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path: root/drivers/webp/utils/bit_reader.c
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Diffstat (limited to 'drivers/webp/utils/bit_reader.c')
-rw-r--r--drivers/webp/utils/bit_reader.c120
1 files changed, 71 insertions, 49 deletions
diff --git a/drivers/webp/utils/bit_reader.c b/drivers/webp/utils/bit_reader.c
index bfa4d7d2e2..1afb1db890 100644
--- a/drivers/webp/utils/bit_reader.c
+++ b/drivers/webp/utils/bit_reader.c
@@ -1,10 +1,8 @@
// Copyright 2010 Google Inc. All Rights Reserved.
//
-// Use of this source code is governed by a BSD-style license
-// that can be found in the COPYING file in the root of the source
-// tree. An additional intellectual property rights grant can be found
-// in the file PATENTS. All contributing project authors may
-// be found in the AUTHORS file in the root of the source tree.
+// This code is licensed under the same terms as WebM:
+// Software License Agreement: http://www.webmproject.org/license/software/
+// Additional IP Rights Grant: http://www.webmproject.org/license/additional/
// -----------------------------------------------------------------------------
//
// Boolean decoder
@@ -13,12 +11,12 @@
#include "./bit_reader.h"
-#ifndef USE_RIGHT_JUSTIFY
-#define MK(X) (((range_t)(X) << (BITS)) | (MASK))
-#else
-#define MK(X) ((range_t)(X))
+#if defined(__cplusplus) || defined(c_plusplus)
+extern "C" {
#endif
+#define MK(X) (((bit_t)(X) << (BITS)) | (MASK))
+
//------------------------------------------------------------------------------
// VP8BitReader
@@ -31,7 +29,7 @@ void VP8InitBitReader(VP8BitReader* const br,
br->buf_ = start;
br->buf_end_ = end;
br->value_ = 0;
- br->bits_ = -8; // to load the very first 8bits
+ br->missing_ = 8; // to load the very first 8bits
br->eof_ = 0;
}
@@ -48,7 +46,7 @@ const uint8_t kVP8Log2Range[128] = {
};
// range = (range << kVP8Log2Range[range]) + trailing 1's
-const range_t kVP8NewRange[128] = {
+const bit_t kVP8NewRange[128] = {
MK(127), MK(127), MK(191), MK(127), MK(159), MK(191), MK(223), MK(127),
MK(143), MK(159), MK(175), MK(191), MK(207), MK(223), MK(239), MK(127),
MK(135), MK(143), MK(151), MK(159), MK(167), MK(175), MK(183), MK(191),
@@ -73,19 +71,9 @@ void VP8LoadFinalBytes(VP8BitReader* const br) {
assert(br != NULL && br->buf_ != NULL);
// Only read 8bits at a time
if (br->buf_ < br->buf_end_) {
-#ifndef USE_RIGHT_JUSTIFY
- br->value_ |= (bit_t)(*br->buf_++) << ((BITS) - 8 - br->bits_);
-#else
- br->value_ = (bit_t)(*br->buf_++) | (br->value_ << 8);
-#endif
- br->bits_ += 8;
- } else if (!br->eof_) {
-#ifdef USE_RIGHT_JUSTIFY
- // These are not strictly needed, but it makes the behaviour
- // consistent for both USE_RIGHT_JUSTIFY and !USE_RIGHT_JUSTIFY.
- br->value_ <<= 8;
- br->bits_ += 8;
-#endif
+ br->value_ |= (bit_t)(*br->buf_++) << ((BITS) - 8 + br->missing_);
+ br->missing_ -= 8;
+ } else {
br->eof_ = 1;
}
}
@@ -111,10 +99,6 @@ int32_t VP8GetSignedValue(VP8BitReader* const br, int bits) {
#define MAX_NUM_BIT_READ 25
-#define LBITS 64 // Number of bits prefetched.
-#define WBITS 32 // Minimum number of bytes needed after VP8LFillBitWindow.
-#define LOG8_WBITS 4 // Number of bytes needed to store WBITS bits.
