The Tor Browser: media/libopus/silk/fixed/residual_energy16

Implement a real Private Browsing Mode condition by changing the API/ABI;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

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    26 ***********************************************************************/

    28 #ifdef HAVE_CONFIG_H

    29 #include "config.h"

    30 #endif

    32 #include "main_FIX.h"

    34 /* Residual energy: nrg = wxx - 2 * wXx * c + c' * wXX * c */

    35 opus_int32 silk_residual_energy16_covar_FIX(

    36     const opus_int16                *c,                                     /* I    Prediction vector                                                           */

    37     const opus_int32                *wXX,                                   /* I    Correlation matrix                                                          */

    38     const opus_int32                *wXx,                                   /* I    Correlation vector                                                          */

    39     opus_int32                      wxx,                                    /* I    Signal energy                                                               */

    40     opus_int                        D,                                      /* I    Dimension                                                                   */

    41     opus_int                        cQ                                      /* I    Q value for c vector 0 - 15                                                 */

    42 )

    43 {

    44     opus_int   i, j, lshifts, Qxtra;

    45     opus_int32 c_max, w_max, tmp, tmp2, nrg;

    46     opus_int   cn[ MAX_MATRIX_SIZE ];

    47     const opus_int32 *pRow;

    49     /* Safety checks */

    50     silk_assert( D >=  0 );

    51     silk_assert( D <= 16 );

    52     silk_assert( cQ >  0 );

    53     silk_assert( cQ < 16 );

    55     lshifts = 16 - cQ;

    56     Qxtra = lshifts;

    58     c_max = 0;

    59     for( i = 0; i < D; i++ ) {

    60         c_max = silk_max_32( c_max, silk_abs( (opus_int32)c[ i ] ) );

    61     }

    62     Qxtra = silk_min_int( Qxtra, silk_CLZ32( c_max ) - 17 );

    64     w_max = silk_max_32( wXX[ 0 ], wXX[ D * D - 1 ] );

    65     Qxtra = silk_min_int( Qxtra, silk_CLZ32( silk_MUL( D, silk_RSHIFT( silk_SMULWB( w_max, c_max ), 4 ) ) ) - 5 );

    66     Qxtra = silk_max_int( Qxtra, 0 );

    67     for( i = 0; i < D; i++ ) {

    68         cn[ i ] = silk_LSHIFT( ( opus_int )c[ i ], Qxtra );

    69         silk_assert( silk_abs(cn[i]) <= ( silk_int16_MAX + 1 ) ); /* Check that silk_SMLAWB can be used */

    70     }

    71     lshifts -= Qxtra;

    73     /* Compute wxx - 2 * wXx * c */

    74     tmp = 0;

    75     for( i = 0; i < D; i++ ) {

    76         tmp = silk_SMLAWB( tmp, wXx[ i ], cn[ i ] );

    77     }

    78     nrg = silk_RSHIFT( wxx, 1 + lshifts ) - tmp;                         /* Q: -lshifts - 1 */

    80     /* Add c' * wXX * c, assuming wXX is symmetric */

    81     tmp2 = 0;

    82     for( i = 0; i < D; i++ ) {

    83         tmp = 0;

    84         pRow = &wXX[ i * D ];

    85         for( j = i + 1; j < D; j++ ) {

    86             tmp = silk_SMLAWB( tmp, pRow[ j ], cn[ j ] );

    87         }

    88         tmp  = silk_SMLAWB( tmp,  silk_RSHIFT( pRow[ i ], 1 ), cn[ i ] );

    89         tmp2 = silk_SMLAWB( tmp2, tmp,                        cn[ i ] );

    90     }

    91     nrg = silk_ADD_LSHIFT32( nrg, tmp2, lshifts );                       /* Q: -lshifts - 1 */

    93     /* Keep one bit free always, because we add them for LSF interpolation */

    94     if( nrg < 1 ) {

    95         nrg = 1;

    96     } else if( nrg > silk_RSHIFT( silk_int32_MAX, lshifts + 2 ) ) {

    97         nrg = silk_int32_MAX >> 1;

    98     } else {

    99         nrg = silk_LSHIFT( nrg, lshifts + 1 );                           /* Q0 */

   100     }

   101     return nrg;

   103 }

The Tor Browser / file revision

media/libopus/silk/fixed/residual_energy16_FIX.c@ac0c01689b40

media/libopus/silk/fixed/residual_energy16_FIX.c