Function log2

include/pybind11/detail/common.h:609–609

PYBIND11_NAMESPACE_BEGIN(detail)

static constexpr int log2(size_t n, int k = 0) { return (n <= 1) ? k : log2(n >> 1, k + 1); }

// Returns the size as a multiple of sizeof(void *), rounded up.
static constexpr size_t size_in_ptrs(size_t s) { return 1 + ((s - 1) >> log2(sizeof(void *))); }