Vignesh Venkatasubramanian | 2bd8b54 | 2014-02-20 10:50:35 -0800 | [diff] [blame] | 1 | /*********************************************************************** |
| 2 | Copyright (c) 2006-2011, Skype Limited. All rights reserved. |
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| 27 | |
| 28 | /* * |
| 29 | * silk_biquad_alt.c * |
| 30 | * * |
| 31 | * Second order ARMA filter * |
| 32 | * Can handle slowly varying filter coefficients * |
| 33 | * */ |
| 34 | |
| 35 | #ifdef HAVE_CONFIG_H |
| 36 | #include "config.h" |
| 37 | #endif |
| 38 | |
| 39 | #include "SigProc_FIX.h" |
| 40 | |
| 41 | /* Second order ARMA filter, alternative implementation */ |
Felicia Lim | 0c2090c | 2017-07-05 17:36:56 -0700 | [diff] [blame] | 42 | void silk_biquad_alt_stride1( |
Vignesh Venkatasubramanian | 2bd8b54 | 2014-02-20 10:50:35 -0800 | [diff] [blame] | 43 | const opus_int16 *in, /* I input signal */ |
| 44 | const opus_int32 *B_Q28, /* I MA coefficients [3] */ |
| 45 | const opus_int32 *A_Q28, /* I AR coefficients [2] */ |
| 46 | opus_int32 *S, /* I/O State vector [2] */ |
| 47 | opus_int16 *out, /* O output signal */ |
Felicia Lim | 0c2090c | 2017-07-05 17:36:56 -0700 | [diff] [blame] | 48 | const opus_int32 len /* I signal length (must be even) */ |
Vignesh Venkatasubramanian | 2bd8b54 | 2014-02-20 10:50:35 -0800 | [diff] [blame] | 49 | ) |
| 50 | { |
| 51 | /* DIRECT FORM II TRANSPOSED (uses 2 element state vector) */ |
| 52 | opus_int k; |
| 53 | opus_int32 inval, A0_U_Q28, A0_L_Q28, A1_U_Q28, A1_L_Q28, out32_Q14; |
| 54 | |
| 55 | /* Negate A_Q28 values and split in two parts */ |
| 56 | A0_L_Q28 = ( -A_Q28[ 0 ] ) & 0x00003FFF; /* lower part */ |
| 57 | A0_U_Q28 = silk_RSHIFT( -A_Q28[ 0 ], 14 ); /* upper part */ |
| 58 | A1_L_Q28 = ( -A_Q28[ 1 ] ) & 0x00003FFF; /* lower part */ |
| 59 | A1_U_Q28 = silk_RSHIFT( -A_Q28[ 1 ], 14 ); /* upper part */ |
| 60 | |
| 61 | for( k = 0; k < len; k++ ) { |
| 62 | /* S[ 0 ], S[ 1 ]: Q12 */ |
Felicia Lim | 0c2090c | 2017-07-05 17:36:56 -0700 | [diff] [blame] | 63 | inval = in[ k ]; |
Vignesh Venkatasubramanian | 2bd8b54 | 2014-02-20 10:50:35 -0800 | [diff] [blame] | 64 | out32_Q14 = silk_LSHIFT( silk_SMLAWB( S[ 0 ], B_Q28[ 0 ], inval ), 2 ); |
| 65 | |
| 66 | S[ 0 ] = S[1] + silk_RSHIFT_ROUND( silk_SMULWB( out32_Q14, A0_L_Q28 ), 14 ); |
| 67 | S[ 0 ] = silk_SMLAWB( S[ 0 ], out32_Q14, A0_U_Q28 ); |
| 68 | S[ 0 ] = silk_SMLAWB( S[ 0 ], B_Q28[ 1 ], inval); |
| 69 | |
| 70 | S[ 1 ] = silk_RSHIFT_ROUND( silk_SMULWB( out32_Q14, A1_L_Q28 ), 14 ); |
| 71 | S[ 1 ] = silk_SMLAWB( S[ 1 ], out32_Q14, A1_U_Q28 ); |
| 72 | S[ 1 ] = silk_SMLAWB( S[ 1 ], B_Q28[ 2 ], inval ); |
| 73 | |
| 74 | /* Scale back to Q0 and saturate */ |
