- Synopsis
-
Vector Reverse Bytes
- Mnemonic
-
vrev8.v vd, vs2, vm
- Encoding (Vector)
{reg:[
{bits: 7, name: 'OP-V'},
{bits: 5, name: 'vd'},
{bits: 3, name: 'OPMVV'},
{bits: 5, name: '01001'},
{bits: 5, name: 'vs2'},
{bits: 1, name: 'vm'},
{bits: 6, name: '010010'},
]}
- Arguments
| Register | Direction | Definition |
|---|---|---|
Vs2 |
input |
Input elements |
Vd |
output |
Byte-reversed elements |
- Description
-
A byte reversal is performed on each element of
vs2, effectively performing an endian swap.
|
Note
|
This element-wise endian swapping is needed for several cryptographic algorithms including SHA2 and SM3. |
- Operation
function clause execute (VREV8(vs2)) = {
foreach (i from vstart to vl-1) {
input = get_velem(vs2, SEW, i);
let output : SEW = 0;
let j = SEW - 1;
foreach (k from 0 to (SEW - 8) by 8) {
output[k..(k + 7)] = input[(j - 7)..j];
j = j - 8;
set_velem(vd, SEW, i, output)
}
RETIRE_SUCCESS
}