ase/cmd/awk/asm.awk

@@ -0,0 +1,52 @@
+#
+# $Id: asm.awk,v 1.4 2007/09/27 11:33:45 bacon Exp $
+#
+# Taken from the book "The AWK Programming Language"
+# aseawk++ -si asm.awk -a asm.s -nostripspaces -baseone
+#
+
+BEGIN {
+	srcfile = ARGV[1];
+	ARGV[1] = "";
+	tempfile = "asm.temp";
+	n = split("const get put ld st add sub jpos jz j halt", x);
+	for (i = 1; i <= n; i++) op[x[i]] = i - 1;
+
+# PASS 1
+	FS = "[ \t]+";
+	while (getline <srcfile > 0) {
+		sub (/#.*/, "");
+		symtab[$1] = nextmem;
+
+		if ($2 != "") {
+			print $2 "\t" $3 >tempfile;
+			nextmem++;
+		}	
+	}
+	close (tempfile);
+
+# PASS 2
+	nextmem = 0;
+	while (getline <tempfile > 0) {
+		if ($2 !~ /^[0-9]*$/) $2 = symtab[$2];
+		mem[nextmem++] = 1000 * op[$1] + $2;
+	}
+
+# INTERPRETER
+	for (pc = 0; pc >= 0; ) {
+		addr = mem[pc] % 1000;
+		code = int(mem[pc++] / 1000);
+		if      (code == op["get"])  { if (getline acc <= 0) acc = 0; }
+		else if (code == op["put"])  { print acc; }
+		else if (code == op["st"])   { mem[addr] = acc; }
+		else if (code == op["ld"])   { acc = mem[addr]; }
+		else if (code == op["add"])  { acc += mem[addr]; }
+		else if (code == op["sub"])  { acc -= mem[addr]; }
+		else if (code == op["jpos"]) { if (acc > 0) pc = addr; }
+		else if (code == op["jz"])   { if (acc == 0) pc = addr; }
+		else if (code == op["j"])    { pc = addr; }
+		else if (code == op["halt"]) { pc = -1; }
+		else                         { pc = -1; }
+	}
+}
+