gst_plugins_base/gst/videoscale/vs_4tap.c
changeset 16 8e837d1bf446
parent 0 0e761a78d257
child 30 7e817e7e631c
--- a/gst_plugins_base/gst/videoscale/vs_4tap.c	Wed Mar 24 17:58:42 2010 -0500
+++ b/gst_plugins_base/gst/videoscale/vs_4tap.c	Wed Mar 24 18:04:17 2010 -0500
@@ -1,6 +1,7 @@
 /*
  * Image Scaling Functions (4 tap)
  * Copyright (c) 2005 David A. Schleef <ds@schleef.org>
+ * Copyright (c) 2009 Sebastian Dröge <sebastian.droege@collabora.co.uk>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -30,12 +31,12 @@
 
 #include "vs_4tap.h"
 
-#include <gst/liboil.h>
+#include <liboil/liboil.h>
+#ifdef __SYMBIAN32__
+#include <liboil/globals.h>
+#endif
 #include <math.h>
 
-
-
-
 #define SHIFT 10
 
 #define MAX(a,b) (((a) > (b)) ? (a) : (b))
@@ -182,8 +183,15 @@
   int xacc;
   int k;
 
-  y_increment = ((src->height - 1) << 16) / (dest->height - 1);
-  x_increment = ((src->width - 1) << 16) / (dest->width - 1);
+  if (dest->height == 1)
+    y_increment = 0;
+  else
+    y_increment = ((src->height - 1) << 16) / (dest->height - 1);
+
+  if (dest->width == 1)
+    x_increment = 0;
+  else
+    x_increment = ((src->width - 1) << 16) / (dest->width - 1);
 
   k = 0;
   for (i = 0; i < 4; i++) {
@@ -219,3 +227,1213 @@
     yacc += y_increment;
   }
 }
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+void
+vs_scanline_resample_4tap_Y16 (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;
+  uint16_t *d = (uint16_t *) dest, *s = (uint16_t *) src;
+
+  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] * s[MAX (j - 1, 0)];
+      y += vs_4tap_taps[x][1] * s[j];
+      y += vs_4tap_taps[x][2] * s[j + 1];
+      y += vs_4tap_taps[x][3] * s[j + 2];
+    } else {
+      y = vs_4tap_taps[x][0] * s[CLAMP (j - 1, 0, src_width - 1)];
+      y += vs_4tap_taps[x][1] * s[CLAMP (j, 0, src_width - 1)];
+      y += vs_4tap_taps[x][2] * s[CLAMP (j + 1, 0, src_width - 1)];
+      y += vs_4tap_taps[x][3] * s[CLAMP (j + 2, 0, src_width - 1)];
+    }
+    y += (1 << (SHIFT - 1));
+    d[i] = CLAMP (y >> SHIFT, 0, 65535);
+    acc += increment;
+  }
+  *xacc = acc;
+}
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+void
+vs_scanline_merge_4tap_Y16 (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;
+  uint16_t *de = (uint16_t *) dest, *s1 = (uint16_t *) src1;
+  uint16_t *s2 = (uint16_t *) src2, *s3 = (uint16_t *) src3;
+  uint16_t *s4 = (uint16_t *) src4;
+
+  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 * s1[i];
+    y += b * s2[i];
+    y += c * s3[i];
+    y += d * s4[i];
+    y += (1 << (SHIFT - 1));
+    de[i] = CLAMP (y >> SHIFT, 0, 65535);
+  }
+}
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+
+void
+vs_image_scale_4tap_Y16 (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;
+
+  if (dest->height == 1)
+    y_increment = 0;
+  else
+    y_increment = ((src->height - 1) << 16) / (dest->height - 1);
+
+  if (dest->width == 1)
+    x_increment = 0;
+  else
+    x_increment = ((src->width - 1) << 16) / (dest->width - 1);
+
+  k = 0;
+  for (i = 0; i < 4; i++) {
+    xacc = 0;
+    vs_scanline_resample_4tap_Y16 (tmpbuf + i * dest->stride,
+        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_Y16 (tmpbuf + ((k + 3) & 3) * dest->stride,
+            src->pixels + (k + 3) * src->stride,
+            dest->width, src->width, &xacc, x_increment);
+      }
+    }
+
+    t0 = tmpbuf + (CLAMP (j - 1, 0, src->height - 1) & 3) * dest->stride;
+    t1 = tmpbuf + (CLAMP (j, 0, src->height - 1) & 3) * dest->stride;
+    t2 = tmpbuf + (CLAMP (j + 1, 0, src->height - 1) & 3) * dest->stride;
+    t3 = tmpbuf + (CLAMP (j + 2, 0, src->height - 1) & 3) * dest->stride;
+    vs_scanline_merge_4tap_Y16 (dest->pixels + i * dest->stride,
+        t0, t1, t2, t3, dest->width, yacc & 0xffff);
+
+    yacc += y_increment;
+  }
+}
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+
+void
+vs_scanline_resample_4tap_RGBA (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;
+  int off;
+
+  acc = *xacc;
+  for (i = 0; i < n; i++) {
+    j = acc >> 16;
