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Diffstat (limited to '')
-rw-r--r-- | third_party/aom/aom_dsp/bitwriter_buffer.c | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/third_party/aom/aom_dsp/bitwriter_buffer.c b/third_party/aom/aom_dsp/bitwriter_buffer.c new file mode 100644 index 0000000000..7d0ab9486a --- /dev/null +++ b/third_party/aom/aom_dsp/bitwriter_buffer.c @@ -0,0 +1,141 @@ +/* + * 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 <limits.h> +#include <stdlib.h> + +#include "config/aom_config.h" + +#include "aom_dsp/bitwriter_buffer.h" +#include "aom_dsp/recenter.h" +#include "aom_ports/bitops.h" + +int aom_wb_is_byte_aligned(const struct aom_write_bit_buffer *wb) { + return (wb->bit_offset % CHAR_BIT == 0); +} + +uint32_t aom_wb_bytes_written(const struct aom_write_bit_buffer *wb) { + return wb->bit_offset / CHAR_BIT + (wb->bit_offset % CHAR_BIT > 0); +} + +void aom_wb_write_bit(struct aom_write_bit_buffer *wb, int bit) { + const int off = (int)wb->bit_offset; + const int p = off / CHAR_BIT; + const int q = CHAR_BIT - 1 - off % CHAR_BIT; + if (q == CHAR_BIT - 1) { + // Zero next char and write bit + wb->bit_buffer[p] = bit << q; + } else { + wb->bit_buffer[p] &= ~(1 << q); + wb->bit_buffer[p] |= bit << q; + } + wb->bit_offset = off + 1; +} + +void aom_wb_overwrite_bit(struct aom_write_bit_buffer *wb, int bit) { + // Do not zero bytes but overwrite exisiting values + const int off = (int)wb->bit_offset; + const int p = off / CHAR_BIT; + const int q = CHAR_BIT - 1 - off % CHAR_BIT; + wb->bit_buffer[p] &= ~(1 << q); + wb->bit_buffer[p] |= bit << q; + wb->bit_offset = off + 1; +} + +void aom_wb_write_literal(struct aom_write_bit_buffer *wb, int data, int bits) { + assert(bits <= 31); + int bit; + for (bit = bits - 1; bit >= 0; bit--) aom_wb_write_bit(wb, (data >> bit) & 1); +} + +void aom_wb_write_unsigned_literal(struct aom_write_bit_buffer *wb, + uint32_t data, int bits) { + assert(bits <= 32); + int bit; + for (bit = bits - 1; bit >= 0; bit--) aom_wb_write_bit(wb, (data >> bit) & 1); +} + +void aom_wb_overwrite_literal(struct aom_write_bit_buffer *wb, int data, + int bits) { + int bit; + for (bit = bits - 1; bit >= 0; bit--) + aom_wb_overwrite_bit(wb, (data >> bit) & 1); +} + +void aom_wb_write_inv_signed_literal(struct aom_write_bit_buffer *wb, int data, + int bits) { + aom_wb_write_literal(wb, data, bits + 1); +} + +void aom_wb_write_uvlc(struct aom_write_bit_buffer *wb, uint32_t v) { + int64_t shift_val = ++v; + int leading_zeroes = 1; + + assert(shift_val > 0); + + while (shift_val >>= 1) leading_zeroes += 2; + + aom_wb_write_literal(wb, 0, leading_zeroes >> 1); + aom_wb_write_unsigned_literal(wb, v, (leading_zeroes + 1) >> 1); +} + +static void wb_write_primitive_quniform(struct aom_write_bit_buffer *wb, + uint16_t n, uint16_t v) { + if (n <= 1) return; + const int l = get_msb(n) + 1; + const int m = (1 << l) - n; + if (v < m) { + aom_wb_write_literal(wb, v, l - 1); + } else { + aom_wb_write_literal(wb, m + ((v - m) >> 1), l - 1); + aom_wb_write_bit(wb, (v - m) & 1); + } +} + +static void wb_write_primitive_subexpfin(struct aom_write_bit_buffer *wb, + uint16_t n, uint16_t k, uint16_t v) { + int i = 0; + int mk = 0; + while (1) { + int b = (i ? k + i - 1 : k); + int a = (1 << b); + if (n <= mk + 3 * a) { + wb_write_primitive_quniform(wb, n - mk, v - mk); + break; + } else { + int t = (v >= mk + a); + aom_wb_write_bit(wb, t); + if (t) { + i = i + 1; + mk += a; + } else { + aom_wb_write_literal(wb, v - mk, b); + break; + } + } + } +} + +static void wb_write_primitive_refsubexpfin(struct aom_write_bit_buffer *wb, + uint16_t n, uint16_t k, + uint16_t ref, uint16_t v) { + wb_write_primitive_subexpfin(wb, n, k, recenter_finite_nonneg(n, ref, v)); +} + +void aom_wb_write_signed_primitive_refsubexpfin(struct aom_write_bit_buffer *wb, + uint16_t n, uint16_t k, + int16_t ref, int16_t v) { + ref += n - 1; + v += n - 1; + const uint16_t scaled_n = (n << 1) - 1; + wb_write_primitive_refsubexpfin(wb, scaled_n, k, ref, v); +} |