ref: e8b186eedbda385faae2991068020cf9282afe5d
parent: c1c0720cc3b4e2d782784b261cadea9e6f940194
author: Alexei Podtelezhnikov <[email protected]>
date: Mon Jul 27 19:22:34 EDT 2015
* src/base/ftcalc.c (FT_Vector_NormLen): Explicate type conversions.
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2015-07-27 Alexei Podtelezhnikov <[email protected]>
+
+ * src/base/ftcalc.c (FT_Vector_NormLen): Explicate type conversions.
+
2015-07-26 Matthias Clasen <[email protected]>
[cff] Don't use `hmtx' table for LSB (#45520).
--- a/src/base/ftcalc.c
+++ b/src/base/ftcalc.c
@@ -790,16 +790,19 @@
FT_BASE_DEF( FT_UInt32 )
FT_Vector_NormLen( FT_Vector* vector )
{- FT_Int32 x = vector->x;
- FT_Int32 y = vector->y;
+ FT_Int32 x_ = vector->x;
+ FT_Int32 y_ = vector->y;
FT_Int32 b, z;
- FT_UInt32 u, v, l;
+ FT_UInt32 x, y, u, v, l;
FT_Int sx = 1, sy = 1, shift;
- FT_MOVE_SIGN( x, sx );
- FT_MOVE_SIGN( y, sy );
+ FT_MOVE_SIGN( x_, sx );
+ FT_MOVE_SIGN( y_, sy );
+ x = (FT_UInt32)x_;
+ y = (FT_UInt32)y_;
+
/* trivial cases */
if ( x == 0 )
{@@ -814,12 +817,15 @@
return x;
}
- /* estimate length and prenormalize */
- l = x > y ? (FT_UInt32)x + ( y >> 1 )
- : (FT_UInt32)y + ( x >> 1 );
+ /* estimate length and prenormalize by shifting so that */
+ /* the new approximate length is between 2/3 and 4/3. */
+ /* The magic contsnt 0xAAAAAAAAUL (2/3 of 2^32) helps */
+ /* to achive this in 16.16 fixed-point representation. */
+ l = x > y ? x + ( y >> 1 )
+ : y + ( x >> 1 );
shift = 31 - FT_MSB( l );
- shift -= 15 + ( l >= 0xAAAAAAAAUL >> shift );
+ shift -= 15 + ( l >= ( 0xAAAAAAAAUL >> shift ) );
if ( shift > 0 )
{@@ -827,8 +833,8 @@
y <<= shift;
/* reestimate length for tiny vectors */
- l = x > y ? (FT_UInt32)x + ( y >> 1 )
- : (FT_UInt32)y + ( x >> 1 );
+ l = x > y ? x + ( y >> 1 )
+ : y + ( x >> 1 );
}
else
{@@ -840,11 +846,14 @@
/* lower linear approximation for reciprocal length minus one */
b = 0x10000 - (FT_Int32)l;
+ x_ = (FT_Int32)x;
+ y_ = (FT_Int32)y;
+
/* Newton's iterations */
do
{- u = (FT_UInt32)( x + ( x * b >> 16 ) );
- v = (FT_UInt32)( y + ( y * b >> 16 ) );
+ u = (FT_UInt32)( x_ + ( x_ * b >> 16 ) );
+ v = (FT_UInt32)( y_ + ( y_ * b >> 16 ) );
/* converting to signed gives difference with 2^32 */
z = -(FT_Int32)( u * u + v * v ) / 0x200;