tweaks to cal_binary() so that it gets the last, least significant

bit correct.

diff --git a/comedi_calibrate/calib.h b/comedi_calibrate/calib.h
index f82163f118ffc3977d960b47fe8604b2718eda16..90d4eb22568d3e1488199e4907c4ea0d7f6559df 100644 (file)
--- a/comedi_calibrate/calib.h
+++ b/comedi_calibrate/calib.h
@@ -195,7 +195,6 @@ typedef struct{
 
        comedi_range *rng;
 
-       int n;
        double average;
        double stddev;
        double error;

diff --git a/comedi_calibrate/comedi_calibrate.c b/comedi_calibrate/comedi_calibrate.c
index db651ff7314240ba4b40ab3475a0252fd3d6f96e..9ca21f6ebf95be938dc3a06afcf503db7f09e82f 100644 (file)
--- a/comedi_calibrate/comedi_calibrate.c
+++ b/comedi_calibrate/comedi_calibrate.c
@@ -463,52 +463,54 @@ void cal1_fine( calibration_setup_t *setup, int obs, int dac )
 
 void cal_binary( calibration_setup_t *setup, int obs, int dac)
 {
-       int x1, x2, x;
-       double y1, y2, y;
+       int x0, x;
+       unsigned int bit;
+       double y0, y;
        new_sv_t sv;
        double target = setup->observables[obs].target;
        unsigned int chanspec = setup->observables[obs].observe_insn.chanspec;
+       int polarity;
 
        DPRINT(0,"binary: %s\n", setup->observables[obs].name);
        preobserve( setup, obs);
 
-       x1 = 0;
-       x2 = setup->caldacs[dac].maxdata;
+       bit = 1;
+       while( ( bit << 1 ) < setup->caldacs[dac].maxdata )
+               bit <<= 1;
 
        new_sv_init(&sv, setup->dev,0,chanspec);
        sv.settling_time_ns = setup->settling_time_ns;
-       update_caldac( setup, dac, x1 );
+
+       x0 = 0;
+       update_caldac( setup, dac, x0 );
        usleep(100000);
        new_sv_measure( setup->dev, &sv);
-       y1 = sv.average;
+       y0 = sv.average;
 
-       new_sv_init(&sv, setup->dev,0,chanspec);
-       sv.settling_time_ns = setup->settling_time_ns;
-       update_caldac( setup, dac, x2 );
+       x = bit;
+       update_caldac( setup, dac, x );
        usleep(100000);
        new_sv_measure( setup->dev, &sv);
-       y2 = sv.average;
+       y = sv.average;
 
-       x = 0;
-       while(x2-x1 > 1){
-               x = (x1 + x2 + 1)/2;
+       if( y > y0 ) polarity = 1;
+       else polarity = -1;
+
+       if( (y - target) * polarity > 0.0 )
+               x &= ~bit;
+
+       for( bit = bit >> 1; bit; bit >>= 1 ){
+               x |= bit;
                DPRINT(3,"trying %d\n",x);
 
-               new_sv_init(&sv, setup->dev,0,chanspec);
-               sv.settling_time_ns = setup->settling_time_ns;
                update_caldac( setup, dac, x );
                usleep(100000);
 
                new_sv_measure( setup->dev, &sv);
                y = sv.average;
 
-               if(fabs(y2 - target) > fabs(y1 - target)){
-                       x2 = x;
-                       y2 = y;
-               }else{
-                       x1 = x;
-                       y1 = y;
-               }
+               if( (y - target) * polarity > 0.0 )
+                       x &= ~bit;
 
                if(verbose>=3){
                        measure_observable( setup, obs);