Bcopy, bzero and bcmp on a not-Berkeley machine

[Michael Kaercher]

In article <1155 at radig.UUCP> peter at radig.UUCP (Peter Radig) writes:
>Is is possible to replace calls to `bcopy', `bzero' and `bcmp' by
>the following macros:
>
>	#ifdef USG
>	#define bcmp(s1,s2,cnt)  memcpy(s1,s2,cnt)
				 ^^^^^^ This should be memcmp!
>	#define bcopy(fr,to,cnt) memcpy(to,fr,cnt)
>	#define bzero(addr,cnt)  memset(addr,'\0',cnt)
>	#endif USG

There may be a big surprise when using these definitions! bcopy does
handle overlapping memory areas correctly whereas memcpy is usually *not*
implemented this way. In case you are porting to Microsoft C: there is a
function in the runtime library called 'memmove' which does handle over-
lapping regions properly.

You can check out whether your definitions are proper with a little
program similar to the following:

	main()
	{
	    static char abc[] = "abcdefghi";
	    static char buffer[50];

	    strcpy (buffer, abc);
	    bcopy (buffer, buffer + 1, sizeof(abc));
	    puts (buffer);

	    strcpy (buffer, abc);
	    bcopy (buffer + 1, buffer, sizeof(abc));
	    puts (buffer);
	}

You should get:  'aabcd...' and 'bbcde...'. If the first line of output
shows up as 'aaaaaa...', bcopy (or the program above(?)) is borken...

BTW, i suppose that this feature in bcopy is due to the VAX MOVC3 instruction

Hope this helps,
Michael