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Diffstat (limited to '')
-rw-r--r-- | third_party/aom/aom_dsp/binary_codes_reader.c | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/third_party/aom/aom_dsp/binary_codes_reader.c b/third_party/aom/aom_dsp/binary_codes_reader.c new file mode 100644 index 0000000000..ee0ce62278 --- /dev/null +++ b/third_party/aom/aom_dsp/binary_codes_reader.c @@ -0,0 +1,55 @@ +/* + * Copyright (c) 2017, Alliance for Open Media. All rights reserved + * + * This source code is subject to the terms of the BSD 2 Clause License and + * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License + * was not distributed with this source code in the LICENSE file, you can + * obtain it at www.aomedia.org/license/software. If the Alliance for Open + * Media Patent License 1.0 was not distributed with this source code in the + * PATENTS file, you can obtain it at www.aomedia.org/license/patent. + */ + +#include "aom_dsp/binary_codes_reader.h" +#include "aom_dsp/recenter.h" + +uint16_t aom_read_primitive_quniform_(aom_reader *r, + uint16_t n ACCT_STR_PARAM) { + if (n <= 1) return 0; + const int l = get_msb(n) + 1; + const int m = (1 << l) - n; + const int v = aom_read_literal(r, l - 1, ACCT_STR_NAME); + return v < m ? v : (v << 1) - m + aom_read_bit(r, ACCT_STR_NAME); +} + +// Decode finite subexponential code that for a symbol v in [0, n-1] with +// parameter k +uint16_t aom_read_primitive_subexpfin_(aom_reader *r, uint16_t n, + uint16_t k ACCT_STR_PARAM) { + int i = 0; + int mk = 0; + + while (1) { + int b = (i ? k + i - 1 : k); + int a = (1 << b); + + if (n <= mk + 3 * a) { + return aom_read_primitive_quniform(r, n - mk, ACCT_STR_NAME) + mk; + } + + if (!aom_read_bit(r, ACCT_STR_NAME)) { + return aom_read_literal(r, b, ACCT_STR_NAME) + mk; + } + + i = i + 1; + mk += a; + } + + assert(0); + return 0; +} + +uint16_t aom_read_primitive_refsubexpfin_(aom_reader *r, uint16_t n, uint16_t k, + uint16_t ref ACCT_STR_PARAM) { + return inv_recenter_finite_nonneg( + n, ref, aom_read_primitive_subexpfin(r, n, k, ACCT_STR_NAME)); +} |