Merge branch 'master' of github:szmoore/MCTX3420 into report

[matches/MCTX3420.git] / server / data.c

diff --git a/server/data.c b/server/data.c
index edfd4c3..19828bc 100644 (file)
--- a/server/data.c
+++ b/server/data.c
@@ -356,3 +356,51 @@ DataFormat Data_GetFormat(FCGIValue * fmt)
        }
        return JSON;
 }
+
+/**
+ * Binary search for index of a double in an array
+ * @param value - The value
+ * @param x - The array
+ * @param size - Sizeof the array
+ */
+int FindClosest(double value, double x[], int size)
+{
+       int upper = size-1;
+       int lower = 0;
+       int index = 0;
+       while (upper - lower > 1)
+       {
+               index = lower + ((upper - lower)/2);
+               double look = x[index];
+               if (look > value)
+                       upper = index;
+               else if (look < value)
+                       lower = index;
+               else
+                       return index;
+       }
+
+       if (x[index] > value && index > 0)
+               --index;
+       return index;
+
+}
+
+/**
+ * Get calibrated value by interpolation in array y
+ * @param value - Raw measured value
+ * @param x - x values (raw values) of the data
+ * @param y - calibrated values
+ * @param size - Number of values in the arrays
+ * @returns interpolated calibrated value
+ */
+double Data_Calibrate(double value, double x[], double y[], int size)
+{
+       int i = FindClosest(value, x, size);
+       if (i >= size-1)
+       {
+               i = size-2;     
+       }
+       double dist = (value - x[i])/(x[i+1] - x[i]);
+       return y[i] + dist*(y[i+1]-y[i]);
+}