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vp3: Simplify init_block_mapping 

Originally committed as revision 22494 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
David Conrad 2010-03-13 05:56:01 +00:00
parent 3477897e5a
commit a16389c18f
1 changed files with 17 additions and 96 deletions
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113
libavcodec/vp3.c
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@ -260,105 +260,26 @@ typedef struct Vp3DecodeContext {
*/
static int init_block_mapping(Vp3DecodeContext *s)
{
int i, j;
signed int hilbert_walk_mb[4];
int sb_x, sb_y, plane;
int x, y, i, j = 0;
int current_fragment = 0;
int current_width = 0;
int current_height = 0;
int right_edge = 0;
int bottom_edge = 0;
int superblock_row_inc = 0;
int mapping_index = 0;
for (plane = 0; plane < 3; plane++) {
int sb_width = plane ? s->c_superblock_width : s->y_superblock_width;
int sb_height = plane ? s->c_superblock_height : s->y_superblock_height;
int frag_width = s->fragment_width >> !!plane;
int frag_height = s->fragment_height >> !!plane;
static const signed char travel_width[16] = {
1, 1, 0, -1,
0, 0, 1, 0,
1, 0, 1, 0,
0, -1, 0, 1
};
for (sb_y = 0; sb_y < sb_height; sb_y++)
for (sb_x = 0; sb_x < sb_width; sb_x++)
for (i = 0; i < 16; i++) {
x = 4*sb_x + hilbert_offset[i][0];
y = 4*sb_y + hilbert_offset[i][1];
static const signed char travel_height[16] = {
0, 0, 1, 0,
1, 1, 0, -1,
0, 1, 0, -1,
-1, 0, -1, 0
};
hilbert_walk_mb[0] = 1;
hilbert_walk_mb[1] = s->macroblock_width;
hilbert_walk_mb[2] = 1;
hilbert_walk_mb[3] = -s->macroblock_width;
/* iterate through each superblock (all planes) and map the fragments */
for (i = 0; i < s->superblock_count; i++) {
/* time to re-assign the limits? */
if (i == 0) {
/* start of Y superblocks */
right_edge = s->fragment_width;
bottom_edge = s->fragment_height;
current_width = -1;
current_height = 0;
superblock_row_inc = 3 * s->fragment_width -
(s->y_superblock_width * 4 - s->fragment_width);
/* the first operation for this variable is to advance by 1 */
current_fragment = -1;
} else if (i == s->u_superblock_start) {
/* start of U superblocks */
right_edge = s->fragment_width / 2;
bottom_edge = s->fragment_height / 2;
current_width = -1;
current_height = 0;
superblock_row_inc = 3 * (s->fragment_width / 2) -
(s->c_superblock_width * 4 - s->fragment_width / 2);
/* the first operation for this variable is to advance by 1 */
current_fragment = s->fragment_start[1] - 1;
} else if (i == s->v_superblock_start) {
/* start of V superblocks */
right_edge = s->fragment_width / 2;
bottom_edge = s->fragment_height / 2;
current_width = -1;
current_height = 0;
superblock_row_inc = 3 * (s->fragment_width / 2) -
(s->c_superblock_width * 4 - s->fragment_width / 2);
/* the first operation for this variable is to advance by 1 */
current_fragment = s->fragment_start[2] - 1;
}
if (current_width >= right_edge - 1) {
/* reset width and move to next superblock row */
current_width = -1;
current_height += 4;
/* fragment is now at the start of a new superblock row */
current_fragment += superblock_row_inc;
}
/* iterate through all 16 fragments in a superblock */
for (j = 0; j < 16; j++) {
current_fragment += travel_width[j] + right_edge * travel_height[j];
current_width += travel_width[j];
current_height += travel_height[j];
/* check if the fragment is in bounds */
if ((current_width < right_edge) &&
(current_height < bottom_edge)) {
s->superblock_fragments[mapping_index] = current_fragment;
} else {
s->superblock_fragments[mapping_index] = -1;
}
mapping_index++;
}
if (x < frag_width && y < frag_height)
s->superblock_fragments[j++] = s->fragment_start[plane] + y*frag_width + x;
else
s->superblock_fragments[j++] = -1;
}
}
return 0; /* successful path out */