This client-side code alone improves the typical transfer speed of a
51572-byte file from 91.85 seconds to 25.89 seconds.
This appears to be heavily bottlenecked by the python side of the
transfer--increasing the serial line speed has nearly zero affect on
the total transfer time.
The serial_transfer loader, as long as the target program voluntarily
terminates itself at some point, is able to load multiple programs
consecutively without requiring a physical power cycle to reload the
transfer program from CD.
The current example.mk juggles between two different "memory layouts",
one for "burn to a physical CD" and another for "load via serial
cable". Because the serial_transfer program now relocates itself to
the end of system memory, this means the 0x8c010000 area is now usable
by programs that are loaded by serial_transfer.
From the GCC manual.
> GCC permits a C structure to have no members:
struct empty {
};
> The structure has size zero. In C++, empty structures are part of the
> language. G++ treats empty structures as if they had a single member of type
> char.
I was not aware of the different behavior in C++.
This fixes every maple example--most were broken for multiple reasons, including
this one.
This also enables SH4 caching. This includes linking code/data into the P1
area (previously this was not the case).
The maple examples (which indeed involve much use of DMA) require much work to
successfully work with the operand and copyback caches. The vibration example
currently is the most complete, though I should consider more on how I want to
structure maple response operand cache invalidation more generally.
