Decoding
Decoding of instructions.
Instructions are encoded as specified in [ISA] and [ISAP].
We define an executable decoder that maps the encodings of instructions
to the corresponding instruction fixtypes
defined in instructions.
Currently we only cover the decoding of
the instructions defined in instructions;
this is for both RV32I and RV64I.
We only handle the normal encodings,
i.e. not the compressed ones in the C extension [ISA:26];
thus, our decoder operates on 32-bit encodings.
Subtopics
- Decode
- Decode an instruction.
- Decode-rtype
- Retrieve the non-opcode fields of an R-type instruction
[ISA:2.2] [ISA:2.3].
- Decode-stype
- Retrieve the non-opcode fields of an S-type instruction
[ISA:2.2] [ISA:2.3].
- Decode-itype
- Retrieve the non-opcode fields of an I-type instruction
[ISA:2.2] [ISA:2.3].
- Decode-btype
- Retrieve the non-opcode fields of a B-type instruction
[ISA:2.3].
- Get-imm-jtype
- Retrieve the immediate field of a J-type instruction.
- Get-imm-btype
- Retrieve the immediate field of a B-type instruction.
- Get-imm-utype
- Retrieve the immediate field of a U-type instruction.
- Get-imm-stype
- Retrieve the immediate field of an S-type instruction.
- Get-imm-itype
- Retrieve the immediate field of an I-type instruction.
- Decode-utype
- Retrieve the non-opcode fields of a U-type instruction
[ISA:2.2] [ISA:2.3].
- Decode-jtype
- Retrieve the non-opcode fields of a J-type instruction
[ISA:2.3].
- Get-rs2
- Retrieve the rs2 field of an instruction.
- Get-rs1
- Retrieve the rs1 field of an instruction.
- Get-rd
- Retrieve the rd field of an instruction.
- Get-opcode
- Retrieve the opcode field of an instruction.
- Get-funct7
- Retrieve the funct7 field of an instruction.
- Get-funct3
- Retrieve the funct3 field of an instruction.
