Minimize computation in rotate_pixel().

- Deactivate tests.
- Check if delta is on integer values.

rotation.cpp

@@ -595,9 +595,12 @@ inline
 void rotate_pixel(Image const& src, /*uint8_t* rotated,*/
                   DPoint const& src_rotated_point, /*Point const& rot_point,*/
                   unsigned int const src_limit, unsigned int const rot_limit,
-                  uint8_t* rotate_buffer, unsigned int rot_index)
+                  uint8_t* rotate_buffer, unsigned int rot_index,
+                  bool full_delta)
 {
-  unsigned int src_index = ((int) src_rotated_point.y * src.width + (int) src_rotated_point.x) * 3;
+  int const src_x = (int) src_rotated_point.x;
+  int const src_y = (int) src_rotated_point.y;
+  unsigned int src_index = (src_y * src.width + src_x) * 3;
 //  unsigned int rot_index = (rot_point.y * rotated.width + rot_point.x) * 3;
 
   // Out-of-bounds check
@@ -614,46 +617,27 @@ void rotate_pixel(Image const& src, /*uint8_t* rotated,*/
   if (src_index_4 >= src_limit)
     return;
 
-  double x_delta = src_rotated_point.x - floor(src_rotated_point.x);
-  round_if_very_small(x_delta);
-  double y_delta = src_rotated_point.y - floor(src_rotated_point.y);
-  round_if_very_small(y_delta);
-
   // special case if we can directly map the src to the dest
-  if (x_delta == 0 && y_delta == 0)
+  if (full_delta)
   {
-  //  memcpy(&rotated.buffer[rot_index], &src.buffer[src_index], 3 * sizeof (uint8_t));
+    memcpy(&rotate_buffer[rot_index], &src.buffer[src_index], 3 * sizeof (uint8_t));
-    rotate_buffer[rot_index] = src.buffer[src_index];
-    rotate_buffer[rot_index + 1] = src.buffer[src_index + 1];
-    rotate_buffer[rot_index + 2] = src.buffer[src_index + 2];
     return;
   }
 
-  // SIMD
+  double x_delta = src_rotated_point.x - src_x;
-  __m128 const x_d = _mm_set_ps1(x_delta);
+  //round_if_very_small(x_delta);
-  __m128 const inv_x_d = _mm_set_ps1(1 - x_delta);
+  double y_delta = src_rotated_point.y - src_y;
-  __m128 top_left = _mm_set_ps(src.buffer[src_index_1], src.buffer[src_index_1 + 1], src.buffer[src_index_1 + 2], 0.0);
+  //round_if_very_small(y_delta);
-  __m128 top_right = _mm_set_ps(src.buffer[src_index_2], src.buffer[src_index_2 + 1], src.buffer[src_index_2 + 2], 0.0);
+  double const inv_x = 1 - x_delta;
-  top_left = _mm_mul_ps(top_left, inv_x_d);
+  double const inv_y = 1 - y_delta;
-  top_right = _mm_mul_ps(top_right, x_d);
-  top_left = _mm_add_ps(top_left, top_right);
 
-  __m128 bottom_left = _mm_set_ps(src.buffer[src_index_3], src.buffer[src_index_3 + 1], src.buffer[src_index_3 + 2], 0.0);
+  // No SIMD
-  __m128 bottom_right = _mm_set_ps(src.buffer[src_index_4], src.buffer[src_index_4 + 1], src.buffer[src_index_4 + 2], 0.0);
+  rotate_buffer[rot_index] = (src.buffer[src_index_1] * inv_x + src.buffer[src_index_2] * x_delta) * inv_y
-  bottom_left = _mm_mul_ps(bottom_left, inv_x_d);
+                           + (src.buffer[src_index_3] * inv_x + src.buffer[src_index_4] * x_delta) * y_delta;
-  bottom_right = _mm_mul_ps(bottom_right, x_d);
+  rotate_buffer[rot_index + 1] = (src.buffer[src_index_1 + 1] * inv_x + src.buffer[src_index_2 + 1] * x_delta) * inv_y
-  bottom_left = _mm_add_ps(bottom_left, bottom_right);
+                               + (src.buffer[src_index_3 + 1] * inv_x + src.buffer[src_index_4 + 1] * x_delta) * y_delta;
-
+  rotate_buffer[rot_index + 2] = (src.buffer[src_index_1 + 2] * inv_x + src.buffer[src_index_2 + 2] * x_delta) * inv_y
-  __m128 const y_d = _mm_set_ps1(y_delta);
+                               + (src.buffer[src_index_3 + 2] * inv_x + src.buffer[src_index_4 + 2] * x_delta) * y_delta;
-  __m128 const inv_y_d = _mm_set_ps1(1 - y_delta);
-  top_left = _mm_mul_ps(top_left, inv_y_d);
-  bottom_left = _mm_mul_ps(bottom_left, y_d);
-  top_left = _mm_add_ps(top_left, bottom_left);
-
-  // convert float values to uint8_t
-  rotate_buffer[rot_index] = top_left[3];
-  rotate_buffer[rot_index + 1] = top_left[2];
-  rotate_buffer[rot_index + 2] = top_left[1];
 }
 
