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Noticed recently that bitcount16() isn't 16-bit clean due to signed

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shift right. It doesn't actually matter in the current code since
the input word only ever uses the bottom 9 bits, but if I ever
extended Mines to work in a triangular grid then all 16 bits might
be required. Fix this now, while I'm cleaning things up, so that it
won't bite me unexpectedly in future.

[originally from svn r6415]
This commit is contained in:
Simon Tatham
2005-10-22 16:38:15 +00:00
parent b7f192eea3
commit b44d75aa4e
1 changed files with 4 additions and 2 deletions
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6
mines.c
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@ -275,14 +275,16 @@ static char *validate_params(game_params *params, int full)
/*
* Count the bits in a word. Only needs to cope with 16 bits.
*/
static int bitcount16(int word)
static int bitcount16(int inword)
{
unsigned int word = inword;
word = ((word & 0xAAAA) >> 1) + (word & 0x5555);
word = ((word & 0xCCCC) >> 2) + (word & 0x3333);
word = ((word & 0xF0F0) >> 4) + (word & 0x0F0F);
word = ((word & 0xFF00) >> 8) + (word & 0x00FF);
return word;
return (int)word;
}
/*