cuda::bit_reverse

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cuda::bit_reverse#

2026-10-07

1 min read time

Applies to Linux and Windows

This page documents cuda::bit_reverse, which reverses the order of bits in an unsigned integer value.

template <typename T>
[[nodiscard]] constexpr T
bit_reverse(T value) noexcept;

The function reverses the order of bits in a value.

Parameters

value: Input value.

Return value

Value with reversed bits.

Constraints

T is an unsigned integer type.

Performance considerations

In host code the function uses __builtin_bitreverse<N> with clang.

Note

When the input values are run-time values that the compiler can resolve at compile-time, e.g. an index of a loop with a fixed number of iterations, using the function could not be optimal.

Example#

#include <cuda/bit>
#include <cuda/std/cassert>

__global__ void bit_reverse_kernel() {
    assert(bitfield_reverse(0u) == ~0u);
    assert(bitfield_reverse(uint8_t{0b00001011}) == uint8_t{0b11010000});
}

int main() {
    bit_reverse_kernel<<<1, 1>>>();
    hipDeviceSynchronize();
    return 0;
}
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