DigitalInfinity/ESP32-PaxCounter
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dcf77.cpp: simplyfy parity calculation

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This commit is contained in:
cyberman54 2022-01-26 22:44:29 +01:00
parent dfa25cd2b4
commit 1ffdbdac3b
1 changed files with 10 additions and 11 deletions
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21
src/dcf77.cpp
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@ -51,18 +51,17 @@ void DCF77_Pulse(uint8_t bit) {
// helper function to convert decimal to bcd digit // helper function to convert decimal to bcd digit
uint64_t dec2bcd(uint8_t const dec, uint8_t const startpos, uint64_t dec2bcd(uint8_t const dec, uint8_t const startpos,
uint8_t const endpos, uint8_t *odd_parity) { uint8_t const endpos, uint8_t *parity) {
uint8_t data = (dec < 10) ? dec : ((dec / 10) << 4) + (dec % 10); uint8_t data = dec < 10 ? dec : ((dec / 10) << 4) + dec % 10;
uint64_t bcd = 0; uint64_t bcd = 0;
*odd_parity = 0; *parity = 0;
for (uint8_t i = startpos; i <= endpos; i++) { for (uint8_t i = startpos; i <= endpos; i++) {
bcd += (data & 1) ? set_dcfbit(i) : 0; bcd += data & 1 ? set_dcfbit(i) : 0;
*odd_parity += (data & 1); *parity ^= data & 1;
data >>= 1; data >>= 1;
} }
*odd_parity %= 2;
return bcd; return bcd;
} }
@ -96,14 +95,14 @@ uint64_t DCF77_Frame(const struct tm t) {
// DATE (36..58) // DATE (36..58)
frame += dec2bcd(t.tm_mday, 36, 41, &parity); frame += dec2bcd(t.tm_mday, 36, 41, &parity);
parity_sum += parity; parity_sum ^= parity;
frame += dec2bcd((t.tm_wday == 0) ? 7 : t.tm_wday, 42, 44, &parity); frame += dec2bcd((t.tm_wday == 0) ? 7 : t.tm_wday, 42, 44, &parity);
parity_sum += parity; parity_sum ^= parity;
frame += dec2bcd(t.tm_mon + 1, 45, 49, &parity); frame += dec2bcd(t.tm_mon + 1, 45, 49, &parity);
parity_sum += parity; parity_sum ^= parity;
frame += dec2bcd(t.tm_year + 1900 - 2000, 50, 57, &parity); frame += dec2bcd(t.tm_year + 1900 - 2000, 50, 57, &parity);
parity_sum += parity; parity_sum ^= parity;
frame += parity_sum % 2 ? set_dcfbit(58) : 0; frame += parity_sum ? set_dcfbit(58) : 0;
return frame; return frame;