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ISA change: New behaviour for the X flag #165
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That list seems complete. |
As mentioned in #160 (comment) I support @bernd-ulmann 's proposal for the X-flag. |
I have already changed the following things:
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I've updated the I've done a smoke-test of our demo programs on the emulator. |
Fixed and verified in hardware. |
Great job, both of you gentlemen! And speedy ;-) @bernd-ulmann Could you rename all ISA version references (is it just the headline in the intro.pdf or are there more) to V1.7? This ISA change leads to a new ISA version number... |
I still need to update the |
Actually, the routine already worked :-) I've updated the test program NOTE: In the current implementation, the routine Likewise the routine This is done to simplify the implementation. This is a (slight) difference from the semantics of the SHL and SHR instructions. I added a short comment about this in I hope this is ok ? |
@MJoergen For me it is absolutely OK. Though it "feels" like a slight inconsistency. As I am currently in a rush I did not look at the code so a quick question to you: Save the X or the C flag before the routine and restoring it on exit for not having it undefined but as it was on entry: Would this break the elegance of the implementation? |
I don't know about "elegance" :-D But it would require some more instructions, and I'm just asking whether it is worth it? I mean, would anyone use it? The tricky part is to restore the X flag without destroying the newly generated C flag (or vice versa). So several instructions must be used to mask the particular status flag to be copied. |
Done. :-) |
When doing my initial grep to check the X register usage, I did only grep for the positive X, but not for the negative !X. So doing a
and in
@MJoergen I will take care of my sources, i.e. all but https://github.com/sy2002/QNICE-FPGA/blob/develop/test_programs/vga_int.asm#L148
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Fixed and verified on hardware |
First of all, the following decision has to be made:
Shall the X flag act as Bernd described it here: Math Lib in Monitor: Add SHL32 and SHR32 #160 (comment)
Or shall the X-flag act as Michael described it here: Math Lib in Monitor: Add SHL32 and SHR32 #160 (comment)
After that has been decided (@bernd-ulmann), the following TODOs need to be done.
X
?)@MJoergen and @bernd-ulmann: Is this list complete?
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