implemented fixed point sin(); fixed CLUTTER_FIXED_TO_FLOAT/DOUBLE macros

clutter/Makefile.am

@@ -94,6 +94,7 @@ CLEANFILES = \
 source_c = clutter-main.c 		\
 	   clutter-util.c 		\
 	   clutter-feature.c 		\
+	   clutter-fixed.c		\
            clutter-event.c 		\
 	   clutter-color.c 		\
 	   clutter-timeline.c 		\

clutter/clutter-alpha.c

@@ -491,6 +491,13 @@ clutter_ramp_func (ClutterAlpha *alpha,
     }
 }
 
+static guint32
+sincx_func (ClutterAlpha *alpha, 
+	   float         angle,
+	   float         offset)
+{
+}
+
 static guint32
 sinc_func (ClutterAlpha *alpha, 
 	   float         angle,

clutter/clutter-fixed.c

@@ -0,0 +1,154 @@
+#include <clutter-fixed.h>
+
+/* pre-computed sin table for 1st quadrant
+ *
+ * Currently contains 257 entries.
+ *
+ * The current error (compared to system sin) is about
+ * 0.5% for values near the start of the table where the
+ * curve is steep, but improving rapidly. If this precission
+ * is not enough, we can increase the size of the table
+ */
+static ClutterFixed sin_tbl [] =
+{
+ 0x00000000L, 0x00000192L, 0x00000324L, 0x000004B6L,
+ 0x00000648L, 0x000007DAL, 0x0000096CL, 0x00000AFEL,
+ 0x00000C90L, 0x00000E21L, 0x00000FB3L, 0x00001144L,
+ 0x000012D5L, 0x00001466L, 0x000015F7L, 0x00001787L,
+ 0x00001918L, 0x00001AA8L, 0x00001C38L, 0x00001DC7L,
+ 0x00001F56L, 0x000020E5L, 0x00002274L, 0x00002402L,
+ 0x00002590L, 0x0000271EL, 0x000028ABL, 0x00002A38L,
+ 0x00002BC4L, 0x00002D50L, 0x00002EDCL, 0x00003067L,
+ 0x000031F1L, 0x0000337CL, 0x00003505L, 0x0000368EL,
+ 0x00003817L, 0x0000399FL, 0x00003B27L, 0x00003CAEL,
+ 0x00003E34L, 0x00003FBAL, 0x0000413FL, 0x000042C3L,
+ 0x00004447L, 0x000045CBL, 0x0000474DL, 0x000048CFL,
+ 0x00004A50L, 0x00004BD1L, 0x00004D50L, 0x00004ECFL,
+ 0x0000504DL, 0x000051CBL, 0x00005348L, 0x000054C3L,
+ 0x0000563EL, 0x000057B9L, 0x00005932L, 0x00005AAAL,
+ 0x00005C22L, 0x00005D99L, 0x00005F0FL, 0x00006084L,
+ 0x000061F8L, 0x0000636BL, 0x000064DDL, 0x0000664EL,
+ 0x000067BEL, 0x0000692DL, 0x00006A9BL, 0x00006C08L,
+ 0x00006D74L, 0x00006EDFL, 0x00007049L, 0x000071B2L,
+ 0x0000731AL, 0x00007480L, 0x000075E6L, 0x0000774AL,
+ 0x000078ADL, 0x00007A10L, 0x00007B70L, 0x00007CD0L,
+ 0x00007E2FL, 0x00007F8CL, 0x000080E8L, 0x00008243L,
+ 0x0000839CL, 0x000084F5L, 0x0000864CL, 0x000087A1L,
+ 0x000088F6L, 0x00008A49L, 0x00008B9AL, 0x00008CEBL,
+ 0x00008E3AL, 0x00008F88L, 0x000090D4L, 0x0000921FL,
+ 0x00009368L, 0x000094B0L, 0x000095F7L, 0x0000973CL,
+ 0x00009880L, 0x000099C2L, 0x00009B03L, 0x00009C42L,
+ 0x00009D80L, 0x00009EBCL, 0x00009FF7L, 0x0000A130L,
+ 0x0000A268L, 0x0000A39EL, 0x0000A4D2L, 0x0000A605L,
+ 0x0000A736L, 0x0000A866L, 0x0000A994L, 0x0000AAC1L,
+ 0x0000ABEBL, 0x0000AD14L, 0x0000AE3CL, 0x0000AF62L,
+ 0x0000B086L, 0x0000B1A8L, 0x0000B2C9L, 0x0000B3E8L,
+ 0x0000B505L, 0x0000B620L, 0x0000B73AL, 0x0000B852L,
+ 0x0000B968L, 0x0000BA7DL, 0x0000BB8FL, 0x0000BCA0L,
+ 0x0000BDAFL, 0x0000BEBCL, 0x0000BFC7L, 0x0000C0D1L,
+ 0x0000C1D8L, 0x0000C2DEL, 0x0000C3E2L, 0x0000C4E4L,
