--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/insn_tfm.c	Fri Jan 02 03:35:29 2009 +0000
@@ -0,0 +1,111 @@
+/*
+insn_tfm.c
+Copyright © 2008 William Astle
+
+This file is part of LWASM.
+
+LWASM is free software: you can redistribute it and/or modify it under the
+terms of the GNU General Public License as published by the Free Software
+Foundation, either version 3 of the License, or (at your option) any later
+version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+more details.
+
+You should have received a copy of the GNU General Public License along with
+this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/*
+for handling inherent mode instructions
+*/
+
+#define __insn_inh_c_seen__
+
+#include <ctype.h>
+#include <string.h>
+
+#include "lwasm.h"
+#include "instab.h"
+
+OPFUNC(insn_tfm)
+{
+	static const char *reglist = "DXYUS   AB  00EF";
+	int r0, r1;
+	char *c;
+	int tfm = 0;
+			
+	c = strchr(reglist, toupper(*(*p)++));
+	if (!c)
+	{
+		register_error(as, l, 1, "Unknown operation");
+		return;
+	}
+	r0 = c - reglist;
+	if (**p == '+')
+	{
+		(*p)++;
+		tfm = 1;
+	}
+	else if (**p == '-')
+	{
+		(*p)++;
+		tfm = 2;
+	}
+	if (*(*p)++ != ',')
+	{
+		register_error(as, l, 1, "Unknown operation");
+		return;
+	}
+	c = strchr(reglist, toupper(*(*p)++));
+	if (!c)
+	{
+		register_error(as, l, 1, "Unknown operation");
+		return;
+	}
+	r1 = c - reglist;
+
+	if (**p == '+')
+	{
+		(*p)++;
+		tfm |= 4;
+	}
+	else if (**p == '-')
+	{
+		(*p)++;
+		tfm |= 8;
+	}
+	
+	if (**p && !isspace(**p))
+	{
+		register_error(as, l, 1, "Bad operand");
+		return;
+	}
+			
+	// valid values of tfm here are:
+	// 1: r0+,r1 (2)
+	// 4: r0,r1+ (3)
+	// 5: r0+,r1+ (0)
+	// 10: r0-,r1- (1)
+	switch (tfm)
+	{
+	case 5: //r0+,r1+
+		lwasm_emitop(as, l, instab[opnum].ops[0]);
+		break;
+	case 10: //r0-,r1-
+		lwasm_emitop(as, l, instab[opnum].ops[1]);
+		break;
+	case 1: // r0+,r1
+		lwasm_emitop(as, l, instab[opnum].ops[2]);
+		break;
+	case 4: // r0,r1+
+		lwasm_emitop(as, l, instab[opnum].ops[3]);
+		break;
+	default:
+		register_error(as, l, 1, "Unknown operation");
+		return;
+	}
+	lwasm_emit(as, l, (r0 << 4) | r1);
+}