e300 (MPC5121) dlmzb

[Kumar Gala]

On Sep 25, 2009, at 4:07 AM, Fortini Matteo wrote:

> I was trying to insert an optimized strlen() function using the  
> following code taken from the ibm site on an MPC5121, but it crashes  
> the kernel.
> Is it because it's an unsupported op, or because I'm missing some  
> needed steps?
>
> Thank you,
> Matteo
>
> _GLOBAL(strlen)
>   addi   r4,0,8    // Load byte count of 8
>   mtxer  r4        // Set byte count for load string
>   xor    r4,r4,r4  // r4 = 0, r4 == accumulator
> 1:
>   lswx   r5,r3,r4  // load string into r5 & r6
>   dlmzb. r12,r5,r6 // find NULL byte and record in r7.
>   add    r4,r4,r12 // Update accumulator.
>   beq    1b        // Loop if NULL not found.
>   addi   r3,r4,-1  // Subtract 1 for NULL byte.
>   blr              // Return length

dlmzb. isn't supported on e300.  I believe only 4xx supports it.

- k