godot/thirdparty/astcenc/astcenc_symbolic_physical.cpp

// SPDX-License-Identifier: Apache-2.0
// ----------------------------------------------------------------------------
// Copyright 2011-2023 Arm Limited
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy
// of the License at:
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations
// under the License.
// ----------------------------------------------------------------------------

/**
 * @brief Functions for converting between symbolic and physical encodings.
 */

#include "astcenc_internal.h"

#include <cassert>

/**
 * @brief Reverse bits in a byte.
 *
 * @param p   The value to reverse.
  *
 * @return The reversed result.
 */
static inline int bitrev8(int p)
{ … }


/**
 * @brief Read up to 8 bits at an arbitrary bit offset.
 *
 * The stored value is at most 8 bits, but can be stored at an offset of between 0 and 7 bits so may
 * span two separate bytes in memory.
 *
 * @param         bitcount    The number of bits to read.
 * @param         bitoffset   The bit offset to read from, between 0 and 7.
 * @param[in,out] ptr         The data pointer to read from.
 *
 * @return The read value.
 */
static inline int read_bits(
	int bitcount,
	int bitoffset,
	const uint8_t* ptr
) { … }

#if !defined(ASTCENC_DECOMPRESS_ONLY)

/**
 * @brief Write up to 8 bits at an arbitrary bit offset.
 *
 * The stored value is at most 8 bits, but can be stored at an offset of between 0 and 7 bits so
 * may span two separate bytes in memory.
 *
 * @param         value       The value to write.
 * @param         bitcount    The number of bits to write, starting from LSB.
 * @param         bitoffset   The bit offset to store at, between 0 and 7.
 * @param[in,out] ptr         The data pointer to write to.
 */
static inline void write_bits(
	int value,
	int bitcount,
	int bitoffset,
	uint8_t* ptr
) { … }

/* See header for documentation. */
void symbolic_to_physical(
	const block_size_descriptor& bsd,
	const symbolic_compressed_block& scb,
	uint8_t pcb[16]
) { … }

#endif

/* See header for documentation. */
void physical_to_symbolic(
	const block_size_descriptor& bsd,
	const uint8_t pcb[16],
	symbolic_compressed_block& scb
) { … }