-"""Cascading Power ISA Decoder
+# moved to openpower-isa
+# https://git.libre-soc.org/?p=openpower-isa.git;a=summary
+# wildcard imports here ONLY to support migration
-This module uses CSV tables in a hierarchical/peer cascading fashion,
-to create a multi-level instruction decoder by recognising appropriate
-patterns. The output is a wide, flattened (1-level) series of bitfields,
-suitable for a simple RISC engine.
-
-This is based on Anton Blanchard's excellent microwatt work:
-https://github.com/antonblanchard/microwatt/blob/master/decode1.vhdl
-
-The basic principle is that the python code does the heavy lifting
-(reading the CSV files, constructing the hierarchy), creating the HDL
-AST with for-loops generating switch-case statements.
-
-Where "normal" HDL would do this, in laborious excruciating detail:
-
- switch (opcode & major_mask_bits):
- case opcode_2: decode_opcode_2()
- case opcode_19:
- switch (opcode & minor_19_mask_bits)
- case minor_opcode_19_operation_X:
- case minor_opcode_19_operation_y:
-
-we take *full* advantage of the decoupling between python and the
-nmigen AST data structure, to do this:
-
- with m.Switch(opcode & self.mask):
- for case_bitmask in subcases:
- with m.If(opcode & case_bitmask): {do_something}
-
-this includes specifying the information sufficient to perform subdecoding.
-
-create_pdecode()
-
- the full hierarchical tree for decoding POWER9 is specified here
-
-PowerDecoder
-
- takes a *list* of CSV files with an associated bit-range that it
- is requested to match against the "opcode" row of the CSV file.
- This pattern can be either an integer, a binary number, *or* a
- wildcard nmigen Case pattern of the form "001--1-100".
-
-Subdecoders
-
- these are *additional* cases with further decoding. The "pattern"
- argument is specified as one of the Case statements (a peer of the
- opcode row in the CSV file), and thus further fields of the opcode
- may be decoded giving increasing levels of detail.
-
-Top Level:
-
- [ (extra.csv: bit-fields entire 32-bit range
- opcode -> matches
- 000000---------------01000000000 -> ILLEGAL instruction
- 01100000000000000000000000000000 -> SIM_CONFIG instruction
- ................................ ->
- ),
- (major.csv: first 6 bits ONLY
- opcode -> matches
- 001100 -> ALU,OP_ADD (add)
- 001101 -> ALU,OP_ADD (another type of add)
- ...... -> ...
- ...... -> ...
- subdecoders:
- 001011 this must match *MAJOR*.CSV
- [ (minor_19.csv: bits 21 through 30 inclusive:
- opcode -> matches
- 0b0000000000 -> ALU,OP_MCRF
- ............ -> ....
- ),
- (minor_19_00000.csv: bits 21 through 25 inclusive:
- opcode -> matches
- 0b00010 -> ALU,add_pcis
- )
- ]
- ),
- ]
-
-"""
-
-from collections import namedtuple
-from nmigen import Module, Elaboratable, Signal, Cat, Mux
-from nmigen.cli import rtlil
-from soc.decoder.power_enums import (Function, Form, InternalOp,
- In1Sel, In2Sel, In3Sel, OutSel, RC, LdstLen,
- CryIn, get_csv, single_bit_flags,
- get_signal_name, default_values)
-from soc.decoder.power_fields import DecodeFields
-from soc.decoder.power_fieldsn import SigDecode, SignalBitRange
-
-
-# key data structure in which the POWER decoder is specified,
-# in a hierarchical fashion
-Subdecoder = namedtuple("Subdecoder",
- ["pattern", # the major pattern to search for (e.g. major opcode)
- "opcodes", # a dictionary of minor patterns to find
- "opint", # true => the pattern must not be in "10----11" format
- "bitsel", # the bits (as a range) against which "pattern" matches
- "suffix", # shift the opcode down before decoding
- "subdecoders" # list of further subdecoders for *additional* matches,
- # *ONLY* after "pattern" has *ALSO* been matched against.
- ])
-
-
-class PowerOp:
- """PowerOp: spec for execution. op type (ADD etc.) reg specs etc.
