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[/] [zipcpu/] [trunk/] [rtl/] [core] - Rev 177

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81 Trying to clean up ISE generated warnings. dgisselq 3030d 03h /zipcpu/trunk/rtl/core
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 3030d 03h /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 3035d 06h /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 3041d 11h /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 3102d 11h /zipcpu/trunk/rtl/core
63 Simplified bus interactions, and added support for detecting illegal
instructions (i.e. bus errors) in the pipefetch routine.
dgisselq 3102d 11h /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 3102d 11h /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 3112d 14h /zipcpu/trunk/rtl/core
49 Final set of changes finishing the Dhrystone package. Dhrystone, as
implemented by hand in assembly, now works.
dgisselq 3122d 05h /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 3122d 05h /zipcpu/trunk/rtl/core

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