diff options
Diffstat (limited to '')
-rw-r--r-- | third_party/aom/aom_dsp/bitreader_buffer.c | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/third_party/aom/aom_dsp/bitreader_buffer.c b/third_party/aom/aom_dsp/bitreader_buffer.c new file mode 100644 index 0000000000..d79feea6a3 --- /dev/null +++ b/third_party/aom/aom_dsp/bitreader_buffer.c @@ -0,0 +1,116 @@ +/* + * Copyright (c) 2016, 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 <assert.h> + +#include "config/aom_config.h" + +#include "aom_dsp/bitreader_buffer.h" +#include "aom_dsp/recenter.h" +#include "aom_ports/bitops.h" + +size_t aom_rb_bytes_read(const struct aom_read_bit_buffer *rb) { + return (rb->bit_offset + 7) >> 3; +} + +int aom_rb_read_bit(struct aom_read_bit_buffer *rb) { + const uint32_t off = rb->bit_offset; + const uint32_t p = off >> 3; + const int q = 7 - (int)(off & 0x7); + if (rb->bit_buffer + p < rb->bit_buffer_end) { + const int bit = (rb->bit_buffer[p] >> q) & 1; + rb->bit_offset = off + 1; + return bit; + } else { + if (rb->error_handler) rb->error_handler(rb->error_handler_data); + return 0; + } +} + +int aom_rb_read_literal(struct aom_read_bit_buffer *rb, int bits) { + assert(bits <= 31); + int value = 0, bit; + for (bit = bits - 1; bit >= 0; bit--) value |= aom_rb_read_bit(rb) << bit; + return value; +} + +uint32_t aom_rb_read_unsigned_literal(struct aom_read_bit_buffer *rb, + int bits) { + assert(bits <= 32); + uint32_t value = 0; + int bit; + for (bit = bits - 1; bit >= 0; bit--) + value |= (uint32_t)aom_rb_read_bit(rb) << bit; + return value; +} + +int aom_rb_read_inv_signed_literal(struct aom_read_bit_buffer *rb, int bits) { + const int nbits = sizeof(unsigned) * 8 - bits - 1; + const unsigned value = (unsigned)aom_rb_read_literal(rb, bits + 1) << nbits; + return ((int)value) >> nbits; +} + +uint32_t aom_rb_read_uvlc(struct aom_read_bit_buffer *rb) { + int leading_zeros = 0; + while (leading_zeros < 32 && !aom_rb_read_bit(rb)) ++leading_zeros; + // Maximum 32 bits. + if (leading_zeros == 32) return UINT32_MAX; + const uint32_t base = (1u << leading_zeros) - 1; + const uint32_t value = aom_rb_read_literal(rb, leading_zeros); + return base + value; +} + +static uint16_t aom_rb_read_primitive_quniform(struct aom_read_bit_buffer *rb, + uint16_t n) { + if (n <= 1) return 0; + const int l = get_msb(n) + 1; + const int m = (1 << l) - n; + const int v = aom_rb_read_literal(rb, l - 1); + return v < m ? v : (v << 1) - m + aom_rb_read_bit(rb); +} + +static uint16_t aom_rb_read_primitive_subexpfin(struct aom_read_bit_buffer *rb, + uint16_t n, uint16_t k) { + 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_rb_read_primitive_quniform(rb, n - mk) + mk; + } + + if (!aom_rb_read_bit(rb)) { + return aom_rb_read_literal(rb, b) + mk; + } + + i = i + 1; + mk += a; + } + + assert(0); + return 0; +} + +static uint16_t aom_rb_read_primitive_refsubexpfin( + struct aom_read_bit_buffer *rb, uint16_t n, uint16_t k, uint16_t ref) { + return inv_recenter_finite_nonneg(n, ref, + aom_rb_read_primitive_subexpfin(rb, n, k)); +} + +int16_t aom_rb_read_signed_primitive_refsubexpfin( + struct aom_read_bit_buffer *rb, uint16_t n, uint16_t k, int16_t ref) { + ref += n - 1; + const uint16_t scaled_n = (n << 1) - 1; + return aom_rb_read_primitive_refsubexpfin(rb, scaled_n, k, ref) - n + 1; +} |