Add read buffer to bitbang, improving performance.

[openocd.git] / src / jtag / drivers / bitbang.h

diff --git a/src/jtag/drivers/bitbang.h b/src/jtag/drivers/bitbang.h
index c5b44bfd54d16fa333f281dc5a5f76a5f6d0d855..577717ebd241a6ba8e1ab83e6d2fd0e453ffafd4 100644 (file)
--- a/src/jtag/drivers/bitbang.h
+++ b/src/jtag/drivers/bitbang.h
@@ -24,13 +24,35 @@
 
 #include <jtag/swd.h>
 
+typedef enum {
+       BB_LOW,
+       BB_HIGH,
+       BB_ERROR
+} bb_value_t;
+
+/** Low level callbacks (for bitbang).
+ *
+ * Either read(), or sample() and read_sample() must be implemented.
+ *
+ * The sample functions allow an interface to batch a number of writes and
+ * sample requests together. Not waiting for a value to come back can greatly
+ * increase throughput. */
 struct bitbang_interface {
-       /* low level callbacks (for bitbang)
-        */
-       int (*read)(void);
-       void (*write)(int tck, int tms, int tdi);
-       void (*reset)(int trst, int srst);
-       void (*blink)(int on);
+       /** Sample TDO. */
+       bb_value_t (*read)(void);
+
+       /** The number of TDO samples that can be buffered up before the caller has
+        * to call read_sample. */
+       size_t buf_size;
+       /** Sample TDO and put the result in a buffer. */
+       int (*sample)(void);
+       /** Return the next unread value from the buffer. */
+       bb_value_t (*read_sample)(void);
+
+       /** Set TCK, TMS, and TDI to the given values. */
+       int (*write)(int tck, int tms, int tdi);
+       int (*reset)(int trst, int srst);
+       int (*blink)(int on);
        int (*swdio_read)(void);
        void (*swdio_drive)(bool on);
 };