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-rw-r--r--core/units.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/core/units.h b/core/units.h
index 8839dde1d..4232e24a3 100644
--- a/core/units.h
+++ b/core/units.h
@@ -13,6 +13,8 @@ extern "C" {
#include <stdbool.h>
#endif
+#define FRACTION(n, x) ((unsigned)(n) / (x)), ((unsigned)(n) % (x))
+
#define O2_IN_AIR 209 // permille
#define N2_IN_AIR 781
#define O2_DENSITY 1331 // mg/Liter