MMDVM/MMDVMHost
1
0
Fork 0
mirror of https://github.com/g4klx/MMDVMHost synced 2025-12-23 08:45:48 +08:00
Code Issues Packages Projects Releases Wiki Activity

Get the CRC and callsign mangling working correctly.

Browse Source
This commit is contained in:
Jonathan Naylor
2020-10-18 20:04:44 +01:00
parent 521da9b54d
commit a00ecbe7d9
2 changed files with 64 additions and 59 deletions
Download Patch File Download Diff File Expand all files Collapse all files

79
M17Utils.cpp
View File

@@ -20,64 +20,53 @@
#include <cassert>
const std::string M17_CHARS = " ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-/.";
void CM17Utils::encodeCallsign(const std::string& callsign, unsigned char* encoded)
{
assert(encoded != NULL);
std::string call = callsign;
call.resize(8U, ' ');
unsigned int len = callsign.size();
if (len > 9U)
len = 9U;
uint64_t enc = 0ULL;
for (int i = 7U; i >= 0; i--) {
char c = call.at(i);
uint64_t enc = 0ULL;
for (int i = len - 1; i >= 0; i--) {
size_t pos = M17_CHARS.find(callsign[i]);
if (pos == std::string::npos)
pos = 0ULL;
enc *= 40ULL;
enc *= 40ULL;
enc += pos;
}
// If speed is more important than code space, you can replace this with a lookup into a 256 byte array.
if (c >= 'A' && c <= 'Z') // 1-26
enc += c - 'A' + 1ULL;
else if (c >= '0' && c <= '9') // 27-36
enc += c - '0' + 27ULL;
else if (c == '-') // 37
enc += 37ULL;
// These are just place holders. If other characters make more sense, change these.
// Be sure to change them in the decode array below too.
else if (c == '/') // 38
enc += 38ULL;
else if (c == '.') // 39
enc += 39ULL;
else
// Invalid character or space, represented by 0, decoded as a space.
enc += 0ULL;
}
encoded[0U] = enc >> 40;
encoded[1U] = enc >> 32;
encoded[2U] = enc >> 24;
encoded[3U] = enc >> 16;
encoded[4U] = enc >> 8;
encoded[5U] = enc >> 0;
encoded[0U] = enc >> 40;
encoded[1U] = enc >> 32;
encoded[2U] = enc >> 24;
encoded[3U] = enc >> 16;
encoded[4U] = enc >> 8;
encoded[5U] = enc >> 0;
}
void CM17Utils::decodeCallsign(const unsigned char* encoded, std::string& callsign)
{
assert(encoded != NULL);
assert(encoded != NULL);
callsign.empty();
callsign.empty();
uint64_t enc = (uint64_t(encoded[5U]) << 40) +
(uint64_t(encoded[4U]) << 32) +
(uint64_t(encoded[3U]) << 24) +
(uint64_t(encoded[2U]) << 16) +
(uint64_t(encoded[1U]) << 8) +
(uint64_t(encoded[0U]) << 0);
uint64_t enc = (uint64_t(encoded[0U]) << 40) +
(uint64_t(encoded[1U]) << 32) +
(uint64_t(encoded[2U]) << 24) +
(uint64_t(encoded[3U]) << 16) +
(uint64_t(encoded[4U]) << 8) +
(uint64_t(encoded[5U]) << 0);
if (enc >= 262144000000000ULL) // 40^9
return;
if (enc >= 262144000000000ULL) // 40^9
return;
while (enc > 0ULL) {
callsign += " ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-/."[enc % 40ULL];
enc /= 40ULL;
}
while (enc > 0ULL) {
callsign += " ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-/."[enc % 40ULL];
enc /= 40ULL;
}
}