- """
-
- def __init__(self):
- self.function_unit = Signal(Function, reset_less=True)
- self.internal_op = Signal(InternalOp, reset_less=True)
- self.form = Signal(Form, reset_less=True)
- self.in1_sel = Signal(In1Sel, reset_less=True)
- self.in2_sel = Signal(In2Sel, reset_less=True)
- self.in3_sel = Signal(In3Sel, reset_less=True)
- self.out_sel = Signal(OutSel, reset_less=True)
- self.ldst_len = Signal(LdstLen, reset_less=True)
- self.rc_sel = Signal(RC, reset_less=True)
- self.cry_in = Signal(CryIn, reset_less=True)
- for bit in single_bit_flags:
- name = get_signal_name(bit)
- setattr(self, name, Signal(reset_less=True, name=name))
-
- def _eq(self, row=None):
- if row is None:
- row = default_values
- res = [self.function_unit.eq(Function[row['unit']]),
- self.form.eq(Form[row['form']]),
- self.internal_op.eq(InternalOp[row['internal op']]),
- self.in1_sel.eq(In1Sel[row['in1']]),
- self.in2_sel.eq(In2Sel[row['in2']]),
- self.in3_sel.eq(In3Sel[row['in3']]),
- self.out_sel.eq(OutSel[row['out']]),
- self.ldst_len.eq(LdstLen[row['ldst len']]),
- self.rc_sel.eq(RC[row['rc']]),
- self.cry_in.eq(CryIn[row['cry in']]),
- ]
- for bit in single_bit_flags:
- sig = getattr(self, get_signal_name(bit))
- res.append(sig.eq(int(row.get(bit, 0))))
- return res
-
- def eq(self, otherop):
- res = [self.function_unit.eq(otherop.function_unit),
- self.form.eq(otherop.form),
- self.internal_op.eq(otherop.internal_op),
- self.in1_sel.eq(otherop.in1_sel),
- self.in2_sel.eq(otherop.in2_sel),
- self.in3_sel.eq(otherop.in3_sel),
- self.out_sel.eq(otherop.out_sel),
- self.rc_sel.eq(otherop.rc_sel),
- self.ldst_len.eq(otherop.ldst_len),
- self.cry_in.eq(otherop.cry_in)]
- for bit in single_bit_flags:
- sig = getattr(self, get_signal_name(bit))
- res.append(sig.eq(getattr(otherop, get_signal_name(bit))))
- return res
-
- def ports(self):
- regular = [self.function_unit,
- self.in1_sel,
- self.in2_sel,
- self.in3_sel,
- self.out_sel,
- self.ldst_len,
- self.rc_sel,
- self.internal_op,
- self.form]
- single_bit_ports = [getattr(self, get_signal_name(x))
- for x in single_bit_flags]
- return regular + single_bit_ports
-
-
-class PowerDecoder(Elaboratable):
- """PowerDecoder - decodes an incoming opcode into the type of operation
- """
-
- def __init__(self, width, dec):
- if not isinstance(dec, list):
- dec = [dec]
- self.dec = dec
- self.opcode_in = Signal(width, reset_less=True)
-
- self.op = PowerOp()
- for d in dec:
- if d.suffix is not None and d.suffix >= width:
- d.suffix = None
- self.width = width
-
- def suffix_mask(self, d):
- return ((1 << d.suffix) - 1)
-
- def divide_opcodes(self, d):
- divided = {}
- mask = self.suffix_mask(d)
- print("mask", hex(mask))
- for row in d.opcodes:
- opcode = row['opcode']
- if d.opint and '-' not in opcode:
- opcode = int(opcode, 0)
- key = opcode & mask
- opcode = opcode >> d.suffix
- if key not in divided:
- divided[key] = []
- r = row.copy()
- r['opcode'] = opcode
- divided[key].append(r)
- return divided
-
- def elaborate(self, platform):
- m = Module()
- comb = m.d.comb
-
- # note: default opcode is "illegal" as this is a combinatorial block
- # this only works because OP_ILLEGAL=0 and the default (unset) is 0
-
- # go through the list of CSV decoders first
- for d in self.dec:
- opcode_switch = Signal(d.bitsel[1] - d.bitsel[0],
- reset_less=True)
- comb += opcode_switch.eq(self.opcode_in[d.bitsel[0]:d.bitsel[1]])
- if d.suffix:
- opcodes = self.divide_opcodes(d)
- opc_in = Signal(d.suffix, reset_less=True)
- comb += opc_in.eq(opcode_switch[:d.suffix])
- # begin the dynamic Switch statement here
- with m.Switch(opc_in):
- for key, row in opcodes.items():
- bitsel = (d.suffix+d.bitsel[0], d.bitsel[1])
- sd = Subdecoder(pattern=None, opcodes=row,
- bitsel=bitsel, suffix=None,
- opint=False, subdecoders=[])
- subdecoder = PowerDecoder(width=32, dec=sd)
- setattr(m.submodules, "dec_sub%d" % key, subdecoder)
- comb += subdecoder.opcode_in.eq(self.opcode_in)
- # add in the dynamic Case statement here
- with m.Case(key):
- comb += self.op.eq(subdecoder.op)
- else:
- # TODO: arguments, here (all of them) need to be a list.
- # a for-loop around the *list* of decoder args.