 Image* rotate(Image const& src, double angle)
@@ -689,6 +673,12 @@ Image* rotate(Image const& src, double angle)
   src_delta_y.y = src_delta_y.y - src_origin.y;
   round_if_very_small(src_delta_y.x);
   round_if_very_small(src_delta_y.y);
+  bool full_delta = false;
+  if (src_delta_x.x - (int) src_delta_x.x == 0
+      && src_delta_x.y - (int) src_delta_x.y == 0
+      && src_delta_y.x - (int) src_delta_y.x == 0
+      && src_delta_y.y - (int) src_delta_y.y == 0)
+    full_delta = true;
 
 
   // // steps for first column in source image (y)
@@ -705,57 +695,19 @@ Image* rotate(Image const& src, double angle)
   unsigned int const src_limit = src.width * src.height * 3;
   unsigned int const rot_limit = rotated->width * rotated->height * 3;
 
-//  for (int y_i = 0; y_i <= (int) origin_nb_steps; ++y_i)
-//  {
-//    // first column origin
-//    Point const rot_origin(tl.x + y_i * rotated_step.x, tl.y + y_i * rotated_step.y);
-//    Point rot_point(rot_origin.x, rot_origin.y);
-//    DPoint rot_delta(0.0, 0.0);
-//
-//    Point previous = rot_origin;
-//
-//    for (int x_i = 0; x_i <= (int) line_nb_steps; ++x_i)
-//    {
-//
-//      Point const delta(rot_point.x - tl.x, rot_point.y - tl.y);
-//      DPoint src_rotated_point(src_tl.x + delta.x * src_delta_x.x + delta.y * src_delta_y.x,
-//                               src_tl.y + delta.x * src_delta_x.y + delta.y * src_delta_y.y);
-//
-//      rotate_pixel(src, *rotated, src_rotated_point, rot_point, src_limit, rot_limit);
-//
-//      if (previous.x != rot_point.x && previous.y != rot_point.y)
-//      {
-//        int y_slope = rot_point.y > previous.y ? 1 : -1;
-//        int tmp_y = rot_point.y;
-//        rot_point.y = previous.y;
-//
-//        src_rotated_point.x -= y_slope * src_delta_y.x;
-//        src_rotated_point.y -= y_slope * src_delta_y.y;
-//
-//        rotate_pixel(src, *rotated, src_rotated_point, rot_point, src_limit, rot_limit);
-//
-//        rot_point.y = tmp_y;
-//      }
-//
-//      previous = rot_point;
-//
-//      rot_delta.x += bresenham.x;
-//      rot_point.x = rot_origin.x + (int) rot_delta.x;
-//
-//      rot_delta.y += bresenham.y;
-//      rot_point.y = rot_origin.y + (int) rot_delta.y;
-//    }
-//  }
-
   DPoint const rot_origin_in_src_grid = get_mapped_point(*rotated, Point(0, 0), -rotation);
   DPoint const rot_origin_in_src = convert_img_coord_precision(src, rot_origin_in_src_grid);
 
-  unsigned int const buffer_size = rotated->width * 3;
+  unsigned int const buffer_pixel_capacity = 128 / 3;
+  unsigned int const buffer_size = buffer_pixel_capacity * 3;
+  unsigned int buffer_index = 0;
   uint8_t buffer[buffer_size];
+  memset(buffer, 0, buffer_size);
+  unsigned int buffer_offset = 0;
 
   for (unsigned int y = 0; y < rotated->height; ++y)
   {
-    memset(buffer, 0, buffer_size);
+    //memset(buffer, 0, buffer_size);
     DPoint src_rotated_point(rot_origin_in_src.x + y * src_delta_y.x,
                              rot_origin_in_src.y + y * src_delta_y.y);
 
