As you've discovered in bug #13325, dealing with external constants in
static expressions is sometimes a little tricky. I would avoid casting
for now (as happens in the bug) in favor of stronger types. For
example, this compiles and runs for me:
extern {
fn foo();
fn bar();
}
static table: &'static [extern unsafe fn()] = &[foo, bar];
pub mod test {
#[no_mangle] pub extern fn foo() { println!("foo"); }
#[no_mangle] pub extern fn bar() { println!("bar"); }
}
fn main() {
for f in table.iter() {
unsafe { (*f)(); }
}
}
Note that in rust, a value of type `extern fn()` cannot be null, but
`Option<extern fn()>` can indeed be null. You'll probably want
something along the lines of:
#[link_section = ".isr_vector"]
pub static ISR_VECTOR_TABLE: [Option<extern unsafe fn()>, ..N] =
[Some(...), None, Some(...), ...];
On Fri, Apr 4, 2014 at 12:53 PM, Vladimir Pouzanov <[email protected]> wrote:
> Is it possible to port the following C code to rust?
>
> __attribute__ ((section(".isr_vector")))
> void (* const isr_vector_table[])(void) = {
> &_stack_base,
> main, // Reset
> isr_nmi, // NMI
> isr_hardfault, // Hard Fault
> 0, // CM3 Memory Management Fault
> 0, // CM3 Bus Fault
> 0, // CM3 Usage Fault
> &_boot_checksum, // NXP Checksum code
> 0, // Reserved
> 0, // Reserved
> 0, // Reserved
> isr_svcall, // SVCall
> 0, // Reserved for debug
> 0, // Reserved
> isr_pendsv, // PendSV
> isr_systick, // SysTick
> };
>
> here main and isr_* are rust external functions, and _stack_base is defined
> as
>
> extern void _stack_base()
>
> and gets loaded from linker script.
>
> Also, is it possible to make a weak symbol in rust or somehow emulate it?
> Weak symbols are used in C code to provide the following functionality:
> isr_* functions are stubs with default implementation (morse out id code
> with led, loop forever), but if any of those requires actual code, than it
> is overrides the weak "morse-blinking" function symbol.
>
> --
> Sincerely,
> Vladimir "Farcaller" Pouzanov
> http://farcaller.net/
>
> _______________________________________________
> Rust-dev mailing list
> [email protected]
> https://mail.mozilla.org/listinfo/rust-dev
>
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