59 lines
1.4 KiB
C
59 lines
1.4 KiB
C
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/*
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* Copyright 1992 by Jutta Degener and Carsten Bormann, Technische
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* Universitaet Berlin. See the accompanying file "COPYRIGHT" for
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* details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
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*/
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#include <stdio.h>
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#include "gsm610_priv.h"
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/*
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* 4.3 FIXED POINT IMPLEMENTATION OF THE RPE-LTP DECODER
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*/
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static void Postprocessing (
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struct gsm_state * S,
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register int16_t * s)
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{
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register int k ;
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register int16_t msr = S->msr ;
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register int16_t tmp ;
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for (k = 160 ; k-- ; s++)
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{ tmp = GSM_MULT_R (msr, 28180) ;
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msr = GSM_ADD (*s, tmp) ; /* Deemphasis */
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*s = GSM_ADD (msr, msr) & 0xFFF8 ; /* Truncation & Upscaling */
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}
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S->msr = msr ;
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}
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void Gsm_Decoder (
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struct gsm_state * S,
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int16_t * LARcr, /* [0..7] IN */
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int16_t * Ncr, /* [0..3] IN */
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int16_t * bcr, /* [0..3] IN */
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int16_t * Mcr, /* [0..3] IN */
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int16_t * xmaxcr, /* [0..3] IN */
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int16_t * xMcr, /* [0..13*4] IN */
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int16_t * s) /* [0..159] OUT */
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{
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int j, k ;
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int16_t erp [40], wt [160] ;
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int16_t *drp = S->dp0 + 120 ;
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for (j = 0 ; j <= 3 ; j++, xmaxcr++, bcr++, Ncr++, Mcr++, xMcr += 13)
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{ Gsm_RPE_Decoding (/*-S,-*/ *xmaxcr, *Mcr, xMcr, erp) ;
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Gsm_Long_Term_Synthesis_Filtering (S, *Ncr, *bcr, erp, drp) ;
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for (k = 0 ; k <= 39 ; k++) wt [j * 40 + k] = drp [k] ;
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}
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Gsm_Short_Term_Synthesis_Filter (S, LARcr, wt, s) ;
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Postprocessing (S, s) ;
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}
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