mirror of
https://github.com/webmproject/libwebp.git
synced 2025-01-28 15:42:55 +01:00
Create LUT for PrefixEncode.
This speeds up lossless compression by 5%. Change-Id: Ifd114b1d9850dc3aac74593809e7d48529d35e3d
This commit is contained in:
Vikas Arora
parent
988b70844e
commit
69257f70df
@ -232,6 +232,112 @@ const float kSLog2Table[LOG_LOOKUP_IDX_MAX] = {
|
||||
2010.27454072f, 2019.69737440f, 2029.12591044f, 2038.56012640f
|
||||
};
|
||||
|
||||
const int8_t kPrefixEncodeCode[PREFIX_LOOKUP_IDX_MAX] = {
|
||||
0, 0, 1, 2, 3, 4, 4, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7,
|
||||
8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9,
|
||||
10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
|
||||
11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
|
||||
12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
|
||||
12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
|
||||
13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
|
||||
13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
|
||||
14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
|
||||
14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
|
||||
14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
|
||||
14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
|
||||
15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
|
||||
15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
|
||||
15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
|
||||
15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
|
||||
16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
|
||||
16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
|
||||
16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
|
||||
16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
|
||||
16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
|
||||
16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
|
||||
16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
|
||||
16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
|
||||
17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17,
|
||||
17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17,
|
||||
17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17,
|
||||
17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17,
|
||||
17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17,
|
||||
17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17,
|
||||
17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17,
|
||||
17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17
|
||||
};
|
||||
|
||||
const int8_t kPrefixEncodeExtraBits[PREFIX_LOOKUP_IDX_MAX] = {
|
||||
0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2,
|
||||
3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
|
||||
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
|
||||
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
|
||||
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
|
||||
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
|
||||
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
|
||||
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
|
||||
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
|
||||
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
|
||||
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
|
||||
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
|
||||
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
|
||||
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
|
||||
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
|
||||
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
|
||||
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
|
||||
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
|
||||
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
|
||||
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
|
||||
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
|
||||
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
|
||||
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
|
||||
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
|
||||
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
|
||||
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
|
||||
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
|
||||
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
|
||||
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
|
||||
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
|
||||
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
|
||||
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
|
||||
};
|
||||
|
||||
const uint8_t kPrefixEncodeExtraBitsVal[PREFIX_LOOKUP_IDX_MAX] = {
|
||||
0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 2, 3, 0, 1, 2, 3,
|
||||
0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, 4, 5, 6, 7,
|
||||
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
|
||||
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
|
||||
0, 1, 2, 3, 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,
|
||||
0, 1, 2, 3, 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,
|
||||
0, 1, 2, 3, 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, 59, 60, 61, 62, 63,
|
||||
0, 1, 2, 3, 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, 59, 60, 61, 62, 63,
|
||||
0, 1, 2, 3, 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, 59, 60, 61, 62, 63,
|
||||
64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79,
|
||||
80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95,
|
||||
96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111,
|
||||
112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126,
|
||||
127,
|
||||
0, 1, 2, 3, 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, 59, 60, 61, 62, 63,
|
||||
64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79,
|
||||
80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95,
|
||||
96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111,
|
||||
112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126
|
||||
};
|
||||
|
||||
float VP8LFastSLog2Slow(int v) {
|
||||
assert(v >= LOG_LOOKUP_IDX_MAX);
|
||||
if (v < APPROX_LOG_MAX) {
|
||||
|
||||
@ -99,6 +99,80 @@ static WEBP_INLINE float VP8LFastSLog2(int v) {
|
||||
return (v < LOG_LOOKUP_IDX_MAX) ? kSLog2Table[v] : VP8LFastSLog2Slow(v);
|
||||
}
|
||||
|
||||
// -----------------------------------------------------------------------------
|
||||
// PrefixEncode()
|
||||
|
||||
// use GNU builtins where available.
|
||||
#if defined(__GNUC__) && \
|
||||
((__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || __GNUC__ >= 4)
|
||||
static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
|
||||
return 31 ^ __builtin_clz(n);
|
||||
}
|
||||
#elif defined(_MSC_VER) && (defined(_M_X64) || defined(_M_IX86))
|
||||
#include <intrin.h>
|
||||
#pragma intrinsic(_BitScanReverse)
|
||||
|
||||
static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
|
||||
unsigned long first_set_bit;
|
||||
_BitScanReverse(&first_set_bit, n);
|
||||
return first_set_bit;
|
||||
}
|
||||
#else
|
||||
// Returns (int)floor(log2(n)). n must be > 0.
