FreeCalypso > hg > sms-coding-utils

comparison libcoding/grokdcs.c @ 27:7418ca2e9949

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libcoding: add functions from freecalypso-tools/uptools/libcoding that are needed for sms-pdu-decode & pcm-sms-decode
author Mychaela Falconia <falcon@freecalypso.org>
date Thu, 13 Jun 2024 02:29:29 +0000
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26:c8cb05b69118 27:7418ca2e9949
1 /*
2 * This library module implements the function that distills the complex
3 * set of possible SMS DCS octet values to just one of 4 possibilities:
4 * 7-bit text (7), 8-bit data octets (8), UCS-2 text (16) or compressed
5 * data (9).
6 *
7 * The decoding is based on the 3GPP TS 23.038 V11.0.0 spec;
8 * reserved encodings are treated as 7-bit text as the spec instructs.
9 */
10
11 sms_dcs_classify(dcs)
12 {
13 if (!(dcs & 0x80)) {
14 if (dcs & 0x20)
15 return(9);
16 switch (dcs & 0xC) {
17 case 0:
18 return(7);
19 case 4:
20 return(8);
21 case 8:
22 return(16);
23 default:
24 /* reserved, treating as 7-bit per the spec */
25 return(7);
26 }
27 }
28 switch (dcs & 0xF0) {
29 case 0x80:
30 case 0x90:
31 case 0xA0:
32 case 0xB0:
33 /* reserved, treating as 7-bit per the spec */
34 return(7);
35 case 0xC0:
36 case 0xD0:
37 return(7);
38 case 0xE0:
39 return(16);
40 case 0xF0:
41 if (dcs & 4)
42 return(8);
43 else
44 return(7);
45 }
46 }