The previous texture_memory_alloc.hpp was written based on an
incorrect understanding of the "32-bit" and "64-bit" texture memory
address mapping.
The primary motivation is to rearrange the texture memory address map
so that "textures" (64-bit access) do not overlap with 32-bit
accesses, such as REGION_BASE or PARAM_BASE.
This makes it possible to change the serial baud rate without
uploading a new serial transfer program. I'm not sure how useful this
will be, but it is simple enough to add.
The client program is also substantially improved. Sincerely I do not
understand how/why this works. Experimentally, I found that feeding
the ft232h data in chunks of up to roughly 384 bytes works reliably,
both for reads and writes. Larger chunk sizes are (as expected)
faster, but the tranfers do not appear to be consistently correct in
this case.
I have no logical explanation for this. The size of the ft232h FIFO is
1K each for the transmit and receive buffer respectively.
This also enables RTS/CTS hardware flow control. Surprisingly, this
doesn't appear to affect reliability significantly.
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.
