/*
 * This module implements a wrapper around the main processing functions
 * of our full decoder, handling RTP input per TW-TS-001.
 */

#include <stdint.h>
#include "tw_gsmfr.h"

int gsmfr_fulldec_rtp_in(struct gsmfr_fulldec_state *st, const uint8_t *rtp_pl,
			 unsigned rtp_pl_len, int16_t *pcm)
{
	switch (rtp_pl_len) {
	case 0:
		/* BFI-no-data, but not an invalid RTP input per se */
		gsmfr_fulldec_bfi(st, 0, pcm);
		return 0;
	case 1:
		if ((rtp_pl[0] & 0xF6) != 0xE6)
			goto bad_rtp_input;
		/* TW-TS-001 No_Data frame */
		gsmfr_fulldec_bfi(st, rtp_pl[0] & 1, pcm);
		return 0;
	case GSMFR_RTP_FRAME_LEN:
		if ((rtp_pl[0] & 0xF0) != 0xD0)
			goto bad_rtp_input;
		/* basic RTP format */
		gsmfr_fulldec_good_frame(st, rtp_pl, pcm);
		return 0;
	case GSMFR_RTP_FRAME_LEN+1:
		if ((rtp_pl[0] & 0xF4) != 0xE0)
			goto bad_rtp_input;
		if ((rtp_pl[1] & 0xF0) != 0xD0)
			goto bad_rtp_input;
		/* extended RTP format (TW-TS-001) */
		if (rtp_pl[0] & 0x02)
			gsmfr_fulldec_bfi_bits(st, rtp_pl + 1, rtp_pl[0] & 1,
						pcm);
		else
			gsmfr_fulldec_good_frame(st, rtp_pl + 1, pcm);
		return 0;
	default:
	bad_rtp_input:
		/*
		 * Treat it like BFI-no-data, and tell the caller
		 * that we received an invalid RTP payload.
		 */
		gsmfr_fulldec_bfi(st, 0, pcm);
		return -1;
	}
}