This is the mail archive of the
gcc-help@gcc.gnu.org
mailing list for the GCC project.
Re: Inline assembly and ldm/stm
- From: Ian Lance Taylor <iant at google dot com>
- To: "Bryce Schober" <bryce dot schober at dynonavionics dot com>
- Cc: gcc-help at gcc dot gnu dot org
- Date: 10 Apr 2007 10:59:05 -0700
- Subject: Re: Inline assembly and ldm/stm
- References: <932d0ae60704091404t5f4674ekd72691451d36d50b@mail.gmail.com>
"Bryce Schober" <bryce.schober@dynonavionics.com> writes:
> So how should I go about wrapping ldm / stm for usage in C land?
>
> I tried:
>
> typedef struct
> {
> UNS_32 reg[2];
> } arm_2_registers_t;
>
> static inline
> arm_2_registers_t arm_2_registers_load(
> UNS_32 *src_addr_ptr )
> {
> arm_2_registers_t result;
> __asm__ (
> "ldmia %0, {%1,%2} \n\t"
> : "+r" (src_addr_ptr), "=r" (result.reg[0]), "=r" (result.reg[1])
> );
> return( result );
> }
>
> That seems to work fine until the compiler decides to use registers
> for %1 and %2 that aren't in ascending order. I've examined the
> assembly constraints and I don't see anything obvious.
There is in general no way to do that.
Sorry.
Ian