Quick Term_erase question.

[PaulBlay]

And the question is ... what's this bit in aid of?

	if ((n > 0) && (scr_cc[x] == (char) -1) && (scr_aa[x] == 255))
	{
		x--;
		n++;
	}

Apart from not understanding it and wanting to my problem is that I am using wchar_t not char for text so that "(char) -1" and "255" might well not be compatible with the rest of the code now.

Incidentally, if I was going to guess, I'd suspect it might have something to do with BIGTILE mode? (Maybe not).

[EDIT] Yeah, looks like it's BIGTILE stuff. I think I've got a handle on it, but I guess I'll end up changing some code for this.

[Pete Mack]

Ain't that some nice 80's-style code. Sweet!

It's stepping back the pad character of a tile in double-wide mode.

[PaulBlay]

Originally Posted by Pete Mack

Ain't that some nice 80's-style code. Sweet!

Tell me about it. There don't seem to be any #defines for attribute values so you just have to hope somebody left a comment or hope your psychic powers are up to stuff.

It's stepping back the pad character of a tile in double-wide mode.

Yeah, I figured it was something like that. I'm going to have to do similar stuff for handling double-width characters as well.

[Pete Mack]

I can write it more efficiently, if you like. The if statement is unnecessarily verbose.

         (n > 0) && (scr_cc[x] == (char) -1) && (scr_aa[x] == 255) && (x--, n++);

[Nick]

Originally Posted by PaulBlay

Yeah, I figured it was something like that. I'm going to have to do similar stuff for handling double-width characters as well.

Andrew Doull has extended this for double and triple tiles - which I stole for FA. Working that out and debugging edge effect issues was a lot of fun You may find it useful to look at one of those implementations (Un or FA or O110u), or you may have a neater way of doing it.

[PaulBlay]

Originally Posted by Nick

Andrew Doull has extended this for double and triple tiles - which I stole for FA.

Thanks, I'll probably have a look at that later.

Originally Posted by Nick

or you may have a neater way of doing it.

That seems unlikely.

[zaimoni]

Originally Posted by PaulBlay

And the question is ... what's this bit in aid of?

	if ((n > 0) && (scr_cc[x] == (char) -1) && (scr_aa[x] == 255))
	{
		x--;
		n++;
	}

Apart from not understanding it and wanting to my problem is that I am using wchar_t not char for text so that "(char) -1" and "255" might well not be compatible with the rest of the code now.

(char)(-1) is just plain living dangerously. It's a warning silencer because char isn't guaranteed to be equivalent to signed char.

scr_aa originally was unsigned char; 255 is UCHAR_MAX assuming CHAR_BIT is 8 (which the entire V codebase does, I put a preprocessor test for this into Zaiband to trigger a preprocessing error on such unsupported systems).

If you're not using a proper UNICODE library, try WCHAR_MAX (C++) or WINT_MAX (C) in place of 255/UCHAR_MAX. [Note that the standards do *not* guarantee any particular encoding for wchar_t/wint_t . As usual, Solaris will give you a porting sunburn.] Note that you will want to use a proper UNICODE library, because Linux will railroad you into UTF-8 while Windows demands you use UCS-2 in practice.

[PaulBlay]

Originally Posted by zaimoni

(char)(-1) is just plain living dangerously. It's a warning silencer because char isn't guaranteed to be equivalent to signed char.

scr_aa originally was unsigned char; 255 is UCHAR_MAX assuming CHAR_BIT is 8 (which the entire V codebase does, I put a preprocessor test for this into Zaiband to trigger a preprocessing error on such unsupported systems).

If you're not using a proper UNICODE library, try WCHAR_MAX (C++) or WINT_MAX (C) in place of 255/UCHAR_MAX.

I can see I'm going to have to stare blankly at the Term* functions for a few days for it to seep in.

[Note that the standards do *not* guarantee any particular encoding for wchar_t/wint_t . As usual, Solaris will give you a porting sunburn.] Note that you will want to use a proper UNICODE library, because Linux will railroad you into UTF-8 while Windows demands you use UCS-2 in practice.

My, admittedly simplistic, reasoning is that it's going to be hard enough to get everything working in Windows XP - I'll worry about the rest after I get that far. This is after all as much about practice getting my hands dirty with C++ as it is anything else as I'm very much a novice.