1 /* 2 * Copyright 1992 by Jutta Degener and Carsten Bormann, Technische 3 * Universitaet Berlin. See the accompanying file "COPYRIGHT" for 4 * details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE. 5 */ 6 7 /* $Header: /tmp_amd/presto/export/kbs/jutta/src/gsm/RCS/decode.c,v 1.1 1992/10/28 00:15:50 jutta Exp $ */ 8 9 #include <stdio.h> 10 11 #include "private.h" 12 #include "gsm.h" 13 #include "proto.h" 14 15 /* 16 * 4.3 FIXED POINT IMPLEMENTATION OF THE RPE-LTP DECODER 17 */ 18 19 static void Postprocessing P2((S,s), 20 struct gsm_state * S, 21 register word * s) 22 { 23 register int k; 24 register word msr = S->msr; 25 register longword ltmp; /* for GSM_ADD */ 26 register word tmp; 27 28 for (k = 160; k--; s++) { 29 tmp = GSM_MULT_R( msr, 28180 ); 30 msr = GSM_ADD(*s, tmp); /* Deemphasis */ 31 *s = GSM_ADD(msr, msr) & 0xFFF8; /* Truncation & Upscaling */ 32 } 33 S->msr = msr; 34 } 35 36 void Gsm_Decoder P8((S,LARcr, Ncr,bcr,Mcr,xmaxcr,xMcr,s), 37 struct gsm_state * S, 38 39 word * LARcr, /* [0..7] IN */ 40 41 word * Ncr, /* [0..3] IN */ 42 word * bcr, /* [0..3] IN */ 43 word * Mcr, /* [0..3] IN */ 44 word * xmaxcr, /* [0..3] IN */ 45 word * xMcr, /* [0..13*4] IN */ 46 47 word * s) /* [0..159] OUT */ 48 { 49 int j, k; 50 word erp[40], wt[160]; 51 word * drp = S->dp0 + 120; 52 53 for (j=0; j <= 3; j++, xmaxcr++, bcr++, Ncr++, Mcr++, xMcr += 13) { 54 55 Gsm_RPE_Decoding( S, *xmaxcr, *Mcr, xMcr, erp ); 56 Gsm_Long_Term_Synthesis_Filtering( S, *Ncr, *bcr, erp, drp ); 57 58 for (k = 0; k <= 39; k++) wt[ j * 40 + k ] = drp[ k ]; 59 } 60 61 Gsm_Short_Term_Synthesis_Filter( S, LARcr, wt, s ); 62 Postprocessing(S, s); 63 } 64