+    x = (acc & 0xffff) >> 8;
+
+    for (off = 0; off < 4; off++) {
+      if (j - 1 >= 0 && j + 2 < src_width) {
+        y = vs_4tap_taps[x][0] * src[MAX ((j - 1) * 4 + off, 0)];
+        y += vs_4tap_taps[x][1] * src[j * 4 + off];
+        y += vs_4tap_taps[x][2] * src[(j + 1) * 4 + off];
+        y += vs_4tap_taps[x][3] * src[(j + 2) * 4 + off];
+      } else {
+        y = vs_4tap_taps[x][0] * src[CLAMP ((j - 1) * 4 + off, 0,
+                4 * (src_width - 1) + off)];
+        y += vs_4tap_taps[x][1] * src[CLAMP (j * 4 + off, 0,
+                4 * (src_width - 1) + off)];
+        y += vs_4tap_taps[x][2] * src[CLAMP ((j + 1) * 4 + off, 0,
+                4 * (src_width - 1) + off)];
+        y += vs_4tap_taps[x][3] * src[CLAMP ((j + 2) * 4 + off, 0,
+                4 * (src_width - 1) + off)];
+      }
+      y += (1 << (SHIFT - 1));
+      dest[i * 4 + off] = CLAMP (y >> SHIFT, 0, 255);
+    }
+    acc += increment;
+  }
+  *xacc = acc;
+}
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+
+void
+vs_scanline_merge_4tap_RGBA (uint8_t * dest, uint8_t * src1, uint8_t * src2,
+    uint8_t * src3, uint8_t * src4, int n, int acc)
+{
+  int i;
+  int y;
+  int off;
+  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++) {
+    for (off = 0; off < 4; off++) {
+      y = a * src1[i * 4 + off];
+      y += b * src2[i * 4 + off];
+      y += c * src3[i * 4 + off];
+      y += d * src4[i * 4 + off];
+      y += (1 << (SHIFT - 1));
+      dest[i * 4 + off] = CLAMP (y >> SHIFT, 0, 255);
+    }
+  }
+}
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+
+void
+vs_image_scale_4tap_RGBA (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;
+
+  if (dest->height == 1)
+    y_increment = 0;
+  else
+    y_increment = ((src->height - 1) << 16) / (dest->height - 1);
+
+  if (dest->width == 1)
+    x_increment = 0;
+  else
+    x_increment = ((src->width - 1) << 16) / (dest->width - 1);
+
+  k = 0;
+  for (i = 0; i < 4; i++) {
+    xacc = 0;
+    vs_scanline_resample_4tap_RGBA (tmpbuf + i * dest->stride,
+        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_RGBA (tmpbuf + ((k + 3) & 3) * dest->stride,
+            src->pixels + (k + 3) * src->stride,
+            dest->width, src->width, &xacc, x_increment);
+      }
+    }
+
+    t0 = tmpbuf + (CLAMP (j - 1, 0, src->height - 1) & 3) * dest->stride;
+    t1 = tmpbuf + (CLAMP (j, 0, src->height - 1) & 3) * dest->stride;
+    t2 = tmpbuf + (CLAMP (j + 1, 0, src->height - 1) & 3) * dest->stride;
+    t3 = tmpbuf + (CLAMP (j + 2, 0, src->height - 1) & 3) * dest->stride;
+    vs_scanline_merge_4tap_RGBA (dest->pixels + i * dest->stride,
+        t0, t1, t2, t3, dest->width, yacc & 0xffff);
+
+    yacc += y_increment;
+  }
+}
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+
+void
+vs_scanline_resample_4tap_RGB (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;
+  int off;
+
+  acc = *xacc;
+  for (i = 0; i < n; i++) {
+    j = acc >> 16;
+    x = (acc & 0xffff) >> 8;
+
+    for (off = 0; off < 3; off++) {
+      if (j - 1 >= 0 && j + 2 < src_width) {
+        y = vs_4tap_taps[x][0] * src[MAX ((j - 1) * 3 + off, 0)];
+        y += vs_4tap_taps[x][1] * src[j * 3 + off];
+        y += vs_4tap_taps[x][2] * src[(j + 1) * 3 + off];
+        y += vs_4tap_taps[x][3] * src[(j + 2) * 3 + off];
+      } else {
+        y = vs_4tap_taps[x][0] * src[CLAMP ((j - 1) * 3 + off, 0,
+                3 * (src_width - 1) + off)];
+        y += vs_4tap_taps[x][1] * src[CLAMP (j * 3 + off, 0,
+                3 * (src_width - 1) + off)];
+        y += vs_4tap_taps[x][2] * src[CLAMP ((j + 1) * 3 + off, 0,
+                3 * (src_width - 1) + off)];
+        y += vs_4tap_taps[x][3] * src[CLAMP ((j + 2) * 3 + off, 0,
+                3 * (src_width - 1) + off)];
+      }
+      y += (1 << (SHIFT - 1));
+      dest[i * 3 + off] = CLAMP (y >> SHIFT, 0, 255);
+    }
+    acc += increment;
+  }
+  *xacc = acc;
+}
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+
+void
+vs_scanline_merge_4tap_RGB (uint8_t * dest, uint8_t * src1, uint8_t * src2,
