{-# LANGUAGE DataKinds #-}
{-# LANGUAGE NumericUnderscores #-}

module Isa.Forms(
  FUNCT7, RS2, RS1, FUNCT3, RD, OPCODE,
  IMM12, IMM13, IMM20, IMM21,

  RTypeFields(..), ITypeFields(..), STypeFields(..),
  BTypeFields(..), UTypeFields(..), JTypeFields(..),

  Opcode(..)
) where
import Clash.Prelude
import Types(Mem, Addr, Insn)

type FUNCT7 = Unsigned 7
type RS2    = Unsigned 5
type RS1    = Unsigned 5
type FUNCT3 = Unsigned 3
type RD     = Unsigned 5
type OPCODE = Unsigned 7

type IMM12  = Unsigned 12
type IMM13  = Unsigned 13
type IMM20  = Unsigned 20
type IMM21  = Unsigned 21

data RTypeFields = RTypeFields OPCODE RD FUNCT3 RS1 RS2 FUNCT7 deriving (Generic, Show, Eq, NFDataX)
data ITypeFields = ITypeFields OPCODE RD FUNCT3 RS1 IMM12 deriving (Generic, Show, Eq, NFDataX)
data STypeFields = STypeFields OPCODE FUNCT3 RS1 RS2 IMM12 deriving (Generic, Show, Eq, NFDataX)
data BTypeFields = BTypeFields OPCODE FUNCT3 RS1 RS2 IMM13 deriving (Generic, Show, Eq, NFDataX)
data UTypeFields = UTypeFields OPCODE RD IMM20 deriving (Generic, Show, Eq, NFDataX)
data JTypeFields = JTypeFields OPCODE RD IMM21 deriving (Generic, Show, Eq, NFDataX)

data Opcode
  =
  -- R-Type
    ADD   RTypeFields
  | SUB   RTypeFields
  | XOR   RTypeFields
  | OR    RTypeFields
  | AND   RTypeFields
  | SLL   RTypeFields
  | SRL   RTypeFields
  | SRA   RTypeFields
  | SLT   RTypeFields
  | SLTU  RTypeFields

  -- I-Type
  | ADDI  ITypeFields
  | XORI  ITypeFields
  | ORI   ITypeFields
  | ANDI  ITypeFields
  | SLLI  ITypeFields
  | SRLI  ITypeFields
  | SRAI  ITypeFields
  | SLTI  ITypeFields
  | SLTIU ITypeFields
  | LB    ITypeFields
  | LH    ITypeFields
  | LW    ITypeFields
  | LBU   ITypeFields
  | LHU   ITypeFields
  | ECALL ITypeFields
  | EBREAK ITypeFields

  -- S-Type
  | SB    STypeFields
  | SH    STypeFields
  | SW    STypeFields

  -- B-Type
  | BEQ   BTypeFields
  | BNE   BTypeFields
  | BLT   BTypeFields
  | BGE   BTypeFields
  | BLTU  BTypeFields
  | BGEU  BTypeFields

  -- J-Type
  | JAL   JTypeFields
  | JALR  ITypeFields

  -- U-Type
  | LUI   UTypeFields
  | AUIPC UTypeFields

  | Unimplemented
  deriving (Generic, Show, Eq, NFDataX)