Yann Guidon / YGDESBy whygee on Wednesday 5 February 2014, 22:27 - Architecture
With the resolution of the auto-update flags problem, other fundamental issues were ripe to be addressed. And they are now solved ! So here is the overview of the next major revision of the YASEP architecture :
The update fields are not the only one that changed. The immediate fields have been harmonised and the condition and destination fields have been swapped, which reduces the instruction decoder's complexity a bit (fewer wires and MUXes).
I'm also changing the rules that govern the assembly language's syntax. This will put the immediate values always after the opcode, which will save some code by dropping the Ri/RRi/RI/RRI forms that are seldom used. Less code makes better code :-)
New memory-handling instructions will also appear, like BSWAP, and a pair of "shift & OR" opcodes for bitstream extraction.
The VHDL code also needs a full rewrite that also offers a debugging and testing through an auxiliary port.
These changes are quite deep and require a full review of the whole code base, but it was necessary and now seems to be the right time to do things right, before new features are added on top. The changes will take a lot of time to mature and will not be published on the main site for a while. Stay tuned !
20200411:
This rewrite is so far not complete, unfortunately... But the stage is now set for the next round !
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