Re: Cross-compiler

[David Jones <drj@...>]

On 12 Aug 2008, at 02:38, Tim Maxwell wrote:

> Hi,
>
> Attached are modified versions of ldump.c, lundump.h, and luac.c to  
> allow for cross-compilation. They should work as drop-in  
> replacements. I've done some basic testing, but I only have access  
> to one architecture so I can't test endianness.
>
> This code lets you specify:
> * the endianness of the target platform
> * the size of int as 8, 16, or 32 (no 64-bit support right now)
> * lua_Number as an int (8, 16, or 32 bits) or a float (32 or 64 bits)
>
> ldump.c exports a new function called "luaU_dump_crosscompile" that  
> works like luaU_dump except that it takes a DumpTargetInfo structure.
>
> luaU_dump_crosscompile supports different sizes of size_t but luac  
> does not allow it to be set from the command line. Are there any  
> targets where sizeof(int) is different from sizeof(size_t)?

Plenty.

Almost every C compiler for processors where a 16-bit int made sense  
(PDP, MC68000, Intel) had a 16-bit int and a 32-bit size_t.  Some C  
compilers for 64-bit processors have 32-bit int and 64-bit size_t.   
Quite possibly some embedded ARMs have compiler modes where int is 16- 
bit because it fits better with an external RAM bus and it feels more  
"embedded".

All the world's a VAX.

> This code assumes that 'float' is a standard 32-bit float and  
> 'double' is a standard 64-bit double. It will trip a lua_assert if  
> lua_Number is not integer but sizeof(lua_Number) is not 32 or 64.  
> Is that portable enough?

Probably.  For now.

drj