@@ -764,13 +716,22 @@ Image* rotate(Image const& src, double angle)
       if (src_rotated_point.x >= 0 && src_rotated_point.x < src.width
           && src_rotated_point.y >= 0 && src_rotated_point.y < src.height)
       {
-        rotate_pixel(src, src_rotated_point, src_limit, rot_limit, buffer, x * 3);
+        rotate_pixel(src, src_rotated_point,
+                     src_limit, rot_limit,
+                     buffer, buffer_index * 3, full_delta);
       }
 
       src_rotated_point.x += src_delta_x.x;
       src_rotated_point.y += src_delta_x.y;
+      ++buffer_index;
+      if (buffer_index == buffer_pixel_capacity)
+      {
+        memcpy(rotated->buffer + buffer_offset, buffer, buffer_size);
+        buffer_offset += buffer_size;
+        buffer_index = 0;
+        memset(buffer, 0, buffer_size);
+      }
     }
-    memcpy(rotated->buffer + buffer_size * y, buffer, buffer_size);
   }
 
   return rotated;
@@ -784,55 +745,42 @@ Image* rotate(Image const& src, double angle)
 template<unsigned int W, unsigned int H>
 void rotate_pixel(TiledImage<W, H> const& src,
                   DPoint const& src_rotated_point,
-                  uint8_t* rot_tile, unsigned int rot_index)
+                  uint8_t* rot_tile, unsigned int rot_index,
+                  bool full_delta)
 {
-  uint8_t const* src_index_1 = src.access_pixel((int) src_rotated_point.x, (int) src_rotated_point.y);
+  int const src_x = (int) src_rotated_point.x;
-
+  int const src_y = (int) src_rotated_point.y;
-  double x_delta = src_rotated_point.x - (int) src_rotated_point.x;
+  uint8_t const* src_index_1 = src.access_pixel(src_x, src_y);
-  round_if_very_small(x_delta);
-  double y_delta = src_rotated_point.y - (int) src_rotated_point.y;
-  round_if_very_small(y_delta);
 
   // special case if we can directly map the src to the dest
-  if (x_delta == 0 && y_delta == 0)
+  if (full_delta)
   {
     memcpy(&rot_tile[rot_index], src_index_1, 3 * sizeof (uint8_t));
     return;
   }
 
-  uint8_t const* src_index_2 = src.access_pixel((int) src_rotated_point.x + 1, (int) src_rotated_point.y);
+  double x_delta = src_rotated_point.x - src_x;
-  uint8_t const* src_index_3 = src.access_pixel((int) src_rotated_point.x, (int) src_rotated_point.y + 1);
+  //round_if_very_small(x_delta);
-  uint8_t const* src_index_4 = src.access_pixel((int) src_rotated_point.x + 1, (int) src_rotated_point.y + 1);
+  double y_delta = src_rotated_point.y - src_y;
+  //round_if_very_small(y_delta);
+  double const inv_x = 1 - x_delta;
+  double const inv_y = 1 - y_delta;
+
+  uint8_t const* src_index_2 = src.access_pixel(src_x + 1, src_y);
+  uint8_t const* src_index_3 = src.access_pixel(src_x, src_y + 1);
+  uint8_t const* src_index_4 = src.access_pixel(src_x + 1, src_y + 1);
 
   // FIXME: deal with image border
-  if (!src_index_1 || !src_index_2 || !src_index_3 || !src_index_4)
+  if (!src_index_4)
     return;
 
