Combee bitmap patch

Consider adding Ben Coombe's bitmap changes, as listed in the PATCHES file...

From: Ben Combee [mailto:ben.combee@gmail.com] On Behalf Of Ben Combee
Sent: Thursday, February 28, 2008 8:56 AM
To: atari2600@taswegian.com
Subject: Bitmap format patch for DASM

Hi, Andrew... I just started up a 2600 project of my own, and I've done
a few local modifications to the DASM source -- most are to make it
compile without warnings in CodeWarrior for Windows, but I also added a
new integer representation inspired by some of the disassemblies I've
seen. I call it bitmap format, and instead of a leading %, you use a
leading | followed by dots and Xs. A trailing | is allowed, but not
required. Here's an example.

PfDataStart
   .byte |..XXX...|
   .byte |....X...|
   .byte |X..XX..X|
   .byte |.XX..XXX|
   .byte |.XX..XXX|
   .byte |X..XX..X|
   .byte |....X...|
   .byte |..XXX...|
PfDataEnd

I find it easier to visualize the bitmaps in the code using this format,
as 0's and 1's aren't that distinctive.

Here's the code change made to exp.c. I added this new function just
before pushbin():

char *pushbitmap(char *str)
{
    long val = 0;
    while (*str == '.' || *str == 'X') {
        val = (val << 1) | (*str == 'X');
        ++str;
    }
    if (*str == '|') {
        ++str;
    }
    stackarg(val, 0, NULL);
    return str;
}

Then I modified the case statement around line 314:

    case '|':   /*  13: |   11: ||              */

        if (str[1] == '.' || str[1] == 'X')
        {
            str = pushbitmap(str+1);
        }
        else if (str[1] == '|')
        {
            doop((opfunc_t)op_oror, 11);
            str += 2;
        }
        else
        {
            doop((opfunc_t)op_or, 13);
            ++str;
        }
        break;

I'd be glad to send the other changes, but they're mostly just adding
"static" in front of local functions and cleaning up some loops that
used a ";" to do nothing into using "{ }" instead (it tells the compiler
that you intended on the empty action rather than just using a semicolon
accidentally by habit.

Review PATCHES and exp.c, especially the parser case around line 314 and the existing pushbin() handling. Confirm how bitmap literals should coexist with the existing | and || operators, then implement the requested syntax and verify that the bitmap examples in the issue assemble as intended.