*

.clang-format

@@ -1,11 +1,11 @@
 AlignAfterOpenBracket: DontAlign
 AlignEscapedNewlines: DontAlign
 AlignOperands: DontAlign
-AllowShortBlocksOnASingleLine: Empty
+AllowShortBlocksOnASingleLine: Always
 AllowShortCaseLabelsOnASingleLine: true
 AllowShortEnumsOnASingleLine: true
-AllowShortIfStatementsOnASingleLine: false
-AllowShortLoopsOnASingleLine: false
+AllowShortIfStatementsOnASingleLine: true
+AllowShortLoopsOnASingleLine: true
 AlwaysBreakAfterDefinitionReturnType: TopLevel
 BinPackArguments: false
 BinPackParameters: false

README.md

@@ -11,26 +11,23 @@ cc uxn.c -std=c89 -Os -DNDEBUG -g0 -s -Wall -Wno-unknown-pragmas -o uxn
 ## Assembly Syntax
 
 ```
-: 	starting a definition
-& 	obtaining pointers
-( 	stack comments
-` 	inlining bytecodes
-' 	strings
-# 	numbers
-$ 	characters
-~   vector
-[ 12 34 ] real values
-< 12 34 > relative values
-( 12 34 ) deadzone
-```
+< comment >
 
-```
-;add-two JSR
++01 < literal >
 
-BRK
+[ 01 02 03 04 ] < block of literals >
 
-:add-two
-	[ 2 ] ADD RTS
+$01 < pointer8 >
+
+{ 01 02 03 04 } < block of pointer8 >
+
+~ff0f < pointer16 >
+
+( ff00 ff01 ff02 ff03 ) < block of pointer16 >
+
+=const +ff
+
+:label ADD RTS
 ```
 
 ## Design
@@ -57,3 +54,12 @@ BRK
 ### Emulator
 
 - SDL Layer
+
+
+## Refs
+
+https://code.9front.org/hg/plan9front/file/a7f9946e238f/sys/src/games/nes/cpu.c
+http://www.w3group.de/stable_glossar.html
+http://www.emulator101.com/6502-addressing-modes.html
+http://forth.works/8f0c04f616b6c34496eb2141785b4454
+https://justinmeiners.github.io/lc3-vm/

example.usm

@@ -1 +1,5 @@
-{ 25 26 27 28 } SWP POP DUP BRK
+< comment >
+
+[3 1 2 3 ] pop dup swp ovr rot 
+
+brk

uxn.c

@@ -29,19 +29,23 @@ typedef struct {
 	Uint8 address[STACK_DEPTH];
 } Computer;
 
+Computer cpu;
+
+#pragma mark - Helpers
+
 void
-setflag(Computer *cpu, char flag, int b)
+setflag(char flag, int b)
 {
 	if(b)
-		cpu->status |= flag;
+		cpu.status |= flag;
 	else
-		cpu->status &= (~flag);
+		cpu.status &= (~flag);
 }
 
 int
-getflag(Computer *cpu, char flag)
+getflag(char flag)
 {
-	return cpu->status & flag;
+	return cpu.status & flag;
 }
 
 void
@@ -57,30 +61,31 @@ echo(Uint8 *s, Uint8 len, char *name)
 	printf("\n\n");
 }
 
+#pragma mark - Operations
+
 void
 op_push(Uint8 *s, Uint8 *ptr, Uint8 v)
 {
-	s[*ptr] = v;
-	(*ptr) += 1;
+	s[(*ptr)++] = v;
 }
 
-void
+Uint8
 op_pop(Uint8 *s, Uint8 *ptr)
 {
-	s[*ptr--] = 0x00;
+	return s[--*ptr];
 }
 
 void
-reset(Computer *cpu)
+reset(void)
 {
 	int i;
-	cpu->status = 0x00;
-	cpu->counter = 0x00;
-	cpu->mptr = 0x00;
-	cpu->sptr = 0x00;
-	cpu->literal = 0x00;
+	cpu.status = 0x00;
+	cpu.counter = 0x00;
+	cpu.mptr = 0x00;
+	cpu.sptr = 0x00;
+	cpu.literal = 0x00;
 	for(i = 0; i < 256; i++)
-		cpu->stack[i] = 0x00;
+		cpu.stack[i] = 0x00;
 }
 
