fn from_float()

in candle-core/src/quantized/k_quants.rs [1788:1825]

• 36 lines of code
• 9 McCabe index (conditional complexity)

    fn from_float(xs: &[f32], ys: &mut [Self]) -> Result<()> {
        let k = xs.len();
        if k % QK_K != 0 {
            crate::bail!("quantize_row_q8k: {k} is not divisible by {QK_K}")
        }
        for (i, y) in ys.iter_mut().enumerate() {
            let mut max = 0f32;
            let mut amax = 0f32;
            let xs = &xs[i * QK_K..(i + 1) * QK_K];
            for &x in xs.iter() {
                if amax < x.abs() {
                    amax = x.abs();
                    max = x;
                }
            }
            if amax == 0f32 {
                y.d = 0f32;
                y.qs.fill(0)
            } else {
                let iscale = -128f32 / max;
                for (j, q) in y.qs.iter_mut().enumerate() {
                    // ggml uses nearest_int with bit magic here, maybe we want the same
                    // but we would have to test and benchmark it.
                    let v = (iscale * xs[j]).round();
                    *q = v.min(127.) as i8
                }
                for j in 0..QK_K / 16 {
                    let mut sum = 0i32;
                    for ii in 0..16 {
                        sum += y.qs[j * 16 + ii] as i32
                    }
                    y.bsums[j] = sum as i16
                }
                y.d = 1.0 / iscale
            }
        }
        Ok(())
    }