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[/] [zipcpu/] [trunk/] [rtl/] - Rev 144

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Rev Log message Author Age Path
144 Makes the auto-reload capability a configuration option, and fills out the
reset so that it is properly implemented.
dgisselq 2462d 05h /zipcpu/trunk/rtl/
140 Minor changes, but fixes build of zippy_tb.cpp. dgisselq 2465d 18h /zipcpu/trunk/rtl/
138 This updates the CPU multiply instruction into a set of three instructions.
MPY is a 32x32-bit multiply instruction, returning the low 32-bit result,
MPYUHI returns the upper 32-bits assuming the result was unsigned and MPYSHI
returns the upper 32-bits assuming the result was signed.
dgisselq 2468d 16h /zipcpu/trunk/rtl/
133 Changes preceding an instruction set update, which will change the multiply
operation from a 16x16 bit multiply to three types of 32x32-bit multiplies.
dgisselq 2483d 06h /zipcpu/trunk/rtl/
132 Lots of minor bug fixes. dgisselq 2483d 06h /zipcpu/trunk/rtl/
131 Fixed a variable use before declaration error. dgisselq 2483d 07h /zipcpu/trunk/rtl/
130 Simplified the lock logic, and removed it when pipelining was not defined. This
also means the file is now dependent upon cpudefs.v. In another change, brev
was modified so as not to update the flags. This makes it useable with GCC
as a potential move or load immediate instruction.
dgisselq 2483d 07h /zipcpu/trunk/rtl/
129 Bug fix. Fixes some ugly race conditions that would cause code from the wrong
address to be executed.
dgisselq 2483d 07h /zipcpu/trunk/rtl/
128 Cleaned up some comments. dgisselq 2483d 07h /zipcpu/trunk/rtl/
118 Fixes two bugs: 1) in the early branching code within the instruction decoder.
This prevented the early branching from working when built with Xilinx's tools,
while the code worked with Verilator. 2) The CPU was not working with the
traditional cache and early branching disabled. These two bugs masked each
other. The replacement code is simpler.
dgisselq 2502d 07h /zipcpu/trunk/rtl/
115 A bug fix, applies to when there are more than 9 interrupt lines into the CPU. dgisselq 2502d 15h /zipcpu/trunk/rtl/
105 Fixed some nasty early branching bugs. Adjusted the Makefile to declare that
cpudefs.h was automatically generated from cpudefs.v, and made sure that
zipbones included the cpudefs.v so it could get the DEBUG_SCOPE define.
In addition, the test.S was updated to test long jumps, the early branching
bug we found, and all three early branching instructions: ADD #x,PC, LOC(PC),PC,
and LDI #x,PC.
dgisselq 2526d 15h /zipcpu/trunk/rtl/
91 Minor updates. dgisselq 2567d 09h /zipcpu/trunk/rtl/
90 Removed MOV x(PC),PC from the list of possible early branching instructions.
ADD X,PC and LDI X,PC are now the only recognized early branching instructions.
This was done to spare logic, although I don't think I spared more than a
LUT or two.
dgisselq 2567d 09h /zipcpu/trunk/rtl/
88 Eliminated some warnings. The div fixes were to simplify the logic, even though
the result is less readable ...
dgisselq 2591d 08h /zipcpu/trunk/rtl/
84 Minor updates. dgisselq 2593d 07h /zipcpu/trunk/rtl/
83 Added a flag to indicate whether an exception took place on the first
or second half of a VLIW instruction--will be zero in non-VLIW mode,
equivalent to the second half of the instruction having caused the
exception. (Expect these flags to be reordered some time in the future into
a less haphazard ordering ...)

Vastly simplified the pipeline logic, primarily for op_stall, but also touched
opA and opB. (Trying to fit within timing on Spartan 6 ...)

Changed division instruction to include a reset on clear_pipeline, to make
certain [BC $addr; DIV Rx,Ry ] works regardless of whether the condition is
true.
dgisselq 2593d 07h /zipcpu/trunk/rtl/
82 Found and (I hope) fixed a nasty bug that would send the prefetch into an
endless loop whenever you jumped to an instruction at the last location
in an unloaded cache line.
dgisselq 2593d 07h /zipcpu/trunk/rtl/
81 Trying to clean up ISE generated warnings. dgisselq 2593d 07h /zipcpu/trunk/rtl/
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 2593d 07h /zipcpu/trunk/rtl/
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 2598d 10h /zipcpu/trunk/rtl/
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 2604d 15h /zipcpu/trunk/rtl/
66 Adjusted the support for the DEBUG_SCOPE within these so that it can be
compiled in, or not, based upon an external build configuration file: cpudefs.v.
That allows me to make that file project specific, while the rest of the CPU
is shared among all projects.
dgisselq 2665d 15h /zipcpu/trunk/rtl/
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 2665d 15h /zipcpu/trunk/rtl/
64 Shuffled some comments into here from elsewhere. dgisselq 2665d 15h /zipcpu/trunk/rtl/
63 Simplified bus interactions, and added support for detecting illegal
instructions (i.e. bus errors) in the pipefetch routine.
dgisselq 2665d 15h /zipcpu/trunk/rtl/
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 2665d 15h /zipcpu/trunk/rtl/
61 Simplified the bus delay logic. Depends upon the stall line being irrelevant
outside of a bus cycle.
dgisselq 2665d 15h /zipcpu/trunk/rtl/
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 2675d 17h /zipcpu/trunk/rtl/
49 Final set of changes finishing the Dhrystone package. Dhrystone, as
implemented by hand in assembly, now works.
dgisselq 2685d 09h /zipcpu/trunk/rtl/

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