Design progress

README.md

@@ -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`, a pointer to a label
-- `.pointer`, pointer to a label
+- `@0010`, a position in the program
 
 ```
 < conditionals >
 
-0302	ADD 
+.there ( 0a 05 GTH ) JMC
-05		EQU
-
-.there	JMZ
 
 :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

examples/arithmetic.usm

@@ -1,6 +1,6 @@
 < arithmetic >
 
-0203 LTH .true JMZ
+0203 LTH .true JMC
 
 :false ee BRK
 :true ff BRK

examples/conditionals.usm

@@ -1,9 +1,6 @@
 < conditionals >
 
-0302	ADD 
+.there ( 0a 05 GTH ) JMC
-05		EQU
-
-.there	JMZ
 
 :here
 	< when not equal >

examples/core.usm

@@ -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

examples/loop.usm

@@ -4,5 +4,5 @@
 
 :loop 
 	01 ADD
-	0f NEQ .loop JMZ
+	0f NEQ .loop JMC
 	RTS

uxn.c

@@ -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_jmu() { cpu.rom.ptr = wspop(); }
-void op_jsi() { rspush(cpu.rom.ptr); cpu.rom.ptr = wspop(); }
+void op_jsu() { 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_jmc() { if(wspop()) op_jmu(); }
-void op_jsz() { Uint8 a = wspop(); if(getflag(FLAG_ZERO)){ rspush(cpu.rom.ptr); cpu.rom.ptr = a; } setflag(FLAG_ZERO,0); }
+void op_jsc() { if(wspop()) op_jsu(); }
-void op_equ() { setflag(FLAG_ZERO, wspop() == wspeek()); }
+void op_equ() { wspush(wspop() == wspop()); }
-void op_neq() { setflag(FLAG_ZERO, wspop() != wspeek()); }
+void op_neq() { wspush(wspop() != wspop()); }
-void op_gth() {	setflag(FLAG_ZERO, wspop() < wspeek()); }
+void op_gth() {	wspush(wspop() < wspop()); }
-void op_lth() {	setflag(FLAG_ZERO, wspop() > wspeek()); }
+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}
 };

uxnasm.c

@@ -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;
+	return w[0] == '(' || w[0] == ')' || w[0] == '{' || w[0] == '}';
-	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;
 }
 
 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(iscomment(word, &skip) || ismarker(word)) continue;
-		if((op = findop(word)) || scmp(word, "BRK"))
+		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);