- with m.Switch(opcode_switch):
- self.handle_subdecoders(m, d)
- for row in d.opcodes:
- opcode = row['opcode']
- if d.opint and '-' not in opcode:
- opcode = int(opcode, 0)
- if not row['unit']:
- continue
- # add in the dynamic Case statement here
- with m.Case(opcode):
- comb += self.op._eq(row)
- return m
-
- def handle_subdecoders(self, m, d):
- for dec in d.subdecoders:
- subdecoder = PowerDecoder(self.width, dec)
- if isinstance(dec, list): # XXX HACK: take first pattern
- dec = dec[0]
- setattr(m.submodules, "dec%d" % dec.pattern, subdecoder)
- m.d.comb += subdecoder.opcode_in.eq(self.opcode_in)
- with m.Case(dec.pattern):
- m.d.comb += self.op.eq(subdecoder.op)
-
- def ports(self):
- return [self.opcode_in] + self.op.ports()
-
-
-class TopPowerDecoder(PowerDecoder):
- """TopPowerDecoder
-
- top-level hierarchical decoder for POWER ISA
- bigendian dynamically switches between big and little endian decoding
- (reverses byte order). See V3.0B p44 1.11.2
- """
-
- def __init__(self, width, dec):
- PowerDecoder.__init__(self, width, dec)
- self.fields = df = DecodeFields(SignalBitRange, [self.opcode_in])
- self.fields.create_specs()
- self.raw_opcode_in = Signal.like(self.opcode_in, reset_less=True)
- self.bigendian = Signal(reset_less=True)
-
- for name, value in self.fields.common_fields.items():
- sig = Signal(value[0:-1].shape(), reset_less=True, name=name)
- setattr(self, name, sig)
-
- # create signals for all field forms
- self.form_names = forms = self.fields.instrs.keys()
- self.sigforms = {}
- for form in forms:
- fields = self.fields.instrs[form]
- fk = fields.keys()
- Fields = namedtuple("Fields", fk)
- sf = {}
- for k, value in fields.items():
- name = "%s_%s" % (form, k)
- sig = Signal(value[0:-1].shape(), reset_less=True, name=name)
- sf[k] = sig
- instr = Fields(**sf)
- setattr(self, "Form%s" % form, instr)
- self.sigforms[form] = instr
-
- def elaborate(self, platform):
- m = PowerDecoder.elaborate(self, platform)
- comb = m.d.comb
- raw_be = self.raw_opcode_in
- l = []
- for i in range(0, self.width, 8):
- l.append(raw_be[i:i+8])
- l.reverse()
- raw_le = Cat(*l)
- comb += self.opcode_in.eq(Mux(self.bigendian, raw_be, raw_le))
-
- # add all signal from commonly-used fields
- for name, value in self.fields.common_fields.items():
- sig = getattr(self, name)
- comb += sig.eq(value[0:-1])
-
- # link signals for all field forms
- forms = self.form_names
- for form in forms:
- sf = self.sigforms[form]
- fields = self.fields.instrs[form]
- for k, value in fields.items():
- sig = getattr(sf, k)
- comb += sig.eq(value[0:-1])
-
- return m
-
- def ports(self):
- return [self.raw_opcode_in, self.bigendian] + PowerDecoder.ports(self)
-
-
-####################################################
-# PRIMARY FUNCTION SPECIFYING THE FULL POWER DECODER
-
-def create_pdecode():
- """create_pdecode - creates a cascading hierarchical POWER ISA decoder
- """
-
- # minor 19 has extra patterns
- m19 = []
- m19.append(Subdecoder(pattern=19, opcodes=get_csv("minor_19.csv"),
- opint=True, bitsel=(1, 11), suffix=None, subdecoders=[]))
- m19.append(Subdecoder(pattern=19, opcodes=get_csv("minor_19_00000.csv"),
- opint=True, bitsel=(1, 6), suffix=None, subdecoders=[]))
-
- # minor opcodes.
- pminor = [
- m19,
- Subdecoder(pattern=30, opcodes=get_csv("minor_30.csv"),
- opint=True, bitsel=(1, 6), suffix=None, subdecoders=[]),
- Subdecoder(pattern=31, opcodes=get_csv("minor_31.csv"),
- opint=True, bitsel=(1, 11), suffix=0b00101, subdecoders=[]),
- Subdecoder(pattern=58, opcodes=get_csv("minor_58.csv"),
- opint=True, bitsel=(0, 2), suffix=None, subdecoders=[]),
- Subdecoder(pattern=62, opcodes=get_csv("minor_62.csv"),
- opint=True, bitsel=(0, 2), suffix=None, subdecoders=[]),
- ]
-
- # top level: extra merged with major
- dec = []
- opcodes = get_csv("major.csv")
- dec.append(Subdecoder(pattern=None, opint=True, opcodes=opcodes,
- bitsel=(26, 32), suffix=None, subdecoders=pminor))
- opcodes = get_csv("extra.csv")
- dec.append(Subdecoder(pattern=None, opint=False, opcodes=opcodes,
- bitsel=(0, 32), suffix=None, subdecoders=[]))
-
- return TopPowerDecoder(32, dec)
-
-
-if __name__ == '__main__':
- pdecode = create_pdecode()
- vl = rtlil.convert(pdecode, ports=pdecode.ports())
- with open("decoder.il", "w") as f:
- f.write(vl)
+from openpower.decoder.power_decoder import *
projects / soc.git / blobdiff