dany/libwebp
1
0
Fork 0
mirror of https://github.com/webmproject/libwebp.git synced 2024-12-26 05:38:22 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity

remove a gcc warning about type pun by using a proper union'd type

Browse Source 
Change-Id: Ie2dd4aa696318daa84b90de009218311153c0613
This commit is contained in:
Pascal Massimino 2011-03-09 07:18:51 -08:00
parent e1863715bf
commit b3ce8c522a
1 changed files with 28 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

51
src/dec/vp8.c
View File

@ -428,12 +428,18 @@ static int GetCoeffs(VP8BitReader* const br, ProbaArray prob,
return 0;
}
// alias-safe way of converting 4bytes to 32bits
typedef union {
uint8_t i8[4];
uint32_t i32;
} PackedNz;
// Table to unpack four bits into four bytes
static const uint8_t kUnpackTab[16][4] = {
{0, 0, 0, 0}, {1, 0, 0, 0}, {0, 1, 0, 0}, {1, 1, 0, 0},
{0, 0, 1, 0}, {1, 0, 1, 0}, {0, 1, 1, 0}, {1, 1, 1, 0},
{0, 0, 0, 1}, {1, 0, 0, 1}, {0, 1, 0, 1}, {1, 1, 0, 1},
{0, 0, 1, 1}, {1, 0, 1, 1}, {0, 1, 1, 1}, {1, 1, 1, 1} };
static const PackedNz kUnpackTab[16] = {
{{0, 0, 0, 0}}, {{1, 0, 0, 0}}, {{0, 1, 0, 0}}, {{1, 1, 0, 0}},
{{0, 0, 1, 0}}, {{1, 0, 1, 0}}, {{0, 1, 1, 0}}, {{1, 1, 1, 0}},
{{0, 0, 0, 1}}, {{1, 0, 0, 1}}, {{0, 1, 0, 1}}, {{1, 1, 0, 1}},
{{0, 0, 1, 1}}, {{1, 0, 1, 1}}, {{0, 1, 1, 1}}, {{1, 1, 1, 1}} };
// Macro to pack four LSB of four bytes into four bits.
#if defined(__PPC__) || defined(_M_PPC) || defined(_ARCH_PPC) || \
@ -442,7 +448,7 @@ static const uint8_t kUnpackTab[16][4] = {
#else
#define PACK_CST 0x01020408U
#endif
#define PACK(X, S) ((((*(uint32_t*)(X)) * PACK_CST) & 0xff000000) >> (S))
#define PACK(X, S) ((((X).i32 * PACK_CST) & 0xff000000) >> (S))
static int ParseResiduals(VP8Decoder* const dec,
VP8MB* const mb, VP8BitReader* const token_br) {
@ -451,10 +457,10 @@ static int ParseResiduals(VP8Decoder* const dec,
const VP8QuantMatrix* q = &dec->dqm_[dec->segment_];
int16_t* dst = dec->coeffs_;
VP8MB* const left_mb = dec->mb_info_ - 1;
uint8_t nz_ac[4], nz_dc[4];
PackedNz nz_ac, nz_dc;
PackedNz tnz, lnz;
uint32_t non_zero_ac = 0;
uint32_t non_zero_dc = 0;
uint8_t tnz[4], lnz[4];
int x, y, ch;
memset(dst, 0, 384 * sizeof(*dst));
@ -472,40 +478,39 @@ static int ParseResiduals(VP8Decoder* const dec,
ac_prob = (ProbaArray)dec->proba_.coeffs_[3];
}
memcpy(tnz, kUnpackTab[mb->nz_ & 0xf], sizeof(tnz));
memcpy(lnz, kUnpackTab[left_mb->nz_ & 0xf], sizeof(lnz));
tnz = kUnpackTab[mb->nz_ & 0xf];
lnz = kUnpackTab[left_mb->nz_ & 0xf];
for (y = 0; y < 4; ++y) {
int l = lnz[y];
int l = lnz.i8[y];
for (x = 0; x < 4; ++x) {
const int ctx = l + tnz[x];
const int ctx = l + tnz.i8[x];
l = GetCoeffs(token_br, ac_prob, ctx,
q->y1_mat_, first, dst);
nz_dc[x] = (dst[0] != 0);
nz_ac[x] = tnz[x] = l;
nz_dc.i8[x] = (dst[0] != 0);
nz_ac.i8[x] = tnz.i8[x] = l;
dst += 16;
}
lnz[y] = l;
lnz.i8[y] = l;
non_zero_dc |= PACK(nz_dc, 24 - y * 4);
non_zero_ac |= PACK(nz_ac, 24 - y * 4);
}
out_t_nz = PACK(tnz, 24);
out_l_nz = PACK(lnz, 24);
memcpy(tnz, kUnpackTab[mb->nz_ >> 4], sizeof(tnz));
memcpy(lnz, kUnpackTab[left_mb->nz_ >> 4], sizeof(lnz));
tnz = kUnpackTab[mb->nz_ >> 4];
lnz = kUnpackTab[left_mb->nz_ >> 4];
for (ch = 0; ch < 4; ch += 2) {
for (y = 0; y < 2; ++y) {
int l = lnz[ch + y];
int l = lnz.i8[ch + y];
for (x = 0; x < 2; ++x) {
const int ctx = l + tnz[ch + x];
const int ctx = l + tnz.i8[ch + x];
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] = tnz[ch + x] = l;
nz_dc.i8[y * 2 + x] = (dst[0] != 0);
nz_ac.i8[y * 2 + x] = tnz.i8[ch + x] = l;
dst += 16;
}
lnz[ch + y] = l;
lnz.i8[ch + y] = l;
}
non_zero_dc |= PACK(nz_dc, 8 - ch * 2);
non_zero_ac |= PACK(nz_ac, 8 - ch * 2);