X-Git-Url: https://git.rohieb.name/hackover2013-badge-firmware.git/blobdiff_plain/113fbd0d57be3df9bc6ac56b44d8bd154cc90d38..f80406559852f60c406f655c6138d1b7bcbee2e2:/badge/util/fixed_point.h?ds=inline

diff --git a/badge/util/fixed_point.h b/badge/util/fixed_point.h
index 05a8c79..43c7bf0 100644
--- a/badge/util/fixed_point.h
+++ b/badge/util/fixed_point.h
@@ -23,13 +23,19 @@ static inline bool fixed_point_eq(fixed_point x, fixed_point y) { return x.data
 static inline bool fixed_point_ne(fixed_point x, fixed_point y) { return x.data != y.data; }
 
 #define FIXED_POINT_I(x, y) { ((x) * 256) + ((y) * 256 / 1000) }
+#define FIXED_INT_I(x) FIXED_POINT_I(x, 0)
 
-static inline fixed_point FIXED_POINT(unsigned x, unsigned y) {
-  fixed_point r = { ((int) x * 256) + ((int) y * 256 / 1000) };
+static inline fixed_point FIXED_POINT(int32_t x, int32_t y) {
+  fixed_point r = FIXED_POINT_I(x, y);
   return r;
 }
 
-static inline int fixed_point_cast_int(fixed_point x) { return x.data / 256; }
+static inline fixed_point FIXED_INT(int32_t x) { return FIXED_POINT(x, 0); }
+
+// sign bit is shifted in if x.data < 0, so this is x.data / 256 - (x.data < 0).
+// This means 0.123 is cast to 1, which is what we want when we cast a model coordinate
+// to a screen coordinate.
+static inline int fixed_point_cast_int(fixed_point x) { return x.data >> 8; }
 
 static inline fixed_point fixed_point_min(fixed_point x, fixed_point y) { return fixed_point_lt(x, y) ? x : y; }
 static inline fixed_point fixed_point_max(fixed_point x, fixed_point y) { return fixed_point_gt(x, y) ? x : y; }