opus-rs 0.1.2

pure Rust implementation of Opus codec
Documentation 
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use crate::silk::define::*;
use crate::silk::macros::*;

/* Entropy constrained matrix-weighted VQ, hard-coded to 5-element vectors, for a single input data vector */
pub fn silk_vq_wmat_ec(
    ind: &mut i8,           /* O    index of best codebook vector               */
    res_nrg_q15: &mut i32,  /* O    best residual energy                        */
    rate_dist_q7: &mut i32, /* O    best total bitrate                          */
    gain_q7_out: &mut i32,  /* O    sum of absolute LTP coefficients            */
    xx_q17: &[i32],         /* I    correlation matrix                          */
    xx_q17_ptr: usize,
    xx_q17_in: &[i32], /* I    correlation vector                          */
    xx_q17_in_ptr: usize,
    cb_q7: &[[i8; LTP_ORDER]], /* I    codebook                                    */
    cb_gain_q7: &[u8],         /* I    codebook effective gain                     */
    cl_q5: &[u8],              /* I    code length for each codebook vector        */
    subfr_len: i32,            /* I    number of samples per subframe              */
    max_gain_q7: i32,          /* I    maximum sum of absolute LTP coefficients    */
    l: i32,                    /* I    number of vectors in codebook               */
) {
    let mut neg_xx_q24 = [0i32; 5];
    let mut sum1_q15: i32;
    let mut sum2_q24: i32;

    /* Negate and convert to new Q domain */
    neg_xx_q24[0] = -silk_lshift(xx_q17_in[xx_q17_in_ptr + 0], 7);
    neg_xx_q24[1] = -silk_lshift(xx_q17_in[xx_q17_in_ptr + 1], 7);
    neg_xx_q24[2] = -silk_lshift(xx_q17_in[xx_q17_in_ptr + 2], 7);
    neg_xx_q24[3] = -silk_lshift(xx_q17_in[xx_q17_in_ptr + 3], 7);
    neg_xx_q24[4] = -silk_lshift(xx_q17_in[xx_q17_in_ptr + 4], 7);

    /* Loop over codebook */
    *rate_dist_q7 = i32::MAX;
    *res_nrg_q15 = i32::MAX;
    *ind = 0;

    for k in 0..l {
        let gain_tmp_q7 = cb_gain_q7[k as usize] as i32;
        /* Weighted rate */
        /* Quantization error: 1 - 2 * xX * cb + cb' * XX * cb */
        sum1_q15 = 32801; // SILK_FIX_CONST( 1.001, 15 )

        /* Penalty for too large gain */
        let penalty = silk_lshift((gain_tmp_q7 - max_gain_q7).max(0), 11);

        let cb_row = &cb_q7[k as usize];

        /* first row of XX_Q17 */
        sum2_q24 = silk_mla(neg_xx_q24[0], xx_q17[xx_q17_ptr + 1], cb_row[1] as i32);
        sum2_q24 = silk_mla(sum2_q24, xx_q17[xx_q17_ptr + 2], cb_row[2] as i32);
        sum2_q24 = silk_mla(sum2_q24, xx_q17[xx_q17_ptr + 3], cb_row[3] as i32);
        sum2_q24 = silk_mla(sum2_q24, xx_q17[xx_q17_ptr + 4], cb_row[4] as i32);
        sum2_q24 = silk_lshift(sum2_q24, 1);
        sum2_q24 = silk_mla(sum2_q24, xx_q17[xx_q17_ptr + 0], cb_row[0] as i32);
        sum1_q15 = silk_smlawb(sum1_q15, sum2_q24, cb_row[0] as i32);

        /* second row of XX_Q17 */
        sum2_q24 = silk_mla(neg_xx_q24[1], xx_q17[xx_q17_ptr + 7], cb_row[2] as i32);
        sum2_q24 = silk_mla(sum2_q24, xx_q17[xx_q17_ptr + 8], cb_row[3] as i32);
        sum2_q24 = silk_mla(sum2_q24, xx_q17[xx_q17_ptr + 9], cb_row[4] as i32);
        sum2_q24 = silk_lshift(sum2_q24, 1);
        sum2_q24 = silk_mla(sum2_q24, xx_q17[xx_q17_ptr + 6], cb_row[1] as i32);
        sum1_q15 = silk_smlawb(sum1_q15, sum2_q24, cb_row[1] as i32);

        /* third row of XX_Q17 */
        sum2_q24 = silk_mla(neg_xx_q24[2], xx_q17[xx_q17_ptr + 13], cb_row[3] as i32);
        sum2_q24 = silk_mla(sum2_q24, xx_q17[xx_q17_ptr + 14], cb_row[4] as i32);
        sum2_q24 = silk_lshift(sum2_q24, 1);
        sum2_q24 = silk_mla(sum2_q24, xx_q17[xx_q17_ptr + 12], cb_row[2] as i32);
        sum1_q15 = silk_smlawb(sum1_q15, sum2_q24, cb_row[2] as i32);

        /* fourth row of XX_Q17 */
        sum2_q24 = silk_mla(neg_xx_q24[3], xx_q17[xx_q17_ptr + 19], cb_row[4] as i32);
        sum2_q24 = silk_lshift(sum2_q24, 1);
        sum2_q24 = silk_mla(sum2_q24, xx_q17[xx_q17_ptr + 18], cb_row[3] as i32);
        sum1_q15 = silk_smlawb(sum1_q15, sum2_q24, cb_row[3] as i32);

        /* last row of XX_Q17 */
        sum2_q24 = silk_lshift(neg_xx_q24[4], 1);
        sum2_q24 = silk_mla(sum2_q24, xx_q17[xx_q17_ptr + 24], cb_row[4] as i32);
        sum1_q15 = silk_smlawb(sum1_q15, sum2_q24, cb_row[4] as i32);

        /* find best */
        if sum1_q15 >= 0 {
            /* Translate residual energy to bits using high-rate assumption (6 dB ==> 1 bit/sample) */
            let bits_res_q8 = silk_smulbb(subfr_len, silk_lin2log(sum1_q15 + penalty) - (15 << 7));
            /* In the following line we reduce the codelength component by half ("-1"); seems to slightly improve quality */
            let bits_tot_q8 = bits_res_q8 + ((cl_q5[k as usize] as i32) << (3 - 1));
            if bits_tot_q8 <= *rate_dist_q7 {
                *rate_dist_q7 = bits_tot_q8;
                *res_nrg_q15 = sum1_q15 + penalty;
                *ind = k as i8;
                *gain_q7_out = gain_tmp_q7;
            }
        }

        /* Go to next cbk vector */
    }
}