src/soc/decoder/isa/caller.py

   1 """core of the python-based POWER9 simulator
   2
   3 this is part of a cycle-accurate POWER9 simulator.  its primary purpose is
   4 not speed, it is for both learning and educational purposes, as well as
   5 a method of verifying the HDL.
   6
   7 related bugs:
   8
   9 * https://bugs.libre-soc.org/show_bug.cgi?id=424
  10 """
  11
  12 from functools import wraps
  13 from copy import copy
  14 from soc.decoder.orderedset import OrderedSet
  15 from soc.decoder.selectable_int import (FieldSelectableInt, SelectableInt,
  16                                         selectconcat)
  17 from soc.decoder.power_enums import (spr_dict, spr_byname, XER_bits,
  18                                      insns, MicrOp)
  19 from soc.decoder.helpers import exts, gtu, ltu
  20 from soc.consts import PIb, MSRb  # big-endian (PowerISA versions)
  21
  22 from collections import namedtuple
  23 import math
  24 import sys
  25
  26 instruction_info = namedtuple('instruction_info',
  27                               'func read_regs uninit_regs write_regs ' +
  28                               'special_regs op_fields form asmregs')
  29
  30 special_sprs = {
  31     'LR': 8,
  32     'CTR': 9,
  33     'TAR': 815,
  34     'XER': 1,
  35     'VRSAVE': 256}
  36
  37
  38 def swap_order(x, nbytes):
  39     x = x.to_bytes(nbytes, byteorder='little')
  40     x = int.from_bytes(x, byteorder='big', signed=False)
  41     return x
  42
  43
  44 def create_args(reglist, extra=None):
  45     args = OrderedSet()
  46     for reg in reglist:
  47         args.add(reg)
  48     args = list(args)
  49     if extra:
  50         args = [extra] + args
  51     return args
  52
  53
  54 class Mem:
  55
  56     def __init__(self, row_bytes=8, initial_mem=None):
  57         self.mem = {}
  58         self.bytes_per_word = row_bytes
  59         self.word_log2 = math.ceil(math.log2(row_bytes))
  60         print("Sim-Mem", initial_mem, self.bytes_per_word, self.word_log2)
  61         if not initial_mem:
  62             return
  63
  64         # different types of memory data structures recognised (for convenience)
  65         if isinstance(initial_mem, list):
  66             initial_mem = (0, initial_mem)
  67         if isinstance(initial_mem, tuple):
  68             startaddr, mem = initial_mem
  69             initial_mem = {}
  70             for i, val in enumerate(mem):
  71                 initial_mem[startaddr + row_bytes*i] = (val, row_bytes)
  72
  73         for addr, (val, width) in initial_mem.items():
  74             #val = swap_order(val, width)
  75             self.st(addr, val, width, swap=False)
  76
  77     def _get_shifter_mask(self, wid, remainder):
  78         shifter = ((self.bytes_per_word - wid) - remainder) * \
  79             8  # bits per byte
  80         # XXX https://bugs.libre-soc.org/show_bug.cgi?id=377
  81         # BE/LE mode?
  82         shifter = remainder * 8
  83         mask = (1 << (wid * 8)) - 1
  84         print("width,rem,shift,mask", wid, remainder, hex(shifter), hex(mask))
  85         return shifter, mask
  86
  87     # TODO: Implement ld/st of lesser width
  88     def ld(self, address, width=8, swap=True, check_in_mem=False):
  89         print("ld from addr 0x{:x} width {:d}".format(address, width))
  90         remainder = address & (self.bytes_per_word - 1)
  91         address = address >> self.word_log2
  92         assert remainder & (width - 1) == 0, "Unaligned access unsupported!"
  93         if address in self.mem:
  94             val = self.mem[address]
  95         elif check_in_mem:
  96             return None
  97         else:
  98             val = 0
  99         print("mem @ 0x{:x} rem {:d} : 0x{:x}".format(address, remainder, val))
 100
 101         if width != self.bytes_per_word:
 102             shifter, mask = self._get_shifter_mask(width, remainder)
 103             print("masking", hex(val), hex(mask << shifter), shifter)
 104             val = val & (mask << shifter)
 105             val >>= shifter
 106         if swap:
 107             val = swap_order(val, width)
 108         print("Read 0x{:x} from addr 0x{:x}".format(val, address))
 109         return val
 110
 111     def st(self, addr, v, width=8, swap=True):
 112         staddr = addr
 113         remainder = addr & (self.bytes_per_word - 1)
 114         addr = addr >> self.word_log2
 115         print("Writing 0x{:x} to ST 0x{:x} "
 116               "memaddr 0x{:x}/{:x}".format(v, staddr, addr, remainder, swap))
 117         assert remainder & (width - 1) == 0, "Unaligned access unsupported!"