+ 0x0000C5E4L, 0x0000C6E2L, 0x0000C7DEL, 0x0000C8D9L,
+ 0x0000C9D1L, 0x0000CAC7L, 0x0000CBBCL, 0x0000CCAEL,
+ 0x0000CD9FL, 0x0000CE8EL, 0x0000CF7AL, 0x0000D065L,
+ 0x0000D14DL, 0x0000D234L, 0x0000D318L, 0x0000D3FBL,
+ 0x0000D4DBL, 0x0000D5BAL, 0x0000D696L, 0x0000D770L,
+ 0x0000D848L, 0x0000D91EL, 0x0000D9F2L, 0x0000DAC4L,
+ 0x0000DB94L, 0x0000DC62L, 0x0000DD2DL, 0x0000DDF7L,
+ 0x0000DEBEL, 0x0000DF83L, 0x0000E046L, 0x0000E107L,
+ 0x0000E1C6L, 0x0000E282L, 0x0000E33CL, 0x0000E3F4L,
+ 0x0000E4AAL, 0x0000E55EL, 0x0000E610L, 0x0000E6BFL,
+ 0x0000E76CL, 0x0000E817L, 0x0000E8BFL, 0x0000E966L,
+ 0x0000EA0AL, 0x0000EAABL, 0x0000EB4BL, 0x0000EBE8L,
+ 0x0000EC83L, 0x0000ED1CL, 0x0000EDB3L, 0x0000EE47L,
+ 0x0000EED9L, 0x0000EF68L, 0x0000EFF5L, 0x0000F080L,
+ 0x0000F109L, 0x0000F18FL, 0x0000F213L, 0x0000F295L,
+ 0x0000F314L, 0x0000F391L, 0x0000F40CL, 0x0000F484L,
+ 0x0000F4FAL, 0x0000F56EL, 0x0000F5DFL, 0x0000F64EL,
+ 0x0000F6BAL, 0x0000F724L, 0x0000F78CL, 0x0000F7F1L,
+ 0x0000F854L, 0x0000F8B4L, 0x0000F913L, 0x0000F96EL,
+ 0x0000F9C8L, 0x0000FA1FL, 0x0000FA73L, 0x0000FAC5L,
+ 0x0000FB15L, 0x0000FB62L, 0x0000FBADL, 0x0000FBF5L,
+ 0x0000FC3BL, 0x0000FC7FL, 0x0000FCC0L, 0x0000FCFEL,
+ 0x0000FD3BL, 0x0000FD74L, 0x0000FDACL, 0x0000FDE1L,
+ 0x0000FE13L, 0x0000FE43L, 0x0000FE71L, 0x0000FE9CL,
+ 0x0000FEC4L, 0x0000FEEBL, 0x0000FF0EL, 0x0000FF30L,
+ 0x0000FF4EL, 0x0000FF6BL, 0x0000FF85L, 0x0000FF9CL,
+ 0x0000FFB1L, 0x0000FFC4L, 0x0000FFD4L, 0x0000FFE1L,
+ 0x0000FFECL, 0x0000FFF5L, 0x0000FFFBL, 0x0000FFFFL,
+ 0x00010000L,
+};
+
+/* the difference of the angle for two adjacent values in the table
+ * expressed as ClutterFixed number
+ */
+#define CFX_SIN_STEP 0x00000192
+
+ClutterFixed
+clutter_fixed_sin (ClutterFixed anx)
+{
+    /* reduce to <0, 2*pi) */
+    if (anx >= CFX_2PI)
+    {
+	ClutterFixed f = CLUTTER_FIXED_DIV (anx, CFX_2PI);
+	anx = anx - f;
+    }
+
+    /* reduce to first quadrant and sign */
+    int sign = 1;
+
+    if (anx > CFX_PI)
+    {
+	sign = -1;
+	if (anx > CFX_PI + CFX_PI_2)
+	{
+	    /* fourth qudrant */
+	    anx = CFX_2PI - anx;
+	}
+	else
+	{
+	    /* third quadrant */
+	    anx -= CFX_PI;
+	}
+    }
+    else
+    {
+	if (anx > CFX_PI_2)
+	{
+	    /* second quadrant */
+	    anx = CFX_PI - anx;
+	}
+    }
+
+    /* Calculate indexes of the two nearest values in our table
+     * and return weighted average
+     *
+     * Handle the end of the table gracefully
+     */
+    int indx1 = CLUTTER_FIXED_DIV (anx, CFX_SIN_STEP);
+    int indx2;
+    
+    indx1 = CLUTTER_FIXED_INT (indx1);
+
+    if (indx1 == sizeof (sin_tbl)/sizeof (ClutterFixed) - 1)
+    {
+	indx2 = indx1;
+	indx1 = indx2 - 1;
+    }
+    else
+    {
+	indx2 = indx1 + 1;
+    }
+    
+    ClutterFixed low  = sin_tbl[indx1];
+    ClutterFixed high = sin_tbl[indx2];
+
+    ClutterFixed d1 = anx - indx1 * CFX_SIN_STEP;
+    ClutterFixed d2 = indx2 * CFX_SIN_STEP - anx;
+
+    anx = ((low * d2 + high * d1) / (CFX_SIN_STEP));
+
+    if (sign < 0)
+	anx = (1 + ~anx);
+    
+    return anx;
+}

