view libtwamr/prm2bits.c @ 605:63f774192906

gsmhr_decoder_twts002_in(): set BFI=1 SID=1 for invalid SID When a received TW-TS-002 RTP payload indicates invalid SID, which of the 3 possible BFI/SID combinations should we pass to our internal ETSI-based speech decoder or TFO engine? Our original code passed BFI=0 SID=1, but upon further reflection, BFI=1 SID=1 is a better choice. In the corner case where received invalid SID is fed to a full decoder in homed state, setting BFI=1 allows that decoder to emit zeros on PCM and stay homed, instead of launching into full decoding.
author Mychaela Falconia <falcon@freecalypso.org>
date Thu, 04 Dec 2025 21:01:46 +0000
parents ffd48f0a2ab5
children
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/*
 * A cleaner reimplementation of AMR Prm2bits() function.
 */

#include "typedef.h"
#include "namespace.h"
#include "bitno.h"
#include "prm2bits.h"

void Prm2bits(enum Mode mode, const Word16 prm[], Word16 bits[])
{
	const Word16 *t = bitno[mode];
	unsigned nparam = prmno[mode];
	unsigned n, p, mask;
	Word16 *b = bits;

	for (n = 0; n < nparam; n++) {
		p = prm[n];
		mask = 1 << (*t++ - 1);
		for (; mask; mask >>= 1) {
			if (p & mask)
				*b++ = 1;
			else
				*b++ = 0;
		}
	}
}