BACK               41 regex/regexec.c #define	BACK(dst, src, n)	((dst) |= ((unsigned)(src)&(here)) >> (n))
BACK               65 regex/regexec.c #undef	BACK
BACK               90 regex/regexec.c #define	BACK(dst, src, n)	((dst)[here-(n)] |= (src)[here])