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spth / OpenRabbit

Loader and Debugger for Rabbit Semiconductor µC, such as the Rabbit 2000,Rabbit 3000 and Rabbit 4000.
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Auto-detect secondary loader format #15

Closed spth closed 4 years ago

spth commented 4 years ago

OpenRabbit currently has the --dc8pilot option for the use of a DC8-style secondary loader.

It could make sense to instead auto-detect the secondary loader style, so the user doesn't have to specify this explicitly.

tomlogic commented 4 years ago

I like the command-line option, and I don't think there will be a reliable way to identify which Pilot BIOS protocol is in use by a given pilot.bin file.

spth commented 4 years ago

Well, the secondary loader is placed at 0x6000. A DC9 pilot.bin contains data to be placed from there. It starts with the first instruction, which typically is nonzero. A DC8 pilot.bin contains the data as seen in memory later: Data at addresses 0x0000 to 0x5fff in a DC 8 pilot.bin is all zero.

tomlogic commented 4 years ago

Good point. I noticed that discrepancy in some of the older DC 9 pilot.bin files (or maybe the "ram-only" version). I am assuming that RFU and Dynamic C had code to skip over those opening 0x00 bytes, but at some point the build process for pilot.bin was able to exclude the extra 0x00 bytes at the start of the file.

spth commented 4 years ago

Implemented in 527d184.