Need to duplicate new altitude conversion code in aoview.

[fw/altos] / ao-tools / ao-view / aoview_convert.c

diff --git a/ao-tools/ao-view/aoview_convert.c b/ao-tools/ao-view/aoview_convert.c
index 02416647ed6ae4f13815f3992f67bf6429b58ec6..8ee05e1d20384baccfc1e14d2f5b64e5ee78b635 100644 (file)
--- a/ao-tools/ao-view/aoview_convert.c
+++ b/ao-tools/ao-view/aoview_convert.c
@@ -17,26 +17,50 @@
 
 #include "aoview.h"
 
 
 #include "aoview.h"
 

-static int16_t altitude_table[2048] = {
+static int16_t altitude_table[] = {

 #include "altitude.h"
 };
 
 #include "altitude.h"
 };
 

+#define ALT_FRAC_SCALE (1 << ALT_FRAC_BITS)
+#define ALT_FRAC_MASK  (ALT_FRAC_SCALE - 1)
+

 int16_t
 aoview_pres_to_altitude(int16_t pres)
 {
 int16_t
 aoview_pres_to_altitude(int16_t pres)
 {

-       pres = pres >> 4;
-       if (pres < 0) pres = 0;
-       if (pres > 2047) pres = 2047;
-       return altitude_table[pres];
+       uint8_t o;
+       int16_t part;
+
+       if (pres < 0)
+               pres = 0;
+       o = pres >> ALT_FRAC_BITS;
+       part = pres & ALT_FRAC_MASK;
+
+       return ((int32_t) altitude_table[o] * (ALT_FRAC_SCALE - part) +
+               (int32_t) altitude_table[o+1] * part + (ALT_FRAC_SCALE >> 1)) >> ALT_FRAC_BITS;

 }
 
 int16_t
 aoview_altitude_to_pres(int16_t alt)
 {
 }
 
 int16_t
 aoview_altitude_to_pres(int16_t alt)
 {

-       int16_t pres;
+       int16_t span, sub_span;
+       uint8_t l, h, m;
+       int32_t pres;

 
 

-       for (pres = 0; pres < 2047; pres++)
-               if (altitude_table[pres] <= alt)
-                       break;
-       return pres << 4;
+       l = 0;
+       h = NALT - 1;
+       while ((h - l) != 1) {
+               m = (l + h) >> 1;
+               if (altitude_table[m] < alt)
+                       h = m;
+               else
+                       l = m;
+       }
+       span = altitude_table[l] - altitude_table[h];
+       sub_span = altitude_table[l] - alt;
+       pres = ((((int32_t) l * (span - sub_span) + (int32_t) h * sub_span) << ALT_FRAC_BITS) + (span >> 1)) / span;
+       if (pres > 32767)
+               pres = 32767;
+       if (pres < 0)
+               pres = 0;
+       return (int16_t) pres;

 }
 }