-
static const uint32_t kBitMask[MAX_NUM_BIT_READ] = {
0, 1, 3, 7, 15, 31, 63, 127, 255, 511, 1023, 2047, 4095, 8191, 16383, 32767,
65535, 131071, 262143, 524287, 1048575, 2097151, 4194303, 8388607, 16777215
@@ -136,7 +120,7 @@ void VP8LInitBitReader(VP8LBitReader* const br,
br->eos_ = 0;
br->error_ = 0;
for (i = 0; i < sizeof(br->val_) && i < br->len_; ++i) {
- br->val_ |= ((vp8l_val_t)br->buf_[br->pos_]) << (8 * i);
+ br->val_ |= ((uint64_t)br->buf_[br->pos_]) << (8 * i);
++br->pos_;
}
}
@@ -151,57 +135,95 @@ void VP8LBitReaderSetBuffer(VP8LBitReader* const br,
br->len_ = len;
}
-// If not at EOS, reload up to LBITS byte-by-byte
static void ShiftBytes(VP8LBitReader* const br) {
while (br->bit_pos_ >= 8 && br->pos_ < br->len_) {
br->val_ >>= 8;
- br->val_ |= ((vp8l_val_t)br->buf_[br->pos_]) << (LBITS - 8);
+ br->val_ |= ((uint64_t)br->buf_[br->pos_]) << 56;
++br->pos_;
br->bit_pos_ -= 8;
}
}
void VP8LFillBitWindow(VP8LBitReader* const br) {
- if (br->bit_pos_ >= WBITS) {
-#if (defined(__x86_64__) || defined(_M_X64))
- if (br->pos_ + sizeof(br->val_) < br->len_) {
- br->val_ >>= WBITS;
- br->bit_pos_ -= WBITS;
+ if (br->bit_pos_ >= 32) {
+#if defined(__x86_64__) || defined(_M_X64)
+ if (br->pos_ + 8 < br->len_) {
+ br->val_ >>= 32;
// The expression below needs a little-endian arch to work correctly.
// This gives a large speedup for decoding speed.
- br->val_ |= *(const vp8l_val_t*)(br->buf_ + br->pos_) << (LBITS - WBITS);
- br->pos_ += LOG8_WBITS;
- return;
+ br->val_ |= *(const uint64_t *)(br->buf_ + br->pos_) << 32;
+ br->pos_ += 4;
+ br->bit_pos_ -= 32;
+ } else {
+ // Slow path.
+ ShiftBytes(br);
}
+#else
+ // Always the slow path.
+ ShiftBytes(br);
#endif
- ShiftBytes(br); // Slow path.
- if (br->pos_ == br->len_ && br->bit_pos_ >= LBITS) {
+ }
+ if (br->pos_ == br->len_ && br->bit_pos_ == 64) {
+ br->eos_ = 1;
+ }
+}
+
+uint32_t VP8LReadOneBit(VP8LBitReader* const br) {
+ const uint32_t val = (br->val_ >> br->bit_pos_) & 1;
+ // Flag an error at end_of_stream.
+ if (!br->eos_) {
+ ++br->bit_pos_;
+ if (br->bit_pos_ >= 32) {
+ ShiftBytes(br);
+ }
+ // After this last bit is read, check if eos needs to be flagged.
+ if (br->pos_ == br->len_ && br->bit_pos_ == 64) {
br->eos_ = 1;
}
+ } else {
+ br->error_ = 1;
}
+ return val;
}
uint32_t VP8LReadBits(VP8LBitReader* const br, int n_bits) {
+ uint32_t val = 0;
assert(n_bits >= 0);
// Flag an error if end_of_stream or n_bits is more than allowed limit.
if (!br->eos_ && n_bits < MAX_NUM_BIT_READ) {
- const uint32_t val =
- (uint32_t)(br->val_ >> br->bit_pos_) & kBitMask[n_bits];
- const int new_bits = br->bit_pos_ + n_bits;
- br->bit_pos_ = new_bits;
// If this read is going to cross the read buffer, set the eos flag.
if (br->pos_ == br->len_) {
- if (new_bits >= LBITS) {
+ if ((br->bit_pos_ + n_bits) >= 64) {
br->eos_ = 1;
+ if ((br->bit_pos_ + n_bits) > 64) return val;
+ }
+ }
+ val = (br->val_ >> br->bit_pos_) & kBitMask[n_bits];
+ br->bit_pos_ += n_bits;
+ if (br->bit_pos_ >= 40) {
+ if (br->pos_ + 5 < br->len_) {
+ br->val_ >>= 40;
+ br->val_ |=
+ (((uint64_t)br->buf_[br->pos_ + 0]) << 24) |
+ (((uint64_t)br->buf_[br->pos_ + 1]) << 32) |
+ (((uint64_t)br->buf_[br->pos_ + 2]) << 40) |
+ (((uint64_t)br->buf_[br->pos_ + 3]) << 48) |
+ (((uint64_t)br->buf_[br->pos_ + 4]) << 56);
+ br->pos_ += 5;
+ br->bit_pos_ -= 40;
+ }
+ if (br->bit_pos_ >= 8) {
+ ShiftBytes(br);
}
}
- ShiftBytes(br);
- return val;
} else {
br->error_ = 1;
- return 0;
}
+ return val;
}
//------------------------------------------------------------------------------
+#if defined(__cplusplus) || defined(c_plusplus)
+} // extern "C"
+#endif
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-23 23:39:37 +0000