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 @unique
  30 class In1Sel(Enum):
  31     RA = 0
  32     RA_OR_ZERO = 1
  33     NONE = 2
  34     SPR = 3
  35
  36
  37 @unique
  38 class In2Sel(Enum):
  39     CONST_SI = 0
  40     CONST_SI_HI = 1
  41     CONST_UI = 2
  42     CONST_UI_HI = 3
  43     CONST_LI = 4
  44     CONST_BD = 5
  45     CONST_SH32 = 6
  46     RB = 7
  47
  48
  49 @unique
  50 class In3Sel(Enum):
  51     NONE = 0
  52     RS = 1
  53
  54
  55 @unique
  56 class OutSel(Enum):
  57     RT = 0
  58     RA = 1
  59     NONE = 2
  60     SPR = 3
  61
  62
  63
  64 def get_csv(name):
  65     file_dir = os.path.dirname(os.path.realpath(__file__))
  66     with open(os.path.join(file_dir, name)) as csvfile:
  67         reader = csv.DictReader(csvfile)
  68         return list(reader)
  69
  70
  71 major_opcodes = get_csv("major.csv")
  72
  73
  74 class PowerMajorDecoder(Elaboratable):
  75     def __init__(self):
  76         self.opcode_in = Signal(6, reset_less=True)
  77
  78         self.function_unit = Signal(Function, reset_less=True)
  79         self.internal_op = Signal(InternalOp, reset_less=True)
  80         self.in1_sel = Signal(In1Sel, reset_less=True)
  81         self.in2_sel = Signal(In2Sel, reset_less=True)
  82         self.in3_sel = Signal(In3Sel, reset_less=True)
  83         self.out_sel = Signal(OutSel, reset_less=True)
  84
  85     def elaborate(self, platform):
  86         m = Module()
  87         comb = m.d.comb
  88
  89         with m.Switch(self.opcode_in):
  90             for row in major_opcodes:
  91                 opcode = int(row['opcode'])
  92                 with m.Case(opcode):
  93                     comb += self.function_unit.eq(Function[row['unit']])
  94                     comb += self.internal_op.eq(InternalOp[row['internal op']])
  95                     comb += self.in1_sel.eq(In1Sel[row['in1']])
  96                     comb += self.in2_sel.eq(In2Sel[row['in2']])
  97                     comb += self.in3_sel.eq(In3Sel[row['in3']])
  98                     comb += self.out_sel.eq(OutSel[row['out']])
  99         return m
 100
 101     def ports(self):
 102         return [self.opcode_in,
 103                 self.function_unit,
 104                 self.in1_sel,
 105                 self.in2_sel,
 106                 self.in3_sel,
 107                 self.out_sel,
 108                 self.internal_op]