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GRAPHICS: Turn sqrt(2) and cosine values into constants ;)

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svn-id: r55586
This commit is contained in:
Max Horn 2011-01-28 09:46:39 +00:00
parent baf6af4fa6
commit 96d91ec182
2 changed files with 18 additions and 14 deletions
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30
graphics/jpeg.cpp
View File

@ -33,6 +33,10 @@
namespace Graphics {
#ifndef M_SQRT2
#define M_SQRT2 1.41421356237309504880 /* sqrt(2) */
#endif /* M_SQRT2 */
// Order used to traverse the quantization tables
static const uint8 _zigZagOrder[64] = {
0, 1, 8, 16, 9, 2, 3, 10,
@ -45,6 +49,17 @@ static const uint8 _zigZagOrder[64] = {
53, 60, 61, 54, 47, 55, 62, 63
};
static const float _cosine32[32] = {
1.000000000000000, 0.980785280403230, 0.923879532511287, 0.831469612302545,
0.707106781186548, 0.555570233019602, 0.382683432365090, 0.195090322016128,
0.000000000000000, -0.195090322016128, -0.382683432365090, -0.555570233019602,
-0.707106781186547, -0.831469612302545, -0.923879532511287, -0.980785280403230,
-1.000000000000000, -0.980785280403230, -0.923879532511287, -0.831469612302545,
-0.707106781186548, -0.555570233019602, -0.382683432365090, -0.195090322016129,
-0.000000000000000, 0.195090322016128, 0.382683432365090, 0.555570233019602,
0.707106781186547, 0.831469612302545, 0.923879532511287, 0.980785280403230
};
JPEG::JPEG() :
_stream(NULL), _w(0), _h(0), _numComp(0), _components(NULL), _numScanComp(0),
_scanComp(NULL), _currentComp(NULL) {
@ -60,15 +75,6 @@ JPEG::JPEG() :
_huff[i].sizes = NULL;
_huff[i].codes = NULL;
}
// Initialize sqrt_2 and cosine lookups
_sqrt_2 = sqrt(2.0f);
debug(2, "JPEG: _sqrt_2: %f", _sqrt_2);
for(byte i = 0; i < 32; i++) {
_cosine_32[i] = cos(i * PI / 16);
debug(2, "JPEG: _cosine_32[%d]: %f", i, _cosine_32[i]);
}
}
JPEG::~JPEG() {
@ -504,13 +510,13 @@ bool JPEG::readMCU(uint16 xMCU, uint16 yMCU) {
float JPEG::idct(int x, int y, int weight, int fx, int fy) {
byte vx_in = ((int32)((2 * x) + 1) * fx) % 32;
byte vy_in = ((int32)((2 * y) + 1) * fy) % 32;
float ret = (float)weight * _cosine_32[vx_in] * _cosine_32[vy_in];
float ret = (float)weight * _cosine32[vx_in] * _cosine32[vy_in];
if (fx == 0)
ret /= _sqrt_2;
ret /= M_SQRT2;
if (fy == 0)
ret /= _sqrt_2;
ret /= M_SQRT2;
return ret;
}

2
graphics/jpeg.h
View File

@ -118,8 +118,6 @@ private:
uint8 _bitsData;
uint8 _bitsNumber;
float _sqrt_2;
float _cosine_32[32];
// Discrete Cosine Transformation
float idct(int x, int y, int weight, int fx, int fy);
};