-extern void jtag_add_ir_scan(int num_fields, scan_field_t *fields, enum tap_state endstate);
-extern int interface_jtag_add_ir_scan(int num_fields, scan_field_t *fields, enum tap_state endstate);
-extern void jtag_add_dr_scan(int num_fields, scan_field_t *fields, enum tap_state endstate);
-extern int interface_jtag_add_dr_scan(int num_fields, scan_field_t *fields, enum tap_state endstate);
-extern void jtag_add_plain_ir_scan(int num_fields, scan_field_t *fields, enum tap_state endstate);
-extern int interface_jtag_add_plain_ir_scan(int num_fields, scan_field_t *fields, enum tap_state endstate);
-extern void jtag_add_plain_dr_scan(int num_fields, scan_field_t *fields, enum tap_state endstate);
-extern int interface_jtag_add_plain_dr_scan(int num_fields, scan_field_t *fields, enum tap_state endstate);
-/* run a TAP_RESET reset. End state is TAP_RESET, regardless
- * of start state.
+extern void jtag_alloc_in_value32(scan_field_t *field);
+
+extern void jtag_add_dr_scan(int num_fields, const scan_field_t* fields, tap_state_t endstate);
+/// A version of jtag_add_dr_scan() that uses the check_value/mask fields
+extern void jtag_add_dr_scan_check(int num_fields, scan_field_t* fields, tap_state_t endstate);
+extern void jtag_add_plain_ir_scan(int num_fields, const scan_field_t* fields, tap_state_t endstate);
+extern void jtag_add_plain_dr_scan(int num_fields, const scan_field_t* fields, tap_state_t endstate);
+
+
+/**
+ * Defines a simple JTAG callback that can allow conversions on data
+ * scanned in from an interface.
+ *
+ * This callback should only be used for conversion that cannot fail.
+ * For conversion types or checks that can fail, use the more complete
+ * variant: jtag_callback_t.
+ */
+typedef void (*jtag_callback1_t)(u8 *in);
+
+/// A simpler version of jtag_add_callback4().
+extern void jtag_add_callback(jtag_callback1_t, u8 *in);
+
+
+/**
+ * Defines the type of data passed to the jtag_callback_t interface.
+ * The underlying type must allow storing an @c int or pointer type.
+ */
+typedef intptr_t jtag_callback_data_t;
+
+/**
+ * Defines the interface of the JTAG callback mechanism.
+ *
+ * @param in the pointer to the data clocked in
+ * @param data1 An integer big enough to use as an @c int or a pointer.
+ * @param data2 An integer big enough to use as an @c int or a pointer.
+ * @param data3 An integer big enough to use as an @c int or a pointer.
+ * @returns an error code
+ */
+typedef int (*jtag_callback_t)(u8 *in, jtag_callback_data_t data1, jtag_callback_data_t data2, jtag_callback_data_t data3);
+
+
+/**
+ * This callback can be executed immediately the queue has been flushed.
+ *
+ * The JTAG queue can be executed synchronously or asynchronously.
+ * Typically for USB, the queue is executed asynchronously. For
+ * low-latency interfaces, the queue may be executed synchronously.
+ *
+ * The callback mechanism is very general and does not make many
+ * assumptions about what the callback does or what its arguments are.
+ * These callbacks are typically executed *after* the *entire* JTAG
+ * queue has been executed for e.g. USB interfaces, and they are
+ * guaranteeed to be invoked in the order that they were queued.
+ *
+ * If the execution of the queue fails before the callbacks, then --
+ * depending on driver implementation -- the callbacks may or may not be
+ * invoked. @todo Can we make this behavior consistent?
+ *
+ * The strange name is due to C's lack of overloading using function
+ * arguments.
+ *
+ * @param f The callback function to add.
+ * @param in Typically used to point to the data to operate on.
+ * Frequently this will be the data clocked in during a shift operation.
+ * @param data1 An integer big enough to use as an @c int or a pointer.
+ * @param data2 An integer big enough to use as an @c int or a pointer.
+ * @param data3 An integer big enough to use as an @c int or a pointer.
+ *
+ */
+extern void jtag_add_callback4(jtag_callback_t f, u8 *in,
+ jtag_callback_data_t data1, jtag_callback_data_t data2,
+ jtag_callback_data_t data3);
+
+
+/**
+ * Run a TAP_RESET reset where the end state is TAP_RESET,
+ * regardless of the start state.