A C++ template library for embedded applications
Embedded Template Library
MIT licensed
Designed and
maintained by
John Wellbelove
Binary
Utility functions for manipulating binary numbers.
ETL_CONSTEXPR = constexpr for C++11 or above
ETL_CONSTEXPR14 = constexpr for C++14 or above
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Rotate
Rotate the bits in the value left or right.
template <typename T>
ETL_CONSTEXPR14 T rotate_left(T value)
template <typename T>
ETL_CONSTEXPR14 T rotate_left(T value, size_t distance)
template <typename T>
ETL_CONSTEXPR14 T rotate_right(T value)
template <typename T>
ETL_CONSTEXPR14 T rotate_right(T value, size_t distance)
template <typename T>
ETL_CONSTEXPR14 T rotate(T value, typename etl::make_signed<size_t>::type distance)
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Reverse bits
Reverse the order of the bits in a value.
template <typename T>
ETL_CONSTEXPR14 T reverse_bits(T value)
The structures below define a member constant value that is Value reversed in bits.
template <int8_t Value>
struct reverse_bits_const<int8_t, Value>
template <uint8_t Value>
struct reverse_bits_const<uint8_t, Value>
template <int16_t Value>
struct reverse_bits_const<int16_t, Value>
template <uint16_t Value>
struct reverse_bits_const<uint16_t, Value>
template <int32_t Value>
struct reverse_bits_const<int32_t, Value>
template <uint32_t Value>
struct reverse_bits_const<uint32_t, Value>
template <int64_t Value>
struct reverse_bits_const<int64_t, Value>
template <uint64_t Value>
struct reverse_bits_const<uint64_t, Value>
Defines value The reversed bits.
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Reverse bytes
Reverse the order of the bytes in a value.
template <typename T>
ETL_CONSTEXPR T reverse_bytes(T value)
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Gray to binary
Converts a gray code value to binary.
template <typename T>
ETL_CONSTEXPR14 T gray_to_binary(T value)
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Binary to gray
Converts a binary value to the gray code equivalent.
template <typename T>
ETL_CONSTEXPR T binary_to_gray(T value)
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Count bits
Counts the number of set bits in a value.
template <typename T>
ETL_CONSTEXPR14 T count_bits(T value)
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Parity
Returns 1 if the parity of the value is odd, 0 if it is even.
template <typename T>
ETL_CONSTEXPR14 T parity(T value)
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Max value for N bits
Returns maximum unsigned value a particular number of bits can represent.
template <size_t NBits>
struct max_value_for_nbits
value_type The type for the value.
value The maximum value.
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Fold bits
Fold a binary number down to a set number of bits using XOR.
template <typename TReturn, size_t NBits, typename TValue>
ETL_CONSTEXPR14 TReturn fold_bits(TValue value)
Example
0xE8C9AACCBC3D9A8F folded down to 20 bits = 0x998E8
uint32_t result = etl::fold_bits<uint32_t, 20>(0xE8C9AACCBC3D9A8F);
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Sign extend
Sign extends a binary number.
template <typename TReturn, const size_t NBits, typename TValue>
ETL_CONSTEXPR14 TReturn sign_extend(TValue value)
Converts an N bit binary number, where bit N-1 is the sign bit, to a signed integral type.
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template <typename TReturn, const size_t NBits, const size_t Shift, typename TValue>
ETL_CONSTEXPR14 TReturn sign_extend(TValue value)
Converts an N bit binary number, where bit N-1 is the sign bit, and SHIFT is the right shift amount, to a signed integral
type.
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template <typename TReturn, typename TValue>
ETL_CONSTEXPR14 TReturn sign_extend(TValue value, size_t nbits)
Converts an N bit binary number, where bit N-1 is the sign bit, to a signed integral type.
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template <typename TReturn, typename TValue>
ETL_CONSTEXPR14 TReturn sign_extend(TValue value, size_t nbits, size_t shift)
Converts an N bit binary number, where bit N-1 is the sign bit, and shift is the right shift amount, to a signed integral
type.
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Count leading zeros
Counts the number of leading zeros in a binary number
template <typename T>
ETL_CONSTEXPR14 T count_leading_zeros(T value)
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Count trailing zeros
Counts the number of trailing zeros in a binary number
template <typename T>
ETL_CONSTEXPR14 T count_trailing_zeros(T value)
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Count leading ones
Counts the number of leading ones in a binary number
template <typename T>
ETL_CONSTEXPR14 T count_leading_ones(T value)
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Count trailing ones
Counts the number of trailing ones in a binary number
template <typename T>
ETL_CONSTEXPR14 T count_trailing_ones(T value)
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First set position
Finds the index of the first set bit from lsb.
template <typename T>
ETL_CONSTEXPR14 uint_least8_t first_set_bit_position(T value)
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First clear position
Finds the index of the first clear bit from lsb.
template <typename T>
ETL_CONSTEXPR14 uint_least8_t first_clear_bit_position(T value)
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First position of bit in the specified state
Finds the index of the first bit in the specified state, from lsb.
template <typename T>
ETL_CONSTEXPR14 uint_least8_t first_bit_position(bool state, T value)
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Fill a binary value with a pattern
Fills a value of the specified width with a repeating binary pattern.
Run time
template <typename TResult, typename TValue>
ETL_CONSTEXPR TResult binary_fill(TValue value)
Generate 0x12121212
etl::binary_fill<uint32_t>(uint8_t(0x12));
Partial compile time
template <typename TResult, typename TValue, TValue N>
ETL_CONSTEXPR TResult binary_fill(TValue value)
Generate 0x12121212
etl::binary_fill<uint32_t, uint8_t, 0x12>();
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Check a binary value for a zero byte
Checks to see if a value contains a byte of value zero.