|
||||
static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
|
||||
int log = 0;
|
||||
uint32_t value = n;
|
||||
int i;
|
||||
|
||||
for (i = 4; i >= 0; --i) {
|
||||
const int shift = (1 << i);
|
||||
const uint32_t x = value >> shift;
|
||||
if (x != 0) {
|
||||
value = x;
|
||||
log += shift;
|
||||
}
|
||||
}
|
||||
return log;
|
||||
}
|
||||
#endif
|
||||
|
||||
static WEBP_INLINE int VP8LBitsLog2Ceiling(uint32_t n) {
|
||||
const int log_floor = BitsLog2Floor(n);
|
||||
if (n == (n & ~(n - 1))) // zero or a power of two.
|
||||
return log_floor;
|
||||
else
|
||||
return log_floor + 1;
|
||||
}
|
||||
|
||||
// Splitting of distance and length codes into prefixes and
|
||||
// extra bits. The prefixes are encoded with an entropy code
|
||||
// while the extra bits are stored just as normal bits.
|
||||
static WEBP_INLINE void VP8LPrefixEncodeNoLUT(int distance, int* const code,
|
||||
int* const extra_bits,
|
||||
int* const extra_bits_value) {
|
||||
const int highest_bit = BitsLog2Floor(--distance);
|
||||
const int second_highest_bit = (distance >> (highest_bit - 1)) & 1;
|
||||
*extra_bits = highest_bit - 1;
|
||||
*extra_bits_value = distance & ((1 << *extra_bits) - 1);
|
||||
*code = 2 * highest_bit + second_highest_bit;
|
||||
}
|
||||
|
||||
#define PREFIX_LOOKUP_IDX_MAX 512
|
||||
// These tables are derived using VP8LPrefixEncodeNoLUT.
|
||||
extern const int8_t kPrefixEncodeCode[PREFIX_LOOKUP_IDX_MAX];
|
||||
extern const int8_t kPrefixEncodeExtraBits[PREFIX_LOOKUP_IDX_MAX];
|
||||
extern const uint8_t kPrefixEncodeExtraBitsVal[PREFIX_LOOKUP_IDX_MAX];
|
||||
static WEBP_INLINE void VP8LPrefixEncode(int distance, int* const code,
|
||||
int* const extra_bits,
|
||||
int* const extra_bits_value) {
|
||||
if (distance < PREFIX_LOOKUP_IDX_MAX) {
|
||||
*code = kPrefixEncodeCode[distance];
|
||||
*extra_bits = kPrefixEncodeExtraBits[distance];
|
||||
*extra_bits_value = kPrefixEncodeExtraBitsVal[distance];
|
||||
} else {
|
||||
VP8LPrefixEncodeNoLUT(distance, code, extra_bits, extra_bits_value);
|
||||
}
|
||||
}
|
||||
|
||||
// In-place difference of each component with mod 256.
|
||||
static WEBP_INLINE uint32_t VP8LSubPixels(uint32_t a, uint32_t b) {
|
||||
|
||||
@ -462,16 +462,16 @@ static WEBP_INLINE double GetCacheCost(const CostModel* const m, uint32_t idx) {
|
||||
|
||||
static WEBP_INLINE double GetLengthCost(const CostModel* const m,
|
||||
uint32_t length) {
|
||||
int code, extra_bits_count, extra_bits_value;
|
||||
PrefixEncode(length, &code, &extra_bits_count, &extra_bits_value);
|
||||
return m->literal_[VALUES_IN_BYTE + code] + extra_bits_count;
|
||||
int code, extra_bits, extra_bits_val;
|
||||
VP8LPrefixEncode(length, &code, &extra_bits, &extra_bits_val);
|
||||
return m->literal_[VALUES_IN_BYTE + code] + extra_bits;
|
||||
}
|
||||
|
||||
static WEBP_INLINE double GetDistanceCost(const CostModel* const m,
|
||||
uint32_t distance) {
|
||||
int code, extra_bits_count, extra_bits_value;
|
||||
PrefixEncode(distance, &code, &extra_bits_count, &extra_bits_value);
|
||||
return m->distance_[code] + extra_bits_count;
|
||||
int code, extra_bits, extra_bits_val;
|
||||
VP8LPrefixEncode(distance, &code, &extra_bits, &extra_bits_val);
|
||||
return m->distance_[code] + extra_bits;
|
||||
}
|
||||
|
||||
static int BackwardReferencesHashChainDistanceOnly(
|
||||
|
||||
@ -30,73 +30,6 @@ extern "C" {
|
||||
#define PIX_OR_COPY_CODES_MAX \
|
||||
(NUM_LITERAL_CODES + NUM_LENGTH_CODES + (1 << MAX_COLOR_CACHE_BITS))
|
||||
|
||||
// -----------------------------------------------------------------------------
|
||||
// PrefixEncode()
|
||||
|
||||
// use GNU builtins where available.
