Does SHA512SUM1 use floating-point or vector registers?
No. These scalar crypto extension instructions use integer X registers.
SHA512SUM1
RISC-V SHA512SUM1 Instruction Details
Instruction ManualI-typeSHA-512 Σ1 function (uppercase, RV64): ROTR(rs1,14) ^ ROTR(rs1,18) ^ ROTR(rs1,41)
Instruction Syntax
sha512sum1 rd, rs1
Operand Breakdown
Destination rd: general-purpose register receiving the result.
Source rs1: register holding the first operand.
Immediate imm: 12-bit signed value, sign-extended before operation with rs1.
ZknhCrypto & Security
Instruction Behavior
sha512sum1 is defined only for RV64. It computes the SHA2-512 Sum1 transform, ROTR64(X(rs1), 14) ^ ROTR64(X(rs1), 18) ^ ROTR64(X(rs1), 41), and writes the 64-bit result to rd. sha512sum1r is the RV32 split form.
SHA512SUM1 Decode And Execute Animation
Bounded teaching inputs execute the official SHA-512 fixed-width bit operations; this does not model a complete algorithm or microarchitecture.
rd
rs1
sha512sum1
,
SHA512SUM1 is defined only for RV64 and operates on the complete 64-bit X(rs1).
fixed selector
source
fixed
destination
OP-IMM
31..20
000100000101
19..15
rs1=x11
14..12
001
11..7
rd=x10
6..0
0010011
Execution Data Path
inb
0x0123456789ABCDEF
ror64(inb, 14)
0x37BC048D159E26AF
ror64(inb, 18)
0xF37BC048D159E26A
ror64(inb, 41)
0xB3C4D5E6F78091A2
result
0x7703112333475567
Architectural Result
a0(x10) = 0x7703112333475567
This animation shows only official ISA fields and architectural state; it does not model a complete hash algorithm, pipeline, cache, or timing implementation.
Quick Understanding & Search Notes
SHA512SUM1 is a Zknh scalar cryptography instruction for SHA-512 RV64 transform. This page is checked against the official scalar crypto extension, avoiding confusion among round functions, key schedule steps, and operand sources.
sha512sum1 is the RV64 SHA-512 uppercase Sigma compression transform.
Scalar crypto instructions use integer X registers, and the official spec requires the relevant crypto instructions to be implemented with data-independent execution latency.
Common Usage Scenarios
Crypto & Security
Understand this scenario with real code like «sha512sum1 a0, a1».
Hash Algorithms
Understand this scenario with real code like «sha512sum1 a0, a1».
Pre-Use Checklist
Syntax Check
- Verify the immediate field is within the valid range.
- Confirm source register rs1 points to the correct operand.
Semantic Check
- Check if the immediate sign-extension matches expectations.
- Ensure the result register rd has a clear purpose.
Pitfalls / Common Confusions
RV64 only. RV32 uses sha512sum1r.
Rotate amounts (14, 18, 41) differ from SHA-256 Σ1 (6, 11, 25).
FAQ
Is SHA512SUM1 a complete algorithm implementation?
No. It implements one SHA2-512 Sum1 transform defined by the manual.