 118         if swap:
 119             v = swap_order(v, width)
 120         if width != self.bytes_per_word:
 121             if addr in self.mem:
 122                 val = self.mem[addr]
 123             else:
 124                 val = 0
 125             shifter, mask = self._get_shifter_mask(width, remainder)
 126             val &= ~(mask << shifter)
 127             val |= v << shifter
 128             self.mem[addr] = val
 129         else:
 130             self.mem[addr] = v
 131         print("mem @ 0x{:x}: 0x{:x}".format(addr, self.mem[addr]))
 132
 133     def __call__(self, addr, sz):
 134         val = self.ld(addr.value, sz, swap=False)
 135         print("memread", addr, sz, val)
 136         return SelectableInt(val, sz*8)
 137
 138     def memassign(self, addr, sz, val):
 139         print("memassign", addr, sz, val)
 140         self.st(addr.value, val.value, sz, swap=False)
 141
 142
 143 class GPR(dict):
 144     def __init__(self, decoder, regfile):
 145         dict.__init__(self)
 146         self.sd = decoder
 147         for i in range(32):
 148             self[i] = SelectableInt(regfile[i], 64)
 149
 150     def __call__(self, ridx):
 151         return self[ridx]
 152
 153     def set_form(self, form):
 154         self.form = form
 155
 156     def getz(self, rnum):
 157         # rnum = rnum.value # only SelectableInt allowed
 158         print("GPR getzero", rnum)
 159         if rnum == 0:
 160             return SelectableInt(0, 64)
 161         return self[rnum]
 162
 163     def _get_regnum(self, attr):
 164         getform = self.sd.sigforms[self.form]
 165         rnum = getattr(getform, attr)
 166         return rnum
 167
 168     def ___getitem__(self, attr):
 169         print("GPR getitem", attr)
 170         rnum = self._get_regnum(attr)
 171         return self.regfile[rnum]
 172
 173     def dump(self):
 174         for i in range(0, len(self), 8):
 175             s = []
 176             for j in range(8):
 177                 s.append("%08x" % self[i+j].value)
 178             s = ' '.join(s)
 179             print("reg", "%2d" % i, s)
 180
 181
 182 class PC:
 183     def __init__(self, pc_init=0):
 184         self.CIA = SelectableInt(pc_init, 64)
 185         self.NIA = self.CIA + SelectableInt(4, 64)
 186
 187     def update(self, namespace):
 188         self.CIA = namespace['NIA'].narrow(64)
 189         self.NIA = self.CIA + SelectableInt(4, 64)
 190         namespace['CIA'] = self.CIA
 191         namespace['NIA'] = self.NIA
 192
 193
 194 class SPR(dict):
 195     def __init__(self, dec2, initial_sprs={}):
 196         self.sd = dec2
 197         dict.__init__(self)
 198         for key, v in initial_sprs.items():
 199             if isinstance(key, SelectableInt):
 200                 key = key.value
 201             key = special_sprs.get(key, key)
 202             if isinstance(key, int):
 203                 info = spr_dict[key]
 204             else:
 205                 info = spr_byname[key]
 206             if not isinstance(v, SelectableInt):
 207                 v = SelectableInt(v, info.length)
 208             self[key] = v
 209
 210     def __getitem__(self, key):
 211         print("get spr", key)
 212         print("dict", self.items())
 213         # if key in special_sprs get the special spr, otherwise return key
 214         if isinstance(key, SelectableInt):
 215             key = key.value
 216         if isinstance(key, int):
 217             key = spr_dict[key].SPR
 218         key = special_sprs.get(key, key)
 219         if key == 'HSRR0': # HACK!
 220             key = 'SRR0'
 221         if key == 'HSRR1': # HACK!
 222             key = 'SRR1'
 223         if key in self:
 224             res = dict.__getitem__(self, key)
 225         else:
 226             if isinstance(key, int):
 227                 info = spr_dict[key]
 228             else:
 229                 info = spr_byname[key]
 230             dict.__setitem__(self, key, SelectableInt(0, info.length))
 231             res = dict.__getitem__(self, key)
 232         print("spr returning", key, res)
 233         return res
 234
 235     def __setitem__(self, key, value):
 236         if isinstance(key, SelectableInt):
 237             key = key.value
 238         if isinstance(key, int):
 239             key = spr_dict[key].SPR
 240             print("spr key", key)
 241         key = special_sprs.get(key, key)
 242         if key == 'HSRR0': # HACK!
 243             self.__setitem__('SRR0', value)
 244         if key == 'HSRR1': # HACK!
