Re: [f-cpu] Supported Instructions

[Yann Guidon <whygee@f-cpu.org>]

hi,

nico wrote:
> Most instruction are defined as "optional". If a fcpu is release without
> such instruction it must give an interrupt handler to handel such
> instruction.
> 
> Imagine that FMUL r1 r2 r3 are supported. So the instruction trap and ...
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"not" supported, i guess...

> - "something" (a register?) point on the faulty instruction.
in the CMB (the instruction pointer).
After the instruction is "simulated", the IP must be incremented...

> - The handler try to extract the register number to emulate the instruction
use the IP from the CMB, fetch the 4-byte data and extract the fields.

>  - by using some others registers ?
these are in the new "task". SRB is certainly triggered.

>  - We need to save some of them (slow?)
why "slow" ?

>  - How to access indirectly the register set ? (to extract data)
fetch them from the CMB.

> So ?
as you say :-)

> I propose to define (later, much later) the subgroup of instructions. It
> will depend on space used and the impact on performance.
time to wait ;-)

read you soon,

> nicO
WHYGEE
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