Clear. Thanks for the explanation. Reinserted bitfields in r12303
Regards, K.
Op 22/04/2013 17:34, Krzysztof Kosiński schreef:
The relevant change is:
=== modified file 'src/style.h' --- src/style.h 2013-04-08 12:16:02 +0000 +++ src/style.h 2013-04-22 12:19:57 +0000 @@ -136,11 +136,11 @@
/// Paint type internal to SPStyle. struct SPIPaint {
- unsigned set : 1;
- unsigned inherit : 1;
- unsigned currentcolor : 1;
- unsigned int colorSet : 1;
- unsigned int noneSet : 1;
- bool set; //todo check if other properties are also booleans
- unsigned inherit;
- unsigned currentcolor;
- unsigned int colorSet;
- unsigned int noneSet;
All these properties were declared as unsigned, one-bit bitfields (that's what ": 1" after the name meant), not as full unsigned integers.
See here for details: http://www.tutorialspoint.com/cprogramming/c_bit_fields.htm
Bitfields are slightly slower than unsigned ints, but on modern processors which internally support only aligned adressing modes and emulate non-aligned accesses in microcode, bitfields should have performance equivalent to bools. If there are more than 4 boolean values, as in the case of SPStyle, one-bit bitfields will save space compared to bools.
Comparing one-bit bitfields to booleans is entirely acceptable, since the former can only have the values 0 or 1.
Regards, Krzysztof