|
||||
#if defined(__GNUC__) && \
|
||||
((__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || __GNUC__ >= 4)
|
||||
static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
|
||||
assert(n != 0);
|
||||
return 31 ^ __builtin_clz(n);
|
||||
}
|
||||
#elif defined(_MSC_VER) && (defined(_M_X64) || defined(_M_IX86))
|
||||
#include <intrin.h>
|
||||
#pragma intrinsic(_BitScanReverse)
|
||||
|
||||
static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
|
||||
unsigned long first_set_bit;
|
||||
assert(n != 0);
|
||||
_BitScanReverse(&first_set_bit, n);
|
||||
return first_set_bit;
|
||||
}
|
||||
#else
|
||||
// Returns (int)floor(log2(n)). n must be > 0.
|
||||
static WEBP_INLINE int BitsLog2Floor(uint32_t n) {
|
||||
int log = 0;
|
||||
uint32_t value = n;
|
||||
int i;
|
||||
|
||||
assert(n != 0);
|
||||
for (i = 4; i >= 0; --i) {
|
||||
const int shift = (1 << i);
|
||||
const uint32_t x = value >> shift;
|
||||
if (x != 0) {
|
||||
value = x;
|
||||
log += shift;
|
||||
}
|
||||
}
|
||||
return log;
|
||||
}
|
||||
#endif
|
||||
|
||||
static WEBP_INLINE int VP8LBitsLog2Ceiling(uint32_t n) {
|
||||
const int log_floor = BitsLog2Floor(n);
|
||||
if (n == (n & ~(n - 1))) // zero or a power of two.
|
||||
return log_floor;
|
||||
else
|
||||
return log_floor + 1;
|
||||
}
|
||||
|
||||
// Splitting of distance and length codes into prefixes and
|
||||
// extra bits. The prefixes are encoded with an entropy code
|
||||
// while the extra bits are stored just as normal bits.
|
||||
static WEBP_INLINE void PrefixEncode(int distance, int* const code,
|
||||
int* const extra_bits_count,
|
||||
int* const extra_bits_value) {
|
||||
if (distance > 2) { // Collect the two most significant bits.
|
||||
const int highest_bit = BitsLog2Floor(--distance);
|
||||
const int second_highest_bit = (distance >> (highest_bit - 1)) & 1;
|
||||
*extra_bits_count = highest_bit - 1;
|
||||
*extra_bits_value = distance & ((1 << *extra_bits_count) - 1);
|
||||
*code = 2 * highest_bit + second_highest_bit;
|
||||
} else {
|
||||
*extra_bits_count = 0;
|
||||
*extra_bits_value = 0;
|
||||
*code = (distance == 2) ? 1 : 0;
|
||||
}
|
||||
}
|
||||
|
||||
// -----------------------------------------------------------------------------
|
||||
// PixOrCopy
|
||||
|
||||
|
||||
@ -90,12 +90,10 @@ void VP8LHistogramAddSinglePixOrCopy(VP8LHistogram* const histo,
|
||||
int literal_ix = 256 + NUM_LENGTH_CODES + PixOrCopyCacheIdx(v);
|
||||
++histo->literal_[literal_ix];
|
||||
} else {
|
||||
int code, extra_bits_count, extra_bits_value;
|
||||
PrefixEncode(PixOrCopyLength(v),
|
||||
&code, &extra_bits_count, &extra_bits_value);
|
||||
int code, extra_bits, extra_bits_val;
|
||||
VP8LPrefixEncode(PixOrCopyLength(v), &code, &extra_bits, &extra_bits_val);
|
||||
++histo->literal_[256 + code];
|
||||
PrefixEncode(PixOrCopyDistance(v),
|
||||
&code, &extra_bits_count, &extra_bits_value);
|
||||
VP8LPrefixEncode(PixOrCopyDistance(v), &code, &extra_bits, &extra_bits_val);
|
||||
++histo->distance_[code];
|
||||
}
|
||||
}
|
||||
|
||||
@ -448,12 +448,12 @@ static void StoreImageToBitMask(
|
||||
int bits, n_bits;
|
||||
int code, distance;
|
||||
|
||||
PrefixEncode(v->len, &code, &n_bits, &bits);
|
||||
VP8LPrefixEncode(v->len, &code, &n_bits, &bits);
|
||||
WriteHuffmanCode(bw, codes, 256 + code);
|
||||
VP8LWriteBits(bw, n_bits, bits);
|
||||
|
||||
distance = PixOrCopyDistance(v);
|
||||
PrefixEncode(distance, &code, &n_bits, &bits);
|
||||
VP8LPrefixEncode(distance, &code, &n_bits, &bits);
|
||||
WriteHuffmanCode(bw, codes + 4, code);
|
||||
VP8LWriteBits(bw, n_bits, bits);
|
||||
}
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user