Does ZIP access memory?
No. It only rearranges bit fields or performs register lookup within integer registers.
ZIP
RISC-V ZIP Instruction Details
Instruction ManualI-typeRV32 bit interleave (Zbkb), RV32-only.
Instruction Syntax
zip 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.
ZbkbBit Manipulation
Instruction Behavior
ZIP (Zbkb, RV32-only) interleaves the low and high halves of the source register into the destination: for i=0..15, rd[2*i]=rs1[i] and rd[2*i+1]=rs1[i+16]. It is the inverse of UNZIP and is useful for SHA3 bit interleaving on 32-bit architectures.
ZIP Decode And Execute Animation
RV32 interleaves the low and high halves of rs1 into rd's even and odd bit positions.
XLEN
RV32
RV32
imm[11:0]
31..20
000010001111rs1
19..15
01011funct3
14..12
001rd
11..7
01010opcode
6..0
0010011Current calculation
rd[2i] = rs1[i]; rd[2i+1] = rs1[i+16], i = 0..15
0xD2C4B8A1 -> 0xE748E421
Step: decode
Shows the instruction's fixed and register fields.
x[a0] <- 0xE748E421
1/4: decode
Quick Understanding & Search Notes
ZIP is a Zbkb cryptographic bit-manipulation instruction; this page follows the official B-extension operation.
The official encoding and semantics are RV32-only.
These instructions rearrange bit/byte fields and do not access memory.
Common Usage Scenarios
Crypto & Security
Understand this scenario with real code like «zip a0, a1».
Logical Operations
Understand this scenario with real code like «zip 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
ZIP is defined only on RV32; there is no RV64 form.
Even bits come from the source low half and odd bits from the source high half; do not confuse it with byte shuffle.
This instruction is RV32-only; there is no RV64 form.
FAQ
Which extension contains ZIP?
It belongs to the Zbkb cryptographic bit-manipulation extension.