Re: Simple AI Scripting, Help Me!

[Roberto Ierusalimschy <roberto@...>]

> I think Lua has a union in llimits.h which has double in it. I think
> it's supposed to be the size of an instruction. This only needs to be 32
> bit, not 64 so you can save memory. I think the running faster reference
> was wrt to removing all instances of double from Lua.

This union ensures that all memory allocated with lua_newuserdata
satisfies all allignment restrictions (like the result of malloc),
so that you can store any kind of data in that area. You can change
that simply redefining LUSER_ALIGNMENT_T to a type with the maximum
allignment you need in your application (e.g., -DLUSER_ALIGNMENT_T=int).


> I think the only problem I have now is long, which is 64 bit on the PS2.
> There are only a few occurrences in the Lua code, but nevertheless it
> makes sense to remove them (for PS2). It would be nice if the longs were
> ints or user defined. If in Lua long is assumed to be the same size as
> int (i.e. the machines native word size) there seems little point in
> using it at all.

Lua uses longs whenever it needs a type that is at least 32 bits or
where an int may be too small (even a 32 bit int). For most uses we do
define new types (e.g., Instruction, ls_nstr, lu_mem). In a few places,
where performance is not critical, we use long directly in the code to
avoid the complexity of too many user-defined types.

-- Roberto