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WebP/Lossy: Add static data needed for decoding coefficients

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Also add `vp8_short_inv_walsh4x4_c()` from the spec for the inverse
Walsh-Hadamard transform. The YUV output data must bitwise match the
behavior of the spec, so there isn't a ton of flexibility of how to
do this particular function.
This commit is contained in:
Nico Weber 2023-05-28 16:21:40 -04:00 • committed by Andrew Kaster
parent 8ff8309202
commit b7483b636d
1 changed files with 89 additions and 0 deletions
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89
Userland/Libraries/LibGfx/ImageFormats/WebPLoaderLossyTables.h
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@ -237,6 +237,25 @@ enum DCTToken {
num_dct_tokens /* 12 */
};
// clang-format off
const TreeIndex COEFFICIENT_TREE[2 * (num_dct_tokens - 1)] = {
-dct_eob, 2, /* eob = "0" */
-DCT_0, 4, /* 0 = "10" */
-DCT_1, 6, /* 1 = "110" */
8, 12,
-DCT_2, 10, /* 2 = "11100" */
-DCT_3, -DCT_4, /* 3 = "111010", 4 = "111011" */
14, 16,
-dct_cat1, -dct_cat2, /* cat1 = "111100",
cat2 = "111101" */
18, 20,
-dct_cat3, -dct_cat4, /* cat3 = "1111100",
cat4 = "1111101" */
-dct_cat5, -dct_cat6 /* cat4 = "1111110",
cat4 = "1111111" */
};
// clang-format on
// https://datatracker.ietf.org/doc/html/rfc6386#section-13.4 "Token Probability Updates"
// clang-format off
static Prob constexpr COEFFICIENT_UPDATE_PROBABILITIES[4][8][3][num_dct_tokens - 1] = {
@ -585,4 +604,74 @@ static Prob constexpr DEFAULT_COEFFICIENT_PROBABILITIES[4][8][3][num_dct_tokens
};
// clang-format on
// https://datatracker.ietf.org/doc/html/rfc6386#section-14.1 "Dequantization"
// clang-format off
static int constexpr dc_qlookup[] = {
4, 5, 6, 7, 8, 9, 10, 10, 11, 12, 13, 14, 15,
16, 17, 17, 18, 19, 20, 20, 21, 21, 22, 22, 23, 23,
24, 25, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,
36, 37, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 46,
47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59,
60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72,
73, 74, 75, 76, 76, 77, 78, 79, 80, 81, 82, 83, 84,
85, 86, 87, 88, 89, 91, 93, 95, 96, 98, 100, 101, 102,
104, 106, 108, 110, 112, 114, 116, 118, 122, 124, 126, 128, 130,
132, 134, 136, 138, 140, 143, 145, 148, 151, 154, 157,
};
static int constexpr ac_qlookup[] = {
4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42,
43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55,
56, 57, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78,
80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104,
106, 108, 110, 112, 114, 116, 119, 122, 125, 128, 131, 134, 137,
140, 143, 146, 149, 152, 155, 158, 161, 164, 167, 170, 173, 177,
181, 185, 189, 193, 197, 201, 205, 209, 213, 217, 221, 225, 229,
234, 239, 245, 249, 254, 259, 264, 269, 274, 279, 284,
};
// clang-format on
// https://datatracker.ietf.org/doc/html/rfc6386#section-14.3 "Implementation of the WHT Inversion"
inline void vp8_short_inv_walsh4x4_c(i16* input, i16* output)
{
i16* ip = input;
i16* op = output;
for (int i = 0; i < 4; i++) {
int a1 = ip[0] + ip[12];
int b1 = ip[4] + ip[8];
int c1 = ip[4] - ip[8];
int d1 = ip[0] - ip[12];
op[0] = a1 + b1;
op[4] = c1 + d1;
op[8] = a1 - b1;
op[12] = d1 - c1;
ip++;
op++;
}
ip = output;
op = output;
for (int i = 0; i < 4; i++) {
int a1 = ip[0] + ip[3];
int b1 = ip[1] + ip[2];
int c1 = ip[1] - ip[2];
int d1 = ip[0] - ip[3];
int a2 = a1 + b1;
int b2 = c1 + d1;
int c2 = a1 - b1;
int d2 = d1 - c1;
op[0] = (a2 + 3) >> 3;
op[1] = (b2 + 3) >> 3;
op[2] = (c2 + 3) >> 3;
op[3] = (d2 + 3) >> 3;
ip += 4;
op += 4;
}
}
}