, 1, 3);
    else
        *dst11 = w4;
}

static inline void hqx_filter(uint16_t *in, int in_pitch, uint16_t *out, int out_pitch, int width, int height, int n)
{
    int x, y;
    const uint32_t *r2y = yuvtable;
    const int dst_linesize = out_pitch;
    const int src_linesize = in_pitch;
    uint8_t *dst = (uint8_t *)out;
    const uint8_t *src = (uint8_t *)in;

    const int dst16_linesize = dst_linesize >> 1;
    const int src16_linesize = src_linesize >> 1;

    init();

    for (y = 0; y < height; y++)
    {
        const uint16_t *src16 = (const uint16_t *)src;
        uint16_t *dst16 = (uint16_t *)dst;
        const int prevline = y > 0 ? -src16_linesize : 0;
        const int nextline = y < height - 1 ? src16_linesize : 0;

        for (x = 0; x < width; x++)
        {
            const int prevcol = x > 0 ? -1 : 0;
            const int nextcol = x < width - 1 ? 1 : 0;
            const uint16_t w[3 * 3] = {
                src16[prevcol + prevline], src16[prevline], src16[prevline + nextcol],
                src16[prevcol], src16[0], src16[nextcol],
                src16[prevcol + nextline], src16[nextline], src16[nextline + nextcol]
            };
            const uint32_t yuv1 = rgb2yuv(r2y, w[4]);
            const int pattern = (w[4] != w[0] ? (yuv_diff(yuv1, rgb2yuv(r2y, w[0]))) : 0) | (w[4] != w[1] ? (yuv_diff(yuv1, rgb2yuv(r2y, w[1]))) : 0) << 1 | (w[4] != w[2] ? (yuv_diff(yuv1, rgb2yuv(r2y, w[2]))) : 0) << 2 | (w[4] != w[3] ? (yuv_diff(yuv1, rgb2yuv(r2y, w[3]))) : 0) << 3 | (w[4] != w[5] ? (yuv_diff(yuv1, rgb2yuv(r2y, w[5]))) : 0) << 4 | (w[4] != w[6] ? (yuv_diff(yuv1, rgb2yuv(r2y, w[6]))) : 0) << 5 | (w[4] != w[7] ? (yuv_diff(yuv1, rgb2yuv(r2y, w[7]))) : 0) << 6 | (w[4] != w[8] ? (yuv_diff(yuv1, rgb2yuv(r2y, w[8]))) : 0) << 7;

            if (n == 2)
            {
                dst16[dst16_linesize * 0 + 0] = hq2x_interp_1x1(r2y, pattern, w, 0, 1, 2, 3, 4, 5, 6, 7, 8); // 00
                dst16[dst16_linesize * 0 + 1] = hq2x_interp_1x1(r2y, pattern, w, 2, 1, 0, 5, 4, 3, 8, 7, 6); // 01 (vert mirrored)
                dst16[dst16_linesize * 1 + 0] = hq2x_interp_1x1(r2y, pattern, w, 6, 7, 8, 3, 4, 5, 0, 1, 2); // 10 (horiz mirrored)
                dst16[dst16_linesize * 1 + 1] = hq2x_interp_1x1(r2y, pattern, w, 8, 7, 6, 5, 4, 3, 2, 1, 0); // 11 (center mirrored)
            }
            else if (n == 3)
            {
                hq3x_interp_2x1(dst16, dst16_linesize, r2y, pattern, w, 0, 1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 0);                          // 00 01
                hq3x_interp_2x1(dst16 + 1, dst16_linesize, r2y, pattern, w, 1, 3, 2, 5, 8, 1, 4, 7, 0, 3, 6, 1);                      // 02 12 (rotated to the right)
                hq3x_interp_2x1(dst16 + 1 * dst16_linesize, dst16_linesize, r2y, pattern, w, 2, 0, 6, 3, 0, 7, 4, 1, 8, 5, 2, 1);     // 20 10 (rotated to the left)
                hq3x_interp_2x1(dst16 + 1 * dst16_linesize + 1, dst16_linesize, r2y, pattern, w, 3, 2, 8, 7, 6, 5, 4, 3, 2, 1, 0, 0); // 22 21 (center mirrored)
                dst16[dst16_linesize + 1] = w[4];                                                                                     // 11
            }
            else if (n == 4)
            {
                hq4x_interp_2x2(dst16, dst16_linesize, r2y, pattern, w, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 6, 7, 8);                          // 00 01 10 11
                hq4x_interp_2x2(dst16 + 2, dst16_linesize, r2y, pattern, w, 1, 0, 3, 2, 2, 1, 0, 5, 4, 3, 8, 7, 6);                      // 02 03 12 13 (vert mirrored)
                hq4x_interp_2x2(dst16 + 2 * dst16_linesize, dst16_linesize, r2y, pattern, w, 2, 3, 0, 1, 6, 7, 8, 3, 4, 5, 0, 1, 2);     // 20 21 30 31 (horiz mirrored)
                hq4x_interp_2x2(dst16 + 2 * dst16_linesize + 2, dst16_linesize, r2y, pattern, w, 3, 2, 1, 0, 8, 7, 6, 5, 4, 3, 2, 1, 0); // 22 23 32 33 (center mirrored)
            }
            else
            {
            }

            src16 += 1;
            dst16 += n;
        }

        src += src_linesize;
        dst += dst_linesize * n;
    }
}

bool S9xBlitHQ2xFilterInit(void)
{
    return true;
}

void S9xBlitHQ2xFilterDeinit(void)
{
}

void HQ2X_16(uint8_t *in, int in_pitch, uint8_t *out, int out_pitch, int width, int height)
{
    hqx_filter((uint16_t *)in, in_pitch, (uint16_t *)out, out_pitch, width, height, 2);
}

void HQ3X_16(uint8_t *in, int in_pitch, uint8_t *out, int out_pitch, int width, int height)
{
    hqx_filter((uint16_t *)in, in_pitch, (uint16_t *)out, out_pitch, width, height, 3);
}

void HQ4X_16(uint8_t *in, int in_pitch, uint8_t *out, int out_pitch, int width, int height)
{
    hqx_filter((uint16_t *)in, in_pitch, (uint16_t *)out, out_pitch, width, height, 4);
}