Fix INCBIN/BIN unquoted filenames

asm6's documentation states the following syntaxes are allowed:

INCBIN foo.bin
INCBIN foo.bin, $400
INCBIN foo.bin, $200, $2000

The 1st example works, but the 2nd and 3rd fail with a vague error of
"Can't open file."  The filename attempted to be opened isn't shown, so
the user has no idea what's wrong (had it been, I suspect this bug would
have been fixed a lot sooner).

However, if you put the filename part in double-quotes, all 3 forms work
correctly.

The bug: incbin() calls getfilename() (the only piece of code that uses
the getfilename() function).  getfilename() calls getword() with the 3rd
argument (mcheck) being 0.  An mcheck of 0 causes the function to *not*
call strtok() against "mathy letters", meaning it acts like strchr() but
with multiple letters that cause it to stop.  So in the case of the
string "foo.bin, $200, $2000", the string "foo.bin," is returned and
treated as the filename (note the trailing comma).

The fix: extend getword() to support an mcheck of 2, which calls
strtok(dst,",") and thus only gets the filename portion; also consider
that the size/offset arguments to INCBIN are comma-delimited.

I could have simply changed getword() to use an mcheck value of 1, but
that would allow syntactically-incorrect things to work, such as
"INCBIN foo.bin^ $200".

Finally, document all of this in readme.txt, as well as add some basic
test case code in test_cases/incbin.  (Note there is no simple way way
to implement these tests, and I dislike "test suite frameworks," so just
refer to the comments in the test code for now.)

Author: koitsu

.gitignore

@@ -1,4 +1,5 @@
 *.exe
 *.o
 *.obj
-asm6f
+asm6f
+test_cases/incbin/incbin.bin

asm6f.c

@@ -913,13 +913,16 @@ int eval(char **str,int precedence) {
 }
 
 //copy next word from src into dst and advance src
-//mcheck=1 to crop mathy stuff (0 for filenames,etc)
+//mcheck=0 to crop nothing
+//mcheck=1 to crop mathy stuff
+//mcheck=2 to crop comma (e.g. for incbin)
 void getword(char *dst,char **src,int mcheck) {
 	*src+=strspn(*src,whitesp);//eatwhitespace
 	strncpy(dst,*src,WORDMAX-1);
 	dst[WORDMAX-1]=0;
 	strtok(dst,whitesp);//no trailing whitespace
-	if(mcheck) strtok(dst,mathy);
+	if(mcheck==1) strtok(dst,mathy);
+	else if(mcheck==2) strtok(dst,",");
 	*src+=strlen(dst);
 	if(**src==':') (*src)++;//cheesy fix for rept/macro listing
 }
@@ -943,7 +946,7 @@ void getfilename(char *dst, char **next) {
 			*next=end;
 		}
 	} else {
-		getword(dst,next,0);
+		getword(dst,next,2);
 	}
 }
 
@@ -2887,4 +2890,4 @@ void nes2chrbram(label *id, char **next) {
 		errmsg=OutOfRange;
 
 	ines_include++; use_nes2 = 1;
-}
+}

readme.txt

@@ -169,6 +169,21 @@ xaa (X And A) HIGHLY UNSTABLE!!!
 
 lax is currently not supported.
 
+--------------------------------------------------------------
+Assembler directive clarifications
+--------------------------------------------------------------
+
+INCLUDE/INCSRC
+INCBIN/BIN
+
+        Filenames can be double-quoted, permitting names that contain
+        spaces, ex.:
+
+                INCLUDE "some file.bin"
+                INCBIN "some file.bin"
+                INCBIN "some file.bin", $400
+                INCBIN "some file.bin", $200, $2000
+
 --------------------------------------------------------------
 Additional assembler directives
 --------------------------------------------------------------
@@ -275,4 +290,4 @@ freem's To-Do List
 * add ca65 debug format for NintendulatorDX
 
 --------------------------------------------------------------
-<EOF>
+<EOF>

test_cases/incbin/filename with spaces.bin

@@ -0,0 +1,37 @@
+; General INCBIN/BIN string parser test
+; Author: Jeremy Chadwick <jdc@koitsu.org>
+
+; Quoted filename
+
+incbin "filename.bin"             ; entire file (512)     size: 512
+incbin "filename.bin",$100        ; bytes 256-512 (256)   size: 768
+incbin "filename.bin",$100,16     ; bytes 256-272 (16)    size: 784
+incbin "filename.bin",$100, 16    ; bytes 256-272 (16)    size: 800
+incbin "filename.bin", $100       ; bytes 256-512 (256)   size: 1056
+incbin "filename.bin", $100,16    ; bytes 256-272 (16)    size: 1072
+incbin "filename.bin", $100, 16   ; bytes 256-272 (16)    size: 1088
+
+; Unquoted filename
+
+incbin filename.bin               ; entire file (512)     size: 1600
+incbin filename.bin,$100          ; bytes 256-512 (256)   size: 1856
+incbin filename.bin,$100,16       ; bytes 256-272 (16)    size: 1872
+incbin filename.bin,$100, 16      ; bytes 256-272 (16)    size: 1888
+incbin filename.bin, $100         ; bytes 256-512 (256)   size: 2144
+incbin filename.bin, $100,16      ; bytes 256-272 (16)    size: 2160
+incbin filename.bin, $100, 16     ; bytes 256-272 (16)    size: 2176
+
+; Equates and math expressions used as params or args
+
+DATAFILE EQU "filename.bin"
+FOO = (256+184+40)-4+4/2*2        ; FOO = 480
+incbin DATAFILE, FOO              ; bytes 480-512 (32)    size: 2208
+incbin filename.bin, FOO+1, $10   ; bytes 481-497 (16)    size: 2224
+
+; Filenames with spaces (must be quoted)
+
+incbin "filename with spaces.bin"           ; entire file (512)     size: 2736
+incbin "filename with spaces.bin",$100,16   ; bytes 256-272 (16)    size: 2752
+incbin "filename with spaces.bin", $100, 16 ; bytes 256-272 (16)    size: 2768
+
+; Resulting file MD5: 47ecec73da1168b0c0f243d0773b1c76