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