src/decoder/power_major_decoder.py

   1 from nmigen import Module, Elaboratable, Signal
   2 import csv
   3 import os
   4 from enum import Enum, unique
   5
   6 @unique
   7 class Function(Enum):
   8     ALU = 0
   9     LDST = 1
  10
  11 @unique
  12 class InternalOp(Enum):
  13     OP_ADD = 0
  14     OP_AND = 1
  15     OP_B = 2
  16     OP_BC = 3
  17     OP_CMP = 4
  18     OP_LOAD = 5
  19     OP_MUL_L64 = 6
  20     OP_OR = 7
  21     OP_RLC = 8
  22     OP_STORE = 9
  23     OP_TDI = 10
  24     OP_XOR = 11
  25
  26 def get_csv(name):
  27     file_dir = os.path.dirname(os.path.realpath(__file__))
  28     with open(os.path.join(file_dir, name)) as csvfile:
  29         reader = csv.DictReader(csvfile)
  30         return list(reader)
  31
  32 major_opcodes = get_csv("major.csv")
  33
  34 class PowerMajorDecoder(Elaboratable):
  35     def __init__(self):
  36         self.opcode_in = Signal(6, reset_less=True)
  37
  38         self.function_unit = Signal(Function, reset_less=True)
  39         self.internal_op = Signal(InternalOp, reset_less=True)
  40     def elaborate(self, platform):
  41         m = Module()
  42         comb = m.d.comb
  43
  44         with m.Switch(self.opcode_in):
  45             for row in major_opcodes:
  46                 opcode = int(row['opcode'])
  47                 with m.Case(opcode):
  48                     comb += self.function_unit.eq(Function[row['unit']])
  49                     comb += self.internal_op.eq(InternalOp[row['internal op']])
  50         return m
  51
  52
  53
  54