annotate uptools/libcoding/gsm7_unpack.c @ 407:19e5a3e2f9c0

fcup-settime: moved time() retrieval a little closer to the output A fundamental problem with all simple time transfer tools is that there is always some delay between the time retrieval on the source system and that transmitted time being set on the destination, and the resulting time on the destination system is off by that delay amount. This delay cannot be fully eliminated when working in a simple environment like ours, but we should make our best effort to minimize it. In the present case, moving the atinterf_init() call before the time() retrieval should make a teensy-tiny improvement.
author Mychaela Falconia <falcon@freecalypso.org>
date Sat, 11 Aug 2018 21:52:17 +0000
parents d29b45c4c8db
children
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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 }