[vmips] pipeline of mips

[Brian R. Gaeke]

VMIPS does not simulate the MIPS pipeline. It makes no attempts
to be cycle-accurate.  It's mostly because it is simpler to write
a functional simulation, and also because it would be slower to
perform a cycle-accurate simulation.

-Brian



On Tue, Oct 11, 2005 at 10:36:18PM +0800, Zhou Ya Jin wrote:
> Hi Brian:
>     I have read the source code of VMIPS. I found that vmips does not simulate pipeline of MIPS(Am I right?). I mean you use PC in the VMIPS to identify which instruction to simulate at this time. After that you change the value of PC and simulate next instruction. But in mips pipeline, there are several instructions executing in a clock cycle(they are in different step of pipeline, for example, instruction A may be in step IF, instruction B may be in step RD and so on). So I have a question: Why do not you simulate the accurate pipeline of mips? (Because of the efficiency of simulation?).   Thanks. . I am a newbie of mips, so please forgive me if I have asked a fool question. :)
> 
> 
> 
> 
> 
>  Yours Sincerely,
>  Zhou Ya Jin
> 
>  My Person Website:
>  http://mail.ustc.edu.cn/~ncs
> 
> ----- Original Message ----- 
> From: "Brian R. Gaeke" <brg at dgate.ORG>
> To: <vmips at dgate.ORG>
> Sent: Thursday, September 29, 2005 1:07 PM
> Subject: [vmips] About VMIPS
> 
> 
> >> From: Zhou Ya Jin <ncs at mail.ustc.edu.cn>
> >> To: vmips at dgate.org
> >> Subject: About VMIPS
> >> Date: Thu, 29 Sep 2005 12:44:15 +0800
> >> 
> >>    Hi everyone:
> >>        I am very glad finding such a good mips simulator. You know, there are
> >>    few free mips simulators available.But I also have few questions of VMIPS.
> >>        1. As far as I know, VMIPS just simulate a mips cpu, not a full
> >>    system(that is including RAM,peripheral equipment etc). Am I right?
> >>        2. VMIPS simulate a R3000 MIPS CPU, which is a little old. Are there
> >>    anyone having the plan to extend VMIPS to R4000 or above MIPS CPU?
> >>        3. Are there any internal document of VMIPS? I did not find. Can
> >>    anyone do me a favor to send it to me if you have one. Thanks everyone.
> >> 
> >>    ps: Thanks, brg, for your excellent work on VMIPS :)
> >> 
> >> 
> >> 
> >>     Yours Sincerely,
> >>     Zhou Ya Jin
> >> 
> >>     My Person Website:
> >>     [1]http://mail.ustc.edu.cn/~ncs
> >> 
> >> References
> >> 
> >>    Visible links
> >>    1. http://mail.ustc.edu.cn/~ncs
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-- 
Brian R. Gaeke, brg at dgate.org -- GnuPG encrypted mail gleefully accepted