codegen completion kit

To extend the code generator, the main "eval" must handle more n-code instruction. The stub definition is "evalx" and "genwhile".

evalx (op arg e)   ; e is argument list
for NEW
    eval head e, out icArray
for SUB MUL DIV BAND SHL SHR EQ LT GT
    genbop
for LDX STX LDY STY
    LDX LDY has the form (ldx.a idx)
    out get.a/ld.a, eval idx, out icLdx
    STX STY has the form (stx.a idx val)
    out get.a/ld.a, eval idx, eval val, out icStx

genwhile (e)
(while e1 e2)
generate proper jump for the form

    jmp <in>
L: eval e2
in: eval e1
    jt <L>

For patching proper displacement of jumps see how to generate code for "if".

How to use codegen

You must have some n-code object first (such as "t2.obj", "t3.obj"). Compile the code generator

c:>nut31 < gen.txt

use the code generator to generate s-code

c:>nsim31 < t2.obj > t2s.obj

use somv2 to examine the listing of s-code

c:>somv2 -l t2s.obj

or to execute it

c:>somv2 -x t2s.obj

End
2July 2007