clutter/clutter-fixed.h

@@ -32,20 +32,26 @@ G_BEGIN_DECLS
 
 typedef gint32 ClutterFixed;
 
-#define CFX_Q     16		/* Decimal part size in bits */
+#define CFX_Q      16		/* Decimal part size in bits */
-#define CFX_ONE   (1 << CFX_Q)	/* 1 */
+#define CFX_ONE    (1 << CFX_Q)	/* 1 */
-#define CFX_MAX   0x7fffffff
+#define CFX_MAX    0x7fffffff
-#define CFX_MIN   0x80000000
+#define CFX_MIN    0x80000000
+#define CFX_PI     0x0003243f
+#define CFX_2PI    0x0006487f
+#define CFX_PI_2   0x00019220   /* pi/2 */
+#define CFX_PI_4   0x0000c910   /* pi/4 */
+#define CFX_PI8192 0x6487ed51   /* pi * 0x2000, to improve precision */    
 
-#define CLUTTER_FIXED_TO_FLOAT(x) ((float)((x)/65536.0))
+#define CLUTTER_FIXED_TO_FLOAT(x) ((float)((int)(x)/65536.0))
 
-#define CLUTTER_FIXED_TO_DOUBLE(x) ((double)((x)/65536.0))
+#define CLUTTER_FIXED_TO_DOUBLE(x) ((double)((int)(x)/65536.0))
 
 #define CLUTTER_FLOAT_TO_FIXED(x)   \
   ( (ABS(x) > 32767.0) ?            \
             (((x)/(x))*0x7fffffff)  \
           : ((long)((x) * 65536.0  + ((x) < 0 ? -0.5 : 0.5))) )
 
+
 #define CLUTTER_INT_TO_FIXED(x) ((x) << CFX_Q)
 
 #define CLUTTER_FIXED_INT(x) ((x) >> CFX_Q)
@@ -61,6 +67,9 @@ typedef gint32 ClutterFixed;
 
 #define CLUTTER_FIXED_DIV(x,y) ((((x) << 8)/(y)) << 8)
 
+/* Fixed point math routines */
+ClutterFixed clutter_fixed_sin (ClutterFixed anx);
+
 G_END_DECLS
 
 #endif