Path: utzoo!attcan!uunet!husc6!xait!g-rh
From: g-rh@XAIT.Xerox.COM (Richard Harter)
Newsgroups: comp.lang.c
Subject: Re: Hand optimized copying
Message-ID: <35210@XAIT.Xerox.COM>
Date: 18 Oct 88 15:41:42 GMT
References: <34421@XAIT.Xerox.COM> <10130002@hpisod1.HP.COM>
Reply-To: g-rh@XAIT.Xerox.COM (Richard Harter)
Organization: Xerox Corporation, Cambridge, Massachusetts
Lines: 25

In article <10130002@hpisod1.HP.COM> renglish@hpisod1.HP.COM (Robert English) writes:
]/ g-rh@XAIT.Xerox.COM (Richard Harter) /  2:38 pm  Oct  7, 1988 /

]> #define copy(dest,src,nb) {register char *a, *b; register int i;\
]> a = dest; b = src;\
]> for (i = (nb %7)+1; --i;) *a++ = *b++;\
]> for (i = (nb>>3)+1; --i>0;) {\
]> *a++ = *b++; *a++ = *b++; *a++ = *b++; *a++ = *b++;\
]> *a++ = *b++; *a++ = *b++; *a++ = *b++; *a++ = *b++;\
]> }}

]Methinks that line 3 should read:
]for (i = (nb & 07) + 1; --i;)...
]( or " % 8" )

You are correct -- it should read &7 rather than %7.  %8 is slightly
more expensive.  The "%" is a typo.  Also as noted previously, the 
variable a, b, and i should by replaced names specific to the macro,
and dest, src, and nb should be in parenthesis.

-- 

In the fields of Hell where the grass grows high
Are the graves of dreams allowed to die.
	Richard Harter, SMDS  Inc.