Fill in inverse polynomials for first order soft calibrations.

diff --git a/lib/calib_yacc.y b/lib/calib_yacc.y
index 82887da0f02a66ba2ecf196203251082673240c7..b51ff37131a57b99eab7b999fa4156f2ad9a7e38 100644 (file)
--- a/lib/calib_yacc.y
+++ b/lib/calib_yacc.y
@@ -21,8 +21,11 @@
     USA.
 */
 
+#define _GNU_SOURCE
+
 #include <stdio.h>
 #include "libinternal.h"
+#include <math.h>
 #include <string.h>
 #include <stdlib.h>
 #include "calib_yacc.h"
@@ -274,6 +277,43 @@ extern void _comedi_cleanup_calibration( comedi_calibration_t *file_contents )
        free( file_contents );
 }
 
+static comedi_polynomial_t* alloc_inverse_linear_polynomial(const comedi_polynomial_t *polynomial)
+{
+       if(polynomial->order != 1) return NULL;
+       comedi_polynomial_t *inverse = malloc(sizeof(comedi_polynomial_t));
+       memset(inverse, 0, sizeof(comedi_polynomial_t));
+       inverse->order = 1;
+       inverse->expansion_origin = polynomial->coefficients[0];
+       inverse->coefficients[0] = polynomial->expansion_origin;
+       inverse->coefficients[1] = 1. / polynomial->coefficients[1];
+       if(isfinite(inverse->coefficients[1]) == 0)
+       {
+               free(inverse);
+               return NULL;
+       }
+       return inverse;
+}
+
+static void fill_inverse_linear_polynomials(comedi_calibration_t *calibration)
+{
+       unsigned i;
+       for(i = 0; i < calibration->num_settings; ++i)
+       {
+               if(calibration->settings[i].soft_calibration.to_phys)
+               {
+                       if(calibration->settings[i].soft_calibration.from_phys == NULL)
+                       {
+                               calibration->settings[i].soft_calibration.from_phys =
+                                       alloc_inverse_linear_polynomial(calibration->settings[i].soft_calibration.to_phys);
+                       }
+               }else if(calibration->settings[i].soft_calibration.from_phys)
+               {
+                       calibration->settings[i].soft_calibration.to_phys =
+                               alloc_inverse_linear_polynomial(calibration->settings[i].soft_calibration.from_phys);
+               }
+       }
+}
+
 EXPORT_ALIAS_DEFAULT(_comedi_parse_calibration_file,comedi_parse_calibration_file,0.7.20);
 extern comedi_calibration_t* _comedi_parse_calibration_file( const char *cal_file_path )
 {
@@ -300,6 +340,7 @@ extern comedi_calibration_t* _comedi_parse_calibration_file( const char *cal_fil
        }
        calib_yylex_destroy(priv.yyscanner);
        fclose( file );
+       fill_inverse_linear_polynomials(priv.parsed_file);
        return priv.parsed_file;
 }