Run time
template <typename TValue>
ETL_CONSTEXPR14 bool has_zero_byte(const TValue value)
etl::has_zero_byte(uint32_t(0x01234567)) == false
etl::has_zero_byte(uint32_t(0x01230067)) == true
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Check a binary value for a particular value byte
Checks to see if a value contains a byte of a particular value.
Run time
template <typename TValue>
ETL_CONSTEXPR14 bool has_byte_n(TValue value, uint8_t n)
etl::has_byte_n(uint32_t(0x01234567), 0x12) == false
etl::has_byte_n(uint32_t(0x01234567), 0x45) == true
Partial compile time
template <typename TValue, TValue N>
ETL_CONSTEXPR14 bool has_byte_n(TValue value)
etl::has_byte_n<0x12>(uint32_t(0x01234567)) == false
etl::has_byte_n<0x45>(uint32_t(0x01234567)) == true
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Merge two values
Merges two binary values according to a mask.
Bits set in the mask select bits in the first value, clear bits select those in the second.
template <typename T>
ETL_CONSTEXPR T binary_merge(T first, T second, T mask)
uint8_t first = 0x12;
uint8_t second = 0x34;
const uint8_t mask = 0xF0;
etl::binary_merge(first, second, mask) Equals 0x14
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template <typename T, T Mask>
ETL_CONSTEXPR T binary_merge(T first, T second)
uint8_t first = 0x12;
uint8_t second = 0x34;
const uint8_t mask = 0xF0;
etl::binary_merge<uint8_t, mask>(first, second) Equals 0x14
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Interleave two values
Interleaves two values such that bits abcd and efgh will result in eafbgchd.
ETL_CONSTEXPR14 uint16_t binary_interleave(uint8_t first, uint8_t second);
ETL_CONSTEXPR14 int16_t binary_interleave(int8_t first, int8_t second);
ETL_CONSTEXPR14 uint32_t binary_interleave(uint16_t first, uint16_t second);
ETL_CONSTEXPR14 int32_t binary_interleave(int16_t first, int16_t second);
ETL_CONSTEXPR14 uint64_t binary_interleave(uint32_t first, uint32_t second);
ETL_CONSTEXPR14 int64_t binary_interleave(int32_t first, int32_t second);
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Odd / Even
Determines the odd or evenness of a value.
template <typename T>
ETL_CONSTEXPR bool is_odd(T value)
template <typename T>
ETL_CONSTEXPR bool is_even(template <typename T> value);
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Constants
enum binary_constant
An enumeration of 256 constants from b00000000 to b11111111 (0 to 255)
enum bit_constant
An enumeration of 32 constants from b0 to b31 (1 to 4294967296)
template <size_t Position>
struct bit
value_type The type of the value.
value The value of the bit at POSITION.
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Creating bit masks
These classes and constexpr functions help create lsb and msb masks.
template <typename T, size_t NBits>
class lsb_mask;
Defines the member constant value as a binary value of NBits '1' shift to the LSB.
e.g. lsb_mask<int8_t, 3>::value == 0b00000111
20.34.0
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template <typename T>
ETL_CONSTEXPR T make_lsb_mask(size_t nbits)
Returns a binary value of nbits '1' shift to the LSB.
e.g. make_lsb_mask<int8_t>(3) == 0b00000111
20.34.0
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template <typename T, size_t NBits>
ETL_CONSTEXPR T make_lsb_mask()
Returns a binary value of nbits '1' shift to the LSB.
e.g. make_lsb_mask<int8_t, 3>() == 0b00000111
20.38.7
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template <typename T, size_t NBits>
class msb_mask;
Returns a binary value of nbits '1' shift to the MSB.
msb_mask<int8_t, 3>::value == 0b11100000
20.34.0
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template <typename T>
ETL_CONSTEXPR T make_msb_mask(size_t nbits)
Defines the member constant value as a binary value of NBits '1' shift to the MSB.
e.g. make_msb_mask<int8_t>(3) == 0b11100000
20.34.0
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template <typename T, size_t NBits>
ETL_CONSTEXPR T make_msb_mask()
Defines the member constant value as a binary value of NBits '1' shift to the MSB.
e.g. make_msb_mask<int8_t, 3>() == 0b11100000
20.38.7
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Bit manipulation functors
These functors are most useful where lambdas are not available.
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binary_not
template <typename T>
struct binary_not : public etl::unary_function<T, T>;
20.38.11
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ETL_CONTEXPR
binary_not()
Default constructor.
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ETL_CONTEXPR
ETL_NODISCARD
T operator(T value)
Returns ~value.
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binary_and
template <typename T>
struct binary_and : public etl::unary_function<T, T>;
20.38.11
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ETL_CONTEXPR
binary_and(T and_value)
Constructor.
Uses and_value as the second parameter in operator().
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ETL_CONTEXPR
ETL_NODISCARD
T operator(T value)
Returns value & and_value.
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binary_or
template <typename T>
struct binary_or : public etl::unary_function<T, T>;
20.38.11
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ETL_CONTEXPR
binary_and(T or_value)
Constructor.
Uses or_value as the second parameter in operator().
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ETL_CONTEXPR
ETL_NODISCARD
T operator(T value)
Returns value | or_value.
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binary_xor
template <typename T>
struct binary_xor : public etl::unary_function<T, T>;
20.38.11
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ETL_CONTEXPR
binary_xor(T xor_value)
Constructor.
Uses xor_value as the second parameter in operator().
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ETL_CONTEXPR
ETL_NODISCARD
T operator(T value)
Returns value ^ xor_value.
binary.h
