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[/] [zipcpu/] - Rev 65

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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 3337d 08h /zipcpu/
64 Shuffled some comments into here from elsewhere. dgisselq 3337d 08h /zipcpu/
63 Simplified bus interactions, and added support for detecting illegal
instructions (i.e. bus errors) in the pipefetch routine.
dgisselq 3337d 08h /zipcpu/
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 3337d 08h /zipcpu/
61 Simplified the bus delay logic. Depends upon the stall line being irrelevant
outside of a bus cycle.
dgisselq 3337d 08h /zipcpu/
60 Fixed assembler processing of jump instructions, so that the new fast
return instruction can be used. The test file was modified to test
pipelined value passing within the CPU. That's where the value gets
(re)used before being stored back in the register file. As of this release,
all tests work.
dgisselq 3337d 08h /zipcpu/
59 Adjusted these library routines to use the new stack frame and calling
conventions.
dgisselq 3337d 08h /zipcpu/
58 Added a rudimentary profiling support to the simulator. dgisselq 3337d 08h /zipcpu/
57 Some bug fixes to the dhrystone benchmark, and some compile time defines for
the test bench processor. Of the most important note is the fix to detect
lockups on the debug/wishbone bus--that has been a real help in getting the
ZipCPU installed and the debugger working on the various boards I'm working
with. (i.e., it's helped me find and figure out why/when things haven't worked)
Of other note is the new 'G' key in the testbench code, to cause the test
bench to run without user interaction until the next keystroke. This is
very valuable in long programs, as it makes getting to/from breakpoints
easier (i.e. you don't have to wait as long, hit 'G', breathe, hit 'space'
and you're there).
dgisselq 3347d 10h /zipcpu/
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 3347d 10h /zipcpu/
55 A test was added to double check whether carry following right shifts worked.
This was a necessary part of getting two cycle linear feedback shift register
operations working for a memory test on a XuLA2 board. With this, I can now
verify that such feedback registers work for pseudorandom number purposes.
dgisselq 3347d 10h /zipcpu/
54 This builds on the support for backslash character escapes in both single
and multicharacter expressions. Backslash character escapes are now
possible with quotations and backslashes, and the same code to interpret
the escapes is applied to both single and multicharacter sequences.
dgisselq 3347d 10h /zipcpu/
53 Updated the #include/#define directives to work properly for nested includes.
(They were supposed to work properly for nested includes before ... and didn't)
This fixes those bugs.
dgisselq 3347d 10h /zipcpu/
52 Added the capability to "see" character's encoded within a binary file,
by printing the character value(s) of each opcode (if they are printable)
on each line.
dgisselq 3347d 10h /zipcpu/
51 Added the capability to look at binary files and 'see' characters as they
are encoded in memory.
dgisselq 3347d 10h /zipcpu/
50 Dhrystone benchmark updates--added the copyright notice. (Oops!) dgisselq 3357d 02h /zipcpu/
49 Final set of changes finishing the Dhrystone package. Dhrystone, as
implemented by hand in assembly, now works.
dgisselq 3357d 02h /zipcpu/
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 3357d 02h /zipcpu/
47 Added some new graphics, includes the file for the Zip Bones system. dgisselq 3357d 02h /zipcpu/
46 A series of updates associated with getting Dhrystone to work. Includes
updates to getting multiple files to link/work together within the assembler,
as well as getting quoted quotations to work in the lexer, and better
include file support in the preprocessor.
dgisselq 3357d 02h /zipcpu/

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