[10000truths]

I would rather just use a plain for loop and manipulate the index in the loop body:

  for(uint32_t i = 0; i < length; ++i) {
      i = (length - 1) - i;
      // ...
  }

Much easier for me to understand, making it less likely to mess anything up.

[edflsafoiewq]

You'll need a new variable there, but otherwise yeah.

[WalterBright]

Even easier (for D):

    foreach (i; 0 .. length)

D takes care of selecting the correct type for `i`.