fn from_float()

in candle-core/src/quantized/k_quants.rs [1643:1713]
65 lines of code
11 McCabe index (conditional complexity)

    fn from_float(xs: &[f32], ys: &mut [Self]) -> Result<()> {
        if xs.len() != ys.len() * Self::BLCK_SIZE {
            crate::bail!(
                "quantize_row_q6k: size mismatch {} {} {}",
                xs.len(),
                ys.len(),
                Self::BLCK_SIZE
            )
        }
        let mut l = [0i8; QK_K];
        let mut scales = [0f32; QK_K / 16];
        let mut x = xs.as_ptr();
        let l = l.as_mut_ptr();
        unsafe {
            for y in ys.iter_mut() {
                let mut max_scale = 0f32;
                let mut max_abs_scale = 0f32;
                for (ib, scale_) in scales.iter_mut().enumerate() {
                    let scale = make_qx_quants(16, 32, x.add(16 * ib), l.add(16 * ib), 1);
                    *scale_ = scale;
                    let abs_scale = scale.abs();
                    if abs_scale > max_abs_scale {
                        max_abs_scale = abs_scale;
                        max_scale = scale
                    }
                }

                let iscale = -128f32 / max_scale;
                y.d = f16::from_f32(1.0 / iscale);

                for (y_scale, scale) in y.scales.iter_mut().zip(scales.iter()) {
                    *y_scale = nearest_int(iscale * scale).min(127) as i8
                }

                for (j, &y_scale) in y.scales.iter().enumerate() {
                    let d = y.d.to_f32() * y_scale as f32;
                    if d == 0. {
                        continue;
                    }
                    for ii in 0..16 {
                        let ll = nearest_int(*x.add(16 * j + ii) / d).clamp(-32, 31);
                        *l.add(16 * j + ii) = (ll + 32) as i8
                    }
                }

                let mut ql = y.ql.as_mut_ptr();
                let mut qh = y.qh.as_mut_ptr();

                for j in (0..QK_K).step_by(128) {
                    for l_idx in 0..32 {
                        let q1 = *l.add(j + l_idx) & 0xF;
                        let q2 = *l.add(j + l_idx + 32) & 0xF;
                        let q3 = *l.add(j + l_idx + 64) & 0xF;
                        let q4 = *l.add(j + l_idx + 96) & 0xF;
                        *ql.add(l_idx) = (q1 | (q3 << 4)) as u8;
                        *ql.add(l_idx + 32) = (q2 | (q4 << 4)) as u8;
                        *qh.add(l_idx) = ((*l.add(j + l_idx) >> 4)
                            | ((*l.add(j + l_idx + 32) >> 4) << 2)
                            | ((*l.add(j + l_idx + 64) >> 4) << 4)
                            | ((*l.add(j + l_idx + 96) >> 4) << 6))
                            as u8;
                    }
                    ql = ql.add(64);
                    qh = qh.add(32);
                }

                x = x.add(QK_K)
            }
        }
        Ok(())
    }