Porting JamesM's tutorials to c++, ran into 1 issue.

[astrocrep]

So I have been going through the usermode tutorial, and changing things to make it compile in g++ 4.5 (cross)

I've fixed a bunch of stuff, but I am not sure about the following...

I am trying to initialize an array:

Code: Select all

static void *syscalls[3] =
{
    &monitor_write,
    &monitor_write_hex,
    &monitor_write_dec,
};

Where those three functions are:

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void monitor_write(char *c);
void monitor_write_hex(u32int n);
void monitor_write_dec(u32int n);

However g++ is throwing the following errors...

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error: invalid conversion from 'void (*)(char*)' to 'void*'
error: invalid conversion from 'void (*)(u32int)' to 'void*'
error: invalid conversion from 'void (*)(u32int)' to 'void*'

I have tried a couple of different things, but I am getting the feeling this might be illegal in c++...

Hopefully I am just missing something obvious.

Thanks in advance,
Rich

[Combuster]

The standard says that functions may not be converted to variables and vice-versa. Declare syscall as a function array.

[rknox]

http://www.newty.de/fpt/zip/e_fpt.pdf

http://www.netrino.com/node/137

[Creature]

The standard says that functions may not be converted to variables and vice-versa. Declare syscall as a function array.

Or... a bit more hacky: cast all function addresses to void pointers.

[astrocrep]

Thanks guys... thats what I was looking for.