update changelogs for Debian build

[fw/altos] / src / ao_convert.c

diff --git a/src/ao_convert.c b/src/ao_convert.c
index 57ed73701abefe29d99d888ddbe35b4a586b982a..cec4c29f33feff9d87d95cd6e26f2e211cc47043 100644 (file)
--- a/src/ao_convert.c
+++ b/src/ao_convert.c
@@ -15,41 +15,71 @@
  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  */
 
+#ifndef AO_CONVERT_TEST
 #include "ao.h"
+#endif
 
-static const int16_t altitude_table[2048] = {
+static const int16_t altitude_table[] = {
 #include "altitude.h"
 };
 
+#define ALT_FRAC_SCALE (1 << ALT_FRAC_BITS)
+#define ALT_FRAC_MASK  (ALT_FRAC_SCALE - 1)
+
 int16_t
 ao_pres_to_altitude(int16_t pres) __reentrant
 {
-       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
 ao_altitude_to_pres(int16_t alt) __reentrant
 {
-       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;
 }
 
-static __xdata uint8_t ao_temp_mutex;
-
 int16_t
 ao_temp_to_dC(int16_t temp) __reentrant
 {
        int16_t ret;
 
-       ao_mutex_get(&ao_temp_mutex);
-       ret = (int16_t) ((temp >> 4) * 3300L / 2047L) - 500;
-       ao_mutex_put(&ao_temp_mutex);
+       /* Output voltage at 0°C = 0.755V
+        * Coefficient = 0.00247V/°C
+        * Reference voltage = 1.25V
+        *
+        * temp = ((value / 32767) * 1.25 - 0.755) / 0.00247
+        *      = (value - 19791.268) / 32768 * 1.25 / 0.00247
+        *      ≃ (value - 19791) * 1012 / 65536
+        */
+       ret = ((temp - 19791) * 1012L) >> 16;
        return ret;
 }