Import J Hoppe's 20090427 release from http://retrocmp.com/tools/macro-11-on-windows

extree.h

@@ -0,0 +1,66 @@
+
+#ifndef EXTREE__H
+#define EXTREE__H
+
+#include "symbols.h"
+
+typedef struct ex_tree {
+    enum ex_type { EX_LIT = 1,
+        /* Expression is a literal value */
+        EX_SYM = 2,
+        /* Expression has a symbol reference */
+        EX_UNDEFINED_SYM = 3,
+        /* Expression is undefined sym reference */
+        EX_TEMP_SYM = 4,
+        /* Expression is temp sym reference */
+
+        EX_COM = 5,
+        /* One's complement */
+        EX_NEG = 6,
+        /* Negate */
+        EX_ERR = 7,
+        /* Expression with an error */
+
+        EX_ADD = 8,
+        /* Add */
+        EX_SUB = 9,
+        /* Subtract */
+        EX_MUL = 10,
+        /* Multiply */
+        EX_DIV = 11,
+        /* Divide */
+        EX_AND = 12,
+        /* bitwise and */
+        EX_OR = 13                     /* bitwise or */
+    } type;
+
+    char           *cp;         /* points to end of parsed expression */
+
+    union {
+        struct {
+            struct ex_tree *left,
+                           *right;      /* Left, right children */
+        } child;
+        unsigned        lit;    /* Literal value */
+        SYMBOL         *symbol; /* Symbol reference */
+    } data;
+} EX_TREE;
+
+
+EX_TREE        *new_ex_tree(
+    void);
+void            free_tree(
+    EX_TREE *tp);
+
+EX_TREE        *new_ex_lit(
+    unsigned value);
+EX_TREE        *ex_err(
+    EX_TREE *tp,
+    char *cp);
+
+EX_TREE        *evaluate(
+    EX_TREE *tp,
+    int undef);
+
+
+#endif