54 строки
1.7 KiB
C
54 строки
1.7 KiB
C
/*
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* Copyright (c) 2013 The WebM project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "./vpx_config.h"
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#include "./bitreader_buffer.h"
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size_t vpx_rb_bytes_read(struct vpx_read_bit_buffer *rb) {
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return (rb->bit_offset + 7) >> 3;
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}
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int vpx_rb_read_bit(struct vpx_read_bit_buffer *rb) {
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const size_t off = rb->bit_offset;
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const size_t p = off >> 3;
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const int q = 7 - (int)(off & 0x7);
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if (rb->bit_buffer + p < rb->bit_buffer_end) {
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const int bit = (rb->bit_buffer[p] >> q) & 1;
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rb->bit_offset = off + 1;
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return bit;
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} else {
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rb->error_handler(rb->error_handler_data);
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return 0;
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}
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}
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int vpx_rb_read_literal(struct vpx_read_bit_buffer *rb, int bits) {
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int value = 0, bit;
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for (bit = bits - 1; bit >= 0; bit--)
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value |= vpx_rb_read_bit(rb) << bit;
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return value;
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}
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int vpx_rb_read_signed_literal(struct vpx_read_bit_buffer *rb,
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int bits) {
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const int value = vpx_rb_read_literal(rb, bits);
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return vpx_rb_read_bit(rb) ? -value : value;
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}
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int vpx_rb_read_inv_signed_literal(struct vpx_read_bit_buffer *rb,
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int bits) {
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#if CONFIG_MISC_FIXES
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const int nbits = sizeof(unsigned) * 8 - bits - 1;
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const unsigned value = (unsigned)vpx_rb_read_literal(rb, bits + 1) << nbits;
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return ((int) value) >> nbits;
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#else
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return vpx_rb_read_signed_literal(rb, bits);
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#endif
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}
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