+    uint8_t * src3, uint8_t * src4, int n, int acc)
+{
+  int i;
+  int y;
+  int off;
+  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++) {
+    for (off = 0; off < 3; off++) {
+      y = a * src1[i * 3 + off];
+      y += b * src2[i * 3 + off];
+      y += c * src3[i * 3 + off];
+      y += d * src4[i * 3 + off];
+      y += (1 << (SHIFT - 1));
+      dest[i * 3 + off] = CLAMP (y >> SHIFT, 0, 255);
+    }
+  }
+}
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+
+void
+vs_image_scale_4tap_RGB (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;
+
+  if (dest->height == 1)
+    y_increment = 0;
+  else
+    y_increment = ((src->height - 1) << 16) / (dest->height - 1);
+
+  if (dest->width == 1)
+    x_increment = 0;
+  else
+    x_increment = ((src->width - 1) << 16) / (dest->width - 1);
+
+  k = 0;
+  for (i = 0; i < 4; i++) {
+    xacc = 0;
+    vs_scanline_resample_4tap_RGB (tmpbuf + i * dest->stride,
+        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_RGB (tmpbuf + ((k + 3) & 3) * dest->stride,
+            src->pixels + (k + 3) * src->stride,
+            dest->width, src->width, &xacc, x_increment);
+      }
+    }
+
+    t0 = tmpbuf + (CLAMP (j - 1, 0, src->height - 1) & 3) * dest->stride;
+    t1 = tmpbuf + (CLAMP (j, 0, src->height - 1) & 3) * dest->stride;
+    t2 = tmpbuf + (CLAMP (j + 1, 0, src->height - 1) & 3) * dest->stride;
+    t3 = tmpbuf + (CLAMP (j + 2, 0, src->height - 1) & 3) * dest->stride;
+    vs_scanline_merge_4tap_RGB (dest->pixels + i * dest->stride,
+        t0, t1, t2, t3, dest->width, yacc & 0xffff);
+
+    yacc += y_increment;
+  }
+}
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+
+void
+vs_scanline_resample_4tap_YUYV (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;
+  int quads = (n + 1) / 2;
+  int last_y = 2 * (src_width - 1);
+  int last_u =
+      MAX ((2 * (src_width - 1) % 4 ==
+          0) ? 2 * (src_width - 1) + 1 : 2 * (src_width - 1) - 1, 1);
+  int last_v =
+      MAX ((2 * (src_width - 1) % 4 ==
+          2) ? 2 * (src_width - 1) + 1 : 2 * (src_width - 1) - 1, 1);
+
+  acc = *xacc;
+  for (i = 0; i < quads; i++) {
+    j = acc >> 16;
+    x = (acc & 0xffff) >> 8;
+
+    if (j - 1 >= 0 && j + 2 < src_width) {
+      y = vs_4tap_taps[x][0] * src[MAX (j * 2 + 0 - 2, 0)];
+      y += vs_4tap_taps[x][1] * src[j * 2 + 0];
+      y += vs_4tap_taps[x][2] * src[j * 2 + 0 + 2];
+      y += vs_4tap_taps[x][3] * src[j * 2 + 0 + 4];
+    } else {
+      y = vs_4tap_taps[x][0] * src[CLAMP (j * 2 + 0 - 2, 0, last_y)];
+      y += vs_4tap_taps[x][1] * src[CLAMP (j * 2 + 0, 0, last_y)];
+      y += vs_4tap_taps[x][2] * src[CLAMP (j * 2 + 0 + 2, 0, last_y)];
+      y += vs_4tap_taps[x][3] * src[CLAMP (j * 2 + 0 + 4, 0, last_y)];
+    }
+    y += (1 << (SHIFT - 1));
+    dest[i * 4 + 0] = CLAMP (y >> SHIFT, 0, 255);
+
+    j = acc >> 17;
+    x = (acc & 0x1ffff) >> 9;
+
+    if (2 * (j - 1) >= 0 && 2 * (j + 4) < src_width) {
+      y = vs_4tap_taps[x][0] * src[MAX (j * 4 + 1 - 4, 1)];
+      y += vs_4tap_taps[x][1] * src[j * 4 + 1];
+      y += vs_4tap_taps[x][2] * src[j * 4 + 1 + 4];
+      y += vs_4tap_taps[x][3] * src[j * 4 + 1 + 8];
+    } else {
+      y = vs_4tap_taps[x][0] * src[CLAMP (j * 4 + 1 - 4, 1, last_u)];
+      y += vs_4tap_taps[x][1] * src[CLAMP (j * 4 + 1, 1, last_u)];
+      y += vs_4tap_taps[x][2] * src[CLAMP (j * 4 + 1 + 4, 1, last_u)];
+      y += vs_4tap_taps[x][3] * src[CLAMP (j * 4 + 1 + 8, 1, last_u)];
+    }
+    y += (1 << (SHIFT - 1));
+    dest[i * 4 + 1] = CLAMP (y >> SHIFT, 0, 255);
+
+    if (2 * i + 1 < n) {
+      if (2 * (j - 1) >= 0 && 2 * (j + 4) < src_width) {
+        y = vs_4tap_taps[x][0] * src[MAX (j * 4 + 3 - 4, 3)];
+        y += vs_4tap_taps[x][1] * src[j * 4 + 3];
+        y += vs_4tap_taps[x][2] * src[j * 4 + 3 + 4];
+        y += vs_4tap_taps[x][3] * src[j * 4 + 3 + 8];
+      } else {
+        y = vs_4tap_taps[x][0] * src[CLAMP (j * 4 + 3 - 4, 3, last_v)];
+        y += vs_4tap_taps[x][1] * src[CLAMP (j * 4 + 3, 3, last_v)];
