diff options
Diffstat (limited to 'modules/freetype2/src/tools/cordic.py')
-rw-r--r-- | modules/freetype2/src/tools/cordic.py | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/modules/freetype2/src/tools/cordic.py b/modules/freetype2/src/tools/cordic.py new file mode 100644 index 0000000000..6511429889 --- /dev/null +++ b/modules/freetype2/src/tools/cordic.py @@ -0,0 +1,32 @@ +#!/usr/bin/env python3 + +# compute arctangent table for CORDIC computations in fttrigon.c +import math + +# units = 64*65536.0 # don't change !! +units = 180 * 2 ** 16 +scale = units / math.pi +shrink = 1.0 +angles2 = [] + +print("") +print("table of arctan( 1/2^n ) for PI = " + repr(units / 65536.0) + " units") + +for n in range(1, 32): + + x = 0.5 ** n # tangent value + + angle = math.atan(x) # arctangent + angle2 = round(angle * scale) # arctangent in FT_Angle units + + if angle2 <= 0: + break + + angles2.append(repr(int(angle2))) + shrink /= math.sqrt(1 + x * x) + +print(", ".join(angles2)) +print("shrink factor = " + repr(shrink)) +print("shrink factor 2 = " + repr(int(shrink * (2 ** 32)))) +print("expansion factor = " + repr(1 / shrink)) +print("") |