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From: wij <wyniijj5@gmail.com>
Newsgroups: comp.lang.c
Subject: New computation model and perspective of C/C++
Date: Thu, 20 Feb 2025 03:29:21 +0800
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libwy-0.69.6 is released https://sourceforge.net/projects/cscall/
The manpage document (description) for Spu is modifed a bit.
-----------------------
Wy.Sct.Spu(3wy)                                                 Wy.Sct.Spu(=
3wy)

NAME
       Spu - Class of general purpose Soft-CPU

SYNOPSIS
       Except POD types, C structures, all types are declared in namespace =
Wy.

       #include <CSCall/Sct.h>

       Spu  (Soft  CPU)  is  a revised model of Turing Machine and a class =
that
       acts like a general purpose CPU-based computing machine to  provide =
 se=E2=80=90
       mantics for computing language and for remote program communication.

       The  main differences of Spu and general purpose CPU (or TM) is that=
 Spu
       has no =C2=B4register=C2=B4 nor =C2=B4flag=C2=B4, Spu has only a tap=
e. The tape is initially
       empty. Every object (referred to as tape variable) in the tape is  a=
llo=E2=80=90
       cated via instruction Alloc and identified by a continuous index num=
ber.
       Tape variable can be any C++ type, including Spu.

       The  instruction  of Spu is application definable. Except necessary =
few,
       about  >30  instructions  are  defined  for  convenience,  see   man=
page
       Wy.Sct(3wy).

       Documentation following omits the scope name Wy::Sct for each occurr=
ence
       of Spu for clearity.

PUBLIC MEMBERS
        class Reply
        typedef ssize_t IndexType
        Spu()
        ~Spu()

        InstrIdx next_instr
        Array<InstrIdx> istack
        Array<unsign char> tape
        PtrArray<InstrBase> program

        template<T> T& get_data(IndexType) const
        void set_instr_base()
        Errno run(InstrIdx)
        Errno step()
        void add_instr(InstrBase*)
----[cut]

This post is to emphasize the theoretical function and capability of C/C++
language, which is equally important to their practical usage.
Many might be surprised what the hell C/C++ has anything to do with the
theoretical Turing Machine (altho many discussion/program of C/C++ are/were
actually abstract, therefore theoretical) and might think they don't need s=
uch a
'trivial' thing. Probably, but likely naive: Turing Machine is the the mode=
l of
all general purpose computers. ALL things, including C++, are merely differ=
ent
aspects of TM. The real thing is actually even more, all deterministic form=
al
logic and mathemathics (if presented in a formal way) are less powerful tha=
n TM.
C++'s application needs not to be database, html, png...,etc.

Ex1: "Object Oriented": Every function call can be viewed as a method of th=
e
     object involved in the tape... (programing style involves the decompos=
tion
     of the problem, important, but not changing the essence)

Ex2: "Sequence point": The concept of 'sequence pint' is unnecessary in Spu
     program. In C/C++, 'sequence point' has to be invented. Even so, it mi=
ght
     still not be the final term.

Ex3: if((ch>=3D'a')&&(ch<=3D'z')) { /* ... */ };
     In Spu program, the C/C++ expression above would be like:

     Jb(ch,'a',lab1);   // if ch<'a', goto lab1 (exact expression may be a =
bit
                        //  different)
     Ja(ch,'z',lab1);   // if ch>'z', goto lab1
     /* ... */
     lab1: ...

     No need to explain what the logical compound statement really mean (
     tradition logic has the similar prboem, just more subtler).

Ex4: The Peano axiom:
     1. 1=E2=88=88=E2=84=95
     2. n=E2=88=88=E2=84=95 -> S(n)=E2=88=88=E2=84=95

     A problem of Peano axiom is: Is infinity a natural number?
     The basic answer is that, formal logic is inadequate for procedual fac=
t.
     Basically, Peano axiom did not solve what the 'natural number' is, it =
just
     goes in circle changing termonology like C++ does (useful, though, if =
you
     do not dig deeper, and no deeper usage as well).

Ex5: Multi-tasking in Spu is basically just multiple instances of class Spu=
..
     Or, you can make tape variables whose type is Spu...

Ex6: Traditional TM is a simplest case of Spu. It is no sense to restrict
     operations to comparing symbols and only moving r/w head left or right=
 to
     be orthodoxical. And, the idea of Non-Deterministic TM (an obscure,
     obstructive now) can be dropped.

---------
Beside the theoretical part. Class Spu is also useful as the back-end of al=
l
interpreting languages (sufificitate ones may be highly optimized).

Also because the implement of Spu is short, the range of application is hug=
e and
foundamental. Clib may consider adding one such thing.