lua5: questions & suggestions

[mjscod@... (Mark Junker)]

Hi,

first I have to say that Lua is a great script language with a quite small  
footprint, a clean interface and good documentation.

I recently compiled Lua 5 with the Hitachi EC++ compiler for SH4 and I had to  
make some changes. They led to the following questions and suggestions.





My questions:
1. In liolib.c, you use CLOCKS_PER_SEC. Shouldn't it be CLK_TCK?

2. Is it possible to compile Lua in a way that disables all file i/o?

What I mean is:
- compile without the ability to load external libraries/files
- no execute/open/close/input/output/file name handling functions in liolib.c
- leaves stdin, stdout, ...




My suggestions:
1. For the next Lua version, can you save the compiled Lua script in a  
machine-independent way?

It's a big advantage to store a compiled Lua script in a machine-independent  
way when you want to compile the script on the PC side, then transfer it to  
the embedded (big-endian) machine where it'll be executed (no parser to save  
memory, no file i/o needed either).

Example for DumpNumber from ldump.c:
-------------------------- snip --------------------------------------
/* use 8 instead of sizeof(double)
 * because there are compilers where sizeof(float)==sizeof(double) */
#define DOUBLE_SIZE (8)

static void DumpNumber(lua_Number x, DumpState* D)
{
#if LUA_NUM_IS_INTEGRAL==1
    char chTmp[sizeof(x)];
    unsigned i;
    lua_Number mask = UCHAR_MAX;
    for (i=0; i!=sizeof(x); ++i) {
        chTmp[i] = (char) (x & mask);
        x /= (1<<CHAR_BIT);
    }
    DumpBlock(chTmp,sizeof(x),D);
#else
    int iExponent = 0;
    double dblMantissa = frexp((double) x, &iExponent);
    double ipart;
    double dblFactorUL = ldexp(1, CHAR_BIT * sizeof(unsigned long) - 1);

    dblMantissa = ldexp(dblMantissa, CHAR_BIT * sizeof(unsigned long) - 1);
    dblMantissa = modf(dblMantissa, &ipart);
    dblMantissa *= dblFactorUL;

    DumpInt(iExponent, D);
    DumpUL((long) dblMantissa, D);
    DumpUL((long) ipart, D);
#endif
}
-------------------------- snip --------------------------------------

2. Can you define a set of macros (maybe in a different header file) for  
arithmetics with lua_Number variables?

This might be useful when lua_Number is a 64 bit fixed point (48.16) integer  
number for very fast integer arithmetics.

Best regards,
Mark Junker