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Diffstat (limited to 'dev/boot/BootKit/Shared/bit.h')
| -rw-r--r-- | dev/boot/BootKit/Shared/bit.h | 461 |
1 files changed, 221 insertions, 240 deletions
diff --git a/dev/boot/BootKit/Shared/bit.h b/dev/boot/BootKit/Shared/bit.h index fa0fab82..1ac29c89 100644 --- a/dev/boot/BootKit/Shared/bit.h +++ b/dev/boot/BootKit/Shared/bit.h @@ -3,245 +3,226 @@ #include <bit> -namespace utl -{ - - /** - * @brief Size of object in terms of bits. - * - * @tparam T Object type - * @return Number of bits - */ - template <class T> - constexpr auto bit_size() - { - return sizeof(T) * 8; - } - - /** - * @brief Integer with all bits set to 1. - * - * @tparam T Integer type - * @return All set integer - */ - template <class T> - constexpr T bit_full() - { - return T(-1); - } - - /** - * @brief Wrap around mask for power of two number of bits - * within given integer type. For example: - * [ bit_wrap<uint8_t> = 8 - 1 = 0b111 ] - * [ bit_wrap<uint16_t> = 16 - 1 = 0b1111 ] - * [ bit_wrap<uint32_t> = 32 - 1 = 0b11111 ] - * - * @tparam T Integer type - * @return Wrap around mask for number of bits - */ - template <class T> - constexpr T bit_wrap() - { - return bit_size<T>() - 1; - } - - /** - * @brief Number of bits to fit bit_wrap<T> result, in other words - * bit width of (sizeof(T) * 8 - 1). For example: - * [ bit_shft<uint8_t> = bit_width(0b111) = 3 ] - * [ bit_shft<uint16_t> = bit_width(0b1111) = 4 ] - * [ bit_shft<uint32_t> = bit_width(0b11111) = 5 ] - * - * @tparam T Integer type - * @return Number of bits to shift to divide by sizeof(T) * 8 - */ - template <class T> - constexpr auto bit_shft() - { - return std::bit_width(bit_wrap<T>()); - } - - /** - * @brief Round up division by number of bits within given integer type, - * which sizeof(T) * 8 is power of two. - * - * @tparam T Inetegr type - * @param x Dividend - * @return Quotient - */ - template <class T> - constexpr auto bit_ceil(auto x) - { - return (x + bit_wrap<T>()) >> bit_shft<T>(); - } - - /** - * @brief Count leading zeros. - * - * @param x Unsigned integer argument - * @return Number of leading zeros - */ - constexpr unsigned cntlz(auto x) - { - if constexpr (std::is_same_v<decltype(x), int>) - return std::countl_zero(unsigned(x)); - else - return std::countl_zero(x); - } - - /** - * @brief Count trailing zeros. - * - * @param x Unsigned integer argument - * @return Number of trailing zeros - */ - constexpr unsigned cnttz(auto x) - { - if constexpr (std::is_same_v<decltype(x), int>) - return std::countr_zero(unsigned(x)); - else - return std::countr_zero(x); - } - - /** - * @brief Get number of words (integers) required to store N bits. - * - * @tparam T Word integer type - * @param n Number of bits to store - * @return Number of words - */ - template <class T> - constexpr size_t words_in_bits(size_t n) - { - return (n >> bit_shft<T>()) + !!(n & bit_wrap<T>()); - } - - /** - * @brief Get number of bytes required to store N bits. - * - * @param n Number of bits to store - * @return Number of bytes - */ - constexpr size_t bytes_in_bits(size_t n) - { - return words_in_bits<uint8_t>(n); - } - - /** - * @brief Make integer with bit at given position. - * - * @tparam T Inetegr type - * @param n Bit position - * @return Integer with set bit - */ - template <class T = unsigned> - constexpr T bit(int n) - { - return T(1) << n; - } - - /** - * @brief Get n-th bit of an integer. - * - * @tparam T Integer type - * @param x Integer - * @param n Bit position from LSB - * @return true if set - */ - template <class