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authorKarl Berry <karl@freefriends.org>2018-01-17 22:50:15 +0000
committerKarl Berry <karl@freefriends.org>2018-01-17 22:50:15 +0000
commite7dfe5ab98e759081fc73990ed6c1ac6910a105d (patch)
tree1635f79c86856a6aa57a45b8b952b651ef9fcba9 /Build/source/texk/dvisvgm/dvisvgm-src/libs/brotli/enc/context.h
parentae542350b1e3add10d4ee3d7b68f610132f31a50 (diff)
dvisvgm 2.3.1 (patched)
git-svn-id: svn://tug.org/texlive/trunk@46352 c570f23f-e606-0410-a88d-b1316a301751
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+/* Copyright 2013 Google Inc. All Rights Reserved.
+
+ Distributed under MIT license.
+ See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
+*/
+
+/* Functions to map previous bytes into a context id. */
+
+#ifndef BROTLI_ENC_CONTEXT_H_
+#define BROTLI_ENC_CONTEXT_H_
+
+#include <brotli/port.h>
+#include <brotli/types.h>
+
+#if defined(__cplusplus) || defined(c_plusplus)
+extern "C" {
+#endif
+
+/* Second-order context lookup table for UTF8 byte streams.
+
+ If p1 and p2 are the previous two bytes, we calculate the context as
+
+ context = kUTF8ContextLookup[p1] | kUTF8ContextLookup[p2 + 256].
+
+ If the previous two bytes are ASCII characters (i.e. < 128), this will be
+ equivalent to
+
+ context = 4 * context1(p1) + context2(p2),
+
+ where context1 is based on the previous byte in the following way:
+
+ 0 : non-ASCII control
+ 1 : \t, \n, \r
+ 2 : space
+ 3 : other punctuation
+ 4 : " '
+ 5 : %
+ 6 : ( < [ {
+ 7 : ) > ] }
+ 8 : , ; :
+ 9 : .
+ 10 : =
+ 11 : number
+ 12 : upper-case vowel
+ 13 : upper-case consonant
+ 14 : lower-case vowel
+ 15 : lower-case consonant
+
+ and context2 is based on the second last byte:
+
+ 0 : control, space
+ 1 : punctuation
+ 2 : upper-case letter, number
+ 3 : lower-case letter
+
+ If the last byte is ASCII, and the second last byte is not (in a valid UTF8
+ stream it will be a continuation byte, value between 128 and 191), the
+ context is the same as if the second last byte was an ASCII control or space.
+
+ If the last byte is a UTF8 lead byte (value >= 192), then the next byte will
+ be a continuation byte and the context id is 2 or 3 depending on the LSB of
+ the last byte and to a lesser extent on the second last byte if it is ASCII.
+
+ If the last byte is a UTF8 continuation byte, the second last byte can be:
+ - continuation byte: the next byte is probably ASCII or lead byte (assuming
+ 4-byte UTF8 characters are rare) and the context id is 0 or 1.
+ - lead byte (192 - 207): next byte is ASCII or lead byte, context is 0 or 1
+ - lead byte (208 - 255): next byte is continuation byte, context is 2 or 3
+
+ The possible value combinations of the previous two bytes, the range of
+ context ids and the type of the next byte is summarized in the table below:
+
+ |--------\-----------------------------------------------------------------|
+ | \ Last byte |
+ | Second \---------------------------------------------------------------|
+ | last byte \ ASCII | cont. byte | lead byte |
+ | \ (0-127) | (128-191) | (192-) |
+ |=============|===================|=====================|==================|
+ | ASCII | next: ASCII/lead | not valid | next: cont. |
+ | (0-127) | context: 4 - 63 | | context: 2 - 3 |
+ |-------------|-------------------|---------------------|------------------|
+ | cont. byte | next: ASCII/lead | next: ASCII/lead | next: cont. |
+ | (128-191) | context: 4 - 63 | context: 0 - 1 | context: 2 - 3 |
+ |-------------|-------------------|---------------------|------------------|
+ | lead byte | not valid | next: ASCII/lead | not valid |
+ | (192-207) | | context: 0 - 1 | |
+ |-------------|-------------------|---------------------|------------------|
+ | lead byte | not valid | next: cont. | not valid |
+ | (208-) | | context: 2 - 3 | |
+ |-------------|-------------------|---------------------|------------------|
+*/
+static const uint8_t kUTF8ContextLookup[512] = {
+ /* Last byte. */
+ /* */
+ /* ASCII range. */
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 4, 0, 0, 4, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 8, 12, 16, 12, 12, 20, 12, 16, 24, 28, 12, 12, 32, 12, 36, 12,
+ 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 32, 32, 24, 40, 28, 12,
+ 12, 48, 52, 52, 52, 48, 52, 52, 52, 48, 52, 52, 52, 52, 52, 48,
+ 52, 52, 52, 52, 52, 48, 52, 52, 52, 52, 52, 24, 12, 28, 12, 12,
+ 12, 56, 60, 60, 60, 56, 60, 60, 60, 56, 60, 60, 60, 60, 60, 56,
+ 60, 60, 60, 60, 60, 56, 60, 60, 60, 60, 60, 24, 12, 28, 12, 0,
+ /* UTF8 continuation byte range. */
+ 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1,
+ 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1,
+ 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1,
+ 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1,
+ /* UTF8 lead byte range. */
+ 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3,
+ 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3,
+ 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3,
+ 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3,
+ /* Second last byte. */
+ /* */
+ /* ASCII range. */
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1,
+ 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1,
+ 1, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+ 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 1, 1, 1, 1, 0,
+ /* UTF8 continuation byte range. */
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ /* UTF8 lead byte range. */
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+};
+
+/* Context lookup table for small signed integers. */
+static const uint8_t kSigned3BitContextLookup[] = {
+ 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+ 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+ 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+ 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+ 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,
+ 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,
+ 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7,
+};
+
+typedef enum ContextType {
+ CONTEXT_LSB6 = 0,
+ CONTEXT_MSB6 = 1,
+ CONTEXT_UTF8 = 2,
+ CONTEXT_SIGNED = 3
+} ContextType;
+
+static BROTLI_INLINE uint8_t Context(uint8_t p1, uint8_t p2, ContextType mode) {
+ switch (mode) {
+ case CONTEXT_LSB6:
+ return p1 & 0x3f;
+ case CONTEXT_MSB6:
+ return (uint8_t)(p1 >> 2);
+ case CONTEXT_UTF8:
+ return kUTF8ContextLookup[p1] | kUTF8ContextLookup[p2 + 256];
+ case CONTEXT_SIGNED:
+ return (uint8_t)((kSigned3BitContextLookup[p1] << 3) +
+ kSigned3BitContextLookup[p2]);
+ default:
+ return 0;
+ }
+}
+
+#if defined(__cplusplus) || defined(c_plusplus)
+} /* extern "C" */
+#endif
+
+#endif /* BROTLI_ENC_CONTEXT_H_ */