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 "./vpx_config.h" 11 #include "./bitreader_buffer.h" 12 13 size_t vpx_rb_bytes_read(struct vpx_read_bit_buffer *rb) { 14 return (rb->bit_offset + 7) >> 3; 15 } 16 17 int vpx_rb_read_bit(struct vpx_read_bit_buffer *rb) { 18 const size_t off = rb->bit_offset; 19 const size_t p = off >> 3; 20 const int q = 7 - (int)(off & 0x7); 21 if (rb->bit_buffer + p < rb->bit_buffer_end) { 22 const int bit = (rb->bit_buffer[p] >> q) & 1; 23 rb->bit_offset = off + 1; 24 return bit; 25 } else { 26 rb->error_handler(rb->error_handler_data); 27 return 0; 28 } 29 } 30 31 int vpx_rb_read_literal(struct vpx_read_bit_buffer *rb, int bits) { 32 int value = 0, bit; 33 for (bit = bits - 1; bit >= 0; bit--) value |= vpx_rb_read_bit(rb) << bit; 34 return value; 35 } 36 37 int vpx_rb_read_signed_literal(struct vpx_read_bit_buffer *rb, int bits) { 38 const int value = vpx_rb_read_literal(rb, bits); 39 return vpx_rb_read_bit(rb) ? -value : value; 40 } 41 42 int vpx_rb_read_inv_signed_literal(struct vpx_read_bit_buffer *rb, int bits) { 43 return vpx_rb_read_signed_literal(rb, bits); 44 } 45
