43 lines
530 B
C
43 lines
530 B
C
/*
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FUNCTION
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<<ffs>>---find first bit set in a word
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INDEX
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ffs
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ANSI_SYNOPSIS
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int ffs(int <[word]>);
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TRAD_SYNOPSIS
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int ffs(<[word]>);
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DESCRIPTION
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<<ffs>> returns the first bit set in a word.
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RETURNS
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<<ffs>> returns 0 if <[c]> is 0, 1 if <[c]> is odd, 2 if <[c]> is a multiple of
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2, etc.
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PORTABILITY
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<<ffs>> is not ANSI C.
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No supporting OS subroutines are required. */
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int
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ffs (word)
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int word;
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{
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int i;
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if (!word)
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return 0;
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i = 0;
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for (;;)
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{
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if (((1 << i++) & word) != 0)
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return i;
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}
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}
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