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comparison libtwamr/ietf_fo.c @ 441:ebe499058c63

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libtwamr: implement API functions for RFC 4867 I/O
author Mychaela Falconia <falcon@freecalypso.org>
date Thu, 09 May 2024 07:06:31 +0000
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440:bc736a8654af 441:ebe499058c63
1 /*
2 * The function implemented in this module groks the first octet of
3 * an RFC 4867 payload and tells the calling application how many more
4 * bytes need to be read, or if the frame type is invalid.
5 */
6
7 #include <stdint.h>
8 #include "tw_amr.h"
9
10 static const uint8_t extra_bytes_per_ft[9] =
11 {12, 13, 15, 17, 19, 20, 26, 31, 5};
12
13 int amr_ietf_grok_first_octet(uint8_t fo)
14 {
15 uint8_t ft;
16
17 ft = (fo & 0x78) >> 3;
18 if (ft == AMR_FT_NODATA)
19 return 0;
20 if (ft > MRDTX)
21 return -1;
22 return extra_bytes_per_ft[ft];
23 }