Merge pull request #85 from Callum-/dilatometer

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

diff --git a/server/data.c b/server/data.c
index dae3172..38eba83 100644 (file)
--- a/server/data.c
+++ b/server/data.c
@@ -161,13 +161,13 @@ void Data_PrintByIndexes(DataFile * df, int start_index, int end_index, DataForm
        switch (format)
        {
                case JSON:
-                       fmt_string = "[%f,%f]";
+                       fmt_string = "[%.9f,%f]";
                        separator = ',';
                        // For JSON we need an opening bracket
                        FCGI_PrintRaw("["); 
                        break;
                case TSV:
-                       fmt_string = "%f\t%f";
+                       fmt_string = "%.9f\t%f";
                        separator = '\n';
                        break;
        }
@@ -292,7 +292,7 @@ int Data_FindByTime(DataFile * df, double time_stamp, DataPoint * closest)
  * @param df - DataFile to access
  * @param start - Info about start_time param 
  * @param end - Info about end_time param
- * @param fmt - Info about format param
+ * @param format - Info about format param
  * @param current_time - Current time
  */
 void Data_Handler(DataFile * df, FCGIValue * start, FCGIValue * end, DataFormat format, double current_time)
@@ -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]);
+}