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[/] [zipcpu/] [trunk/] [rtl/] [core/] - Rev 176

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80 Bug fix: declared the (combined) multiply to be signed again. Also
changed the name of the generate'd for block, to keep ISE from complaining.
dgisselq 3261d 07h /zipcpu/trunk/rtl/core/
71 This contains a bunch of bug fixes. (A lot ...) For example, the pipeline
stall code has also seriously changed, to fixed the pipeline memory load/op
stage conflict, while maintaining no-stall operation for operands that don't
need an offset. This had a cascading effect, however, so that the multiply
could no longer complete in a single cycle. Therefore, the timing on the
multiplies was slowed down to two cycles from a single cycle. (It's the
only two-cycle ALU operation ...) The illegal instruction code has also been
fixed, so that illegal instructions no longer stalls the prefetch bus.
dgisselq 3266d 11h /zipcpu/trunk/rtl/core/
69 This implements the "new Instruction Set" architecture for the Zip CPU. It's
a massive change set, that touches just about everything but probably not
enough of everything. Please see the spec.pdf for a description of this
new architecture.
dgisselq 3272d 15h /zipcpu/trunk/rtl/core/
65 Lots of logic simplifications to the core, in addition to better support for
illegal instruction detection and bus error detection. The biggest change
had to deal with pushing the debug write interface into the ALU write
processing path. This simplifies the logic of adjusting the PC and CC
registers primarily, but also any writes to other registers. It also delays
these register writes by a clock, but since the debug interface is already
ridiculously slow I doubt that matters any.
dgisselq 3333d 15h /zipcpu/trunk/rtl/core/
63 Simplified bus interactions, and added support for detecting illegal
instructions (i.e. bus errors) in the pipefetch routine.
dgisselq 3333d 15h /zipcpu/trunk/rtl/core/
62 Simplified the subtraction logic, so the carry bit no longer depends on
a separate 32-bit operation but becomes part of the subtract operation.
dgisselq 3333d 15h /zipcpu/trunk/rtl/core/
56 Here's a bit of work in progress for getting the Zip CPU working on a XuLA2
board. Many changes include: the existence of a cpudefs.v file to control
what "options" are included in the ZipCPU build. This allows build control
to be separated from the project directory (one build for a XuLA2 board,
another for a Basys-3 development board). Other changes have made things
perhaps harder to read, but they get rid of warnings from XST.

A big change was the addition of the (* ram_style="distributed" *) comment
for the register set. This was necessary to keep XST from inferring a block
RAM and breaking the logic that was supposed to take place between a register
read and when it was used.
dgisselq 3343d 18h /zipcpu/trunk/rtl/core/
49 Final set of changes finishing the Dhrystone package. Dhrystone, as
implemented by hand in assembly, now works.
dgisselq 3353d 09h /zipcpu/trunk/rtl/core/
48 Files added/updated to get Dhrystone benchmark to work. Several fixes
to the CPU in the process, 'cause it wasn't working. Stall-less ALU
ops now work better, to include grabbing the memory result as it comes out
of the memory unit and placing it straight into either ALU or memory unit
for the next instruction.
dgisselq 3353d 09h /zipcpu/trunk/rtl/core/
38 A couple of quick updates:

- The Zip CPU now supports pipelined memory access at one clock per
instruction (assuming all the instructions are in the cache)
- There is now a 'zipbones' module to build a Zip System without peripherals.
Any peripherals would then need to be external to the CPU.
- Some bug fixes.

Documentation changes coming shortly.
dgisselq 3356d 14h /zipcpu/trunk/rtl/core/

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