Re: porting assembly x86 code

[Philipp Janda <siffiejoe@...>]

Am 27.09.2013 03:58 schröbte Athos Ribeiro:
> Hello,

Hi!

> I would like to know if there is anyone working on the port of lua50
> (5.0.3-6) to arm 64.
> The reason I am asking it:
> Steve Mcintyre posted a list of modules that are written in assembly and
> need port, and this version of Lua was listed there:
> "Lua programming language implementation; x86 asm for performance in
> rounding; low priority".
> (source: https://wiki.linaro.org/LEG/Engineering/OPTIM/Assembly)
>
> Jon 'maddog' Hall has been talking about starting a contest in order to get
> all these assembly code ported to C, to provide portability and in some
> cases even optimizing the code.
>
> So again, is anyone working in porting the assembly code in question? If
> not, who are the developers maintaining that code?
>
> I would like to work on it for my undergraduate thesis at Universidade de
> Brasília, Brazil, but first I would like to estabilish some contact with
> the maintainers. Would anyone want to talk about it?

The whole assembler code in Lua 5.0 is:

    #ifdef USE_FASTROUND
    #define lua_number2int(i,d)	__asm__("fldl %1\nfistpl 
%0":"=m"(i):"m"(d))
    #endif

... and it is completely optional. The default is:

    #define lua_number2int(i,n)	((i)=(int)(n))

I doubt that you can base a thesis on porting this to ARM 64. Some 
similiar code is also included in newer versions of Lua, btw.

> Athos Ribeiro

Philipp