@@ -10,17 +10,15 @@ cc uxn.c -std=c89 -Os -DNDEBUG -g0 -s -Wall -Wno-unknown-pragmas -o uxn

 ## Assembly Syntax

+- `;variable`, a named address(zero-page)

 - `:label`, a named address

-- `+literal`, a numeric value

-- `.pointer`, pointer to a label

+- `.pointer`, a pointer to a label

+- `@0010`, a position in the program

 ```

 < conditionals >

-0302	ADD 

-05		EQU

-

-.there	JMZ

+.there ( 0a 05 GTH ) JMC

 :here

 	< when not equal >

@@ -35,10 +33,15 @@ cc uxn.c -std=c89 -Os -DNDEBUG -g0 -s -Wall -Wno-unknown-pragmas -o uxn

 ## Mission

+### Assembler

+

+- Crash on missing label

 - Catch overflow/underflow

+- Constants

 - Jumps should be relative

-- constants

-- variables

+

+### CPU

+

 - Pointers/Literals

 - A Three-Way Decision Routine(http://www.6502.org/tutorials/compare_instructions.html)

 - Carry flag?

@@ -47,7 +50,7 @@ cc uxn.c -std=c89 -Os -DNDEBUG -g0 -s -Wall -Wno-unknown-pragmas -o uxn

 - Detect mouse click

 - SDL Layer Emulator

 - Build PPU

-- Interrupts

+- Interrupts, vectors

 ### 16 Bit Missions

@@ -56,10 +59,6 @@ cc uxn.c -std=c89 -Os -DNDEBUG -g0 -s -Wall -Wno-unknown-pragmas -o uxn

 - Implement addressing

 - Implement 16 bits operations

-## Notes

-

-- Forth logic operators pop 2 items and add a bool to the stack, is that viable in uxn?

-

 ## Refs

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

@@ -1,6 +1,6 @@

 < arithmetic >

-0203 LTH .true JMZ

+0203 LTH .true JMC

 :false ee BRK

 :true ff BRK

similarity index 75%

rename from examples/cond.usm

rename to examples/conditionals.usm

@@ -1,9 +1,6 @@

 < conditionals >

-0302	ADD 

-05		EQU

-

-.there	JMZ

+.there ( 0a 05 GTH ) JMC

 :here

 	< when not equal >

@@ -1,6 +1,13 @@

-< core >

+< conditionals >

-34 34 EQU .label JSZ ff BRK

+.there ( 0a 05 GTH ) JMC

-:label ee RTS

+:here

+	< when not equal >

+	ee

+	BRK

+:there

+	< when is equal >

+	ff

+	BRK

@@ -4,5 +4,5 @@

 :loop 

 	01 ADD

-	0f NEQ .loop JMZ

+	0f NEQ .loop JMC

 	RTS

@@ -86,14 +86,14 @@ void op_dup() { wspush(wspeek()); }

 void op_swp() { Uint8 b = wspop(), a = wspop(); wspush(b); wspush(a); }

 void op_ovr() { wspush(cpu.wst.dat[cpu.wst.ptr - 2]); }

 void op_rot() { Uint8 c = wspop(),b = wspop(),a = wspop(); wspush(b); wspush(c); wspush(a); }

-void op_jmi() { cpu.rom.ptr = wspop(); }

-void op_jsi() { rspush(cpu.rom.ptr); cpu.rom.ptr = wspop(); }

-void op_jmz() { Uint8 a = wspop(); if(getflag(FLAG_ZERO)){ cpu.rom.ptr = a; } setflag(FLAG_ZERO,0); }

-void op_jsz() { Uint8 a = wspop(); if(getflag(FLAG_ZERO)){ rspush(cpu.rom.ptr); cpu.rom.ptr = a; } setflag(FLAG_ZERO,0); }

-void op_equ() { setflag(FLAG_ZERO, wspop() == wspeek()); }

-void op_neq() { setflag(FLAG_ZERO, wspop() != wspeek()); }

-void op_gth() {	setflag(FLAG_ZERO, wspop() < wspeek()); }

-void op_lth() {	setflag(FLAG_ZERO, wspop() > wspeek()); }

+void op_jmu() { cpu.rom.ptr = wspop(); }

+void op_jsu() { rspush(cpu.rom.ptr); cpu.rom.ptr = wspop(); }

+void op_jmc() { if(wspop()) op_jmu(); }

+void op_jsc() { if(wspop()) op_jsu(); }

+void op_equ() { wspush(wspop() == wspop()); }

+void op_neq() { wspush(wspop() != wspop()); }

+void op_gth() {	wspush(wspop() < wspop()); }

+void op_lth() {	wspush(wspop() > wspop()); }

 void op_and() {	wspush(wspop() & wspop()); }

 void op_ora() {	wspush(wspop() | wspop()); }

 void op_rol() { wspush(wspop() << 1); }

@@ -105,12 +105,12 @@ void op_div() { wspush(wspop() / wspop()); }