-  // SIMD
+  // No SIMD
-  __m128 const x_d = _mm_set_ps1(x_delta);
+  rot_tile[rot_index] = (src_index_1[0] * inv_x + src_index_2[0] * x_delta) * inv_y
-  __m128 const inv_x_d = _mm_set_ps1(1 - x_delta);
+                        + (src_index_3[0] * inv_x + src_index_4[0] * x_delta) * y_delta;
-  __m128 top_left = _mm_set_ps(*src_index_1, *(src_index_1 + 1), *(src_index_1 + 2), 0.0);
+  rot_tile[rot_index + 1] = (src_index_1[1] * inv_x + src_index_2[1] * x_delta) * inv_y
-  __m128 top_right = _mm_set_ps(*src_index_2, *(src_index_2 + 1), *(src_index_2 + 2), 0.0);
+                        + (src_index_3[1] * inv_x + src_index_4[1] * x_delta) * y_delta;
-  top_left = _mm_mul_ps(top_left, inv_x_d);
+  rot_tile[rot_index + 2] = (src_index_1[2] * inv_x + src_index_2[2] * x_delta) * inv_y
-  top_right = _mm_mul_ps(top_right, x_d);
+                        + (src_index_3[2] * inv_x + src_index_4[2] * x_delta) * y_delta;
-  top_left = _mm_add_ps(top_left, top_right);
-
-  __m128 bottom_left = _mm_set_ps(*src_index_3, *(src_index_3 + 1), *(src_index_3 + 2), 0.0);
-  __m128 bottom_right = _mm_set_ps(*src_index_4, *(src_index_4 + 1), *(src_index_4 + 2), 0.0);
-  bottom_left = _mm_mul_ps(bottom_left, inv_x_d);
-  bottom_right = _mm_mul_ps(bottom_right, x_d);
-  bottom_left = _mm_add_ps(bottom_left, bottom_right);
-
-  __m128 const y_d = _mm_set_ps1(y_delta);
-  __m128 const inv_y_d = _mm_set_ps1(1 - y_delta);
-  top_left = _mm_mul_ps(top_left, inv_y_d);
-  bottom_left = _mm_mul_ps(bottom_left, y_d);
-  top_left = _mm_add_ps(top_left, bottom_left);
-
-  // convert float values to uint8_t
-  rot_tile[rot_index] = top_left[3];
-  rot_tile[rot_index + 1] = top_left[2];
-  rot_tile[rot_index + 2] = top_left[1];
 }
 
 template<unsigned int W, unsigned int H>
@@ -857,15 +805,26 @@ rotate(TiledImage<W, H> const& src, double angle)
   src_delta_y.y = src_delta_y.y - src_origin.y;
   round_if_very_small(src_delta_y.x);
   round_if_very_small(src_delta_y.y);
+  bool full_delta = false;
+  if (src_delta_x.x - (int) src_delta_x.x == 0
+      && src_delta_x.y - (int) src_delta_x.y == 0
+      && src_delta_y.x - (int) src_delta_y.x == 0
+      && src_delta_y.y - (int) src_delta_y.y == 0)
+    full_delta = true;
+
 
   DPoint const rot_origin_in_src_grid = get_mapped_point(*rotated, Point(0, 0), -rotation);
   DPoint const rot_origin_in_src = convert_img_coord_precision(src, rot_origin_in_src_grid);
 
+  uint8_t tile[W * H * 3];
+  memset(tile, 0, W * H * 3);
+
   for (unsigned int y = 0; y < rotated->nb_row_tile; ++y)
   {
     for (unsigned int x = 0; x < rotated->nb_col_tile; ++x)
     {
       unsigned int const rot_tile_index = y * rotated->nb_col_tile + x;
+      unsigned int rot_index = 0;
 
       for (unsigned int j = 0; j < H; ++j)
       {
@@ -876,20 +835,21 @@ rotate(TiledImage<W, H> const& src, double angle)
 
         for (unsigned int i = 0; i < W; ++i)
         {
-          unsigned int const rot_index = (j * W + i) * 3;
-
           if (src_rotated_point.x >= 0 && src_rotated_point.x < src.width
               && src_rotated_point.y >= 0 && src_rotated_point.y < src.height)
           {
             rotate_pixel(src, src_rotated_point,
-                         rotated->tiles[rot_tile_index], rot_index);
+                         tile, rot_index, full_delta);
           }
 
           src_rotated_point.x += src_delta_x.x;
           src_rotated_point.y += src_delta_x.y;
-
+          rot_index += 3;
         }
       }
+
+      memcpy(rotated->tiles[rot_tile_index], tile, W * H * 3);
+      memset(tile, 0, W * H * 3);
     }
   }
 
@@ -1059,7 +1019,7 @@ int main(int argc, char* argv[])
     return 1;
   }
 
-  bool perform_check = true;
+  bool perform_check = false;
 
   if (perform_check)
   {
@@ -1077,7 +1037,7 @@ int main(int argc, char* argv[])
   }
 
   Image img(argv[1]);
-  TiledImage<32, 32> tiled_img(argv[1]);
+  TiledImage<8, 8> tiled_img(argv[1]);
 
   for (double rotation = 0; rotation < 360; rotation += 45)
   {