dany/libwebp
1
0
Fork 0
mirror of https://github.com/webmproject/libwebp.git synced 2024-12-25 13:18:22 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity

simplify the logic of GetCoeffs()

Browse Source 
We only need to know _if_ there's some non-zero coeffs at all,
not the exact number of these.

+ code-style nits clean-up

Change-Id: Ice9acf00aef999d70affe4629cb56ae7709140ab
This commit is contained in:
Pascal Massimino 2010-11-26 09:53:26 -08:00
parent f67b5939ad
commit a7ee0559f3
1 changed files with 24 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

53
src/vp8.c
View File

@ -329,24 +329,24 @@ static const uint8_t kBands[16 + 1] = {
0 // extra entry as sentinel
};
static const uint8_t kCat3[] = {173, 148, 140, 0};
static const uint8_t kCat4[] = {176, 155, 140, 135, 0};
static const uint8_t kCat5[] = {180, 157, 141, 134, 130, 0};
static const uint8_t kCat3[] = { 173, 148, 140, 0 };
static const uint8_t kCat4[] = { 176, 155, 140, 135, 0 };
static const uint8_t kCat5[] = { 180, 157, 141, 134, 130, 0 };
static const uint8_t kCat6[] =
{254, 254, 243, 230, 196, 177, 153, 140, 133, 130, 129, 0};
{ 254, 254, 243, 230, 196, 177, 153, 140, 133, 130, 129, 0 };
static const uint8_t * const kCat3456[] = { kCat3, kCat4, kCat5, kCat6 };
static const uint8_t kZigzag[16] = {
0, 1, 4, 8, 5, 2, 3, 6, 9, 12, 13, 10, 7, 11, 14, 15
};
typedef const uint8_t PROBA_ARRAY[NUM_CTX][NUM_PROBAS];
typedef const uint8_t (*ProbaArray)[NUM_CTX][NUM_PROBAS]; // for const-casting
static int GetCoeffs(VP8BitReader* const br,
const uint8_t (*prob)[NUM_CTX][NUM_PROBAS],
// Returns 1 if there's non-zero coeffs, 0 otherwise
static int GetCoeffs(VP8BitReader* const br, ProbaArray prob,
int ctx, const uint16_t dq[2], int n, int16_t* out) {
const uint8_t* p = prob[kBands[n]][ctx];
if (!VP8GetBit(br, p[0])) { // first EOB is more a 'CBP' bit.
return -1;
return 0;
}
while (1) {
++n;
@ -372,12 +372,12 @@ static int GetCoeffs(VP8BitReader* const br,
v = 7 + 2 * VP8GetBit(br, 165) + VP8GetBit(br, 145);
}
} else {
uint8_t* tab;
const uint8_t* tab;
const int bit1 = VP8GetBit(br, p[8]);
const int bit0 = VP8GetBit(br, p[9 + bit1]);
const int cat = 2 * bit1 + bit0;
v = 0;
for (tab = (uint8_t*)kCat3456[cat]; *tab; ++tab) {
for (tab = kCat3456[cat]; *tab; ++tab) {
v += v + VP8GetBit(br, *tab);
}
v += 3 + (8 << cat);
@ -387,13 +387,12 @@ static int GetCoeffs(VP8BitReader* const br,
}
j = kZigzag[n - 1];
out[j] = VP8GetSigned(br, v) * dq[j > 0];
if (n == 16) break;
if (!VP8GetBit(br, p[0])) { // EOB
return n;
if (n == 16 || !VP8GetBit(br, p[0])) { // EOB
return 1;
}
}
}
return 15;
return 0;
}
// Table to unpack four bits into four bytes
@ -412,11 +411,10 @@ static const uint8_t kUnpackTab[16][4] = {
#endif
#define PACK(X, S) ((((*(uint32_t*)(X)) * PACK_CST) & 0xff000000) >> (S))
typedef const uint8_t (*Proba_t)[NUM_CTX][NUM_PROBAS]; // for const-casting
static int ParseResiduals(VP8Decoder* const dec,
VP8MB* const mb, VP8BitReader* const token_br) {
int out_t_nz, out_l_nz, first;
Proba_t ac_prob;
ProbaArray ac_prob;
const VP8QuantMatrix* q = &dec->dqm_[dec->segment_];
int16_t* dst = dec->coeffs_;
VP8MB* const left_mb = dec->mb_info_ - 1;
@ -430,15 +428,15 @@ static int ParseResiduals(VP8Decoder* const dec,
if (!dec->is_i4x4_) { // parse DC
int16_t dc[16] = { 0 };
const int ctx = mb->dc_nz_ + left_mb->dc_nz_;
const int last = GetCoeffs(token_br, (Proba_t)dec->proba_.coeffs_[1],
ctx, q->y2_mat_, 0, dc);
mb->dc_nz_ = left_mb->dc_nz_ = (last >= 0);
mb->dc_nz_ = left_mb->dc_nz_ =
GetCoeffs(token_br, (ProbaArray)dec->proba_.coeffs_[1],
ctx, q->y2_mat_, 0, dc);
first = 1;
ac_prob = (Proba_t)dec->proba_.coeffs_[0];
ac_prob = (ProbaArray)dec->proba_.coeffs_[0];
VP8TransformWHT(dc, dst);
} else {
first = 0;
ac_prob = (Proba_t)dec->proba_.coeffs_[3];
ac_prob = (ProbaArray)dec->proba_.coeffs_[3];
}
memcpy(tnz, kUnpackTab[mb->nz_ & 0xf], sizeof(tnz));
@ -448,11 +446,10 @@ static int ParseResiduals(VP8Decoder* const dec,
for (x = 0; x < 4; ++x) {
const int ctx = l + tnz[x];
const int last = GetCoeffs(token_br, ac_prob, ctx,
q->y1_mat_, first, dst);
l = GetCoeffs(token_br, ac_prob, ctx,
q->y1_mat_, first, dst);
nz_dc[x] = (dst[0] != 0);
nz_ac[x] = (last > 0);
tnz[x] = l = (last >= 0);
nz_ac[x] = tnz[x] = l;
dst += 16;
}
lnz[y] = l;
@ -469,12 +466,10 @@ static int ParseResiduals(VP8Decoder* const dec,
int l = lnz[ch + y];
for (x = 0; x < 2; ++x) {
const int ctx = l + tnz[ch + x];
const int last =
GetCoeffs(token_br, (Proba_t)dec->proba_.coeffs_[2],
l = GetCoeffs(token_br, (ProbaArray)dec->proba_.coeffs_[2],
ctx, q->uv_mat_, 0, dst);
nz_dc[y * 2 + x] = (dst[0] != 0);
nz_ac[y * 2 + x] = (last > 0);
tnz[ch + x] = l = (last >= 0);
nz_ac[y * 2 + x] = tnz[ch + x] = l;
dst += 16;
}
lnz[ch + y] = l;