final construction parts & primitive output

cpu.c

@@ -7,6 +7,7 @@ u8int	rA, rS, rX, rY, rP;
 u16int	pc;
 
 int	irq, nmi;
+int	trace;
 
 void
 nz(u8int v)
@@ -217,6 +218,7 @@ step(void)
 	}
 	cpc = pc;
 	op = fetch8();
+	if(trace)
 		print("%02x %08b %08b %08b %08b %04x %02x\n",
 			op, rA, rX, rY, rP, cpc, rS);
 	switch(op){

dat.h

@@ -12,3 +12,4 @@ extern u8int	*mem;
 extern u8int	*romptr;
 extern u8int	rA, rS, rX, rY, rP;
 extern u16int	pc;
+extern int	trace;

fns.h

@@ -2,4 +2,11 @@ extern int	step(void);
 extern u8int	memread(u16int);
 extern void	memwrite(u16int, u8int);
 
+extern void	push8(u8int);
+extern void	push16(u16int);
+extern u8int	pop8(void);
+extern u16int	pop16(void);
+extern u8int	fetch8(void);
 extern u16int	fetch16(void);
+
+extern void	out(void);

main.c

@@ -6,7 +6,7 @@
 void
 usage(void)
 {
-	fprint(2, "usage: %s [ -s target cycle length ] prog\n", argv0);
+	fprint(2, "usage: %s [ -t ] [ -s target cycle length ] prog\n", argv0);
 	exits("usage");
 }
 
@@ -41,6 +41,7 @@ main(int argc, char **argv)
 	vlong t, t2, t3;
 	vlong target;
 
+	trace = 0;
 	target = 1000;
 	mem = malloc(0x10000);
 	if(mem == nil)
@@ -49,6 +50,9 @@ main(int argc, char **argv)
 	case 's':
 		target = atoll(EARGF(usage()));
 		break;
+	case 't':
+		trace = 1;
+		break;
 	default:
 		usage();
 		break;
@@ -71,6 +75,7 @@ main(int argc, char **argv)
 				t3 = t2-t;
 			}
 		}
+		out();
 	}
 }
 

mkfile

@@ -3,7 +3,7 @@
 BIN=/$objtype/bin
 
 TARG=scemu
-OFILES=main.$O cpu.$O mem.$O
+OFILES=main.$O cpu.$O mem.$O out.$O
 UPDATE=mkfile prog.s ${OFILES:%.$O=%.c}
 
 default:V:	$O.out

out.c

@@ -0,0 +1,17 @@
+#include <u.h>
+#include <libc.h>
+#include "dat.h"
+#include "fns.h"
+
+void
+out(void)
+{
+	int c;
+
+	if(memread(0x7002) == 1){
+		c = memread(0x7000);
+		memwrite(0x7001, 0);
+		print("%c", c);
+		memwrite(0x7001, 1);
+	}
+}

test.s

@@ -1,11 +0,0 @@
-	.org $ff00
-reset:
-	lda #'\'
-	sta $7000
-loop:
-	ror
-	jmp loop
-	.org $fffa
-	.word reset
-	.word reset
-	.word reset