Create NmeaChecksum.h

bareboat-necessities · Nov 5, 2024 · de3865e · de3865e
1 parent 8824b5f
commit de3865e
Showing 1 changed file with 23 additions and 0 deletions.
diff --git a/bbn_m5atomS3_lite_env/NmeaChecksum.h b/bbn_m5atomS3_lite_env/NmeaChecksum.h
@@ -0,0 +1,23 @@
+#ifndef NmeaChecksum_h
+#define NmeaChecksum_h
+
+#define NMEA_END_CHAR_1    '\r'
+
+/*
+  NMEA-0183 checksum
+ */
+
+uint8_t nmea0183_checksum(const char *sentence);
+
+uint8_t nmea0183_checksum(const char *sentence) {
+  const char *n = sentence + 1;
+  uint8_t chk = 0;
+  /* While current char isn't '*' or sentence ending (newline) */
+  while ('*' != *n && NMEA_END_CHAR_1 != *n && '\0' != *n) {
+    chk ^= (uint8_t) *n;
+    n++;
+  }
+  return chk;
+}
+
+#endif