FreeCalypso > hg > gsm-codec-lib
view libgsmefr/agc.c @ 282:9ee8ad3d4d30
frtest: rm gsmfr-hand-test and gsmfr-max-out utils
These hack programs were never properly documented and were written
only as part of a debug chase, in pursuit of a bug that ultimately
turned out to be in our then-hacky patch to osmo-bts-sysmo,
before beginning of proper patches in Osmocom. These hack programs
need to be dropped from the present sw package because they depend
on old libgsm, and we are eliminating that dependency.
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Sun, 14 Apr 2024 05:44:47 +0000 |
parents | 7b11cbe99a0e |
children |
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/************************************************************************* * * FUNCTION: agc * * PURPOSE: Scales the postfilter output on a subframe basis by automatic * control of the subframe gain. * * DESCRIPTION: * sig_out[n] = sig_out[n] * gain[n]; * where gain[n] is the gain at the nth sample given by * gain[n] = agc_fac * gain[n-1] + (1 - agc_fac) g_in/g_out * g_in/g_out is the square root of the ratio of energy at the input * and output of the postfilter. * *************************************************************************/ #include "gsm_efr.h" #include "typedef.h" #include "namespace.h" #include "basic_op.h" #include "no_count.h" #include "cnst.h" #include "dec_state.h" #include "sig_proc.h" void agc ( struct EFR_decoder_state *st, Word16 *sig_in, /* (i) : postfilter input signal */ Word16 *sig_out, /* (i/o) : postfilter output signal */ Word16 agc_fac, /* (i) : AGC factor */ Word16 l_trm /* (i) : subframe size */ ) { Word16 i, exp; Word16 gain_in, gain_out, g0, gain; Word32 s; Word16 temp; /* calculate gain_out with exponent */ temp = shr (sig_out[0], 2); s = L_mult (temp, temp); for (i = 1; i < l_trm; i++) { temp = shr (sig_out[i], 2); s = L_mac (s, temp, temp); } if (s == 0) { st->past_gain = 0; return; } exp = sub (norm_l (s), 1); gain_out = round (L_shl (s, exp)); /* calculate gain_in with exponent */ temp = shr (sig_in[0], 2); s = L_mult (temp, temp); for (i = 1; i < l_trm; i++) { temp = shr (sig_in[i], 2); s = L_mac (s, temp, temp); } if (s == 0) { g0 = 0; } else { i = norm_l (s); gain_in = round (L_shl (s, i)); exp = sub (exp, i); /*---------------------------------------------------* * g0 = (1-agc_fac) * sqrt(gain_in/gain_out); * *---------------------------------------------------*/ s = L_deposit_l (div_s (gain_out, gain_in)); s = L_shl (s, 7); /* s = gain_out / gain_in */ s = L_shr (s, exp); /* add exponent */ s = Inv_sqrt (s); i = round (L_shl (s, 9)); /* g0 = i * (1-agc_fac) */ g0 = mult (i, sub (32767, agc_fac)); } /* compute gain[n] = agc_fac * gain[n-1] + (1-agc_fac) * sqrt(gain_in/gain_out) */ /* sig_out[n] = gain[n] * sig_out[n] */ gain = st->past_gain; for (i = 0; i < l_trm; i++) { gain = mult (gain, agc_fac); gain = add (gain, g0); sig_out[i] = extract_h (L_shl (L_mult (sig_out[i], gain), 3)); } st->past_gain = gain; return; } void agc2 ( Word16 *sig_in, /* (i) : postfilter input signal */ Word16 *sig_out, /* (i/o) : postfilter output signal */ Word16 l_trm /* (i) : subframe size */ ) { Word16 i, exp; Word16 gain_in, gain_out, g0; Word32 s; Word16 temp; /* calculate gain_out with exponent */ temp = shr (sig_out[0], 2); s = L_mult (temp, temp); for (i = 1; i < l_trm; i++) { temp = shr (sig_out[i], 2); s = L_mac (s, temp, temp); } test (); if (s == 0) { return; } exp = sub (norm_l (s), 1); gain_out = round (L_shl (s, exp)); /* calculate gain_in with exponent */ temp = shr (sig_in[0], 2); s = L_mult (temp, temp); for (i = 1; i < l_trm; i++) { temp = shr (sig_in[i], 2); s = L_mac (s, temp, temp); } test (); if (s == 0) { g0 = 0; move16 (); } else { i = norm_l (s); gain_in = round (L_shl (s, i)); exp = sub (exp, i); /*---------------------------------------------------* * g0 = sqrt(gain_in/gain_out); * *---------------------------------------------------*/ s = L_deposit_l (div_s (gain_out, gain_in)); s = L_shl (s, 7); /* s = gain_out / gain_in */ s = L_shr (s, exp); /* add exponent */ s = Inv_sqrt (s); g0 = round (L_shl (s, 9)); } /* sig_out(n) = gain(n) sig_out(n) */ for (i = 0; i < l_trm; i++) { sig_out[i] = extract_h (L_shl (L_mult (sig_out[i], g0), 3)); move16 (); } return; }