added round_to_E_series function to eseries lib.

lib/eseries.c

@@ -38,4 +38,54 @@ ESeriesMaxValue get_E_MAX(ESeries E_series) {
 
 double round_to_E_series (double continuous_value, ESeries E_series) {
 
+    /*
+     * check for range. An E series is defined within one decade.
+     * values from 1 to 10 are accepted
+     */
+    if (continuous_value >= 10 || continuous_value < 1) {
+        printf("eseries:round_to_E_series: Value out of range.\n");
+        return E_NIL;
+    }
+
+    double e_value = 0.0;
+
+    // set the max array index for given e series.
+    unsigned int e_max_values = get_E_MAX(E_series);
+    if (e_max_values == E_NIL) {
+        printf("eseries:round_to_E_series: Unknown E series.\n");
+        return E_NIL;
+    }
+
+    int upper_e_limit = e_max_values;
+    int lower_e_limit = 0;
+
+    for (int i = 0 ; i < log2((e_max_values/3)); i++) {
+
+        if (continuous_value < E_values[E_series][((upper_e_limit - lower_e_limit + 1) / 2) + lower_e_limit]) {
+            upper_e_limit = ((upper_e_limit - lower_e_limit + 1) / 2) + lower_e_limit - 1;
+        }
+        else {
+            lower_e_limit = ((upper_e_limit - lower_e_limit + 1) / 2) + lower_e_limit;
+        }
+    }
+
+    if (continuous_value < E_values[E_series][lower_e_limit + 1])
+    {
+        if (fabs(continuous_value - E_values[E_series][lower_e_limit]) < fabs(continuous_value - E_values[E_series][lower_e_limit + 1])) {
+            e_value = E_values[E_series][lower_e_limit];
+        }
+        else {
+            e_value = E_values[E_series][lower_e_limit + 1];
+        }
+    }
+    else {
+        if (fabs(continuous_value - E_values[E_series][upper_e_limit]) < fabs(continuous_value - E_values[E_series][upper_e_limit - 1])) {
+            e_value = E_values[E_series][upper_e_limit];
+        }
+        else {
+            e_value = E_values[E_series][upper_e_limit - 1];
+        }
+    }
+
+    return e_value;
 }

lib/eseries.h

@@ -2,6 +2,10 @@
 #ifndef ESERIES_H
 #define ESERIES_H
 
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+
 double E3_values[3] = { 1.0, 2.2, 4.7 };
 
 double E6_values[6] = { 1.0, 1.5, 2.2, 3.3, 4.7, 6.8 };
@@ -19,7 +23,7 @@ double E192_values[192] = { 1.00, 1.01, 1.02, 1.04, 1.05, 1.06, 1.07, 1.09, 1.10
 double *E_values[7] = {E3_values, E6_values, E12_values, E24_values, E48_values, E96_values, E192_values};
 
 typedef enum {E3, E6, E12, E24, E48, E96, E192} ESeries;
-typedef enum {E_NIL=0, E3_MAX=3, E6_MAX=6, E12_MAX=12, E24_MAX=24, E48_MAX=48, E96_MAX=96, E192_MAX=192} ESeriesMaxValue;
+typedef enum {E_NIL=0, E3_MAX=2, E6_MAX=5, E12_MAX=11, E24_MAX=23, E48_MAX=47, E96_MAX=95, E192_MAX=191} ESeriesMaxValue;
 
 extern ESeriesMaxValue get_E_MAX(ESeries E_series);
 

lib/max_functions.c

@@ -43,7 +43,7 @@ int set_output_voltage(double setpoint_voltage, ESeries E_resistors) {
 
         R_low_decade_w = i_low;
 
-        for (int j_low = 0; j_low < e_max_values; j_low++) {
+        for (int j_low = 0; j_low <= e_max_values; j_low++) {
 
             // in the 6th decate only examine R_low = 1M, then stop
             if ( i_low == 6 && j_low > 0 )