Ny structure. Start of the "main" branch

Cards/EaserCAT-3000-Digital-Stepper-Analog-Encoder-Frequency/Firmware/src/extend32to64.cpp

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+#include "extend32to64.h"
+
+// Extend from 32-bit to 64-bit precision
+int64_t extend32to64::extendTime(uint32_t in)
+{
+    int64_t c64 = (int64_t)in - HALF_PERIOD; // remove half period to determine (+/-) sign of the wrap
+    int64_t dif = (c64 - previousTimeValue); // core concept: prev + (current - prev) = current
+
+    // wrap difference from -HALF_PERIOD to HALF_PERIOD. modulo prevents differences after the wrap from having an incorrect result
+    int64_t mod_dif = ((dif + HALF_PERIOD) % ONE_PERIOD) - HALF_PERIOD;
+    if (dif < int64_t(-HALF_PERIOD))
+        mod_dif += ONE_PERIOD; // account for mod of negative number behavior in C
+
+    int64_t unwrapped = previousTimeValue + mod_dif;
+    previousTimeValue = unwrapped; // load previous value
+
+    return unwrapped + HALF_PERIOD; // remove the shift we applied at the beginning, and return
+}