| /* |
| * 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 <stdlib.h> |
| #include <string.h> |
| |
| #include "gsm610_priv.h" |
| |
| /* |
| * 4.2 FIXED POINT IMPLEMENTATION OF THE RPE-LTP CODER |
| */ |
| |
| void Gsm_Coder ( |
| |
| struct gsm_state * State, |
| |
| word * s, /* [0..159] samples IN */ |
| |
| /* |
| * The RPE-LTD coder works on a frame by frame basis. The length of |
| * the frame is equal to 160 samples. Some computations are done |
| * once per frame to produce at the output of the coder the |
| * LARc[1..8] parameters which are the coded LAR coefficients and |
| * also to realize the inverse filtering operation for the entire |
| * frame (160 samples of signal d[0..159]). These parts produce at |
| * the output of the coder: |
| */ |
| |
| word * LARc, /* [0..7] LAR coefficients OUT */ |
| |
| /* |
| * Procedure 4.2.11 to 4.2.18 are to be executed four times per |
| * frame. That means once for each sub-segment RPE-LTP analysis of |
| * 40 samples. These parts produce at the output of the coder: |
| */ |
| |
| word * Nc, /* [0..3] LTP lag OUT */ |
| word * bc, /* [0..3] coded LTP gain OUT */ |
| word * Mc, /* [0..3] RPE grid selection OUT */ |
| word * xmaxc,/* [0..3] Coded maximum amplitude OUT */ |
| word * xMc /* [13*4] normalized RPE samples OUT */ |
| ) |
| { |
| int k; |
| word * dp = State->dp0 + 120; /* [ -120...-1 ] */ |
| word * dpp = dp; /* [ 0...39 ] */ |
| |
| word so[160]; |
| |
| Gsm_Preprocess (State, s, so); |
| Gsm_LPC_Analysis (State, so, LARc); |
| Gsm_Short_Term_Analysis_Filter (State, LARc, so); |
| |
| for (k = 0; k <= 3; k++, xMc += 13) { |
| |
| Gsm_Long_Term_Predictor ( State, |
| so+k*40, /* d [0..39] IN */ |
| dp, /* dp [-120..-1] IN */ |
| State->e + 5, /* e [0..39] OUT */ |
| dpp, /* dpp [0..39] OUT */ |
| Nc++, |
| bc++); |
| |
| Gsm_RPE_Encoding ( /*-S,-*/ |
| State->e + 5, /* e ][0..39][ IN/OUT */ |
| xmaxc++, Mc++, xMc ); |
| /* |
| * Gsm_Update_of_reconstructed_short_time_residual_signal |
| * ( dpp, State->e + 5, dp ); |
| */ |
| |
| { register int i; |
| for (i = 0; i <= 39; i++) |
| dp[ i ] = GSM_ADD( State->e[5 + i], dpp[i] ); |
| } |
| dp += 40; |
| dpp += 40; |
| |
| } |
| (void)memcpy( (char *)State->dp0, (char *)(State->dp0 + 160), |
| 120 * sizeof(*State->dp0) ); |
| } |
| |