FreeCalypso > hg > sms-coding-utils

annotate libcoding/gsm7_unpack.c @ 28:6e925aa54727

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libcoding: more sensible naming of GSM time encoding and decoding modules
author Mychaela Falconia <falcon@freecalypso.org>
date Thu, 13 Jun 2024 02:32:11 +0000
parents 7418ca2e9949
children
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7418ca2e9949 libcoding: add functions from freecalypso-tools/uptools/libcoding
Mychaela Falconia <falcon@freecalypso.org>
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1 /*
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2 * This library module implements unpacking of GSM 7-bit data
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3 * from packed octets.
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4 */
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5
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6 #include <sys/types.h>
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7
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8 static u_char shift[8] = {0, 7, 6, 5, 4, 3, 2, 1};
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9
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10 gsm7_unpack(inbuf, outbuf, nseptets)
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11 u_char *inbuf, *outbuf;
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12 unsigned nseptets;
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13 {
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14 u_char *inp = inbuf, *outp = outbuf;
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15 unsigned n;
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16
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17 for (n = 0; n < nseptets; n++) {
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18 *outp++ = (((inp[1] << 8) | inp[0]) >> shift[n&7]) & 0x7F;
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19 if (n & 7)
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20 inp++;
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21 }
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22 }