5 files changed, 243 insertions(+), 49 deletions(-)

A disasm.c
M lc3.c
M lc3.h
M mkfile
A util.c

@@ 0,0 1,139 @@
+#include <u.h>
+#include <libc.h>
+#include <stdio.h>
+#include "lc3.h"
+#include "util.c"
+
+int debug = 0;
+char *imagefile;
+
+void
+usage(void)
+{
+	fprint(2, "disasm -f FILE");
+}
+
+int
+printreg12(int op)
+{
+	switch(op){
+	case OP_ADD:
+	case OP_AND:
+	case OP_LD:
+	case OP_LDI:
+	case OP_LDR:
+	case OP_LEA:
+	case OP_NOT:
+	case OP_ST:
+	case OP_STI:
+	case OP_STR:
+		return 1;
+	default:
+		return 0;
+	}
+}
+
+int
+printpcof9(u16int op)
+{
+	switch(op){
+	case OP_BR:
+	case OP_LD:
+	case OP_LDI:
+	case OP_LEA:
+	case OP_ST:
+	case OP_STI:
+	case OP_STR:
+		return 1;
+	default:
+		return 0;
+	}
+}
+
+int
+printreg9(u16int op)
+{
+	switch(op){
+	case OP_ADD:
+	case OP_AND:
+	case OP_JMP:
+	case OP_LDR:
+	case OP_NOT:
+		return 1;
+	case OP_JSR: // dealt with in separate case
+	default:
+		return 0;
+	}
+}
+
+void
+main(int argc, char* argv[])
+{
+	int c;
+	ARGBEGIN {
+	case 'd':
+		debug++;
+		break;
+	case 'f':
+		imagefile = EARGF(usage());
+		c = readimage(imagefile);
+		if(c < 1) {
+			exits("Could not read image file");
+		}
+		c = c/2;
+	} ARGEND;
+	u16int instr = 0x0000;
+	for(int i = origin; i < origin + c; i++){
+		instr = memread(i);
+		if(instr == 0){
+			print("\tNOP\n");
+			continue;
+		}
+		u16int op = instr >> 12;
+		if(op == OP_JSR) {
+			if((instr >> 11) & 1)
+				print("\tJSR\t0x%x\n", (instr & 0x7FF));
+			else 
+				print("\tJSRR\t%s\n", regname[(instr >> 6) & 0x7]);
+			continue;
+		} else if(op == OP_TRAP){
+			print("\t%s\n", trap[instr & 0xFF]);
+			continue;
+		}
+		if(op >= OP_COUNT)
+			exits("Invalid opcode");
+		print("\t%s", opcode[op]);
+		if(printreg12(op)) {
+			print("\t%s", regname[(instr >> 9) & 0x7]);
+		} else if(op == OP_BR){
+			u16int fl = (instr >> 9) & 0x7;
+			if(fl & FL_POS)
+				print("%c", 'p');
+			if(fl & FL_ZRO)
+				print("%c", 'z');
+			if(fl & FL_NEG)
+				print("%c", 'n');
+		}
+		if(printpcof9(op)){
+			if(op == OP_BR)
+				print("\t");
+			else
+				print(",");
+			print("0x%x\n", (instr & 0x1FF));
+			continue;
+		} else if(printreg9(op)) {
+			print(",%s\n", regname[(instr >> 6) & 0x7]);
+			continue;
+		}
+		if(op == OP_ADD || op == OP_AND){
+			if((instr >> 5) & 1)
+				print(",0x%x", instr & 0x1F);
+			else
+				print(",%s", regname[instr & 0x7]);
+		} else if(op == OP_STR | op == OP_LDR) {
+			print(",0x%x", instr & 0x3f);
+		}
+		print("\n");
+	}
+	exits(nil);
+}

@@ 3,10 3,7 @@
 #include <libc.h>
 #include <stdio.h>
 #include "lc3.h"
-
-u16int memory[MEMORY_MAX];
-u16int reg[R_COUNT];
-
+#include "util.c"
 
 int debug = 0;
 int consctl;


@@ 17,44 14,6 @@ usage(void)
 	fprint(2, "lc3 -f FILE");
 }
 
-u16int
-swap16(u16int x)
-{
-	return (x << 8) | (x >> 8);
-}
-
-int
-readimage(char *file)
-{
-	int c;
-	int f = open(file, OREAD);
-	if(f == -1) return 0;
-	u16int origin;
-	read(f, &origin, sizeof(origin));
-	origin = swap16(origin);
-	c = read(f, memory + origin, MEMORY_MAX - origin);
-	c+=origin;
-	memory[c]=0x00;	
-	while(c-- > origin)
-		memory[c] = swap16(memory[c]);
-	return c;
-}
-
-int
-memread(u16int addr)
-{
-	return memory[addr];
-}
-
-u16int
-signextend(u16int x, u16int count)
-{
-	if((x >> (count-1)) & 1) {
-		x |= (0xFFFF << count);
-	}
-	return x;
-}
-
 void
 updateflags(u16int r)
 {