+        y += vs_4tap_taps[x][2] * src[CLAMP (j * 4 + 3 + 4, 3, last_v)];
+        y += vs_4tap_taps[x][3] * src[CLAMP (j * 4 + 3 + 8, 3, last_v)];
+      }
+      y += (1 << (SHIFT - 1));
+      dest[i * 4 + 3] = CLAMP (y >> SHIFT, 0, 255);
+    }
+
+    acc += increment;
+    j = acc >> 16;
+    x = (acc & 0xffff) >> 8;
+
+    if (2 * i + 1 < n) {
+      if (j - 1 >= 0 && j + 2 < src_width) {
+        y = vs_4tap_taps[x][0] * src[MAX (j * 2 + 0 - 2, 0)];
+        y += vs_4tap_taps[x][1] * src[j * 2 + 0];
+        y += vs_4tap_taps[x][2] * src[j * 2 + 0 + 2];
+        y += vs_4tap_taps[x][3] * src[j * 2 + 0 + 4];
+      } else {
+        y = vs_4tap_taps[x][0] * src[CLAMP (j * 2 + 0 - 2, 0, last_y)];
+        y += vs_4tap_taps[x][1] * src[CLAMP (j * 2 + 0, 0, last_y)];
+        y += vs_4tap_taps[x][2] * src[CLAMP (j * 2 + 0 + 2, 0, last_y)];
+        y += vs_4tap_taps[x][3] * src[CLAMP (j * 2 + 0 + 4, 0, last_y)];
+      }
+      y += (1 << (SHIFT - 1));
+      dest[i * 4 + 2] = CLAMP (y >> SHIFT, 0, 255);
+      acc += increment;
+    }
+  }
+  *xacc = acc;
+}
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+
+void
+vs_scanline_merge_4tap_YUYV (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;
+  int quads = (n + 1) / 2;
+
+  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 < quads; i++) {
+    y = a * src1[i * 4 + 0];
+    y += b * src2[i * 4 + 0];
+    y += c * src3[i * 4 + 0];
+    y += d * src4[i * 4 + 0];
+    y += (1 << (SHIFT - 1));
+    dest[i * 4 + 0] = CLAMP (y >> SHIFT, 0, 255);
+
+    y = a * src1[i * 4 + 1];
+    y += b * src2[i * 4 + 1];
+    y += c * src3[i * 4 + 1];
+    y += d * src4[i * 4 + 1];
+    y += (1 << (SHIFT - 1));
+    dest[i * 4 + 1] = CLAMP (y >> SHIFT, 0, 255);
+
+    if (2 * i + 1 < n) {
+      y = a * src1[i * 4 + 2];
+      y += b * src2[i * 4 + 2];
+      y += c * src3[i * 4 + 2];
+      y += d * src4[i * 4 + 2];
+      y += (1 << (SHIFT - 1));
+      dest[i * 4 + 2] = CLAMP (y >> SHIFT, 0, 255);
+
+      y = a * src1[i * 4 + 3];
+      y += b * src2[i * 4 + 3];
+      y += c * src3[i * 4 + 3];
+      y += d * src4[i * 4 + 3];
+      y += (1 << (SHIFT - 1));
+      dest[i * 4 + 3] = CLAMP (y >> SHIFT, 0, 255);
+    }
+  }
+}
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+
+void
+vs_image_scale_4tap_YUYV (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;
+
+  if (dest->height == 1)
+    y_increment = 0;
+  else
+    y_increment = ((src->height - 1) << 16) / (dest->height - 1);
+
+  if (dest->width == 1)
+    x_increment = 0;
+  else
+    x_increment = ((src->width - 1) << 16) / (dest->width - 1);
+
+  k = 0;
+  for (i = 0; i < 4; i++) {
+    xacc = 0;
+    vs_scanline_resample_4tap_YUYV (tmpbuf + i * dest->stride,
+        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_YUYV (tmpbuf + ((k + 3) & 3) * dest->stride,
+            src->pixels + (k + 3) * src->stride,
+            dest->width, src->width, &xacc, x_increment);
+      }
+    }
+
+    t0 = tmpbuf + (CLAMP (j - 1, 0, src->height - 1) & 3) * dest->stride;
+    t1 = tmpbuf + (CLAMP (j, 0, src->height - 1) & 3) * dest->stride;
+    t2 = tmpbuf + (CLAMP (j + 1, 0, src->height - 1) & 3) * dest->stride;
+    t3 = tmpbuf + (CLAMP (j + 2, 0, src->height - 1) & 3) * dest->stride;
+    vs_scanline_merge_4tap_YUYV (dest->pixels + i * dest->stride,
+        t0, t1, t2, t3, dest->width, yacc & 0xffff);
+
+    yacc += y_increment;
+  }
+}
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+
+void
+vs_scanline_resample_4tap_UYVY (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;
+  int quads = (n + 1) / 2;
+  int last_y = 2 * (src_width - 1) + 1;
+  int last_u =
+      MAX ((2 * (src_width - 1) % 4 ==
+          0) ? 2 * (src_width - 1) : 2 * (src_width - 1) - 2, 0);
+  int last_v =
+      MAX ((2 * (src_width - 1) % 4 ==
+          2) ? 2 * (src_width - 1) : 2 * (src_width - 1) - 2, 0);
+
+  acc = *xacc;
+  for (i = 0; i < quads; i++) {
+    j = acc >> 16;
+    x = (acc & 0xffff) >> 8;
+
+    if (j - 1 >= 0 && j + 2 < src_width) {
+      y = vs_4tap_taps[x][0] * src[MAX (j * 2 + 1 - 2, 1)];
