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Unified Diff: third_party/brotli/enc/literal_cost.c

Issue 2537133002: Update brotli to v1.0.0-snapshot. (Closed)
Patch Set: Fixed typo Created 4 years ago
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Index: third_party/brotli/enc/literal_cost.c
diff --git a/third_party/brotli/enc/literal_cost.cc b/third_party/brotli/enc/literal_cost.c
similarity index 32%
rename from third_party/brotli/enc/literal_cost.cc
rename to third_party/brotli/enc/literal_cost.c
index e6be86fc64ea0d85032511663d3d4a056245b545..2e786003505cb8c00b7d5cf64538e0ad350cea28 100644
--- a/third_party/brotli/enc/literal_cost.cc
+++ b/third_party/brotli/enc/literal_cost.c
@@ -4,30 +4,31 @@
See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
*/
-// Literal cost model to allow backward reference replacement to be efficient.
+/* Literal cost model to allow backward reference replacement to be efficient.
+*/
#include "./literal_cost.h"
-#include <math.h>
-#include <algorithm>
-
+#include <brotli/types.h>
#include "./fast_log.h"
-#include "./types.h"
+#include "./port.h"
#include "./utf8_util.h"
-namespace brotli {
+#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 std::min<size_t>(1, clamp);
+ 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.
+ /* 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 std::min<size_t>(2, clamp);
+ 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);
}
}
}
@@ -35,10 +36,11 @@ static size_t UTF8Position(size_t last, size_t c, size_t 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 max_utf8 = 1; /* should be 2, but 1 compresses better. */
size_t last_c = 0;
size_t utf8_pos = 0;
- for (size_t i = 0; i < len; ++i) {
+ 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];
@@ -55,111 +57,122 @@ static size_t DecideMultiByteStatsLevel(size_t pos, size_t len, size_t mask,
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).
+ /* 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 = std::min(window_half, len);
+ size_t in_window = BROTLI_MIN(size_t, window_half, len);
size_t in_window_utf8[3] = { 0 };
- // Bootstrap histograms.
- size_t last_c = 0;
- size_t utf8_pos = 0;
- for (size_t 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;
+
+ 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 (size_t i = 0; i < len; ++i) {
+ /* 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];
+ /* 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.
+ /* 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]];
- if (histo == 0) {
- histo = 1;
- }
- double 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 - (static_cast<double>(2000 - i) / 2000.0 * 0.35);
+ {
+ 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;
}
- cost[i] = static_cast<float>(lit_cost);
}
}
-void EstimateBitCostsForLiterals(size_t pos, size_t len, size_t mask,
- const uint8_t *data, float *cost) {
- if (IsMostlyUTF8(data, pos, mask, len, kMinUTF8Ratio)) {
+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;
- }
- size_t histogram[256] = { 0 };
- size_t window_half = 2000;
- size_t in_window = std::min(window_half, len);
-
- // Bootstrap histogram.
- for (size_t i = 0; i < in_window; ++i) {
- ++histogram[data[(pos + i) & mask]];
- }
-
- // Compute bit costs with sliding window.
- for (size_t i = 0; i < len; ++i) {
- 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;
- }
- size_t histo = histogram[data[(pos + i) & mask]];
- if (histo == 0) {
- histo = 1;
+ } 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]];
}
- 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;
+
+ /* 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;
+ }
}
- cost[i] = static_cast<float>(lit_cost);
}
}
-
-} // namespace brotli
+#if defined(__cplusplus) || defined(c_plusplus)
+} /* extern "C" */
+#endif
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