Expand comment (cont'd).

This commit is contained in:
Alexei Podtelezhnikov 2021-08-26 15:31:11 +00:00
parent 686e2a5eb3
commit 3785393d1a

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@ -380,6 +380,12 @@ typedef ptrdiff_t FT_PtrDist;
/* each slanted line. Nevertheless, these divisions are noticeable */
/* in the overall performance because flattened curves produce a */
/* very large number of slanted lines. */
/* */
/* The division results here are always within ONE_PIXEL. Therefore */
/* the shift magnitude should be at least PIXEL_BITS wider than the */
/* divisors to provide sufficient accuracy of the multiply-shift. */
/* It should not exceed (64 - PIXEL_BITS) to prevent overflowing and */
/* leave enough room for 64-bit unsigned multiplication however. */
#define FT_UDIVPREP( c, b ) \
FT_Int64 b ## _r = c ? (FT_Int64)( ~(FT_UInt64)0 >> PIXEL_BITS ) / ( b ) \
: 0