altos: Make sure pa to altitude conversion is done with 32 bits

We need 32 bits to hold intermediate values, even if the final
altitude is reported in only 16 bits.

Signed-off-by: Keith Packard <keithp@keithp.com>

diff --git a/src/core/ao_convert_pa.c b/src/core/ao_convert_pa.c
index 55fe6e7da0e3a0ad5c4110b41f2722fc756bbc87..fe6e0ef699b803de2b6109e088ee638ac1be0431 100644 (file)
--- a/src/core/ao_convert_pa.c
+++ b/src/core/ao_convert_pa.c
@@ -43,13 +43,13 @@ ao_pa_to_altitude(int32_t pa)
 
        if (pa < 0)
                pa = 0;
 
        if (pa < 0)
                pa = 0;

-       if (pa > 120000)
-               pa = 120000;
+       if (pa > 120000L)
+               pa = 120000L;

        o = pa >> ALT_SHIFT;
        part = pa & ALT_MASK;
 
        o = pa >> ALT_SHIFT;
        part = pa & ALT_MASK;
 

-       low = (alt_t) FETCH_ALT(o) * (ALT_SCALE - part);
-       high = (alt_t) FETCH_ALT(o+1) * part + (ALT_SCALE >> 1);
+       low = (int32_t) FETCH_ALT(o) * (ALT_SCALE - part);
+       high = (int32_t) FETCH_ALT(o+1) * part + (ALT_SCALE >> 1);

        return (low + high) >> ALT_SHIFT;
 }
 
        return (low + high) >> ALT_SHIFT;
 }
 

diff --git a/src/micropeak/ao_pins.h b/src/micropeak/ao_pins.h
index 187b25442163a47fe0d63631ba3ed226bee125ca..63e9cb1b26663ce0259d2134003d8fa334b54ae0 100644 (file)
--- a/src/micropeak/ao_pins.h
+++ b/src/micropeak/ao_pins.h
@@ -60,6 +60,6 @@
 typedef int32_t alt_t;
 #define FETCH_ALT(o)           ((alt_t) pgm_read_dword(&altitude_table[o]))
 
 typedef int32_t alt_t;
 #define FETCH_ALT(o)           ((alt_t) pgm_read_dword(&altitude_table[o]))
 

-#define AO_ALT_VALUE(x)                ((x) * 10)
+#define AO_ALT_VALUE(x)                ((x) * (alt_t) 10)

 
 #endif /* _AO_PINS_H_ */
 
 #endif /* _AO_PINS_H_ */