+      y += vs_4tap_taps[x][1] * src[j * 2 + 1];
+      y += vs_4tap_taps[x][2] * src[j * 2 + 1 + 2];
+      y += vs_4tap_taps[x][3] * src[j * 2 + 1 + 4];
+    } else {
+      y = vs_4tap_taps[x][0] * src[CLAMP (j * 2 + 1 - 2, 1, last_y)];
+      y += vs_4tap_taps[x][1] * src[CLAMP (j * 2 + 1, 1, last_y)];
+      y += vs_4tap_taps[x][2] * src[CLAMP (j * 2 + 1 + 2, 1, last_y)];
+      y += vs_4tap_taps[x][3] * src[CLAMP (j * 2 + 1 + 4, 1, last_y)];
+    }
+    y += (1 << (SHIFT - 1));
+    dest[i * 4 + 1] = CLAMP (y >> SHIFT, 0, 255);
+
+    j = acc >> 17;
+    x = (acc & 0x1ffff) >> 9;
+
+    if (2 * (j - 2) >= 0 && 2 * (j + 4) < src_width) {
+      y = vs_4tap_taps[x][0] * src[MAX (j * 4 + 0 - 4, 0)];
+      y += vs_4tap_taps[x][1] * src[j * 4 + 0];
+      y += vs_4tap_taps[x][2] * src[j * 4 + 0 + 4];
+      y += vs_4tap_taps[x][3] * src[j * 4 + 0 + 8];
+    } else {
+      y = vs_4tap_taps[x][0] * src[CLAMP (j * 4 + 0 - 4, 0, last_u)];
+      y += vs_4tap_taps[x][1] * src[CLAMP (j * 4 + 0, 0, last_u)];
+      y += vs_4tap_taps[x][2] * src[CLAMP (j * 4 + 0 + 4, 0, last_u)];
+      y += vs_4tap_taps[x][3] * src[CLAMP (j * 4 + 0 + 8, 0, last_u)];
+    }
+    y += (1 << (SHIFT - 1));
+    dest[i * 4 + 0] = CLAMP (y >> SHIFT, 0, 255);
+
+    if (2 * i + 1 < n) {
+      if (2 * (j - 1) >= 0 && 2 * (j + 4) < src_width) {
+        y = vs_4tap_taps[x][0] * src[MAX (j * 4 + 2 - 4, 2)];
+        y += vs_4tap_taps[x][1] * src[j * 4 + 2];
+        y += vs_4tap_taps[x][2] * src[j * 4 + 2 + 4];
+        y += vs_4tap_taps[x][3] * src[j * 4 + 2 + 8];
+      } else {
+        y = vs_4tap_taps[x][0] * src[CLAMP (j * 4 + 2 - 4, 2, last_v)];
+        y += vs_4tap_taps[x][1] * src[CLAMP (j * 4 + 2, 2, last_v)];
+        y += vs_4tap_taps[x][2] * src[CLAMP (j * 4 + 2 + 4, 2, last_v)];
+        y += vs_4tap_taps[x][3] * src[CLAMP (j * 4 + 2 + 8, 2, last_v)];
+      }
+      y += (1 << (SHIFT - 1));
+      dest[i * 4 + 2] = CLAMP (y >> SHIFT, 0, 255);
+    }
+
+    acc += increment;
+    j = acc >> 16;
+    x = (acc & 0xffff) >> 8;
+
+    if (2 * i + 1 < n) {
+      if (j - 1 >= 0 && j + 2 < src_width) {
+        y = vs_4tap_taps[x][0] * src[MAX (j * 2 + 1 - 2, 0)];
+        y += vs_4tap_taps[x][1] * src[j * 2 + 1];
+        y += vs_4tap_taps[x][2] * src[j * 2 + 1 + 2];
+        y += vs_4tap_taps[x][3] * src[j * 2 + 1 + 4];
+      } else {
+        y = vs_4tap_taps[x][0] * src[CLAMP (j * 2 + 1 - 2, 1, last_y)];
+        y += vs_4tap_taps[x][1] * src[CLAMP (j * 2 + 1, 1, last_y)];
+        y += vs_4tap_taps[x][2] * src[CLAMP (j * 2 + 1 + 2, 1, last_y)];
+        y += vs_4tap_taps[x][3] * src[CLAMP (j * 2 + 1 + 4, 1, last_y)];
+      }
+      y += (1 << (SHIFT - 1));
+      dest[i * 4 + 3] = CLAMP (y >> SHIFT, 0, 255);
+      acc += increment;
+    }
+  }
+  *xacc = acc;
+}
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+
+void
+vs_scanline_merge_4tap_UYVY (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;
+  int quads = (n + 1) / 2;
+
+  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 < quads; i++) {
+    y = a * src1[i * 4 + 0];
+    y += b * src2[i * 4 + 0];
+    y += c * src3[i * 4 + 0];
+    y += d * src4[i * 4 + 0];
+    y += (1 << (SHIFT - 1));
+    dest[i * 4 + 0] = CLAMP (y >> SHIFT, 0, 255);
+
+    y = a * src1[i * 4 + 1];
+    y += b * src2[i * 4 + 1];
+    y += c * src3[i * 4 + 1];
+    y += d * src4[i * 4 + 1];
+    y += (1 << (SHIFT - 1));
+    dest[i * 4 + 1] = CLAMP (y >> SHIFT, 0, 255);
+
+    if (2 * i + 1 < n) {
+      y = a * src1[i * 4 + 2];
+      y += b * src2[i * 4 + 2];
+      y += c * src3[i * 4 + 2];
+      y += d * src4[i * 4 + 2];
+      y += (1 << (SHIFT - 1));
+      dest[i * 4 + 2] = CLAMP (y >> SHIFT, 0, 255);
+
+      y = a * src1[i * 4 + 3];
+      y += b * src2[i * 4 + 3];
+      y += c * src3[i * 4 + 3];
+      y += d * src4[i * 4 + 3];
+      y += (1 << (SHIFT - 1));
+      dest[i * 4 + 3] = CLAMP (y >> SHIFT, 0, 255);
+    }
+  }
+}
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+
+void
