1 /* 2 * Copyright (c) 2013 The WebM project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 #include "vp9/decoder/vp9_read_bit_buffer.h" 11 12 size_t vp9_rb_bytes_read(struct vp9_read_bit_buffer *rb) { 13 return (rb->bit_offset + CHAR_BIT - 1) / CHAR_BIT; 14 } 15 16 int vp9_rb_read_bit(struct vp9_read_bit_buffer *rb) { 17 const size_t off = rb->bit_offset; 18 const size_t p = off / CHAR_BIT; 19 const int q = CHAR_BIT - 1 - (int)off % CHAR_BIT; 20 if (rb->bit_buffer + p >= rb->bit_buffer_end) { 21 rb->error_handler(rb->error_handler_data); 22 return 0; 23 } else { 24 const int bit = (rb->bit_buffer[p] & (1 << q)) >> q; 25 rb->bit_offset = off + 1; 26 return bit; 27 } 28 } 29 30 int vp9_rb_read_literal(struct vp9_read_bit_buffer *rb, int bits) { 31 int value = 0, bit; 32 for (bit = bits - 1; bit >= 0; bit--) 33 value |= vp9_rb_read_bit(rb) << bit; 34 return value; 35 } 36 37 int vp9_rb_read_signed_literal(struct vp9_read_bit_buffer *rb, 38 int bits) { 39 const int value = vp9_rb_read_literal(rb, bits); 40 return vp9_rb_read_bit(rb) ? -value : value; 41 } 42