T> - constexpr bool get_bit(T x, int n) - { - return (x >> n) & 1; - } - - /** - * @brief Set n-th bit of an integer. - * - * @tparam T Integer type - * @param x Integer - * @param n Bit position from LSB - */ - template <class T> - constexpr void set_bit(T& x, int n) - { - x |= 1 << n; - } - - /** - * @brief Clear n-th bit of an integer. - * - * @tparam T Integer type - * @param x Integer - * @param n Bit position from LSB - */ - template <class T> - constexpr void clr_bit(T& x, int n) - { - x &= ~(1 << n); - } - - /** - * @brief Get n-th bit in array of words (starting from LSB). - * - * @tparam T Word type - * @param p Array of words - * @param n Index of bit to get - * @return true if set - */ - template <class T> - constexpr bool get_arr_bit(const T* p, unsigned n) - { - return get_bit(p[n >> bit_shft<T>()], n & bit_wrap<T>()); - } - - /** - * @brief Set n-th bit in array of words (starting from LSB). - * - * @tparam T Word type - * @param p Array of words - * @param n Index of bit to set - */ - template <class T> - constexpr void set_arr_bit(T* p, unsigned n) - { - set_bit(p[n >> bit_shft<T>()], n & bit_wrap<T>()); - } - - /** - * @brief Clear n-th bit in array of words (starting from LSB). - * - * @tparam T Word type - * @param p Array of words - * @param n Index of bit to clear - */ - template <class T> - constexpr void clr_arr_bit(T* p, unsigned n) - { - clr_bit(p[n >> bit_shft<T>()], n & bit_wrap<T>()); - } - - /** - * @brief Shift bits left in array of integer elements from least significant bit - * and considering 0-th byte as the right most. - * uint16_t example: 0b10000000'11100001 ==> 0b00000001'11000010. - * - * @tparam T Integer type - * @tparam L Length of array - * @param x Array of integers, nullptr not acceptable! - * @param len Number of elements - */ - template <class T, size_t L> - constexpr void shift_left(T (&x)[L]) - { - for (int i = L - 1; i > 0; --i) - { - x[i] <<= 1; - x[i] |= x[i - 1] >> bit_wrap<T>(); - } - x[0] <<= 1; - } - -} // namespace utl +namespace utl { + +/** + * @brief Size of object in terms of bits. + * + * @tparam T Object type + * @return Number of bits + */ +template <class T> +constexpr auto bit_size() { + return sizeof(T) * 8; +} + +/** + * @brief Integer with all bits set to 1. + * + * @tparam T Integer type + * @return All set integer + */ +template <class T> +constexpr T bit_full() { + return T(-1); +} + +/** + * @brief Wrap around mask for power of two number of bits + * within given integer type. For example: + * [ bit_wrap<uint8_t> = 8 - 1 = 0b111 ] + * [ bit_wrap<uint16_t> = 16 - 1 = 0b1111 ] + * [ bit_wrap<uint32_t> = 32 - 1 = 0b11111 ] + * + * @tparam T Integer type + * @return Wrap around mask for number of bits + */ +template <class T> +constexpr T bit_wrap() { + return bit_size<T>() - 1; +} + +/** + * @brief Number of bits to fit bit_wrap<T> result, in other words + * bit width of (sizeof(T) * 8 - 1). For example: + * [ bit_shft<uint8_t> = bit_width(0b111) = 3 ] + * [ bit_shft<uint16_t> = bit_width(0b1111) = 4 ] + * [ bit_shft<uint32_t> = bit_width(0b11111) = 5 ] + * + * @tparam T Integer type + * @return Number of bits to shift to divide by sizeof(T) * 8 + */ +template <class T> +constexpr auto bit_shft() { + return std::bit_width(bit_wrap<T>()); +} + +/** + * @brief Round up division by number of bits within given integer type, + * which sizeof(T) * 8 is power of two. + * + * @tparam T Inetegr type + * @param x Dividend + * @return Quotient + */ +template <class T> +constexpr auto bit_ceil(auto x) { + return (x + bit_wrap<T>()) >> bit_shft<T>(); +} + +/** + * @brief Count leading zeros. + * + * @param x Unsigned integer argument + * @return Number of leading zeros + */ +constexpr unsigned cntlz(auto x) { + if constexpr (std::is_same_v<decltype(x), int>) + return std::countl_zero(unsigned(x)); + else + return std::countl_zero(x); +} + +/** + * @brief Count trailing zeros. + * + * @param x Unsigned integer argument + * @return Number of trailing zeros + */ +constexpr unsigned cnttz(auto x) { + if constexpr (std::is_same_v<decltype(x), int>) + return std::countr_zero(unsigned(x)); + else + return std::countr_zero(x); +} + +/** + * @brief Get number of words (integers) required to store N bits. + * + * @tparam T Word integer type + * @param n Number of bits to store + * @return Number of words + */ +template <class T> +constexpr size_t words_in_bits(size_t n) { + return (n >> bit_shft<T>()) + !!(n & bit_wrap<T>()); +} + +/** + * @brief Get number of bytes required to store N bits. + * + * @param n Number of bits to store + * @return Number of bytes + */ +constexpr size_t bytes_in_bits(size_t n) { + return words_in_bits<uint8_t>(n); +} + +/** + * @brief Make integer with bit at given position. + * + * @tparam T Inetegr type + * @param n Bit position + * @return Integer with set bit + */ +template <class T = unsigned> +constexpr T bit(int n) { + return T(1) << n; +} + +/** + * @brief Get n-th bit of an integer. + * + * @tparam T Integer type + * @param x Integer + * @param n Bit position from LSB + * @return true if set + */ +template <class T> +constexpr bool get_bit(T x, int n) { + return (x >> n) & 1; +} + +/** + * @brief Set n-th bit of an integer. + * + * @tparam T Integer type + * @param x Integer + * @param n Bit position from LSB + */ +template <class T> +constexpr void set_bit(T& x, int n) { + x |= 1 << n; +} + +/** + * @brief Clear n-th bit of an integer. + * + * @tparam T Integer type + * @param x Integer + * @param n Bit position from LSB + */ +template <class T> +constexpr void clr_bit(T& x, int n) { + x &= ~(1 << n); +} + +/** + * @brief Get n-th bit in array of words (starting from LSB). + * + * @tparam T Word type + * @param p Array of words + * @param n Index of bit to get + * @return true if set + */ +template <class T> +constexpr bool get_arr_bit(const T* p, unsigned n) { + return get_bit(p[n >> bit_shft<T>()], n & bit_wrap<T>()); +} + +/** + * @brief Set n-th bit in array of words (starting from LSB). + * + * @tparam T Word type + * @param p Array of words + * @param n Index of bit to set + */ +template <class T> +constexpr void set_arr_bit(T* p, unsigned n) { + set_bit(p[n >> bit_shft<T>()], n & bit_wrap<T>()); +} + +/** + * @brief Clear n-th bit in array of words (starting from LSB). + * + * @tparam T Word type + * @param p Array of words + * @param n Index of bit to clear + */ +template <class T> +constexpr void clr_arr_bit(T* p, unsigned n) { + clr_bit(p[n >> bit_shft<T>()], n & bit_wrap<T>()); +} + +/** + * @brief Shift bits left in array of integer elements from least significant bit + * and considering 0-th byte as the right most. + * uint16_t example: 0b10000000'11100001 ==> 0b00000001'11000010. + * + * @tparam T Integer type + * @tparam L Length of array + * @param x Array of integers, nullptr not acceptable! + * @param len Number of elements + */ +template <class T, size_t L> +constexpr void shift_left(T (&x)[L]) { + for (int i = L - 1; i > 0; --i) { + x[i] <<= 1; + x[i] |= x[i - 1] >> bit_wrap<T>(); + } + x[0] <<= 1; +} + +} // namespace utl #endif
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