CRC support added #75
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geky
reviewed
Dec 6, 2017
config/mbed_lib.json
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| "FSFAT_SDCARD_INSTALLED": 1, | ||
| "CRC_ENABLED": 1, | ||
| "CRC7": "SlowCRC", | ||
| "CRC16":"FastCRC" |
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Out of curiousity, why is one fast and one slow?
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Both Fast and Slow support CRC7/CRC16.
Using SlowCRC implementation for 7-bit as computation will be less (5bytes per command). SlowCRC does runtime computation.
FastCRC implementation generates CRC table during initialization instead of runtime computation, which makes it faster (but takes up RAM space). Using FastCRC for data makes sense as we need to compute for 512*blocks received for every transaction.
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That makes sense, thanks!
but takes up RAM space
Can this be forced into ROM?
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Is there a chance we could profile an SD card read and see what percentage of runtime is spent calculating the CRC? I'm really curious how the CRC compares to the overhead of the SPI transaction.
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Yes we can check overhead in read as well as write data.
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And correct me if I'm wrong, but this is taking roughly 512 bytes of ROM?
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512 bytes for CRC16, 256 bytes for CRC7 if using FastCRC.
sg-
suggested changes
Dec 20, 2017
|
@sg- CRC support is not conditionally compiled now, but passed as parameter in constructor to add/remove this funcitonality |
sg-
approved these changes
Feb 26, 2018
|
@geky - Please review |
geky
approved these changes
Mar 14, 2018
|
Tested with ARMmbed/mbed-os#6363 will wait for it to get merged to master. |
Corrected version comment : 5.8.0
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CRC Class is added to mbed-os.
PR dependency #ARMmbed/mbed-os#5669
TODO:
Readme should be updated once upstream PR is merged, and add dependency of mbed-os release version.
Proper tag should be created to indicate the dependency