external/freetype 2.3.5

1 files changed, 79 insertions, 0 deletions

diff --git a/src/tools/cordic.py b/src/tools/cordic.py
new file mode 100644
index 0000000..3f80c5f
--- /dev/null
+++ b/src/tools/cordic.py
@@ -0,0 +1,79 @@
+# compute arctangent table for CORDIC computations in fttrigon.c
+import sys, math
+
+#units  = 64*65536.0   # don't change !!
+units  = 256
+scale  = units/math.pi
+shrink = 1.0
+comma  = ""
+
+def calc_val( x ):
+    global units, shrink
+    angle  = math.atan(x)
+    shrink = shrink * math.cos(angle)
+    return angle/math.pi * units
+
+def  print_val( n, x ):
+    global comma
+
+    lo  = int(x)
+    hi  = lo + 1
+    alo = math.atan(lo)
+    ahi = math.atan(hi)
+    ax  = math.atan(2.0**n)
+
+    errlo = abs( alo - ax )
+    errhi = abs( ahi - ax )
+
+    if ( errlo < errhi ):
+      hi = lo
+
+    sys.stdout.write( comma + repr( int(hi) ) )
+    comma = ", "
+
+
+print ""
+print "table of arctan( 1/2^n ) for PI = " + repr(units/65536.0) + " units"
+
+# compute range of "i"
+r = [-1]
+r = r + range(32)
+
+for n in r:
+
+    if n >= 0:
+        x = 1.0/(2.0**n)    # tangent value
+    else:
+        x = 2.0**(-n)
+
+    angle  = math.atan(x)    # arctangent
+    angle2 = angle*scale     # arctangent in FT_Angle units
+
+    # determine which integer value for angle gives the best tangent
+    lo  = int(angle2)
+    hi  = lo + 1
+    tlo = math.tan(lo/scale)
+    thi = math.tan(hi/scale)
+
+    errlo = abs( tlo - x )
+    errhi = abs( thi - x )
+
+    angle2 = hi
+    if errlo < errhi:
+        angle2 = lo
+
+    if angle2 <= 0:
+        break
+
+    sys.stdout.write( comma + repr( int(angle2) ) )
+    comma = ", "
+
+    shrink = shrink * math.cos( angle2/scale)
+
+
+print
+print "shrink factor    = " + repr( shrink )
+print "shrink factor 2  = " + repr( shrink * (2.0**32) )
+print "expansion factor = " + repr(1/shrink)
+print ""
+