ab_riscv_primitives/instructions/rv32/zk/
zbkb.rs

1//! RV32 Zbkb extension
2
3#[cfg(test)]
4mod tests;
5
6use crate::instructions::Instruction;
7use crate::instructions::rv32::b::zbb::Rv32ZbbInstruction;
8use crate::registers::general_purpose::Register;
9use ab_riscv_macros::instruction;
10use core::fmt;
11
12/// RISC-V RV32 Zbkb instruction (Bit-manipulation for Cryptography)
13#[instruction(
14    reorder = [Andn, Orn, Xnor, Rol, Ror, Rori, Rev8, Pack, Packh, Brev8],
15    ignore = [Rv32ZbbInstruction],
16    inherit = [Rv32ZbbInstruction],
17)]
18#[derive(Debug, Clone, Copy, PartialEq, Eq)]
19pub enum Rv32ZbkbInstruction<Reg> {
20    /// Pack low 16 bits of `rs1` into `rd[15:0]`, low 16 bits of `rs2` into `rd[31:16]`
21    Pack { rd: Reg, rs1: Reg, rs2: Reg },
22    /// Pack low 8 bits of `rs1` into `rd[7:0]`, low 8 bits of `rs2` into `rd[15:8]`
23    Packh { rd: Reg, rs1: Reg, rs2: Reg },
24    /// Reverse bits in each byte of `rs1`
25    Brev8 { rd: Reg, rs1: Reg },
26    /// Bit-interleave: scatter lower-half bits of `rs1` to even positions, upper-half bits to odd
27    /// positions
28    Zip { rd: Reg, rs1: Reg },
29    /// Inverse of zip: gather even-position bits of `rs1` to lower half, odd-position bits to upper
30    /// half
31    Unzip { rd: Reg, rs1: Reg },
32}
33
34#[instruction]
35impl<Reg> const Instruction for Rv32ZbkbInstruction<Reg>
36where
37    Reg: [const] Register<Type = u32>,
38{
39    type Reg = Reg;
40
41    #[inline(always)]
42    fn try_decode(instruction: u32) -> Option<Self> {
43        let opcode = (instruction & 0b111_1111) as u8;
44        let rd_bits = ((instruction >> 7) & 0x1f) as u8;
45        let funct3 = ((instruction >> 12) & 0b111) as u8;
46        let rs1_bits = ((instruction >> 15) & 0x1f) as u8;
47        let rs2_bits = ((instruction >> 20) & 0x1f) as u8;
48        let funct7 = ((instruction >> 25) & 0b111_1111) as u8;
49        let funct12 = ((instruction >> 20) & 0xfff) as u16;
50
51        match opcode {
52            // OP-IMM (I-type): brev8, zip, unzip
53            0b0010011 => {
54                let rd = Reg::from_bits(rd_bits)?;
55                let rs1 = Reg::from_bits(rs1_bits)?;
56                match funct3 {
57                    // brev8: funct12 = 0b011010000111 = 0x687
58                    0b101 if funct12 == 0b0110_1000_0111 => Some(Self::Brev8 { rd, rs1 }),
59                    // zip:   funct7=0000100, rs2=01111, funct3=001 -> funct12=0x08F
60                    0b001 if funct12 == 0b0000_1000_1111 => Some(Self::Zip { rd, rs1 }),
61                    // unzip: funct7=0000100, rs2=01111, funct3=101 -> funct12=0x08F
62                    0b101 if funct12 == 0b0000_1000_1111 => Some(Self::Unzip { rd, rs1 }),
63                    _ => None,
64                }
65            }
66            // OP (R-type): pack, packh
67            0b0110011 => {
68                let rd = Reg::from_bits(rd_bits)?;
69                let rs1 = Reg::from_bits(rs1_bits)?;
70                let rs2 = Reg::from_bits(rs2_bits)?;
71                match (funct3, funct7, rs2_bits) {
72                    // pack: funct3=100, funct7=0000100, rs2!=0
73                    // rs2=0 collides with inherited RV32 Zbb zext.h and must fall through.
74                    (0b100, 0b0000100, rs2_bits) if rs2_bits != 0 => {
75                        Some(Self::Pack { rd, rs1, rs2 })
76                    }
77                    // packh: funct3=111, funct7=0000100
78                    (0b111, 0b0000100, _) => Some(Self::Packh { rd, rs1, rs2 }),
79                    _ => None,
80                }
81            }
82            _ => None,
83        }
84    }
85
86    #[inline(always)]
87    fn alignment() -> u8 {
88        align_of::<u32>() as u8
89    }
90
91    #[inline(always)]
92    fn size(&self) -> u8 {
93        size_of::<u32>() as u8
94    }
95}
96
97#[instruction]
98impl<Reg> fmt::Display for Rv32ZbkbInstruction<Reg>
99where
100    Reg: fmt::Display + Copy,
101{
102    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
103        match self {
104            Self::Pack { rd, rs1, rs2 } => write!(f, "pack {}, {}, {}", rd, rs1, rs2),
105            Self::Packh { rd, rs1, rs2 } => write!(f, "packh {}, {}, {}", rd, rs1, rs2),
106            Self::Brev8 { rd, rs1 } => write!(f, "brev8 {}, {}", rd, rs1),
107            Self::Zip { rd, rs1 } => write!(f, "zip {}, {}", rd, rs1),
108            Self::Unzip { rd, rs1 } => write!(f, "unzip {}, {}", rd, rs1),
109        }
110    }
111}
ab_riscv_primitives/instructions/rv32/zk/zbkb.rs

ab_riscv_primitives/instructions/rv32/zk/
zbkb.rs