+vs_image_scale_4tap_UYVY (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;
+
+  if (dest->height == 1)
+    y_increment = 0;
+  else
+    y_increment = ((src->height - 1) << 16) / (dest->height - 1);
+
+  if (dest->width == 1)
+    x_increment = 0;
+  else
+    x_increment = ((src->width - 1) << 16) / (dest->width - 1);
+
+  k = 0;
+  for (i = 0; i < 4; i++) {
+    xacc = 0;
+    vs_scanline_resample_4tap_UYVY (tmpbuf + i * dest->stride,
+        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_UYVY (tmpbuf + ((k + 3) & 3) * dest->stride,
+            src->pixels + (k + 3) * src->stride,
+            dest->width, src->width, &xacc, x_increment);
+      }
+    }
+
+    t0 = tmpbuf + (CLAMP (j - 1, 0, src->height - 1) & 3) * dest->stride;
+    t1 = tmpbuf + (CLAMP (j, 0, src->height - 1) & 3) * dest->stride;
+    t2 = tmpbuf + (CLAMP (j + 1, 0, src->height - 1) & 3) * dest->stride;
+    t3 = tmpbuf + (CLAMP (j + 2, 0, src->height - 1) & 3) * dest->stride;
+    vs_scanline_merge_4tap_UYVY (dest->pixels + i * dest->stride,
+        t0, t1, t2, t3, dest->width, yacc & 0xffff);
+
+    yacc += y_increment;
+  }
+}
+
+/* note that src and dest are uint16_t, and thus endian dependent */
+
+#define RGB565_R(x) (((x)&0xf800)>>8 | ((x)&0xf800)>>13)
+#define RGB565_G(x) (((x)&0x07e0)>>3 | ((x)&0x07e0)>>9)
+#define RGB565_B(x) (((x)&0x001f)<<3 | ((x)&0x001f)>>2)
+
+#define RGB565(r,g,b) \
+  ((((r)<<8)&0xf800) | (((g)<<3)&0x07e0) | (((b)>>3)&0x001f))
+
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+void
+vs_scanline_resample_4tap_RGB565 (uint8_t * dest_u8, uint8_t * src_u8,
+    int n, int src_width, int *xacc, int increment)
+{
+  int i;
+  int j;
+  int acc;
+  int x;
+  int y, y_r, y_b, y_g;
+  uint16_t *dest = (uint16_t *) dest_u8;
+  uint16_t *src = (uint16_t *) src_u8;
+
+  acc = *xacc;
+  for (i = 0; i < n; i++) {
+    j = acc >> 16;
+    x = acc & 0xffff >> 8;
+
+    if (j - 1 >= 0 && j + 2 < src_width) {
+      y = vs_4tap_taps[x][0] * RGB565_R (src[MAX ((j - 1), 0)]);
+      y += vs_4tap_taps[x][1] * RGB565_R (src[j]);
+      y += vs_4tap_taps[x][2] * RGB565_R (src[(j + 1)]);
+      y += vs_4tap_taps[x][3] * RGB565_R (src[(j + 2)]);
+    } else {
+      y = vs_4tap_taps[x][0] * RGB565_R (src[CLAMP ((j - 1), 0,
+                  src_width - 1)]);
+      y += vs_4tap_taps[x][1] * RGB565_R (src[CLAMP (j, 0, src_width - 1)]);
+      y += vs_4tap_taps[x][2] * RGB565_R (src[CLAMP ((j + 1), 0,
+                  src_width - 1)]);
+      y += vs_4tap_taps[x][3] * RGB565_R (src[CLAMP ((j + 2), 0,
+                  src_width - 1)]);
+    }
+    y += (1 << (SHIFT - 1));
+    y_r = CLAMP (y >> SHIFT, 0, 255);
+
+    if (j - 1 >= 0 && j + 2 < src_width) {
+      y = vs_4tap_taps[x][0] * RGB565_G (src[MAX ((j - 1), 0)]);
+      y += vs_4tap_taps[x][1] * RGB565_G (src[j]);
+      y += vs_4tap_taps[x][2] * RGB565_G (src[(j + 1)]);
+      y += vs_4tap_taps[x][3] * RGB565_G (src[(j + 2)]);
+    } else {
+      y = vs_4tap_taps[x][0] * RGB565_G (src[CLAMP ((j - 1), 0,
+                  src_width - 1)]);
+      y += vs_4tap_taps[x][1] * RGB565_G (src[CLAMP (j, 0, src_width - 1)]);
+      y += vs_4tap_taps[x][2] * RGB565_G (src[CLAMP ((j + 1), 0,
+                  src_width - 1)]);
+      y += vs_4tap_taps[x][3] * RGB565_G (src[CLAMP ((j + 2), 0,
+                  src_width - 1)]);
+    }
+    y += (1 << (SHIFT - 1));
+    y_g = CLAMP (y >> SHIFT, 0, 255);
+
+    if (j - 1 >= 0 && j + 2 < src_width) {
+      y = vs_4tap_taps[x][0] * RGB565_B (src[MAX ((j - 1), 0)]);
+      y += vs_4tap_taps[x][1] * RGB565_B (src[j]);
+      y += vs_4tap_taps[x][2] * RGB565_B (src[(j + 1)]);
+      y += vs_4tap_taps[x][3] * RGB565_B (src[(j + 2)]);
+    } else {
+      y = vs_4tap_taps[x][0] * RGB565_B (src[CLAMP ((j - 1), 0,
+                  src_width - 1)]);
+      y += vs_4tap_taps[x][1] * RGB565_B (src[CLAMP (j, 0, src_width - 1)]);
+      y += vs_4tap_taps[x][2] * RGB565_B (src[CLAMP ((j + 1), 0,
+                  src_width - 1)]);
+      y += vs_4tap_taps[x][3] * RGB565_B (src[CLAMP ((j + 2), 0,
+                  src_width - 1)]);
