Thanks for the further feedback. A few assorted replies to the comments.....
I need some pretty precise maths elsewhere in my code, so it was never an option to change conf.h to reduce Lua's default number definition.
Yep, I was aware of the feature with lua_createtable() to pre-create the correct number of storage elements, I have used that a fair bit already in smaller tables I have made. If things look too slow, I will have to look at doing it with userdata, to try and optimise the number of bytes passed.
To answer the question on specs. I am using an 80Mhz Freescale Coldfire chip, it has got a few Megs of ram allocated for Lua, cant remember the exact figure, but well less than 10 Megs. I am using just bog standard Lua 5.1.5
Why was I passing it to Lua, when I said all I wanted was to make a CSV file ? That one is easy to answer. Flexibility !
I have no idea what other folks might want to do with the data ? Heck, I usually don't know what I will end up doing with features and stuff myself a few months down the road, let alone other people :)
Getting embedded firmware changed for small tweaks here and there is a pain in the ass, changing a text file to run a tweaked Lua script is way less hassle.
> Date: Sat, 8 Jun 2013 00:53:39 -0300
> From: email@example.com
> To: firstname.lastname@example.org
> Subject: Re: Fastest way to transfer data from C to Lua ?
> On 07/06/13 22:32, Sean Conner wrote:
> > You mention having some 5,000 samples, which works out to be around
> > 80k (5,000 * 8 (sizeof double) * 2 (two samples)) which would
> > certainly be too large to handle on my first computer (8-bit 6809 with
> > 64K RAM) all my computers since then would be able to handle that
> > amount just fine. For reference, until about mid-2003 I was using a
> > 486 with 32M RAM for serving up my website, and I was using a similar
> > box for development until 2009. So now I'm curious---what *are* the
> > specs of the system you are using? -spc
> Personally, the smallest available RAM i've had when using Lua was a
> couple Mb worth.
> On the other hand, I was very close to using pbLua (Lua on Lego NXT
> controller), and that would've driven the low bar way lower.
> And then there are the eLua guys...