short dohash(const char* thecall)
{
char rootcall[10]; // need to copy call to remove ssid from parse
char *p1 = rootcall;
while ((*thecall != '-') && (*thecall != 0)) *p1++ = toupper(*thecall++);
*p1 = 0;
short hash = kkey; // initialize with the key value
short i = 0;
short len = strlen(rootcall);
char *ptr = rootcall;
while (i < len) { // loop through the string two bytes at a time
hash ^= (*ptr++)<<8; // xor high byte with accumulated hash
hash ^= (*ptr++); // xor low byte with accumulated hash
i += 2;
}
return hash & 0x7fff; // mask off the high bit so number is always positive
}
[表情]
| bg8bin | 2012-01-15 11:01 |
花了一个小时才追到的函数，APRS五位验证码的秘密，能看懂的就自己算吧short dohash(const char* thecall){ char rootcall[10]; // need to copy call to remove ssid from parse char *p1 = rootcall; while ((*thecall != '-') && (*thecall != 0)) *p1++ = toupper(*thecall++); *p1 = 0; short hash = kkey; // initialize with the key value short i = 0; short len = strlen(rootcall); char *ptr = rootcall; while (i < len) { // loop through the string two bytes at a time hash ^= (*ptr++)<<8; // xor high byte with accumulated hash hash ^= (*ptr++); // xor low byte with accumulated hash i += 2; } return hash & 0x7fff; // mask off the high bit so number is always positive }  |
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