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27
28 /* *
29 * File Name: SKP_Silk_resample_4_3.c *
30 * *
31 * Resamples by a factor 4/3 *
32 * *
33 * Copyright 2009 (c), Skype Limited *
34 * All rights reserved. *
35 * *
36 * Date: 090407 *
37 * */
38
39 #include "SKP_Silk_SigProc_FIX.h"
40
41 #define OUT_SUBFR_LEN 80
42
43 /* Resamples by a factor 4/3 */
SKP_Silk_resample_4_3(SKP_int16 * out,SKP_int32 * S,const SKP_int16 * in,const SKP_int inLen)44 void SKP_Silk_resample_4_3(
45 SKP_int16 *out, /* O: Fs_low signal [inLen * 4/3] */
46 SKP_int32 *S, /* I/O: State vector [7+4+4] */
47 const SKP_int16 *in, /* I: Fs_high signal [inLen] */
48 const SKP_int inLen /* I: input length, must be a multiple of 3 */
49 )
50 {
51 SKP_int outLen, LSubFrameIn, LSubFrameOut;
52 SKP_int16 outH[ 3 * OUT_SUBFR_LEN ];
53 SKP_int16 outHH[ 6 * OUT_SUBFR_LEN ];
54 SKP_int32 scratch[ 9 * OUT_SUBFR_LEN / 2 ];
55
56 /* Check that input is multiple of 3 */
57 SKP_assert( inLen % 3 == 0 );
58
59 outLen = SKP_DIV32_16( SKP_LSHIFT( inLen, 2 ), 3 );
60 while( outLen > 0 ) {
61 LSubFrameOut = SKP_min_int( OUT_SUBFR_LEN, outLen );
62 LSubFrameIn = SKP_SMULWB( 49152, LSubFrameOut );
63
64 /* Upsample two times by a factor 2 */
65 /* Scratch size needs to be: 3 * LSubFrameIn * sizeof( SKP_int32 ) */
66 SKP_Silk_resample_2_1_coarse( in, &S[ 0 ], outH, scratch, LSubFrameIn );
67 /* Scratch size needs to be: 6 * LSubFrameIn * sizeof( SKP_int32 ) */
68 SKP_Silk_resample_2_1_coarse( outH, &S[ 4 ], outHH, scratch, SKP_LSHIFT( LSubFrameIn, 1 ) );
69
70 /* Downsample by a factor 3 */
71 SKP_Silk_resample_1_3( out, &S[ 8 ], outHH, SKP_LSHIFT( LSubFrameIn, 2 ) );
72
73 in += LSubFrameIn;
74 out += LSubFrameOut;
75 outLen -= LSubFrameOut;
76 }
77 }
78