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AESD

AES single round decryption.

The AESD instruction reads a 16-byte state array from each 128-bit segment of the first source vector, together with a round key from the corresponding 128-bit segment of the second source vector. Each state array undergoes a single round of the AddRoundKey(), InvSubBytes() and InvShiftRows() transformations in accordance with the AES standard. Each updated state array is destructively placed in the corresponding segment of the first source vector. This instruction is unpredicated.

ID_AA64ZFR0_EL1.AES indicates whether this instruction is implemented.

313029282726252423222120191817161514131211109876543210
0100010100100010111001ZmZdn
size<1>size<0>

AESD <Zdn>.B, <Zdn>.B, <Zm>.B

if !HaveSVE2AES() then UNDEFINED;
integer m = UInt(Zm);
integer dn = UInt(Zdn);

Assembler Symbols

<Zdn>

Is the name of the first source and destination scalable vector register, encoded in the "Zdn" field.

<Zm>

Is the name of the second source scalable vector register, encoded in the "Zm" field.

Operation

CheckSVEEnabled();
integer segments = VL DIV 128;
bits(VL) operand1 = Z[dn];
bits(VL) operand2 = Z[m];
bits(VL) result;

result = operand1 EOR operand2;
for s = 0 to segments-1
    Elem[result, s, 128] = AESInvSubBytes(AESInvShiftRows(Elem[result, s, 128]));

Z[dn] = result;

Operational information

If PSTATE.DIT is 1:

  • The execution time of this instruction is independent of:
    • The values of the data supplied in any of its registers.
    • The values of the NZCV flags.
  • The response of this instruction to asynchronous exceptions does not vary based on:
    • The values of the data supplied in any of its registers.
    • The values of the NZCV flags.