Re: and/or missbehaviour in embedded lua 5.1

[Kein-Hong Man <mkh@...>]

Andreas Stenius wrote:
> Interesting, I implemented luac into my monitor to see the output, and 
> get this:
>
>  > c"local a = true and 0"
>
> main <(string):0,0> (2 instructions, 8 bytes at 0x148f7a)
> 0+ params, 2 slots, 0 upvalues, 1 local, 1 constant, 0 functions
>        1       [1]     LOADK           0 -1    ; 2.1436356971487e-228
>        2       [1]     RETURN          0 1
> constants (1) for 0x148f7a:
>        1       2.1436356971487e-228
> locals (1) for 0x148f7a:
>        0       a       2       2
> upvalues (0) for 0x148f7a:
>  > c"local a = true or 0"

Looking at the bit patterns for double values,

1.0890312344636e-60  = E0FFFFFF05007C33
2.1436356971487e-228 = 000000001100AA10

The first 4 bytes look mighty suspicious... since the expression 
is essentially the same but your earlier sample (=true and 0) gave 
a different value, I guess something is broken. Without more 
information, it's almost impossible for anyone on the list to 
diagnose what had caused it; we would be only speculating.

> [snip]
> The sizes for the various data types is as:
>        ["char"] = 1,
>        ["void *"] = 4,
>        ["int"] = 2,

int is the only data type that is different compared to x86. What 
lua_Number and endianness are you using? Assuming no 
modifications, ldump.c doesn't look like it can introduce such 
funny values, so I guess the values are produced by the code 
generator.

--
Cheers,
Kein-Hong Man (esq.)
Kuala Lumpur, Malaysia