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base repository: whitequark/glasgow
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head repository: whitequark/glasgow
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compare: f7e0ee0919e1
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  • 1 commit
  • 1 file changed
  • 1 contributor

Commits on Mar 8, 2019

  1. applet.interface.jtag_probe: special-case IR segmentation with 1 TAP.

    @whitequark
    whitequark committed Mar 8, 2019
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    f7e0ee0 View commit details
Showing with 15 additions and 5 deletions.
  1. +15 −5 software/glasgow/applet/interface/jtag_probe/__init__.py
20 changes: 15 additions & 5 deletions software/glasgow/applet/interface/jtag_probe/__init__.py
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Original file line number Diff line number Diff line change
@@ -533,12 +533,22 @@ def segment_irs(self, ir_value, count=None):

irs = []
ir_offset = 0
ir_starts = ir_value.search(bitarray("10"))
for ir_start0, ir_start1 in zip(ir_starts, ir_starts[1:] + [len(ir_value)]):
ir_length = ir_start1 - ir_start0
self._log_h("found ir[%d]", ir_length)
if count == 1:
# 1 TAP case; the entire IR belongs to the only TAP we have.
ir_length = len(ir_value)
self._log_h("found ir[%d] (1-tap)", ir_length)
irs.append((ir_offset, ir_length))
ir_offset += ir_length
else:
# >1 TAP case; there is no way to segment IR without knowledge of specific devices
# involved, but an IR always starts with 10, and we can use this to try and guess
# the IR segmentation. Our segmentation is pessimistic, i.e. it always detects either
# as many IRs as TAPs, or more IRs than TAPs.
ir_starts = ir_value.search(bitarray("10"))
for ir_start0, ir_start1 in zip(ir_starts, ir_starts[1:] + [len(ir_value)]):
ir_length = ir_start1 - ir_start0
self._log_h("found ir[%d] (n-tap)", ir_length)
irs.append((ir_offset, ir_length))
ir_offset += ir_length

if count is not None and len(irs) != count:
self._log_h("ir count does not match idcode count")