1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
|
#ifdef _WINDOWS
#include <string.h>
#endif
#include "Navigation.h"
//#include <stdio.h>
/*
void saveposn(size_t posn)
save/push position to history buffer for future use of back() function
*/
void CNavigation::saveposn(size_t posn)
{
//printf("saving position %u, depth %u\n",posn,historycurrent);
history[historycurrent] = posn;
historycurrent=(historycurrent+1)%NAVIGATION_HISTORY_SIZE;
if (historycurrent==historystart)
// circular buffer full, forget oldest record
historystart=(historystart+1)%NAVIGATION_HISTORY_SIZE;
// no forward possible after saveposn
historyend = historycurrent;
}
/*
void writeposn(size_t posn)
overwrite current (unused) position
useful for saving current position before using back button
*/
void CNavigation::writeposn(size_t posn)
{
//printf("witing position %u, depth %u\n",posn,historycurrent);
history[historycurrent] = posn;
}
/*
bool back(size_t& posn)
go back in history
restore last position saved with saveposn() and return true
return false if there is nothing saved in history
*/
bool CNavigation::back(size_t& posn)
{
if (historycurrent!=historystart) {
// buffer is not empty
if (historycurrent==0)
historycurrent=NAVIGATION_HISTORY_SIZE-1;
else
historycurrent--;
posn=history[historycurrent];
//printf("back(): going back to %u depth %u\n",posn,historycurrent);
return true;
} else {
// circular buffer empty
//printf("back(): empty history\n");
return false;
}
}
/*
bool forward(size_t& posn)
go forward in history, if possible
undo calling of back()
*/
bool CNavigation::forward(size_t& posn)
{
if (historycurrent!=historyend) {
// [historycurrent] = current position
// [historycurrent+1] = position we need
historycurrent=(historycurrent+1)%NAVIGATION_HISTORY_SIZE;
posn = history[historycurrent];
//printf("forward(): going to position %d\n",posn);
return true;
} else {
//printf("forward(): there is no future :)\n");
return false;
}
}
void CNavigation::setSaveData(unsigned char*& data, unsigned short& len, unsigned char* src, unsigned short srclen)
{
len = srclen+sizeof(size_t)*(3+NAVIGATION_HISTORY_SIZE);
data = new unsigned char[len];
unsigned char* p = data;
memcpy(p, src, srclen);
p += srclen;
memcpy(p, &historystart, sizeof(size_t));
p += sizeof(size_t);
memcpy(p, &historyend, sizeof(size_t));
p += sizeof(size_t);
memcpy(p, &historycurrent, sizeof(size_t));
p += sizeof(size_t);
memcpy(p, history, sizeof(size_t)*NAVIGATION_HISTORY_SIZE);
/*
printf("<%u,%u,%u>\n", historystart, historyend, historycurrent);
for (int i = historystart; i <= historyend; i++)
printf("<%u> ", history[i]);
printf("\n");
*/
}
void CNavigation::putSaveData(unsigned char*& src, unsigned short& srclen)
{
if (srclen >= sizeof(size_t)*(3+NAVIGATION_HISTORY_SIZE))
{
unsigned char* p = src;
memcpy(&historystart, p, sizeof(size_t));
p += sizeof(size_t);
memcpy(&historyend, p, sizeof(size_t));
p += sizeof(size_t);
memcpy(&historycurrent, p, sizeof(size_t));
p += sizeof(size_t);
memcpy(history, p, sizeof(size_t)*NAVIGATION_HISTORY_SIZE);
src = p + sizeof(size_t)*NAVIGATION_HISTORY_SIZE;
srclen -= sizeof(size_t)*(3+NAVIGATION_HISTORY_SIZE);
}
/*
printf("<%u,%u,%u>\n", historystart, historyend, historycurrent);
for (int i = historystart; i <= historyend; i++)
printf("<%u> ", history[i]);
printf("\n");
*/
}
|
