@@ -12,18 +12,19 @@ cc uxn.c -std=c89 -Os -DNDEBUG -g0 -s -Wall -Wno-unknown-pragmas -o uxn

 ### Write

-- `;variable`, set a name to address on the zero-page

-- `:label`, set a name to an address

+- `;variable`, set a label to an assigned address

+- `:const`, set a label to a constant short

+- `@label`, set a label to an address

 ### Read

-- `,literal`, get a literal pointer

-- `.pointer`, get a raw pointer

+- `,literal`, push label value to stack

+- `.pointer`, read label value

 ### Special

-- `@0010`, move to position in the program

-- `( comment )`

+- `( comment )`, toggle parsing on/off

+- `|0010`, move to position in the program

 ```

 ;value ( alloc a zero-page variable )

@@ -49,7 +50,6 @@ cc uxn.c -std=c89 -Os -DNDEBUG -g0 -s -Wall -Wno-unknown-pragmas -o uxn

 ### Assembler

 - Catch overflow/underflow

-- Constants

 - Jumps should be relative

 ### CPU

@@ -63,6 +63,10 @@ cc uxn.c -std=c89 -Os -DNDEBUG -g0 -s -Wall -Wno-unknown-pragmas -o uxn

 - Build PPU

 - Add flags..

+### Devices

+

+- Devices each have an input byte, an output byte and two request bytes.

+

 ## Refs

 https://code.9front.org/hg/plan9front/file/a7f9946e238f/sys/src/games/nes/cpu.c

similarity index 89%

rename from extras/usm.sublime-syntax

rename to etc/usm.sublime-syntax

@@ -18,7 +18,7 @@ contexts:

     - include: strings

   numbers:

-    - match: '\@(\S+)\s?'

+    - match: '\|(\S+)\s?'

       scope: punctuation.definition

       pop: true

@@ -29,6 +29,9 @@ contexts:

     - match: '\;(\S+)\s?'

       scope: string.control

       pop: true

+    - match: '\_(\S+)\s?'

+      scope: string.control

+      pop: true

     - match: '\,(\S+)\s?'

       scope: keyword.control

       pop: true

new file mode 100644

@@ -0,0 +1,27 @@

+( blank project )

+

+;variable1

+;variable2

+_constant1 abcd

+

+|0100 ( -------------------------------- )

+

+:RESET BRK

+

+|c000 ( -------------------------------- )

+

+:FRAME ( FRAME-START )

+

+

+

+BRK ( FRAME-END )

+

+|d000 ( -------------------------------- )

+

+:ERROR BRK

+

+|FFFA ( -------------------------------- )

+

+.RESET

+.FRAME

+.ERROR

@@ -1,27 +1,29 @@

-( define some variables in the zero-page )

+( blank project )

-;var1

-;var2

+;variable1

+:constant1 9abc

-@0100 

+|0100 ( -------------------------------- )

-:RESET ( --- )

-	,1234

-	BRK

+@RESET

-@c000 ( much further.. )

+,abcd

-:FRAME ( --- )

-	,ab ,0008 str

-	BRK

+BRK ( RESET-END )

-@d000 ( further still.. )

+|c000 ( -------------------------------- )

-:ERROR ( --- )

-	,cdef

-	BRK

+@FRAME ( FRAME-START )

-@FFFA ( vectors, last 3 shorts )

+,abcd

+

+BRK ( FRAME-END )

+

+|d000 ( -------------------------------- )

+

+@ERROR BRK

+

+|FFFA ( -------------------------------- )

 .RESET

 .FRAME

@@ -103,7 +103,7 @@ shex(char *s) /* string to num */

 		else if(c >= 'A' && c <= 'F')

 			n = n * 16 + 10 + (c - 'A');

 		else if(c >= 'a' && c <= 'f')

-			n = n * 16 + 10 + (c - 'f');

+			n = n * 16 + 10 + (c - 'a');

 	return n;

 }

@@ -190,6 +190,14 @@ makelabel(char *id, Uint16 addr)

 	return 1;

 }

+int

+makeconst(char *id, FILE *f)

+{

+	char wv[64];

+	fscanf(f, "%s", wv);

+	return makelabel(id, shex(wv));

+}

+

 int

 pass1(FILE *f)

 {

@@ -199,16 +207,22 @@ pass1(FILE *f)

 	while(fscanf(f, "%s", w) == 1) {

 		if(iscomment(w, &skip)) continue;

 		suca(w);

-		if(w[0] == ':' && !makelabel(w + 1, addr))

+		if(w[0] == '@' && !makelabel(w + 1, addr))

 			return error("Pass1 failed", w);

 		if(w[0] == ';' && !makelabel(w + 1, vars++))

 			return error("Pass1 failed", w);

+		if(w[0] == ':') {

+			if(!makeconst(w + 1, f))

+				return error("Pass1 failed", w);

+			else

+				continue;

+		}

 		/* move addr ptr */

 		if(findop(w) || scmp(w, "BRK"))

 			addr += 1;

-		else if(w[0] == '@') {

+		else if(w[0] == '|')

 			addr = shex(w + 1);

-		} else if(w[0] == ':')

+		else if(w[0] == '@')

 			addr += 0;

 		else if(w[0] == ';')

 			addr += 0;

@@ -233,12 +247,14 @@ pass2(FILE *f)

 	while(fscanf(f, "%s", w) == 1) {

 		Uint8 op = 0;

 		Label *l;

-		if(w[0] == ':') continue;

+		if(w[0] == '@') continue;

 		if(w[0] == ';') continue;

 		suca(w);

 		if(iscomment(w, &skip) || ismarker(w)) continue;

-		if(w[0] == '@')

+		if(w[0] == '|')

 			p.ptr = shex(w + 1);

+		else if(w[0] == ':')

+			fscanf(f, "%s", w);

 		else if((op = findop(w)) || scmp(w, "BRK"))

 			pushbyte(op, 0);

 		else if((l = findlabel(w + 1)))