Make those functions actually inline. Around 20% speedup on coldfire, 10% speedup on arm.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@22344 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 65 insertions, 4 deletions

diff --git a/apps/codecs/libatrac/fixp_math.h b/apps/codecs/libatrac/fixp_math.h
index b6621b6f1a..8a734f6b68 100644
--- a/apps/codecs/libatrac/fixp_math.h
+++ b/apps/codecs/libatrac/fixp_math.h
@@ -9,7 +9,68 @@
 #define fix31tof64(x)     (float)((float)(x) / (float)(1 << 31))
 
 /* Fixed point math routines for use in atrac3.c */
-inline int32_t fixmul16(int32_t x, int32_t y);
-inline int32_t fixmul31(int32_t x, int32_t y);
-inline int32_t fixdiv16(int32_t x, int32_t y);
-inline int32_t fastSqrt(int32_t n);
+
+static inline int32_t fixmul16(int32_t x, int32_t y)
+{
+    int64_t temp;
+    temp = x;
+    temp *= y;
+
+    temp >>= 16;
+
+    return (int32_t)temp;
+}
+
+static inline int32_t fixmul31(int32_t x, int32_t y)
+{
+    int64_t temp;
+    temp = x;
+    temp *= y;
+
+    temp >>= 31;        //16+31-16 = 31 bits
+
+    return (int32_t)temp;
+}
+
+static inline int32_t fixdiv16(int32_t x, int32_t y)
+{
+    int64_t temp;
+    temp = x << 16;
+    temp /= y;
+
+    return (int32_t)temp;
+}
+
+/*
+ * Fast integer square root adapted from algorithm, 
+ * Martin Guy @ UKC, June 1985.
+ * Originally from a book on programming abaci by Mr C. Woo.
+ * This is taken from :
+ * http://wiki.forum.nokia.com/index.php/How_to_use_fixed_point_maths#How_to_get_square_root_for_integers
+ * with a added shift up of the result by 8 bits to return result in 16.16 fixed-point representation.
+ */
+static inline int32_t fastSqrt(int32_t n)
+{
+   /*
+    * Logically, these are unsigned. 
+    * We need the sign bit to test
+    *	whether (op - res - one) underflowed.
+    */
+    int32_t op, res, one;
+    op = n;
+    res = 0;
+    /* "one" starts at the highest power of four <= than the argument. */
+    one = 1 << 30;	/* second-to-top bit set */
+    while (one > op) one >>= 2;
+    while (one != 0) 
+    {
+        if (op >= res + one) 
+        {
+            op = op - (res + one);
+            res = res +  (one<<1);
+        }
+        res >>= 1;
+        one >>= 2;
+    }
+    return(res << 8);
+}