 void (*ops[])(void) = {

 	op_brk, op_rts, op_lit, op_drp, op_dup, op_swp, op_ovr, op_rot, 

-	op_jmi, op_jsi, op_jmz, op_jsz, op_equ, op_neq, op_gth, op_lth, 

+	op_jmu, op_jsu, op_jmc, op_jsc, op_equ, op_neq, op_gth, op_lth, 

 	op_and, op_ora, op_rol, op_ror, op_add, op_sub, op_mul, op_div};

 Uint8 opr[][2] = {

 	{0,0}, {0,0}, {0,0}, {1,0}, {0,1}, {1,1}, {0,1}, {3,3},

-	{1,0}, {1,0}, {1,0}, {1,0}, {1,0}, {1,0}, {1,0}, {1,0},

+	{2,0}, {2,0}, {2,0}, {2,0}, {2,1}, {2,1}, {2,1}, {2,1},

 	{1,0}, {1,0}, {1,0}, {1,0}, {2,1}, {0,0}, {0,0}, {0,0},

 	{2,1}, {2,1}, {2,1}, {2,1}, {2,1}, {2,1}, {2,1}, {2,1}

 };

@@ -17,7 +17,7 @@ WITH REGARD TO THIS SOFTWARE.

 typedef unsigned char Uint8;

 typedef struct {

-	int len;

+	int ptr;

 	Uint8 data[PRGLEN];

 } Program;

@@ -33,7 +33,7 @@ Label labels[256];

 char opcodes[][4] = {

 	"BRK", "RTS", "LIT", "POP", "DUP", "SWP", "OVR", "ROT",

-	"JMI", "JSI", "JMZ", "JSZ", "EQU", "NEQ", "GTH", "LTH",

+	"JMU", "JSU", "JMC", "JSC", "EQU", "NEQ", "GTH", "LTH",

 	"AND", "ORA", "ROL", "ROR", "ADD", "SUB", "MUL", "DIV"};

 /* clang-format on */

@@ -112,7 +112,7 @@ shex(char *s) /* string to num */

 void

 pushprg(Uint8 hex)

 {

-	p.data[p.len++] = hex;

+	p.data[p.ptr++] = hex;

 }

 void

@@ -151,13 +151,13 @@ addlabel(char *id, Uint8 addr)

 	Label *l = &labels[labelslen++];

 	scpy(suca(id), l->name, LABELIDLEN);

 	l->addr = addr;

-	printf("new label: %s=%02x\n", l->name, l->addr);

+	printf("New label: %s[0x%02x]\n", l->name, l->addr);

 }

 void

 addconst(char *id, Uint8 value)

 {

-	printf("new const: %s=%02x\n", id, value);

+	printf("New const: %s[%02x]\n", id, value);

 }

 Label *

@@ -181,18 +181,13 @@ findop(char *s)

 }

 int

-getlength(char *w)

+ismarker(char *w)

 {

-	if(findop(w) || scmp(w, "BRK")) return 1;

-	if(w[0] == '.') return 3;

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

-	if(sihx(w)) { return slen(w) / 2 + 2; }

-	printf("Unknown length %s\n", w);

-	return 0;

+	return w[0] == '(' || w[0] == ')' || w[0] == '{' || w[0] == '}';

 }

 int

-comment(char *w, int *skip)

+iscomment(char *w, int *skip)

 {

 	if(w[0] == '>') {

 		*skip = 0;

@@ -203,15 +198,31 @@ comment(char *w, int *skip)

 	return 0;

 }

+int

+getlength(char *w)

+{

+	if(findop(w) || scmp(w, "BRK")) return 1;

+	if(w[0] == '.') return 3;

+	if(w[0] == ':') return 0;

+	if(w[0] == ';') return 0;

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

+	if(sihx(w)) { return slen(w) / 2 + 2; }

+	if(ismarker(w)) return 0;

+	printf("Unknown length %s\n", w);

+	return 0;

+}

+

 void

 pass1(FILE *f)

 {

 	int skip = 0;

 	int addr = 0;

+	int vars = 0;

 	char word[64];

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

-		if(comment(word, &skip)) continue;

+		if(iscomment(word, &skip)) continue;

 		if(word[0] == ':') addlabel(word + 1, addr);

+		if(word[0] == ';') addlabel(word + 1, vars++);

 		addr += getlength(word);

 	}

 	rewind(f);

@@ -226,9 +237,12 @@ pass2(FILE *f)

 		Uint8 op = 0;

 		Label *l;

 		if(word[0] == ':') continue;

+		if(word[0] == ';') continue;

 		suca(word);

-		if(comment(word, &skip)) continue;

-		if((op = findop(word)) || scmp(word, "BRK"))

+		if(iscomment(word, &skip) || ismarker(word)) continue;

+		if(word[0] == '@')

+			p.ptr = shex(word + 1);

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

 			pushprg(op);

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

 			pushlabel(l);