mbed_math_helpers.h

/* mbed Microcontroller Library
 * Copyright (c) 2026 Jamie Smith
 * SPDX-License-Identifier: Apache-2.0
 *
 * 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.
 */
 
#pragma once
 
#include <stdint.h>
 
/**
 * @brief Check whether an integer is an exact power of two.
 */
// from https://stackoverflow.com/a/600306/7083698
static inline bool mbed_is_power_of_two(const uint32_t x)
{
    return x > 0 && (x & (x - 1)) == 0;
}
 
/**
 * @brief Get the log2 of an integer.
 *
 * Rounds down to the nearest power of 2, i.e. \c mbed_integer_log_2(3) is 1.
 */
static inline uint32_t mbed_integer_log_2(uint32_t x)
{
    return sizeof(uint32_t) * 8 - 1 - __builtin_clz(x);
}
 
/**
 * @brief Align an address (\c addr) to a given \c alignment by adding between 0 and \c alignment-1 bytes to it.
 */
static inline void *mbed_align_up_to(void *addr, size_t alignment)
{
    // Use integer division to divide the address down to the alignment size, which
    // rounds to the block before the given address.
    // So that we always go one cache line back even if the given address is on the start of a block,
    // subtract 1.
    ptrdiff_t prev_block_start = ((ptrdiff_t)(addr) - 1) / alignment;
 
    // Now we just have to multiply up again to get an address (adding 1 to go forward by 1 block)
    return (void *)((prev_block_start + 1) * alignment);
}