tty.c: added a nop hint to nop_putc() so that post-processing can see… #271
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… the characters being output to the serial port
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Mentioning @ericlove @aswaterman who have both implemented this trick elsewhere. |
nick-knight
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Jul 9, 2020
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LGTM.
@BrianGraysonSiV 's original description mentions
A simple awk script like the one attached suffices to parse the output files.
but I didn't see any attachments. Actually, that's probably for the best, because the formatting of the "output files", if any, depends on the machine this is run on (perhaps a simulator).
nick-knight
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nategraff-sifive
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Jul 17, 2020
Port of #271 to Freedom Metal refactor work. Allows standard out to be extracted from an instruction trace when no other stdio method is available. Signed-off-by: Nathaniel Graff <nathaniel.graff@sifive.com>
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… the characters being output to the serial port.
With this change, a "customizable non-reserved NOP hint" instruction (slli x0, a0, 0x11) is used, with the character to be output in the specified register. This allows a post-processing tool to find occurrences of that instruction, grab the character value out of the register fields, and output the character.
A simple awk script suffices to parse the output files. Here's a one-liner version:
awk '/inst=.01151013/{printf "%c",strtonum("0x"substr($(NF-4),21,2));}' myfile