1 /* 2 * Copyright (c) 2019 Facebook. 3 * 4 * SPDX-License-Identifier: Apache-2.0 5 */ 6 7 /** 8 * @brief Extra arithmetic and bit manipulation functions. 9 * @defgroup math_extras Math extras 10 * @ingroup utilities 11 * 12 * Portable wrapper functions for a number of arithmetic and bit-counting functions that are often 13 * provided by compiler builtins. If the compiler does not have an appropriate builtin, a portable C 14 * implementation is used instead. 15 * 16 * @{ 17 */ 18 19 #ifndef ZEPHYR_INCLUDE_SYS_MATH_EXTRAS_H_ 20 #define ZEPHYR_INCLUDE_SYS_MATH_EXTRAS_H_ 21 22 #include <zephyr/types.h> 23 #include <stdbool.h> 24 #include <stddef.h> 25 26 /** 27 * @name Unsigned integer addition with overflow detection. 28 * 29 * These functions compute `a + b` and store the result in `*result`, returning 30 * true if the operation overflowed. 31 */ 32 /**@{*/ 33 34 /** 35 * @brief Add two unsigned 16-bit integers. 36 * @param a First operand. 37 * @param b Second operand. 38 * @param result Pointer to the result. 39 * @return true if the operation overflowed. 40 */ 41 static bool u16_add_overflow(uint16_t a, uint16_t b, uint16_t *result); 42 43 /** 44 * @brief Add two unsigned 32-bit integers. 45 * @param a First operand. 46 * @param b Second operand. 47 * @param result Pointer to the result. 48 * @return true if the operation overflowed. 49 */ 50 51 static bool u32_add_overflow(uint32_t a, uint32_t b, uint32_t *result); 52 53 /** 54 * @brief Add two unsigned 64-bit integers. 55 * @param a First operand. 56 * @param b Second operand. 57 * @param result Pointer to the result. 58 * @return true if the operation overflowed. 59 */ 60 static bool u64_add_overflow(uint64_t a, uint64_t b, uint64_t *result); 61 62 /** 63 * @brief Add two size_t integers. 64 * @param a First operand. 65 * @param b Second operand. 66 * @param result Pointer to the result. 67 * @return true if the operation overflowed. 68 */ 69 static bool size_add_overflow(size_t a, size_t b, size_t *result); 70 71 /**@}*/ 72 73 /** 74 * @name Unsigned integer multiplication with overflow detection. 75 * 76 * These functions compute `a * b` and store the result in `*result`, returning 77 * true if the operation overflowed. 78 */ 79 /**@{*/ 80 81 /** 82 * @brief Multiply two unsigned 16-bit integers. 83 * @param a First operand. 84 * @param b Second operand. 85 * @param result Pointer to the result. 86 * @return true if the operation overflowed. 87 */ 88 static bool u16_mul_overflow(uint16_t a, uint16_t b, uint16_t *result); 89 90 /** 91 * @brief Multiply two unsigned 32-bit integers. 92 * @param a First operand. 93 * @param b Second operand. 94 * @param result Pointer to the result. 95 * @return true if the operation overflowed. 96 */ 97 98 static bool u32_mul_overflow(uint32_t a, uint32_t b, uint32_t *result); 99 /** 100 * @brief Multiply two unsigned 64-bit integers. 101 * @param a First operand. 102 * @param b Second operand. 103 * @param result Pointer to the result. 104 * @return true if the operation overflowed. 105 */ 106 static bool u64_mul_overflow(uint64_t a, uint64_t b, uint64_t *result); 107 108 /** 109 * @brief Multiply two size_t integers. 110 * @param a First operand. 111 * @param b Second operand. 112 * @param result Pointer to the result. 113 * @return true if the operation overflowed. 114 */ 115 static bool size_mul_overflow(size_t a, size_t b, size_t *result); 116 117 /**@}*/ 118 119 /** 120 * @name Count leading zeros. 121 * 122 * Count the number of leading zero bits in the bitwise representation of `x`. 123 * When `x = 0`, this is the size of `x` in bits. 124 */ 125 /**@{*/ 126 127 /** 128 * @brief Count the number of leading zero bits in a 32-bit integer. 129 * @param x Integer to count leading zeros in. 130 * @return Number of leading zero bits in `x`. 131 */ 132 static int u32_count_leading_zeros(uint32_t x); 133 134 /** 135 * @brief Count the number of leading zero bits in a 64-bit integer. 136 * @param x Integer to count leading zeros in. 137 * @return Number of leading zero bits in `x`. 138 */ 139 static int u64_count_leading_zeros(uint64_t x); 140 141 /**@}*/ 142 143 /** 144 * @name Count trailing zeros. 145 * 146 * Count the number of trailing zero bits in the bitwise representation of `x`. 147 * When `x = 0`, this is the size of `x` in bits. 148 */ 149 /**@{*/ 150 151 /** 152 * @brief Count the number of trailing zero bits in a 32-bit integer. 153 * @param x Integer to count trailing zeros in. 154 * @return Number of trailing zero bits in `x`. 155 */ 156 static int u32_count_trailing_zeros(uint32_t x); 157 158 /** 159 * @brief Count the number of trailing zero bits in a 64-bit integer. 160 * @param x Integer to count trailing zeros in. 161 * @return Number of trailing zero bits in `x`. 162 */ 163 static int u64_count_trailing_zeros(uint64_t x); 164 165 /**@}*/ 166 167 /**@}*/ 168 169 #include <zephyr/sys/math_extras_impl.h> 170 171 #endif /* ZEPHYR_INCLUDE_SYS_MATH_EXTRAS_H_ */ 172
