[squeak-dev] Anyone have any processors in Smalltalk or a formal semantics?

Gerardo Richarte gera at corest.com
Fri Oct 31 11:21:16 UTC 2008


Eliot Miranda wrote:
>     I wonder if anyone has any 32-bit processor implementations,
> either in Smalltalk or in some other, preferrably easy-to-parse,
> formal semantics.
    I thought about this several times, but never came down to implement
it: The Intel manuals do have a very concrete pseudocode for every
instruction, and it does look quite parsable. I did start once, but the
need for it disappeared, and I never finished...

the description for ADD is:

DEST ← DEST + SRC + CF;

and for AAA (Ascii adjust after addition) is more complex:
IF 64-Bit Mode
    THEN
         #UD;
    ELSE
         IF ((AL AND 0FH) > 9) or (AF = 1)
               THEN
                   AL ← AL + 6;
                   AH ← AH + 1;
                   AF ← 1;
                   CF ← 1;
                   AL ← AL AND 0FH;
               ELSE
                   AF ← 0;
                   CF ← 0;
                   AL ← AL AND 0FH;
         FI;
FI;

    I think it really is an option to write a compiler from PDF to
Smalltalk :)

    richie



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