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
   7 @unique
   8 class Function(Enum):
   9     ALU = 0
  10     LDST = 1
  11
  12
  13 @unique
  14 class InternalOp(Enum):
  15     OP_ADD = 0
  16     OP_AND = 1
  17     OP_B = 2
  18     OP_BC = 3
  19     OP_CMP = 4
  20     OP_LOAD = 5
  21     OP_MUL_L64 = 6
  22     OP_OR = 7
  23     OP_RLC = 8
  24     OP_STORE = 9
  25     OP_TDI = 10
  26     OP_XOR = 11
  27
  28
  29 def get_csv(name):
  30     file_dir = os.path.dirname(os.path.realpath(__file__))
  31     with open(os.path.join(file_dir, name)) as csvfile:
  32         reader = csv.DictReader(csvfile)
  33         return list(reader)
  34
  35
  36 major_opcodes = get_csv("major.csv")
  37
  38
  39 class PowerMajorDecoder(Elaboratable):
  40     def __init__(self):
  41         self.opcode_in = Signal(6, reset_less=True)
  42
  43         self.function_unit = Signal(Function, reset_less=True)
  44         self.internal_op = Signal(InternalOp, reset_less=True)
  45
  46     def elaborate(self, platform):
  47         m = Module()
  48         comb = m.d.comb
  49
  50         with m.Switch(self.opcode_in):
  51             for row in major_opcodes:
  52                 opcode = int(row['opcode'])
  53                 with m.Case(opcode):
  54                     comb += self.function_unit.eq(Function[row['unit']])
  55                     comb += self.internal_op.eq(InternalOp[row['internal op']])
  56         return m
  57
  58     def ports(self):
  59         return [self.opcode_in,
  60                 self.function_unit,
  61                 self.internal_op]