/*

 * Image Scaling Functions (4 tap)

 * Copyright (c) 2005 David A. Schleef <ds@schleef.org>

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,

 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR

 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING

 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

 * POSSIBILITY OF SUCH DAMAGE.

 */

#include "vs_image.h"

#include "vs_scanline.h"

#include "vs_4tap.h"

#include <math.h>

#define SHIFT 10

#define MAX(a,b) (((a) > (b)) ? (a) : (b))

#define MIN(a,b) (((a) < (b)) ? (a) : (b))

#define CLAMP(x,a,b) MAX(MIN((x),(b)),(a))

#ifndef M_PI

#define M_PI  3.14159265358979323846

#endif

#ifdef WIN32

#define rint(x) (floor((x)+0.5))

#endif

static int16_t vs_4tap_taps[256][4];

static double

vs_4tap_func (double x)

{

#if 0

  if (x < -1)

    return 0;

  if (x > 1)

    return 0;

  if (x < 0)

    return 1 + x;

  return 1 - x;

#endif

#if 0

  if (x == 0)

    return 1;

  return sin (M_PI * x) / (M_PI * x) * (1 - 0.25 * x * x);

#endif

#if 1

  if (x == 0)

    return 1;

  return sin (M_PI * x) / (M_PI * x);

#endif

}

#ifdef __SYMBIAN32__

EXPORT_C

#endif

void

vs_4tap_init (void)

{

  int i;

  double a, b, c, d;

  double sum;

  for (i = 0; i < 256; i++) {

    a = vs_4tap_func (-1 - i / 256.0);

    b = vs_4tap_func (0 - i / 256.0);

    c = vs_4tap_func (1 - i / 256.0);

    d = vs_4tap_func (2 - i / 256.0);

    sum = a + b + c + d;

    vs_4tap_taps[i][0] = rint ((1 << SHIFT) * (a / sum));

    vs_4tap_taps[i][1] = rint ((1 << SHIFT) * (b / sum));

    vs_4tap_taps[i][2] = rint ((1 << SHIFT) * (c / sum));

    vs_4tap_taps[i][3] = rint ((1 << SHIFT) * (d / sum));

  }

}

#ifdef __SYMBIAN32__

EXPORT_C

#endif

void

vs_scanline_resample_4tap_Y (uint8_t * dest, uint8_t * src,

    int n, int src_width, int *xacc, int increment)

{

  int i;

  int j;

  int acc;

  int x;

  int y;

  acc = *xacc;

  for (i = 0; i < n; i++) {

    j = acc >> 16;

    x = (acc & 0xff00) >> 8;

    if (j - 1 >= 0 && j + 2 < src_width) {

      y = vs_4tap_taps[x][0] * src[MAX (j - 1, 0)];

      y += vs_4tap_taps[x][1] * src[j];

      y += vs_4tap_taps[x][2] * src[j + 1];

      y += vs_4tap_taps[x][3] * src[j + 2];

    } else {

      y = vs_4tap_taps[x][0] * src[CLAMP (j - 1, 0, src_width - 1)];

      y += vs_4tap_taps[x][1] * src[CLAMP (j, 0, src_width - 1)];

      y += vs_4tap_taps[x][2] * src[CLAMP (j + 1, 0, src_width - 1)];

      y += vs_4tap_taps[x][3] * src[CLAMP (j + 2, 0, src_width - 1)];

    }

    y += (1 << (SHIFT - 1));

    dest[i] = CLAMP (y >> SHIFT, 0, 255);

    acc += increment;

  }

  *xacc = acc;

}

#ifdef __SYMBIAN32__

EXPORT_C

#endif

void

vs_scanline_merge_4tap_Y (uint8_t * dest, uint8_t * src1, uint8_t * src2,

    uint8_t * src3, uint8_t * src4, int n, int acc)

{

  int i;

  int y;

  int a, b, c, d;

  acc = (acc >> 8) & 0xff;

  a = vs_4tap_taps[acc][0];

  b = vs_4tap_taps[acc][1];

  c = vs_4tap_taps[acc][2];

  d = vs_4tap_taps[acc][3];

  for (i = 0; i < n; i++) {

    y = a * src1[i];

    y += b * src2[i];

    y += c * src3[i];

    y += d * src4[i];

    y += (1 << (SHIFT - 1));

    dest[i] = CLAMP (y >> SHIFT, 0, 255);

  }

}

#ifdef __SYMBIAN32__

EXPORT_C

#endif

void

vs_image_scale_4tap_Y (const VSImage * dest, const VSImage * src,

    uint8_t * tmpbuf)

{

  int yacc;

  int y_increment;

  int x_increment;

  int i;

  int j;

  int xacc;

  int k;

  k = 0;

  for (i = 0; i < 4; i++) {

    xacc = 0;

    vs_scanline_resample_4tap_Y (tmpbuf + i * dest->width,

        src->pixels + i * src->stride, dest->width, src->width,

        &xacc, x_increment);

  }

  yacc = 0;

  for (i = 0; i < dest->height; i++) {

    uint8_t *t0, *t1, *t2, *t3;

    j = yacc >> 16;

    while (j > k) {

      k++;

      if (k + 3 < src->height) {

        xacc = 0;

        vs_scanline_resample_4tap_Y (tmpbuf + ((k + 3) & 3) * dest->width,

            src->pixels + (k + 3) * src->stride,

            dest->width, src->width, &xacc, x_increment);

      }

    }

    t0 = tmpbuf + (CLAMP (j - 1, 0, src->height - 1) & 3) * dest->width;

    t1 = tmpbuf + (CLAMP (j, 0, src->height - 1) & 3) * dest->width;

    t2 = tmpbuf + (CLAMP (j + 1, 0, src->height - 1) & 3) * dest->width;

    t3 = tmpbuf + (CLAMP (j + 2, 0, src->height - 1) & 3) * dest->width;

    vs_scanline_merge_4tap_Y (dest->pixels + i * dest->stride,

        t0, t1, t2, t3, dest->width, yacc & 0xffff);

    yacc += y_increment;

  }

}