Felicia Lim | 0c2090c | 2017-07-05 17:36:56 -0700 | [diff] [blame] | 75 | out[ k ] = (opus_int16)silk_SAT16( silk_RSHIFT( out32_Q14 + (1<<14) - 1, 14 ) ); |
| 76 | } |
| 77 | } |
| 78 | |
| 79 | void silk_biquad_alt_stride2_c( |
| 80 | const opus_int16 *in, /* I input signal */ |
| 81 | const opus_int32 *B_Q28, /* I MA coefficients [3] */ |
| 82 | const opus_int32 *A_Q28, /* I AR coefficients [2] */ |
| 83 | opus_int32 *S, /* I/O State vector [4] */ |
| 84 | opus_int16 *out, /* O output signal */ |
| 85 | const opus_int32 len /* I signal length (must be even) */ |
| 86 | ) |
| 87 | { |
| 88 | /* DIRECT FORM II TRANSPOSED (uses 2 element state vector) */ |
| 89 | opus_int k; |
| 90 | opus_int32 A0_U_Q28, A0_L_Q28, A1_U_Q28, A1_L_Q28, out32_Q14[ 2 ]; |
| 91 | |
| 92 | /* Negate A_Q28 values and split in two parts */ |
| 93 | A0_L_Q28 = ( -A_Q28[ 0 ] ) & 0x00003FFF; /* lower part */ |
| 94 | A0_U_Q28 = silk_RSHIFT( -A_Q28[ 0 ], 14 ); /* upper part */ |
| 95 | A1_L_Q28 = ( -A_Q28[ 1 ] ) & 0x00003FFF; /* lower part */ |
| 96 | A1_U_Q28 = silk_RSHIFT( -A_Q28[ 1 ], 14 ); /* upper part */ |
| 97 | |
| 98 | for( k = 0; k < len; k++ ) { |
| 99 | /* S[ 0 ], S[ 1 ], S[ 2 ], S[ 3 ]: Q12 */ |
| 100 | out32_Q14[ 0 ] = silk_LSHIFT( silk_SMLAWB( S[ 0 ], B_Q28[ 0 ], in[ 2 * k + 0 ] ), 2 ); |
| 101 | out32_Q14[ 1 ] = silk_LSHIFT( silk_SMLAWB( S[ 2 ], B_Q28[ 0 ], in[ 2 * k + 1 ] ), 2 ); |
| 102 | |
| 103 | S[ 0 ] = S[ 1 ] + silk_RSHIFT_ROUND( silk_SMULWB( out32_Q14[ 0 ], A0_L_Q28 ), 14 ); |
| 104 | S[ 2 ] = S[ 3 ] + silk_RSHIFT_ROUND( silk_SMULWB( out32_Q14[ 1 ], A0_L_Q28 ), 14 ); |
| 105 | S[ 0 ] = silk_SMLAWB( S[ 0 ], out32_Q14[ 0 ], A0_U_Q28 ); |
| 106 | S[ 2 ] = silk_SMLAWB( S[ 2 ], out32_Q14[ 1 ], A0_U_Q28 ); |
| 107 | S[ 0 ] = silk_SMLAWB( S[ 0 ], B_Q28[ 1 ], in[ 2 * k + 0 ] ); |
| 108 | S[ 2 ] = silk_SMLAWB( S[ 2 ], B_Q28[ 1 ], in[ 2 * k + 1 ] ); |
| 109 | |
| 110 | S[ 1 ] = silk_RSHIFT_ROUND( silk_SMULWB( out32_Q14[ 0 ], A1_L_Q28 ), 14 ); |
| 111 | S[ 3 ] = silk_RSHIFT_ROUND( silk_SMULWB( out32_Q14[ 1 ], A1_L_Q28 ), 14 ); |
| 112 | S[ 1 ] = silk_SMLAWB( S[ 1 ], out32_Q14[ 0 ], A1_U_Q28 ); |
| 113 | S[ 3 ] = silk_SMLAWB( S[ 3 ], out32_Q14[ 1 ], A1_U_Q28 ); |
| 114 | S[ 1 ] = silk_SMLAWB( S[ 1 ], B_Q28[ 2 ], in[ 2 * k + 0 ] ); |
| 115 | S[ 3 ] = silk_SMLAWB( S[ 3 ], B_Q28[ 2 ], in[ 2 * k + 1 ] ); |
| 116 | |
| 117 | /* Scale back to Q0 and saturate */ |
| 118 | out[ 2 * k + 0 ] = (opus_int16)silk_SAT16( silk_RSHIFT( out32_Q14[ 0 ] + (1<<14) - 1, 14 ) ); |
| 119 | out[ 2 * k + 1 ] = (opus_int16)silk_SAT16( silk_RSHIFT( out32_Q14[ 1 ] + (1<<14) - 1, 14 ) ); |
Vignesh Venkatasubramanian | 2bd8b54 | 2014-02-20 10:50:35 -0800 | [diff] [blame] | 120 | } |
| 121 | } |