isqrt32_ceil()

fl::i32 fl::gfx::detail::isqrt32_ceil ( fl::i32 n )

inline

Integer square root using Newton iteration Computes ceil(sqrt(n)) for positive integers More accurate than digit-by-digit for the ceiling case.

Definition at line 30 of file integer_math.h.

                                   {
    if (n <= 0) return 0;
    fl::u32 x = (fl::u32)n;
    fl::u32 s = 1u << 16;  // initial guess: sqrt(2^32) = 2^16
    for (int i = 0; i < 8; ++i) {  // 8 iterations converges for 32-bit input
        s = (s + x / s) >> 1;  // Newton iteration: s = (s + n/s) / 2
    }
    return (fl::i32)s;
}

References fl::x.