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diff lwasm/lwasm.c @ 241:d0e9dbe9afbe

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Add new heuristic for resolving instruction sizes. Add new heuristic for resolving instruction sizes. This applies to the the decision between extended and base page addressing by calculating the range of possible addresses (if reasonably knowable) and deciding on whether to force extended addressing based on that. (If the whole range is outside the direct page, extended addressing is required.)
author William Astle <lost@l-w.ca>
date Sun, 23 Sep 2012 13:06:43 -0600
parents 41d64951eb32
children 1f1a28b797e1
line wrap: on
line diff
--- a/lwasm/lwasm.c	Tue Aug 14 23:03:59 2012 -0600
+++ b/lwasm/lwasm.c	Sun Sep 23 13:06:43 2012 -0600
@@ -988,3 +988,93 @@
 	debug_message(as, 250, "Returning expression");
 	return e;
 }
+
+struct range_data
+{
+	int min;
+	int max;
+	asmstate_t *as;
+};
+int lwasm_calculate_range(asmstate_t *as, lw_expr_t expr, int *min, int *max);
+int lwasm_calculate_range_tf(lw_expr_t e, void *info)
+{
+	struct range_data *rd = info;
+	int i;
+	
+	if (lw_expr_istype(e, lw_expr_type_int))
+	{
+		i = lw_expr_intval(e);
+		rd -> min += i;
+		rd -> max += i;
+		return 0;
+	}
+	
+	if (lw_expr_istype(e, lw_expr_type_special))
+	{
+		line_t *l;
+		if (lw_expr_specint(e) != lwasm_expr_linelen)
+		{
+			rd -> min = -1;
+			return -1;
+		}
+		l = (line_t *)lw_expr_specptr(e);
+		if (l -> len == -1)
+		{
+			rd -> min += l -> minlen;
+			rd -> max += l -> maxlen;
+		}
+		else
+		{
+			rd -> min += l -> len;
+		}
+		return 0;
+	}
+	
+	if (lw_expr_istype(e, lw_expr_type_var))
+	{
+		lw_expr_t te;
+		te = lw_expr_copy(e);
+		lwasm_reduce_expr(rd -> as, te);
+		if (lw_expr_istype(te, lw_expr_type_int))
+		{
+			i = lw_expr_intval(te);
+			rd -> min += i;
+			rd -> max += i;
+		}
+		else
+		{
+			rd -> min = -1;
+		}
+		lw_expr_destroy(te);
+		if (rd -> min == -1)
+			return -1;
+		return 0;
+	}
+	
+	if (lw_expr_istype(e, lw_expr_type_oper))
+	{
+		if (lw_expr_whichop(e) == lw_expr_oper_plus)
+			return 0;
+		rd -> min = -1;
+		return -1;
+	}
+	
+	rd -> min = -1;
+	return -1;
+}
+
+int lwasm_calculate_range(asmstate_t *as, lw_expr_t expr, int *min, int *max)
+{
+	struct range_data rd;
+	
+	rd.min = 0;
+	rd.max = 0;
+	rd.as = as;
+	
+	lw_expr_testterms(expr, lwasm_calculate_range_tf, (void *)&rd);
+	*min = rd.min;
+	*max = rd.max;
+	if (rd.min == -1)
+		return -1;
+	return 0;
+}