From 960a547587eb3df0760faa3d08247a101c600de6 Mon Sep 17 00:00:00 2001
From: David Turner <david@freetype.org>
Date: Fri, 23 Sep 2005 14:14:15 +0000
Subject: [PATCH]         * src/autofit/afangles.c (af_angle_atan): replaced
 CORDIC-based         implementation with one using lookup tables. This simple
 thing         speeds glyph loading by 18% according to ftbench !

---
 ChangeLog              |   5 ++
 src/autofit/afangles.c | 106 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 111 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index acbfc523a..ee9b78745 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -15,6 +15,11 @@
           removing _many_ compiler warnings when compiling with Visual C++
           at maximum level (/W4)
 
+        * src/autofit/afangles.c (af_angle_atan): replaced CORDIC-based
+        implementation with one using lookup tables. This simple thing
+        speeds glyph loading by 18% according to ftbench !
+
+
 2005-09-22  Werner Lemberg  <wl@gnu.org>
 
 	* docs/CHANGES: Mention SING Glyphlet support.
diff --git a/src/autofit/afangles.c b/src/autofit/afangles.c
index 7411be72f..dfb7bf794 100644
--- a/src/autofit/afangles.c
+++ b/src/autofit/afangles.c
@@ -20,6 +20,111 @@
 #include "aftypes.h"
 
 
+#if 1
+
+  /* the following table has been automatically generated with */
+  /* the `mather.py' Python script                             */
+
+#define  AF_ATAN_BITS  8
+
+  static const FT_Byte  af_arctan[1L << AF_ATAN_BITS] =
+  {
+     0,  0,  1,  1,  1,  2,  2,  2,
+     3,  3,  3,  3,  4,  4,  4,  5,
+     5,  5,  6,  6,  6,  7,  7,  7,
+     8,  8,  8,  9,  9,  9, 10, 10,
+    10, 10, 11, 11, 11, 12, 12, 12,
+    13, 13, 13, 14, 14, 14, 14, 15,
+    15, 15, 16, 16, 16, 17, 17, 17,
+    18, 18, 18, 18, 19, 19, 19, 20,
+    20, 20, 21, 21, 21, 21, 22, 22,
+    22, 23, 23, 23, 24, 24, 24, 24,
+    25, 25, 25, 26, 26, 26, 26, 27,
+    27, 27, 28, 28, 28, 28, 29, 29,
+    29, 30, 30, 30, 30, 31, 31, 31,
+    31, 32, 32, 32, 33, 33, 33, 33,
+    34, 34, 34, 34, 35, 35, 35, 35,
+    36, 36, 36, 36, 37, 37, 37, 38,
+    38, 38, 38, 39, 39, 39, 39, 40,
+    40, 40, 40, 41, 41, 41, 41, 42,
+    42, 42, 42, 42, 43, 43, 43, 43,
+    44, 44, 44, 44, 45, 45, 45, 45,
+    46, 46, 46, 46, 46, 47, 47, 47,
+    47, 48, 48, 48, 48, 48, 49, 49,
+    49, 49, 50, 50, 50, 50, 50, 51,
+    51, 51, 51, 51, 52, 52, 52, 52,
+    52, 53, 53, 53, 53, 53, 54, 54,
+    54, 54, 54, 55, 55, 55, 55, 55,
+    56, 56, 56, 56, 56, 57, 57, 57,
+    57, 57, 57, 58, 58, 58, 58, 58,
+    59, 59, 59, 59, 59, 59, 60, 60,
+    60, 60, 60, 61, 61, 61, 61, 61,
+    61, 62, 62, 62, 62, 62, 62, 63,
+    63, 63, 63, 63, 63, 64, 64, 64
+  };
+
+
+  FT_LOCAL_DEF( AF_Angle )
+  af_angle_atan( FT_Fixed  dx,
+                 FT_Fixed  dy )
+  {
+    AF_Angle  angle;
+
+
+    /* check trivial cases */
+    if ( dy == 0 )
+    {
+      angle = 0;
+      if ( dx < 0 )
+        angle = AF_ANGLE_PI;
+      return angle;
+    }
+    else if ( dx == 0 )
+    {
+      angle = AF_ANGLE_PI2;
+      if ( dy < 0 )
+        angle = -AF_ANGLE_PI2;
+      return angle;
+    }
+
+    angle = 0;
+    if ( dx < 0 )
+    {
+      dx = -dx;
+      dy = -dy;
+      angle = AF_ANGLE_PI;
+    }
+
+    if ( dy < 0 )
+    {
+      FT_Pos  tmp;
+
+
+      tmp = dx;
+      dx  = -dy;
+      dy  = tmp;
+      angle -= AF_ANGLE_PI2;
+    }
+
+    if ( dx == 0 && dy == 0 )
+      return 0;
+
+    if ( dx == dy )
+      angle += AF_ANGLE_PI4;
+    else if ( dx > dy )
+      angle += af_arctan[FT_DivFix( dy, dx ) >> ( 16 - AF_ATAN_BITS )];
+    else
+      angle += AF_ANGLE_PI2 -
+               af_arctan[FT_DivFix( dx, dy ) >> ( 16 - AF_ATAN_BITS )];
+
+    if ( angle > AF_ANGLE_PI )
+      angle -= AF_ANGLE_2PI;
+
+    return angle;
+  }
+
+
+#else /* 0 */
 /*
  * a python script used to generate the following table
  *
@@ -216,6 +321,7 @@ for n in r:
     return v.y;
   }
 
+#endif /* 0 */
 
   FT_LOCAL_DEF( AF_Angle )
   af_angle_diff( AF_Angle  angle1,