[avr-gcc-list] Re: in-line assembler

[David Brown]

Robert von Knobloch wrote:
> Hello,
> I've been trying to decipher the intricacies of in-line assembler (using
> the Inline Assembler Cookbook as my guide).
>
> I have a very simple application that I cannot seem to realise.
>
> I want a C function that will return the contents of the RAM address
> that I give it as argument.
>
> My assembler-based function looks like this:
>
> file is hex.c
> =====
> uint8_t get_ram_byte(uint16_t ram_address)
> {
>     uint8_t    byte;
>
>     asm  ("ld __tmp_reg__, %a1"    "\n\t"
>     "sts %0, __tmp_reg__"    "\n\t"
>     : "=&r" (byte) : "e" (ram_address));
>     return byte;
> }
>
> and is called from
>
>             rambyte = get_ram_byte(i );
>             u_hex8out(rambyte);         // Print byte as 8-bit hex.

Are you doing this as a learning exercise?  If not, why not just use a 
bit of C casting?

uint8_t get_ram_byte(uint16_t ram_address)
{
        return *(uint8_t *)(ram_address);
}