update

idasdk75/module/65816/bt.hpp

@@ -0,0 +1,74 @@
+
+#ifndef __BACKTRACK_HPP__
+#define __BACKTRACK_HPP__
+
+#include <pro.h>
+#include <idp.hpp>
+
+enum btsource_t
+{
+  BT_NONE = 0,
+  BT_STACK,
+  BT_A,
+  BT_X,
+  BT_Y,
+  BT_DP
+};
+
+
+/**
+ * Walk instructions up, and try and determine what's the
+ * (size * 8)-bits value we're looking for.
+ *
+ * For example, let's assume we have the following sequence
+ * of instructions:
+ *   .05:8001                 PHK
+ *   .05:8002                 PLB
+ * We'll call:
+ *   backtrack_value(0x58002, 1, BT_STACK).
+ *
+ * A more complex example is this:
+ *   .C0:0024 A2 00 00                    LDX     #0
+ *   .C0:0027 DA                          PHX
+ *   .C0:0028 2B                          PLD
+ *   .C0:0029 7B                          TDC
+ *   .C0:002A 48                          PHA
+ *   .C0:002B AB                          PLB
+ * We'll call:
+ *   backtrack_value(0xc0002b, 1, BT_STACK), which will call
+ *   backtrack_value(0xc0002a, 1, BT_A),     which will call
+ *   backtrack_value(0xc00029, 1, BT_D),     which will call
+ *   backtrack_value(0xc00028, 2, BT_STACK), which will call
+ *   backtrack_value(0xc00027, 2, BT_X),     which has an immediate value that we can use. Bingo.
+ *
+ * Backtracking will, of course, stop if we hit the top
+ * of a function, as it doesn't make much sense to keep
+ * moving up.
+ *
+ * from_ea : The address from which we'll be analyzing up.
+ * size    : The size, in bytes, of the data we're looking for.
+ * source  : The register/stack that holds the value.
+ *
+ * returns : The value.
+ */
+int32 backtrack_value(ea_t from_ea, uint8 size, btsource_t source);
+
+
+/**
+ * Walk instructions up, until an instruction with the given type
+ * is found.
+ *
+ * Backtracking will, of course, stop if we hit the top
+ * of a function, as it doesn't make much sense to keep
+ * moving up.
+ *
+ * from_ea : The address from which we'll be analyzing up.
+ * itype   : The instruction type.
+ *
+ * returns : The address of the found instruction, or BADADDR
+ *           if not found.
+ */
+ea_t backtrack_prev_ins(ea_t from_ea, m65_itype_t itype);
+
+
+#endif