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josejuan/haszero.c

Created June 17, 2012 00:00
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haszero
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haszero.c
// http://graphics.stanford.edu/~seander/bithacks.html
#define haszero(v) (((v) - 0x01010101UL) & ~(v) & 0x80808080UL)
// en 4 operaciones indica si un byte de entre todos es 0
// para 64 bits será, lógicamente
#define haszero(v) (((v) - 0x0101010101010101UL) & ~(v) & 0x8080808080808080UL)
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