Function time_alpha8

src/fl/math/time_alpha.cpp.hpp:9–23

namespace fl {

u8 time_alpha8(u32 now, u32 start, u32 end) FL_NOEXCEPT {
    if (now < start) {
        return 0;
    }
    if (now > end) {
        return 255;
    }
    u32 elapsed = now - start;
    u32 total = end - start;
    u32 out = (elapsed * 255) / total;
    if (out > 255) {
        out = 255;
    }
    return static_cast<u8>(out);
}

u16 time_alpha16(u32 now, u32 start, u32 end) FL_NOEXCEPT {
    if (now < start) {