+    }
+    y += (1 << (SHIFT - 1));
+    y_b = CLAMP (y >> SHIFT, 0, 255);
+
+    dest[i] = RGB565 (y_r, y_b, y_g);
+    acc += increment;
+  }
+  *xacc = acc;
+}
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+
+void
+vs_scanline_merge_4tap_RGB565 (uint8_t * dest_u8, uint8_t * src1_u8,
+    uint8_t * src2_u8, uint8_t * src3_u8, uint8_t * src4_u8, int n, int acc)
+{
+  int i;
+  int y, y_r, y_b, y_g;
+  int a, b, c, d;
+  uint16_t *dest = (uint16_t *) dest_u8;
+  uint16_t *src1 = (uint16_t *) src1_u8;
+  uint16_t *src2 = (uint16_t *) src2_u8;
+  uint16_t *src3 = (uint16_t *) src3_u8;
+  uint16_t *src4 = (uint16_t *) src4_u8;
+
+  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 * RGB565_R (src1[i]);
+    y += b * RGB565_R (src2[i]);
+    y += c * RGB565_R (src3[i]);
+    y += d * RGB565_R (src4[i]);
+    y += (1 << (SHIFT - 1));
+    y_r = CLAMP (y >> SHIFT, 0, 255);
+
+    y = a * RGB565_G (src1[i]);
+    y += b * RGB565_G (src2[i]);
+    y += c * RGB565_G (src3[i]);
+    y += d * RGB565_G (src4[i]);
+    y += (1 << (SHIFT - 1));
+    y_g = CLAMP (y >> SHIFT, 0, 255);
+
+    y = a * RGB565_B (src1[i]);
+    y += b * RGB565_B (src2[i]);
+    y += c * RGB565_B (src3[i]);
+    y += d * RGB565_B (src4[i]);
+    y += (1 << (SHIFT - 1));
+    y_b = CLAMP (y >> SHIFT, 0, 255);
+
+    dest[i] = RGB565 (y_r, y_b, y_g);
+  }
+}
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+
+void
+vs_image_scale_4tap_RGB565 (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;
+
+  if (dest->height == 1)
+    y_increment = 0;
+  else
+    y_increment = ((src->height - 1) << 16) / (dest->height - 1);
+
+  if (dest->width == 1)
+    x_increment = 0;
+  else
+    x_increment = ((src->width - 1) << 16) / (dest->width - 1);
+
+  k = 0;
+  for (i = 0; i < 4; i++) {
+    xacc = 0;
+    vs_scanline_resample_4tap_RGB565 (tmpbuf + i * dest->stride,
+        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_RGB565 (tmpbuf + ((k + 3) & 3) * dest->stride,
+            src->pixels + (k + 3) * src->stride,
+            dest->width, src->width, &xacc, x_increment);
+      }
+    }
+
+    t0 = tmpbuf + (CLAMP (j - 1, 0, src->height - 1) & 3) * dest->stride;
+    t1 = tmpbuf + (CLAMP (j, 0, src->height - 1) & 3) * dest->stride;
+    t2 = tmpbuf + (CLAMP (j + 1, 0, src->height - 1) & 3) * dest->stride;
+    t3 = tmpbuf + (CLAMP (j + 2, 0, src->height - 1) & 3) * dest->stride;
+    vs_scanline_merge_4tap_RGB565 (dest->pixels + i * dest->stride,
+        t0, t1, t2, t3, dest->width, yacc & 0xffff);
+
+    yacc += y_increment;
+  }
+}
+
+/* note that src and dest are uint16_t, and thus endian dependent */
+
+#define RGB555_R(x) (((x)&0x7c00)>>8 | ((x)&0x7c00)>>13)
+#define RGB555_G(x) (((x)&0x03e0)>>3 | ((x)&0x03e0)>>9)
+#define RGB555_B(x) (((x)&0x001f)<<3 | ((x)&0x001f)>>2)
+
+#define RGB555(r,g,b) \
+  ((((r)<<7)&0x7c00) | (((g)<<2)&0x03e0) | (((b)>>3)&0x001f))
+
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+void
+vs_scanline_resample_4tap_RGB555 (uint8_t * dest_u8, uint8_t * src_u8,
+    int n, int src_width, int *xacc, int increment)
+{
+  int i;
+  int j;
+  int acc;
+  int x;
+  int y, y_r, y_b, y_g;
+  uint16_t *dest = (uint16_t *) dest_u8;
+  uint16_t *src = (uint16_t *) src_u8;
+
+  acc = *xacc;
+  for (i = 0; i < n; i++) {
+    j = acc >> 16;
+    x = acc & 0xffff >> 8;
+
+    if (j - 1 >= 0 && j + 2 < src_width) {
+      y = vs_4tap_taps[x][0] * RGB555_R (src[MAX ((j - 1), 0)]);
+      y += vs_4tap_taps[x][1] * RGB555_R (src[j]);
+      y += vs_4tap_taps[x][2] * RGB555_R (src[(j + 1)]);
+      y += vs_4tap_taps[x][3] * RGB555_R (src[(j + 2)]);
+    } else {
+      y = vs_4tap_taps[x][0] * RGB555_R (src[CLAMP ((j - 1), 0,
+                  src_width - 1)]);
+      y += vs_4tap_taps[x][1] * RGB555_R (src[CLAMP (j, 0, src_width - 1)]);
+      y += vs_4tap_taps[x][2] * RGB555_R (src[CLAMP ((j + 1), 0,
+                  src_width - 1)]);
+      y += vs_4tap_taps[x][3] * RGB555_R (src[CLAMP ((j + 2), 0,
+                  src_width - 1)]);
+    }
+    y += (1 << (SHIFT - 1));
