1 /* 2 * Copyright (c) 2017, Alliance for Open Media. All rights reserved 3 * 4 * This source code is subject to the terms of the BSD 2 Clause License and 5 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License 6 * was not distributed with this source code in the LICENSE file, you can 7 * obtain it at www.aomedia.org/license/software. If the Alliance for Open 8 * Media Patent License 1.0 was not distributed with this source code in the 9 * PATENTS file, you can obtain it at www.aomedia.org/license/patent. 10 */ 11 12 #include "aom_dsp/binary_codes_reader.h" 13 #include "aom_dsp/recenter.h" 14 #include "av1/common/common.h" 15 16 uint16_t aom_read_primitive_quniform_(aom_reader *r, 17 uint16_t n ACCT_STR_PARAM) { 18 if (n <= 1) return 0; 19 const int l = get_msb(n) + 1; 20 const int m = (1 << l) - n; 21 const int v = aom_read_literal(r, l - 1, ACCT_STR_NAME); 22 return v < m ? v : (v << 1) - m + aom_read_bit(r, ACCT_STR_NAME); 23 } 24 25 // Decode finite subexponential code that for a symbol v in [0, n-1] with 26 // parameter k 27 uint16_t aom_read_primitive_subexpfin_(aom_reader *r, uint16_t n, 28 uint16_t k ACCT_STR_PARAM) { 29 int i = 0; 30 int mk = 0; 31 32 while (1) { 33 int b = (i ? k + i - 1 : k); 34 int a = (1 << b); 35 36 if (n <= mk + 3 * a) { 37 return aom_read_primitive_quniform(r, n - mk, ACCT_STR_NAME) + mk; 38 } 39 40 if (!aom_read_bit(r, ACCT_STR_NAME)) { 41 return aom_read_literal(r, b, ACCT_STR_NAME) + mk; 42 } 43 44 i = i + 1; 45 mk += a; 46 } 47 48 assert(0); 49 return 0; 50 } 51 52 uint16_t aom_read_primitive_refsubexpfin_(aom_reader *r, uint16_t n, uint16_t k, 53 uint16_t ref ACCT_STR_PARAM) { 54 return inv_recenter_finite_nonneg( 55 n, ref, aom_read_primitive_subexpfin(r, n, k, ACCT_STR_NAME)); 56 } 57