 int
@@ -91,39 +96,63 @@ error(char *name)
 }
 
 void
-load(Computer *cpu, FILE *f)
+load(FILE *f)
 {
-	fread(cpu->memory, sizeof(cpu->memory), 1, f);
+	fread(cpu.memory, sizeof(cpu.memory), 1, f);
 }
 
 void
-eval(Computer *cpu)
+eval()
 {
-	Uint8 instr = cpu->memory[cpu->mptr++];
-
-	if(cpu->literal > 0) {
-		printf("push: %02x[%d](%d)\n", instr, cpu->literal, cpu->sptr);
-		op_push(cpu->stack, &cpu->sptr, instr);
-		cpu->literal--;
+	Uint8 instr = cpu.memory[cpu.mptr++];
+	Uint8 a, b, c;
+	if(cpu.literal > 0) {
+		printf("push: %02x[%d](%d)\n", instr, cpu.literal, cpu.sptr);
+		op_push(cpu.stack, &cpu.sptr, instr);
+		cpu.literal--;
 		return;
 	}
 	switch(instr) {
-	case 0x0: setflag(cpu, FLAG_HALT, 1); break;
-	case 0x1: cpu->literal += 4; break;
+	case 0x0: setflag(FLAG_HALT, 1); break;
+	case 0x1: cpu.literal += cpu.memory[cpu.mptr++]; break;
+	case 0x2: printf("??\n"); break;
+	case 0x3: /* pop */
+		op_pop(cpu.stack, &cpu.sptr);
+		break;
+	case 0x4: /* dup */
+		op_push(cpu.stack, &cpu.sptr, cpu.stack[cpu.sptr - 1]);
+		break;
+	case 0x5: /* swp */
+		b = op_pop(cpu.stack, &cpu.sptr);
+		a = op_pop(cpu.stack, &cpu.sptr);
+		op_push(cpu.stack, &cpu.sptr, b);
+		op_push(cpu.stack, &cpu.sptr, a);
+		break;
+	case 0x6: /* ovr */
+		op_push(cpu.stack, &cpu.sptr, cpu.stack[cpu.sptr - 2]);
+		break;
+	case 0x7: /* rot */
+		c = op_pop(cpu.stack, &cpu.sptr);
+		b = op_pop(cpu.stack, &cpu.sptr);
+		a = op_pop(cpu.stack, &cpu.sptr);
+		op_push(cpu.stack, &cpu.sptr, b);
+		op_push(cpu.stack, &cpu.sptr, c);
+		op_push(cpu.stack, &cpu.sptr, a);
+		break;
 	default: printf("Unknown instruction: #%02x\n", instr);
 	}
 }
 
 void
-run(Computer *cpu)
+run(void)
 {
 	int i;
-	while((cpu->status & FLAG_HALT) == 0)
+	while((cpu.status & FLAG_HALT) == 0)
 		eval(cpu);
 	/* debug */
-	printf("ended @ %d  |  ", cpu->counter);
+	printf("ended @ %d  |  ", cpu.counter);
 	for(i = 0; i < 4; i++)
-		printf("%d-", (cpu->status & (1 << i)) != 0);
+		printf("%d-", (cpu.status & (1 << i)) != 0);
 	printf("\n\n");
 }
 
@@ -131,14 +160,13 @@ int
 main(int argc, char *argv[])
 {
 	FILE *f;
-	Computer cpu;
 	if(argc < 2)
 		return error("No input.");
 	if(!(f = fopen(argv[1], "rb")))
 		return error("Missing input.");
-	reset(&cpu);
-	load(&cpu, f);
-	run(&cpu);
+	reset();
+	load(f);
+	run();
 	/* print result */
 	echo(cpu.stack, 0x40, "stack");
 	echo(cpu.memory, 0x40, "memory");

uxnasm.c

@@ -16,43 +16,31 @@ WITH REGARD TO THIS SOFTWARE.
 typedef unsigned char Uint8;
 
 typedef struct {
-	int ptr;
+	int len;
 	Uint8 data[PRGLEN];
 } Program;
 
