Aren/toaruos
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

jpeg: even faster with more premultiplications

Browse Source
This commit is contained in:
K. Lange 2018-12-20 19:01:49 +09:00
parent 245fa0a092
commit de26980af2
1 changed files with 15 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
lib/jpeg.c
View File

@ -220,12 +220,12 @@ static double cosines[8][8] = {
{ 0.0975451610081,-0.27778511651,0.415734806151,-0.490392640202,0.490392640202,-0.415734806151,0.27778511651,-0.0975451610081 },
};
static double premul[8][8][8][8]= {{{{0}}}};
static void add_idc(struct idct * self, int n, int m, int coeff) {
for (int y = 0; y < 8; ++y) {
for (int x = 0; x < 8; ++x) {
double nn = cosines[n][x]; // norm_coeff[!!n] * cos((double)n * M_PI * ((double)x + 0.5) / 8.0);
double mm = cosines[m][y]; // norm_coeff[!!m] * cos((double)m * M_PI * ((double)y + 0.5) / 8.0);
self->base[xy_to_lin(x, y)] += nn * mm * coeff;
self->base[xy_to_lin(x, y)] += premul[n][m][x][y] * coeff;
}
}
}
@ -417,6 +417,18 @@ int load_sprite_jpg(sprite_t * tsprite, char * filename) {
memset(huffman_tables, 0, sizeof(huffman_tables));
if (premul[0][0][0][0] == 0.0) {
for (int n = 0; n < 8; ++n) {
for (int m = 0; m < 8; ++m) {
for (int y = 0; y < 8; ++y) {
for (int x = 0; x < 8; ++x) {
premul[n][m][x][y] = cosines[n][x] * cosines[m][y];
}
}
}
}
}
while (1) {
/* Read a header */