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| author | drath <drath@b42882b7-edfa-0310-969c-e2dbd0fdcd60> | 2008-02-24 18:24:04 +0000 |
|---|---|---|
| committer | drath <drath@b42882b7-edfa-0310-969c-e2dbd0fdcd60> | 2008-02-24 18:24:04 +0000 |
| commit | db4fe036131b5f1751bc46b2b79b7139210a6df9 (patch) | |
| tree | bf24f1b5699593a801c685e63f6ff45b7d5334d0 /src | |
| parent | 3fe23f94fb71d838eb86dd7bdeb9e67216b6e801 (diff) | |
| download | openocd_libswd-db4fe036131b5f1751bc46b2b79b7139210a6df9.tar.gz openocd_libswd-db4fe036131b5f1751bc46b2b79b7139210a6df9.tar.bz2 openocd_libswd-db4fe036131b5f1751bc46b2b79b7139210a6df9.tar.xz openocd_libswd-db4fe036131b5f1751bc46b2b79b7139210a6df9.zip | |
- concretize JTAG state transition rules (previously implied behaviour is now documented)
git-svn-id: svn://svn.berlios.de/openocd/trunk@329 b42882b7-edfa-0310-969c-e2dbd0fdcd60
Diffstat (limited to 'src')
| -rw-r--r-- | src/jtag/jtag.h | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/src/jtag/jtag.h b/src/jtag/jtag.h index f70c1ead..e5df6619 100644 --- a/src/jtag/jtag.h +++ b/src/jtag/jtag.h @@ -248,11 +248,24 @@ extern int jtag_add_ir_scan(int num_fields, scan_field_t *fields, enum tap_state extern int jtag_add_dr_scan(int num_fields, scan_field_t *fields, enum tap_state endstate, void *dummy_anachronism); extern int jtag_add_plain_ir_scan(int num_fields, scan_field_t *fields, enum tap_state endstate, void *dummy_anachronism); extern int jtag_add_plain_dr_scan(int num_fields, scan_field_t *fields, enum tap_state endstate, void *dummy_anachronism); -/* execute a state transition within the JTAG standard, but nothing is defined - * w.r.t. the path that is taken. Many implementations use precisely +/* execute a state transition within the JTAG standard, but the exact path + * path that is taken is undefined. Many implementations use precisely * 7 clocks to perform a transition, but it could be more or less * than that. - */
+ * + * The following assertions are made about certain common state moves: + * + * - A state move from Pause-[ID]R to Pause-[ID]R should always go through + * Update-[ID]R and Capture-[ID]R before returning to Pause-[ID]R, otherwise + * there's no way force a register update, if you can't go to Run-Test/Idle for + * some reason. + * + * - A state move from Pause-[ID]R to Shift-[ID]R must not go through + * Update-[ID]R. + * + * - Run-Test/Idle must not be entered unless requested, because R-T/I may have + * side effects. + */ extern int jtag_add_statemove(enum tap_state endstate); /* A list of unambigious single clock state transitions, not * all drivers can support this, but it is required for e.g. |