diff options
Diffstat (limited to 'BaseTools/Source/C/BrotliCompress/enc/literal_cost.c')
-rw-r--r-- | BaseTools/Source/C/BrotliCompress/enc/literal_cost.c | 178 |
1 files changed, 0 insertions, 178 deletions
diff --git a/BaseTools/Source/C/BrotliCompress/enc/literal_cost.c b/BaseTools/Source/C/BrotliCompress/enc/literal_cost.c deleted file mode 100644 index e40a082243..0000000000 --- a/BaseTools/Source/C/BrotliCompress/enc/literal_cost.c +++ /dev/null @@ -1,178 +0,0 @@ -/* Copyright 2013 Google Inc. All Rights Reserved.
-
- Distributed under MIT license.
- See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
-*/
-
-/* Literal cost model to allow backward reference replacement to be efficient.
-*/
-
-#include "./literal_cost.h"
-
-#include "../common/types.h"
-#include "./fast_log.h"
-#include "./port.h"
-#include "./utf8_util.h"
-
-#if defined(__cplusplus) || defined(c_plusplus)
-extern "C" {
-#endif
-
-static size_t UTF8Position(size_t last, size_t c, size_t clamp) {
- if (c < 128) {
- return 0; /* Next one is the 'Byte 1' again. */
- } else if (c >= 192) { /* Next one is the 'Byte 2' of utf-8 encoding. */
- return BROTLI_MIN(size_t, 1, clamp);
- } else {
- /* Let's decide over the last byte if this ends the sequence. */
- if (last < 0xe0) {
- return 0; /* Completed two or three byte coding. */
- } else { /* Next one is the 'Byte 3' of utf-8 encoding. */
- return BROTLI_MIN(size_t, 2, clamp);
- }
- }
-}
-
-static size_t DecideMultiByteStatsLevel(size_t pos, size_t len, size_t mask,
- const uint8_t *data) {
- size_t counts[3] = { 0 };
- size_t max_utf8 = 1; /* should be 2, but 1 compresses better. */
- size_t last_c = 0;
- size_t utf8_pos = 0;
- size_t i;
- for (i = 0; i < len; ++i) {
- size_t c = data[(pos + i) & mask];
- utf8_pos = UTF8Position(last_c, c, 2);
- ++counts[utf8_pos];
- last_c = c;
- }
- if (counts[2] < 500) {
- max_utf8 = 1;
- }
- if (counts[1] + counts[2] < 25) {
- max_utf8 = 0;
- }
- return max_utf8;
-}
-
-static void EstimateBitCostsForLiteralsUTF8(size_t pos, size_t len, size_t mask,
- const uint8_t *data, float *cost) {
- /* max_utf8 is 0 (normal ascii single byte modeling),
- 1 (for 2-byte utf-8 modeling), or 2 (for 3-byte utf-8 modeling). */
- const size_t max_utf8 = DecideMultiByteStatsLevel(pos, len, mask, data);
- size_t histogram[3][256] = { { 0 } };
- size_t window_half = 495;
- size_t in_window = BROTLI_MIN(size_t, window_half, len);
- size_t in_window_utf8[3] = { 0 };
-
-
- size_t i;
- { /* Bootstrap histograms. */
- size_t last_c = 0;
- size_t utf8_pos = 0;
- for (i = 0; i < in_window; ++i) {
- size_t c = data[(pos + i) & mask];
- ++histogram[utf8_pos][c];
- ++in_window_utf8[utf8_pos];
- utf8_pos = UTF8Position(last_c, c, max_utf8);
- last_c = c;
- }
- }
-
- /* Compute bit costs with sliding window. */
- for (i = 0; i < len; ++i) {
- if (i >= window_half) {
- /* Remove a byte in the past. */
- size_t c =
- i < window_half + 1 ? 0 : data[(pos + i - window_half - 1) & mask];
- size_t last_c =
- i < window_half + 2 ? 0 : data[(pos + i - window_half - 2) & mask];
- size_t utf8_pos2 = UTF8Position(last_c, c, max_utf8);
- --histogram[utf8_pos2][data[(pos + i - window_half) & mask]];
- --in_window_utf8[utf8_pos2];
- }
- if (i + window_half < len) {
- /* Add a byte in the future. */
- size_t c = data[(pos + i + window_half - 1) & mask];
- size_t last_c = data[(pos + i + window_half - 2) & mask];
- size_t utf8_pos2 = UTF8Position(last_c, c, max_utf8);
- ++histogram[utf8_pos2][data[(pos + i + window_half) & mask]];
- ++in_window_utf8[utf8_pos2];
- }
- {
- size_t c = i < 1 ? 0 : data[(pos + i - 1) & mask];
- size_t last_c = i < 2 ? 0 : data[(pos + i - 2) & mask];
- size_t utf8_pos = UTF8Position(last_c, c, max_utf8);
- size_t masked_pos = (pos + i) & mask;
- size_t histo = histogram[utf8_pos][data[masked_pos]];
- double lit_cost;
- if (histo == 0) {
- histo = 1;
- }
- lit_cost = FastLog2(in_window_utf8[utf8_pos]) - FastLog2(histo);
- lit_cost += 0.02905;
- if (lit_cost < 1.0) {
- lit_cost *= 0.5;
- lit_cost += 0.5;
- }
- /* Make the first bytes more expensive -- seems to help, not sure why.
- Perhaps because the entropy source is changing its properties
- rapidly in the beginning of the file, perhaps because the beginning
- of the data is a statistical "anomaly". */
- if (i < 2000) {
- lit_cost += 0.7 - ((double)(2000 - i) / 2000.0 * 0.35);
- }
- cost[i] = (float)lit_cost;
- }
- }
-}
-
-void BrotliEstimateBitCostsForLiterals(size_t pos, size_t len, size_t mask,
- const uint8_t *data, float *cost) {
- if (BrotliIsMostlyUTF8(data, pos, mask, len, kMinUTF8Ratio)) {
- EstimateBitCostsForLiteralsUTF8(pos, len, mask, data, cost);
- return;
- } else {
- size_t histogram[256] = { 0 };
- size_t window_half = 2000;
- size_t in_window = BROTLI_MIN(size_t, window_half, len);
-
- /* Bootstrap histogram. */
- size_t i;
- for (i = 0; i < in_window; ++i) {
- ++histogram[data[(pos + i) & mask]];
- }
-
- /* Compute bit costs with sliding window. */
- for (i = 0; i < len; ++i) {
- size_t histo;
- if (i >= window_half) {
- /* Remove a byte in the past. */
- --histogram[data[(pos + i - window_half) & mask]];
- --in_window;
- }
- if (i + window_half < len) {
- /* Add a byte in the future. */
- ++histogram[data[(pos + i + window_half) & mask]];
- ++in_window;
- }
- histo = histogram[data[(pos + i) & mask]];
- if (histo == 0) {
- histo = 1;
- }
- {
- double lit_cost = FastLog2(in_window) - FastLog2(histo);
- lit_cost += 0.029;
- if (lit_cost < 1.0) {
- lit_cost *= 0.5;
- lit_cost += 0.5;
- }
- cost[i] = (float)lit_cost;
- }
- }
- }
-}
-
-#if defined(__cplusplus) || defined(c_plusplus)
-} /* extern "C" */
-#endif
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