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.
16 * 4.3 FIXED POINT IMPLEMENTATION OF THE RPE-LTP DECODER
19 static void Postprocessing P2((S,s),
24 register word msr = S->msr;
25 register longword ltmp; /* for GSM_ADD */
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 */
36 void Gsm_Decoder P8((S,LARcr, Ncr,bcr,Mcr,xmaxcr,xMcr,s),
39 word * LARcr, /* [0..7] IN */
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 */
47 word * s) /* [0..159] OUT */
50 word erp[40], wt[160];
51 word * drp = S->dp0 + 120;
53 for (j=0; j <= 3; j++, xmaxcr++, bcr++, Ncr++, Mcr++, xMcr += 13) {
55 Gsm_RPE_Decoding( S, *xmaxcr, *Mcr, xMcr, erp );
56 Gsm_Long_Term_Synthesis_Filtering( S, *Ncr, *bcr, erp, drp );
58 for (k = 0; k <= 39; k++) wt[ j * 40 + k ] = drp[ k ];
61 Gsm_Short_Term_Synthesis_Filter( S, LARcr, wt, s );