@@ 277,8 236,7 @@ main(int argc, char* argv[])
 	consctl = open("/dev/consctl", OWRITE);
 	if(consctl == -1) exits("can't open /dev/consctl: %r\n");	// exactly one cond flag should be set at all times
 	reg[R_COND] = FL_ZRO;
-	enum { PC_START = OFFSET };
-	reg[R_PC] = PC_START;
+	reg[R_PC] = origin;
 
 	int running = 1;
 	while (running)

@@ 16,6 16,20 @@ enum
 	R_COUNT
 };
 
+static const char* const regname[] =
+{
+	[R_R0]		= "R0",
+	[R_R1]		= "R1",
+	[R_R2]		= "R2",
+	[R_R3]		= "R3",
+	[R_R4]		= "R4",
+	[R_R5]		= "R5",
+	[R_R6]		= "R6",
+	[R_R7]		= "R7",
+	[R_PC]		= "PC",
+	[R_COND]	= "COND"
+};
+
 enum
 {
 	OP_BR = 0,	// branch


@@ 33,7 47,28 @@ enum
 	OP_JMP,		// jump
 	OP_RES,		// reserved (unused)
 	OP_LEA,		// load effective address
-	OP_TRAP		// execute trap
+	OP_TRAP,	// execute trap
+	OP_COUNT
+};
+
+static const char* const opcode[] =
+{
+	[OP_BR]		= "BR",		// branch
+	[OP_ADD]	= "ADD",	// add
+	[OP_LD]		= "LD",		// load
+	[OP_ST]		= "ST",		// store
+	[OP_JSR]	= "JSR",	// jump register
+	[OP_AND]	= "AND",	// bitwise and
+	[OP_LDR]	= "LDR",	// load register
+	[OP_STR]	= "STR",	// store register
+	[OP_RTI]	= "RTI",	// unused
+	[OP_NOT]	= "NOT",	// bitwise not
+	[OP_LDI]	= "LDI",	// load indirect
+	[OP_STI]	= "STI",	// store indirect
+	[OP_JMP]	= "JMP",	// jump
+	[OP_RES]	= "RES",	// reserved (unused)
+	[OP_LEA]	= "LEA",	// load effective address
+	[OP_TRAP]	= "TRAP"	// execute trap
 };
 
 enum


@@ 43,6 78,13 @@ enum
 	FL_NEG = 1 << 2,	// N
 };
 
+static const char* const flag[] =
+{
+	[FL_POS] = "p",
+	[FL_ZRO] = "z",
+	[FL_NEG] = "n"
+};
+
 enum
 {
 	TRAP_GETC = 0x20,


@@ 52,3 94,17 @@ enum
 	TRAP_PUTSP,
 	TRAP_HALT
 };
+
+static const char* const trap[] =
+{
+	[TRAP_GETC]	= "GETC",
+	[TRAP_OUT]	= "OUT",
+	[TRAP_PUTS]	= "PUTS",
+	[TRAP_IN]	= "IN",
+	[TRAP_PUTSP]	= "PUTSP",
+	[TRAP_HALT]	= "HALT"
+};
+
+u16int memory[MEMORY_MAX];
+u16int reg[R_COUNT];
+u16int origin = 0;

@@ 1,10 1,14 @@
 </$objtype/mkfile
 
-TARG=lc3
-BIN=/$objtype/bin
-OFILES=lc3.$O
+TARG=lc3 disasm
+BIN=/$objtype/bin/lc3
 HFILES=lc3.h
 
 default:V: all
 
-</sys/src/cmd/mkone
+</sys/src/cmd/mkmany
+
+install:V:
+	mkdir -p $BIN
+	for (i in $TARG)
+		mk $MKFLAGS $i.install

@@ 0,0 1,37 @@
+u16int
+swap16(u16int x)
+{
+	return (x << 8) | (x >> 8);
+}
+
+int
+readimage(char *file)
+{
+	int c;
+	int f = open(file, OREAD);
+	if(f == -1) return 0;
+	read(f, &origin, sizeof(origin));
+	origin = swap16(origin);
+	c = read(f, memory + origin, MEMORY_MAX - origin);
+	int progsize = c;
+	c+=origin;
+	memory[c]=0x00;	
+	while(c-- > origin)
+		memory[c] = swap16(memory[c]);
+	return progsize;
+}
+
+int
+memread(u16int addr)
+{
+	return memory[addr];
+}
+
+u16int
+signextend(u16int x, u16int count)
+{
+	if((x >> (count-1)) & 1) {
+		x |= (0xFFFF << count);
+	}
+	return x;
+}