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#ifdef CVF
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extern int __stdcall IGRAY(int *n0, int *idir)
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#else
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int igray_(int *n0, int *idir)
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#endif
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{
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int n;
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unsigned long sh;
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unsigned long nn;
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n=*n0;
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if(*idir>0) return (n ^ (n >> 1));
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sh = 1;
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nn = (n >> sh);
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while (nn > 0) {
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n ^= nn;
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sh <<= 1;
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nn = (n >> sh);
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}
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return (n);
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}
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