SHA512H

SHA512 hash update part 1

This instruction takes the values from the three 128-bit source SIMD&FP registers and produces a 128-bit output value that combines the sigma1 and chi functions of two iterations of the SHA512 computation. It returns this value to the destination SIMD&FP register.

Encoding: Advanced SIMD

Variants: FEAT_SHA512 (ARMv8.2)

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
1	1	0	0	1	1	1	0	0	1	1						1	0	0	0	0	0
											Rm						O			opcode		Rn					Rd

SHA512H <Qd>, <Qn>, <Vm>.2D

Decoding algorithm

if !IsFeatureImplemented(FEAT_SHA512) then EndOfDecode(Decode_UNDEF);
constant integer d = UInt(Rd);
constant integer n = UInt(Rn);
constant integer m = UInt(Rm);

Operation

AArch64.CheckFPAdvSIMDEnabled();

bits(128) Vtmp;
bits(64)  MSigma1;
bits(64)  tmp;
constant bits(128) x = V[n, 128];
constant bits(128) y = V[m, 128];
constant bits(128) w = V[d, 128];

MSigma1 =  ROR(y<127:64>, 14) EOR ROR(y<127:64>, 18) EOR ROR(y<127:64>, 41);
Vtmp<127:64> =  (y<127:64> AND x<63:0>) EOR (NOT(y<127:64>) AND x<127:64>);
Vtmp<127:64> = (Vtmp<127:64> + MSigma1 +  w<127:64>);
tmp = Vtmp<127:64> + y<63:0>;
MSigma1 = ROR(tmp, 14) EOR ROR(tmp, 18) EOR ROR(tmp, 41);
Vtmp<63:0> = (tmp AND y<127:64>) EOR (NOT(tmp) AND x<63:0>);
Vtmp<63:0> = (Vtmp<63:0> + MSigma1 + w<63:0>);
V[d, 128] =  Vtmp;

Explanations

<Qd>: Is the 128-bit name of the SIMD&FP source and destination register, encoded in the "Rd" field.
<Qn>: Is the 128-bit name of the second SIMD&FP source register, encoded in the "Rn" field.
<Vm>: Is the name of the third SIMD&FP source register, encoded in the "Rm" field.

Operational Notes

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.