Differences
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| Both sides previous revision Previous revision Next revision | Previous revision Next revision Both sides next revision | ||
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sdk:gps-udp-client-gnsstogps [2019/07/08 14:13] fachet |
sdk:gps-udp-client-gnsstogps [2019/07/12 11:19] fachet |
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| Line 58: | Line 58: | ||
| return gpsd; | return gpsd; | ||
| + | } | ||
| + | |||
| + | string checksum(string s) | ||
| + | { | ||
| + | pos = strchr(s, "*"); | ||
| + | |||
| + | if (is_void(pos)) | ||
| + | return s; /* no checksum to correct */ | ||
| + | |||
| + | cs = 0; | ||
| + | chars = explode(s); | ||
| + | for (i = 1; i < pos; i++) { /* skip $ and *XX */ | ||
| + | c = ord(chars[i]); | ||
| + | cs ^= c; | ||
| + | } | ||
| + | r = sprintf("%s%02X%s", substr(s, 0, pos + 1), cs, substr(s, pos + 3)); | ||
| + | return r; | ||
| } | } | ||
| Line 126: | Line 143: | ||
| a_arr = explode(data); | a_arr = explode(data); | ||
| a_arr[2] = "P"; | a_arr[2] = "P"; | ||
| - | data = implode(a_arr); | + | data = checksum(implode(a_arr)); |
| } | } | ||
| /* skip all messages different from GPGGA | /* skip all messages different from GPGGA | ||