The efficient function (that is nearly the same as
https://graphics.stanford.edu/~seander/bithacks.html#DetermineIfPowerOf2)
replaces one loop based instance (which also reused the xx variable
afterwards, whereas it should have used htabmask instead) and one
instance using the population count a.k.a. Hamming weigth.
This one verifies bitmasks where low bits are set to 1 (hence the name).
Any stray 0 among the lower ones or any stray 1 among the higher zeros
renders the mask invalid.
The edge cases of all zeros and all ones are considered valid masks.
It uses an efficient implementation. It's the counterpart of
https://graphics.stanford.edu/~seander/bithacks.html#DetermineIfPowerOf2
* change File::GetSize to fetch the size directly from the open file instead
of stat'ing it when challed with a FILE*
* use changed File::GetSize(FILE *f) instead of calling with file name in two
places
* remove "seek_pos % file_size" hack for ZTP, so one can seek to the end of
file again. Please check Zelda: Twilight Princess for regressions
* return error codes when reading or writing from/to a file
A lot of those changes are from j4ck.fr0st, so kudos to him.
I did not change the file open mode for ISFS_OPEN_WRITE to "wb". While that
would probably be more correct, it says in the comment that it might affect
Mario Kart Wii. I would prefer somebody with that game try that change
locally first.
Please check your games for regressions (or even improvement). Some games that
may be affected are Zelda - Twilight Princess and Metroid Prime 3.
Fixes issue 1749
git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@6634 8ced0084-cf51-0410-be5f-012b33b47a6e
Niels Boehm