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Debug Port
12-46
•
Write a series of expected values as AP transactions. On each write transaction,
the DP issues an AP read access, compares the result against the value supplied
in the AP write transaction, and sets the STICKYCMP bit in the CRL/STAT
Register if the values do not match. See The Control/Status Register, CTRL/STAT
on page 12-53.
The TAR is incremented on each transaction.
In this way, the series of values supplied is compared against the contents of the AP
locations, and STICKYCMP set if they do not match.
Example use of pushed find operation on a AHB-AP
You can use pushed find to search system memory for a particular word. If you use
pushed find with byte lane masking you can search for one or more bytes.
•
Make sure that the AHB-AP Control/Status Word (CSW) is set up to increment
the TAR after each access. See The Control/Status Register, CTRL/STAT on
page 12-53.
•
Write to the Transfer Address Register (TAR) to indicate the start address of the
Debug Register region that is to be searched. See AHB-AP Transfer Address
Register on page 11-38.
•
Write the value to be searched for as an AP write transaction. The DP repeatedly
reads the location indicated by the TAR. On each DP read:
—
The value returned is compared with the value supplied in the AP write
transaction. If they match, the STICKYCMP flag is set.
—
The TAR is incremented.
This continues until STICKYCMP is set, or ABORT is used to terminate the
search.
You could also use pushed find without address incrementing to poll a single location,
for example to test for a flag being set on completion of an operation.
Copyright © 2005, 2006 ARM Limited. All rights reserved.
ARM DDI 0337B
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