+    y_r = CLAMP (y >> SHIFT, 0, 255);
+
+    if (j - 1 >= 0 && j + 2 < src_width) {
+      y = vs_4tap_taps[x][0] * RGB555_G (src[MAX ((j - 1), 0)]);
+      y += vs_4tap_taps[x][1] * RGB555_G (src[j]);
+      y += vs_4tap_taps[x][2] * RGB555_G (src[(j + 1)]);
+      y += vs_4tap_taps[x][3] * RGB555_G (src[(j + 2)]);
+    } else {
+      y = vs_4tap_taps[x][0] * RGB555_G (src[CLAMP ((j - 1), 0,
+                  src_width - 1)]);
+      y += vs_4tap_taps[x][1] * RGB555_G (src[CLAMP (j, 0, src_width - 1)]);
+      y += vs_4tap_taps[x][2] * RGB555_G (src[CLAMP ((j + 1), 0,
+                  src_width - 1)]);
+      y += vs_4tap_taps[x][3] * RGB555_G (src[CLAMP ((j + 2), 0,
+                  src_width - 1)]);
+    }
+    y += (1 << (SHIFT - 1));
+    y_g = CLAMP (y >> SHIFT, 0, 255);
+
+    if (j - 1 >= 0 && j + 2 < src_width) {
+      y = vs_4tap_taps[x][0] * RGB555_B (src[MAX ((j - 1), 0)]);
+      y += vs_4tap_taps[x][1] * RGB555_B (src[j]);
+      y += vs_4tap_taps[x][2] * RGB555_B (src[(j + 1)]);
+      y += vs_4tap_taps[x][3] * RGB555_B (src[(j + 2)]);
+    } else {
+      y = vs_4tap_taps[x][0] * RGB555_B (src[CLAMP ((j - 1), 0,
+                  src_width - 1)]);
+      y += vs_4tap_taps[x][1] * RGB555_B (src[CLAMP (j, 0, src_width - 1)]);
+      y += vs_4tap_taps[x][2] * RGB555_B (src[CLAMP ((j + 1), 0,
+                  src_width - 1)]);
+      y += vs_4tap_taps[x][3] * RGB555_B (src[CLAMP ((j + 2), 0,
+                  src_width - 1)]);
+    }
+    y += (1 << (SHIFT - 1));
+    y_b = CLAMP (y >> SHIFT, 0, 255);
+
+    dest[i] = RGB555 (y_r, y_b, y_g);
+    acc += increment;
+  }
+  *xacc = acc;
+}
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+
+void
+vs_scanline_merge_4tap_RGB555 (uint8_t * dest_u8, uint8_t * src1_u8,
+    uint8_t * src2_u8, uint8_t * src3_u8, uint8_t * src4_u8, int n, int acc)
+{
+  int i;
+  int y, y_r, y_b, y_g;
+  int a, b, c, d;
+  uint16_t *dest = (uint16_t *) dest_u8;
+  uint16_t *src1 = (uint16_t *) src1_u8;
+  uint16_t *src2 = (uint16_t *) src2_u8;
+  uint16_t *src3 = (uint16_t *) src3_u8;
+  uint16_t *src4 = (uint16_t *) src4_u8;
+
+  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 * RGB555_R (src1[i]);
+    y += b * RGB555_R (src2[i]);
+    y += c * RGB555_R (src3[i]);
+    y += d * RGB555_R (src4[i]);
+    y += (1 << (SHIFT - 1));
+    y_r = CLAMP (y >> SHIFT, 0, 255);
+
+    y = a * RGB555_G (src1[i]);
+    y += b * RGB555_G (src2[i]);
+    y += c * RGB555_G (src3[i]);
+    y += d * RGB555_G (src4[i]);
+    y += (1 << (SHIFT - 1));
+    y_g = CLAMP (y >> SHIFT, 0, 255);
+
+    y = a * RGB555_B (src1[i]);
+    y += b * RGB555_B (src2[i]);
+    y += c * RGB555_B (src3[i]);
+    y += d * RGB555_B (src4[i]);
+    y += (1 << (SHIFT - 1));
+    y_b = CLAMP (y >> SHIFT, 0, 255);
+
+    dest[i] = RGB555 (y_r, y_b, y_g);
+  }
+}
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+
+void
+vs_image_scale_4tap_RGB555 (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;
+
+  if (dest->height == 1)
+    y_increment = 0;
+  else
+    y_increment = ((src->height - 1) << 16) / (dest->height - 1);
+
+  if (dest->width == 1)
+    x_increment = 0;
+  else
+    x_increment = ((src->width - 1) << 16) / (dest->width - 1);
+
+  k = 0;
+  for (i = 0; i < 4; i++) {
+    xacc = 0;
+    vs_scanline_resample_4tap_RGB555 (tmpbuf + i * dest->stride,
+        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_RGB555 (tmpbuf + ((k + 3) & 3) * dest->stride,
+            src->pixels + (k + 3) * src->stride,
+            dest->width, src->width, &xacc, x_increment);
+      }
+    }
+
+    t0 = tmpbuf + (CLAMP (j - 1, 0, src->height - 1) & 3) * dest->stride;
+    t1 = tmpbuf + (CLAMP (j, 0, src->height - 1) & 3) * dest->stride;
+    t2 = tmpbuf + (CLAMP (j + 1, 0, src->height - 1) & 3) * dest->stride;
+    t3 = tmpbuf + (CLAMP (j + 2, 0, src->height - 1) & 3) * dest->stride;
+    vs_scanline_merge_4tap_RGB555 (dest->pixels + i * dest->stride,
+        t0, t1, t2, t3, dest->width, yacc & 0xffff);
+
+    yacc += y_increment;
+  }
+}