FreeCalypso > hg > fc-sim-sniff

comparison sw/sniff-dec/pps.c @ 41:118a12e9483b

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simtrace3-sniff-dec started
author Mychaela Falconia <falcon@freecalypso.org>
date Thu, 31 Aug 2023 08:46:23 +0000
parents
children 2855330ab96f
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40:510bef2b2000 41:118a12e9483b
1 /*
2 * Here we implement PPS request/response message decoding.
3 */
4
5 #include <sys/types.h>
6 #include <stdio.h>
7 #include <stdlib.h>
8 #include <string.h>
9 #include <strings.h>
10 #include "state.h"
11
12 extern char linebuf[];
13 extern int lineno;
14 extern unsigned rx_byte;
15 extern int state;
16
17 #define SUBST_PPS0 0
18 #define SUBST_PPS1 1
19 #define SUBST_PPS2 2
20 #define SUBST_PPS3 3
21 #define SUBST_PCK 4
22
23 static char pps_start_timestamp[18];
24 static int pps_start_line;
25 static int substate;
26 static u_char pps_bytes[6];
27 static unsigned byte_count;
28
29 void
30 start_pps_msg()
31 {
32 strcpy(pps_start_timestamp, linebuf);
33 pps_start_line = lineno;
34 pps_bytes[0] = rx_byte;
35 byte_count = 1;
36 state = STATE_PPS_MSG;
37 substate = SUBST_PPS0;
38 }
39
40 static void
41 advance_state()
42 {
43 if (substate == SUBST_PPS1) {
44 if (pps_bytes[1] & 0x10)
45 return;
46 substate = SUBST_PPS2;
47 }
48 if (substate == SUBST_PPS2) {
49 if (pps_bytes[1] & 0x20)
50 return;
51 substate = SUBST_PPS3;
52 }
53 if (substate == SUBST_PPS3) {
54 if (pps_bytes[2] & 0x40)
55 return;
56 substate = SUBST_PCK;
57 }
58 if (substate == SUBST_PCK)
59 return;
60 fprintf(stderr, "BUG in PPS decoder: bad state in advance_state()\n");
61 abort();
62 }
63
64 static void
65 check_pck()
66 {
67 unsigned n, xor;
68
69 xor = 0;
70 for (n = 0; n < byte_count; n++)
71 xor ^= pps_bytes[n];
72 printf(" PCK is %s\n", xor ? "bad!" : "correct");
73 }
74
75 static void
76 pps_finish()
77 {
78 unsigned n;
79
80 printf("%s line %d: PPS", pps_start_timestamp, pps_start_line);
81 for (n = 0; n < byte_count; n++)
82 printf(" %02X", pps_bytes[n]);
83 putchar('\n');
84 check_pck();
85 state = STATE_READY_FOR_CMD;
86 }
87
88 void
89 pps_byte_in()
90 {
91 pps_bytes[byte_count++] = rx_byte;
92 switch (substate) {
93 case SUBST_PPS0:
94 substate = SUBST_PPS1;
95 advance_state();
96 return;
97 case SUBST_PPS1:
98 substate = SUBST_PPS2;
99 advance_state();
100 return;
101 case SUBST_PPS2:
102 substate = SUBST_PPS3;
103 advance_state();
104 return;
105 case SUBST_PPS3:
106 substate = SUBST_PCK;
107 return;
108 case SUBST_PCK:
109 pps_finish();
110 return;
111 default:
112 fprintf(stderr,
113 "BUG in PPS decoder: bad state in pps_byte_in()\n");
114 abort();
115 }
116 }