Hello,

Read again, i correct about more of my philosophy about coroutines and
about setjmp() and longjmp()..

I am a white arab from Morocco, and i think i am smart since i have also
invented many scalable algorithms and algorithms..

I think i am smart, and i will say that with setjmp() and longjmp()
you can implement a generator or the like, but you can not implement
coroutines with just setjmp() and longjmp(), and so that to understand
it, i invite you to read the following article that shows how when you
yield from a first function with a longjmp() to the main body of a
program and when you call another functions with longjmp(), it can make
the stack frames not work correctly, and when you understand it you will
not use setjmp() and longjmp() alone so that to implement coroutines, so
read the following article so that to understand the problem with
the stack frames, and i am understanding it easily:

https://www.csl.mtu.edu/cs4411.ck/www/NOTES/non-local-goto/coroutine.html

So this is why i have also implemented my sophisticated stackful
coroutines library so that to solve this problem, and here is my
sophisticated coroutines library and read about it and download it from
here:

https://sites.google.com/site/scalable68/object-oriented-stackful-coroutines-library-for-delphi-and-freepascal

More of my philosophy about setjmp() and longjmp() and generators and
coroutines..

I have just quickly implemented setjmp() and longjmp() in x64 assembler,
and after that i have just implemented quickly a good example of a
generator with my setjmp() and longjmp(), look at it below, and in
computer science, a generator is a routine that can be used to control
the iteration behaviour of a loop. All generators are also iterators. A
generator is very similar to a function that returns an array, in that a
generator has parameters, can be called, and generates a sequence of
values. However, instead of building an array containing all the values
and returning them all at once, a generator yields the values one at a
time, which requires less memory and allows the caller to get started
processing the first few values immediately. In short, a generator looks
like a function but behaves like an iterator. So here is my
implementations in freepascal and delphi and they are working perfectly:

Here is my first unit that implements longjmp() and setjmp() and notice
how i am saving the non-volatile registers and how i am coding it in
x64 assembler:

======

{ Volatile registers: The calling program assumes registers
RAX, RCX, RDX, and R8 through R11 are volatile.
The contents of registers RBX, RSI, RDI, RBP, RSP, and
R12 through R15 are considered non-volatile. Functions return
values in RAX. }

unit JmpLib64;

{$IFDEF FPC}
{$ASMMODE intel}
{$ENDIF}
interface

type
jmp_buf = record
RBX,
RSI,
RDI,
RSP,
RBP,
RIP,
R12,
R13,
R14,
R15: UInt64;
end;

{ setjmp captures the complete task state which can later be used to
perform a non-local goto using longjmp. setjmp returns 0 when it is
initially called, and a non-zero value when it is returning from a call
to longjmp. setjmp must be called before longjmp. }

function setjmp(out jmpb: jmp_buf): UInt64;

{ longjmp restores the task state captured by setjmp (and passed in
jmpb). It then returns in such a way that setjmp appears to have
returned with the value retval. setjmp must be called before longjmp. }

procedure longjmp(const jmpb: jmp_buf; retval: UInt64);
implementation

function setjmp(out jmpb: jmp_buf): UInt64; assembler;{$IFDEF FPC}
nostackframe; {$ENDIF}register;
asm
{ -> RCX jmpb }
{ <- RAX Result }
MOV RDX, [RSP] // Fetch return address (RIP)
// Save task state
MOV [RCX+jmp_buf.&RBX], RBX
MOV [RCX+jmp_buf.&RSI], RSI
MOV [RCX+jmp_buf.&RDI], RDI
MOV [RCX+jmp_buf.&RSP], RSP
MOV [RCX+jmp_buf.&RBP], RBP
MOV [RCX+jmp_buf.&RIP], RDX
MOV [RCX+jmp_buf.&R12], R12
MOV [RCX+jmp_buf.&R13], R13
MOV [RCX+jmp_buf.&R14], R14
MOV [RCX+jmp_buf.&R15], R15

SUB RAX, RAX
@@1:
end;

procedure longjmp(const jmpb: jmp_buf; retval: UInt64);assembler;{$IFDEF
FPC} nostackframe; {$ENDIF}register;
asm
{ -> RCX jmpb }
{ RDX retval }
{ <- RAX Result }
XCHG RDX, RCX
MOV RAX,RCX
MOV RCX, [RDX+jmp_buf.&RIP]
// Restore task state
MOV RBX, [RDX+jmp_buf.&RBX]
MOV RSI, [RDX+jmp_buf.&RSI]
MOV RDI, [RDX+jmp_buf.&RDI]
MOV RSP, [RDX+jmp_buf.&RSP]
MOV RBP, [RDX+jmp_buf.&RBP]
MOV R12, [RDX+jmp_buf.&R12]
MOV R13, [RDX+jmp_buf.&R13]
MOV R14, [RDX+jmp_buf.&R14]
MOV R15, [RDX+jmp_buf.&R15]
MOV [RSP], RCX // Restore return address (RIP)

TEST RAX, RAX // Ensure retval is <> 0
JNZ @@1
MOV RAX, 1
@@1:
end;

end.

================

And here is my example of a generator with my longjmp() and setjmp():

{ In computer science, a generator is a routine that can be used to
control the iteration behaviour of a loop. All generators are also
iterators. A generator is very similar to a function that returns an
array, in that a generator has parameters, can be called, and generates
a sequence of values. However, instead of building an array containing
all the values and returning them all at once, a generator yields the
values one at a time, which requires less memory and allows the caller
to get started processing the first few values immediately. In short, a
generator looks like a function but behaves like an iterator. }

program test_generator;

{$APPTYPE CONSOLE}

uses
JmpLib64;

type PtrInt = ^Integer;

var
childtask,maintask: jmp_buf;
myarr1: array of integer;
i,a:integer;
Ptr1:PtrInt;

function generator(var myarr:array of integer):integer;

var i1:integer;
val:integer;
ptr:PtrInt;
begin

i1:=0;

val:= setjmp(childtask);

i1:=val-1;

if val=0 then
begin
new(ptr);
ptr^:=myarr1[i1];
longjmp(maintask,uint64(ptr));
end;

if val=10
then
begin
writeln('Exiting child..');
exit;
end;

inc(i1);
new(ptr);
ptr^:=myarr1[i1];
longjmp(maintask,uint64(ptr));
end;

begin

setlength(myarr1,10);

for i:=0 to 9
do myarr1[i]:=i;

uint64(ptr1):=setjmp(maintask);

if ptr1=nil then generator(myarr1);

a:=ptr1^;
dispose(ptr1);

if (a<=length(myarr1))
then
begin
if a=length(myarr1)
then longjmp(childtask,a+1)
else
begin
writeln('Value retuned by generator is: ',a);
longjmp(childtask,a+1);
end;
end;

setlength(myarr1,0);

end.

====

Thank you,
Amine Moulay Ramdane.