+char labels[256][16];
+
 char opcodes[][4] = {
 	"BRK",
 	"LIT",
+	"---",
+	"POP",
 	"DUP",
-	"DRP",
 	"SWP",
-	"SLP",
-	"PSH",
-	"POP", /* --- */
+	"OVR",
+	"ROT",
+	/* */
 	"JMP",
 	"JSR",
-	"RST",
-	"BEQ",
+	"JEQ",
+	"RTS",
 	"EQU",
 	"NEQ",
 	"LTH",
-	"GTH", /* --- */
-	"---",
-	"---",
-	"---",
-	"---",
-	"---",
-	"---",
-	"---",
-	"---", /* --- */
-	"---",
-	"---",
-	"---",
-	"---",
-	"---",
-	"---",
-	"---",
-	"---"};
+	"GTH",
+	/* */};
 
 Program p;
 
@@ -78,6 +66,17 @@ suca(char *s) /* string to uppercase */
 	return s;
 }
 
+int
+sihx(char *s)
+{
+	int i = 0;
+	char c;
+	while((c = s[i++]))
+		if(!(c >= '0' && c <= '9') && !(c >= 'A' && c <= 'F'))
+			return 0;
+	return 1;
+}
+
 int
 shex(char *s) /* string to num */
 {
@@ -86,36 +85,90 @@ shex(char *s) /* string to num */
 	while((c = s[i++]))
 		if(c >= '0' && c <= '9')
 			n = n * 16 + (c - '0');
-		else if(c >= 'a' && c <= 'f')
-			n = n * 16 + 10 + (c - 'a');
+		else if(c >= 'A' && c <= 'F')
+			n = n * 16 + 10 + (c - 'A');
 	return n;
 }
 
-#pragma mark - Helpers
+#pragma mark - Parser
+
+void
+addprg(Uint8 hex)
+{
+	p.data[p.len++] = hex;
+}
+
+void
+addlabel(char *id, Uint8 addr)
+{
+	printf("new label: %s=%02x\n", id, addr);
+}
+
+void
+addconst(char *id, Uint8 value)
+{
+	printf("new const: %s=%02x\n", id, value);
+}
 
 Uint8
-getopcode(char *s)
+findop(char *s)
 {
 	int i;
-	if(s[0] == '{') /* TODO catch closing */
-		return 0x01;
 	for(i = 0; i < 16; ++i)
-		if(scmp(opcodes[i], suca(s)))
+		if(scmp(opcodes[i], s))
 			return i;
-	return 0xff;
+	return 0;
+}
+
+int
+comment(char *w, int *skip)
+{
+	if(w[0] == '>') {
+		*skip = 0;
+		return 1;
+	}
+	if(w[0] == '<') *skip = 1;
+	if(*skip) return 1;
+	return 0;
 }
 
 void
 pass1(FILE *f)
 {
+	int skip = 0;
 	char word[64];
 	while(fscanf(f, "%s", word) == 1) {
-		int op = getopcode(word);
-		if(word[0] == '}')
+		if(comment(word, &skip))
 			continue;
-		if(op == 0xff)
-			op = shex(word);
-		p.data[p.ptr++] = op;
+	}
+	rewind(f);
+}
+
+void
+pass2(FILE *f)
+{
+	int skip = 0;
+	char word[64];
+	while(fscanf(f, "%s", word) == 1) {
+		Uint8 op;
+		suca(word);
+		if(comment(word, &skip)) continue;
+		if(word[0] == ']') continue;
+		if(word[0] == '+') {
+			addprg(0x01);
+			addprg(1);
+			addprg(shex(word + 1));
+		} else if(word[0] == '[') {
+			addprg(0x01);
+			addprg(shex(word + 1));
+		} else if((op = findop(word)))
+			addprg(op);
+		else if(sihx(word))
+			addprg(shex(word));
+		else if(scmp(word, "BRK"))
+			addprg(0x00);
+		else
+			printf("unknown: %s\n", word);
 	}
 }
 
@@ -135,6 +188,7 @@ main(int argc, char *argv[])
 	if(!(f = fopen(argv[1], "r")))
 		return error("Missing input.");
 	pass1(f);
+	pass2(f);
 	fwrite(p.data, sizeof(p.data), 1, fopen(argv[2], "wb"));
 	fclose(f);
 	return 0;