ref: dcb06f2c5b8279ece7f3dda0cce4aed3286cd79f
dir: /amr-wb/hp6k.c/
/*-------------------------------------------------------------------* * HP6K.C * *-------------------------------------------------------------------* * 15th order band pass 6kHz to 7kHz FIR filter. * * * * frequency: 4kHz 5kHz 5.5kHz 6kHz 6.5kHz 7kHz 7.5kHz 8kHz * * dB loss: -60dB -45dB -13dB -3dB 0dB -3dB -13dB -45dB * *-------------------------------------------------------------------*/ #include "typedef.h" #include "basic_op.h" #include "acelp.h" #include "count.h" #include "cnst.h" #define L_FIR 31 /* filter coefficients (gain=4.0) */ static Word16 fir_6k_7k[L_FIR] = { -32, 47, 32, -27, -369, 1122, -1421, 0, 3798, -8880, 12349, -10984, 3548, 7766, -18001, 22118, -18001, 7766, 3548, -10984, 12349, -8880, 3798, 0, -1421, 1122, -369, -27, 32, 47, -32 }; void Init_Filt_6k_7k(Word16 mem[]) /* mem[30] */ { Set_zero(mem, L_FIR - 1); return; } void Filt_6k_7k( Word16 signal[], /* input: signal */ Word16 lg, /* input: length of input */ Word16 mem[] /* in/out: memory (size=30) */ ) { Word16 i, j, x[L_SUBFR16k + (L_FIR - 1)]; Word32 L_tmp; Copy(mem, x, L_FIR - 1); for (i = 0; i < lg; i++) { x[i + L_FIR - 1] = shr(signal[i], 2); move16(); /* gain of filter = 4 */ } for (i = 0; i < lg; i++) { L_tmp = 0; move32(); for (j = 0; j < L_FIR; j++) L_tmp = L_mac(L_tmp, x[i + j], fir_6k_7k[j]); signal[i] = round(L_tmp); move16(); } Copy(x + lg, mem, L_FIR - 1); return; }