+
−/*
+
− * The function implemented in this module groks the first octet of
+
− * an RFC 4867 payload and tells the calling application how many more
+
− * bytes need to be read, or if the frame type is invalid.
+
− */
+
−
+
−#include <stdint.h>
+
−#include "tw_amr.h"
+
−
+
−static const uint8_t extra_bytes_per_ft[9] =
+
−		{12, 13, 15, 17, 19, 20, 26, 31, 5};
+
−
+
−int amr_ietf_grok_first_octet(uint8_t fo)
+
−{
+
−	uint8_t ft;
+
−
+
−	ft = (fo & 0x78) >> 3;
+
−	if (ft == AMR_FT_NODATA)
+
−		return 0;
+
−	if (ft > MRDTX)
+
−		return -1;
+
−	return extra_bytes_per_ft[ft];
+
−}