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More optimizations to drawing code

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This commit is contained in:
Michał Janiszewski
2016-02-22 16:16:35 +01:00
parent 2744db77d9
commit 60d01a3ddf
1 changed files with 14 additions and 15 deletions
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29
src/drawing/drawing_fast.cpp
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@@ -5,7 +5,7 @@ extern "C"
// This will have -1 (0xffffffff) for (val <= 0), 0 otherwise, so it can act as a mask
// This is expected to generate
// sar $0x1f, %eax
// sar eax, 0x1f (arithmetic shift right by 31)
#define less_or_equal_zero_mask(val) (((val - 1) >> (sizeof(val) * 8 - 1)))
template<int image_type, int zoom_level>
@@ -24,26 +24,27 @@ static void FASTCALL DrawRLESprite2(const uint8* source_bits_pointer,
int line_width = (dpi->width >> zoom_level) + dpi->pitch;
if (source_y_start < 0) {
source_y_start += zoom_amount;
next_dest_pointer += line_width;
height -= zoom_amount;
}
const int source_y_end = height + source_y_start;
const int source_y_start_mask = less_or_equal_zero_mask(source_y_start + 1);
source_y_start += zoom_amount & source_y_start_mask;
next_dest_pointer += line_width & source_y_start_mask;
height -= zoom_amount & source_y_start_mask;
//For every line in the image
for (int y = source_y_start; y < source_y_end; y += zoom_amount) {
for (int i = 0; i < height; i += zoom_amount) {
int y = source_y_start + i;
uint8 i2 = i >> zoom_level;
//The first part of the source pointer is a list of offsets to different lines
//This will move the pointer to the correct source line.
const uint8 *next_source_pointer = source_bits_pointer + ((uint16*)source_bits_pointer)[y];
uint8* loop_dest_pointer = next_dest_pointer + line_width * i2;
uint8 last_data_line = 0;
//For every data section in the line
while (!last_data_line) {
const uint8* source_pointer = next_source_pointer;
uint8* dest_pointer = next_dest_pointer;
uint8* dest_pointer = loop_dest_pointer;
int no_pixels = *source_pointer++;
//gap_size is the number of non drawn pixels you require to
@@ -59,12 +60,13 @@ static void FASTCALL DrawRLESprite2(const uint8* source_bits_pointer,
//Calculates the start point of the image
int x_start = gap_size - source_x_start;
const int x_diff = x_start & ~zoom_mask;
const int x_mask = ~less_or_equal_zero_mask(x_diff);
no_pixels -= x_diff;
x_start += ~zoom_mask & ~less_or_equal_zero_mask(x_diff - 1);
source_pointer += (x_start&~zoom_mask);
x_start += ~zoom_mask & x_mask;
source_pointer += (x_start&~zoom_mask) & x_mask;
// This will have 1 for x_start > 0, 0 otherwise
// This will have -1 (0xffffffff) for (x_start <= 0), 0 otherwise
int sign = less_or_equal_zero_mask(x_start);
dest_pointer += (x_start >> zoom_level) & ~sign;
@@ -117,9 +119,6 @@ static void FASTCALL DrawRLESprite2(const uint8* source_bits_pointer,
}
}
}
//Add a line to the drawing surface pointer
next_dest_pointer += line_width;
}
}