Function clip

fn clip(v: i32) -> u8

This function has been rewritten to encourage auto-vectorization.

Based on src/dsp/yuv.h from the libwebp source.

const YUV_FIX2: i32 = 6;
const YUV_MASK2: i32 = (256 << YUV_FIX2) - 1;
fn clip(v: i32) -> u8 {
    if (v & !YUV_MASK2) == 0 {
        (v >> YUV_FIX2) as u8
    } else if v < 0 {
        0
    } else {
        255
    }
}