Okay, let's talk assembly and Lua (was Re: A bit more on bits...)

[Sean Conner <sean@...>]

It was thus said that the Great Luiz Henrique de Figueiredo once stated:
> Can we please go back to discussing Lua? Thanks.

  Sure.  Here's a Lua module I wrote for 32-bit x86 (Linux in particular,
using nasm, but it could be adopted for other operating systems).  It's a
wrapper around the x86 instruction RDTSC (ReaD TimeStamp Counter) with as
minimal overhead as possible:

;***************************************************************************
;
; Copyright 2020 by Sean Conner.
;
; This library is free software; you can redistribute it and/or modify it
; under the terms of the GNU Lesser General Public License as published by
; the Free Software Foundation; either version 3 of the License, or (at your
; option) any later version.
;
; This library is distributed in the hope that it will be useful, but
; WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
; or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
; License for more details.
;
; You should have received a copy of the GNU Lesser General Public License
; along with this library; if not, see <http://www.gnu.org/licenses/>.
;
; Comments, questions and criticisms can be sent to: sean@conman.org
;
;***************************************************************************

                bits    32
                global  rdtsc
                extern  lua_pushinteger
                extern  lua_pushcclosure

;***************************************************************************
                section .text

ldl_rdtsc:      rdtsc
                push    edx
                push    eax
                push    dword [esp + 12]
                call    lua_pushinteger
                xor     eax,eax
                inc     eax
                lea     esp,[esp + 12]
                ret

;---------------------------------------------------------------------------

rdtsc:          xor     eax,eax
                push    eax
                push    ldl_rdtsc
                push    dword [esp + 12]
                call    lua_pushcclosure
                xor     eax,eax
                inc     eax
                lea     esp,[esp + 12]
                ret

  -spc