 245             self.__setitem__('SRR1', value)
 246         print("setting spr", key, value)
 247         dict.__setitem__(self, key, value)
 248
 249     def __call__(self, ridx):
 250         return self[ridx]
 251
 252
 253 class ISACaller:
 254     # decoder2 - an instance of power_decoder2
 255     # regfile - a list of initial values for the registers
 256     # initial_{etc} - initial values for SPRs, Condition Register, Mem, MSR
 257     # respect_pc - tracks the program counter.  requires initial_insns
 258     def __init__(self, decoder2, regfile, initial_sprs=None, initial_cr=0,
 259                  initial_mem=None, initial_msr=0,
 260                  initial_insns=None, respect_pc=False,
 261                  disassembly=None,
 262                  initial_pc=0,
 263                  bigendian=False):
 264
 265         self.bigendian = bigendian
 266         self.halted = False
 267         self.respect_pc = respect_pc
 268         if initial_sprs is None:
 269             initial_sprs = {}
 270         if initial_mem is None:
 271             initial_mem = {}
 272         if initial_insns is None:
 273             initial_insns = {}
 274             assert self.respect_pc == False, "instructions required to honor pc"
 275
 276         print("ISACaller insns", respect_pc, initial_insns, disassembly)
 277         print("ISACaller initial_msr", initial_msr)
 278
 279         # "fake program counter" mode (for unit testing)
 280         self.fake_pc = 0
 281         disasm_start = 0
 282         if not respect_pc:
 283             if isinstance(initial_mem, tuple):
 284                 self.fake_pc = initial_mem[0]
 285                 disasm_start = self.fake_pc
 286         else:
 287             disasm_start = initial_pc
 288
 289         # disassembly: we need this for now (not given from the decoder)
 290         self.disassembly = {}
 291         if disassembly:
 292             for i, code in enumerate(disassembly):
 293                 self.disassembly[i*4 + disasm_start] = code
 294
 295         # set up registers, instruction memory, data memory, PC, SPRs, MSR
 296         self.gpr = GPR(decoder2, regfile)
 297         self.mem = Mem(row_bytes=8, initial_mem=initial_mem)
 298         self.imem = Mem(row_bytes=4, initial_mem=initial_insns)
 299         self.pc = PC()
 300         self.spr = SPR(decoder2, initial_sprs)
 301         self.msr = SelectableInt(initial_msr, 64)  # underlying reg
 302
 303         # TODO, needed here:
 304         # FPR (same as GPR except for FP nums)
 305         # 4.2.2 p124 FPSCR (definitely "separate" - not in SPR)
 306         #            note that mffs, mcrfs, mtfsf "manage" this FPSCR
 307         # 2.3.1 CR (and sub-fields CR0..CR6 - CR0 SO comes from XER.SO)
 308         #         note that mfocrf, mfcr, mtcr, mtocrf, mcrxrx "manage" CRs
 309         #         -- Done
 310         # 2.3.2 LR   (actually SPR #8) -- Done
 311         # 2.3.3 CTR  (actually SPR #9) -- Done
 312         # 2.3.4 TAR  (actually SPR #815)
 313         # 3.2.2 p45 XER  (actually SPR #1) -- Done
 314         # 3.2.3 p46 p232 VRSAVE (actually SPR #256)
 315
 316         # create CR then allow portions of it to be "selectable" (below)
 317         #rev_cr = int('{:016b}'.format(initial_cr)[::-1], 2)
 318         self.cr = SelectableInt(initial_cr, 64)  # underlying reg
 319         #self.cr = FieldSelectableInt(self._cr, list(range(32, 64)))
 320
 321         # "undefined", just set to variable-bit-width int (use exts "max")
 322         self.undefined = SelectableInt(0, 256)  # TODO, not hard-code 256!
 323
 324         self.namespace = {}
 325         self.namespace.update(self.spr)
 326         self.namespace.update({'GPR': self.gpr,
 327                                'MEM': self.mem,
 328                                'SPR': self.spr,
 329                                'memassign': self.memassign,
 330                                'NIA': self.pc.NIA,
 331                                'CIA': self.pc.CIA,
 332                                'CR': self.cr,
 333                                'MSR': self.msr,
 334                                'undefined': self.undefined,
 335                                'mode_is_64bit': True,
 336                                'SO': XER_bits['SO']
 337                                })
 338
 339         # update pc to requested start point
 340         self.set_pc(initial_pc)
 341
 342         # field-selectable versions of Condition Register TODO check bitranges?
 343         self.crl = []
 344         for i in range(8):
 345             bits = tuple(range(i*4+32, (i+1)*4+32))  # errr... maybe?
 346             _cr = FieldSelectableInt(self.cr, bits)
 347             self.crl.append(_cr)
 348             self.namespace["CR%d" % i] = _cr
 349
 350         self.decoder = decoder2.dec
 351         self.dec2 = decoder2
 352
 353     def TRAP(self, trap_addr=0x700, trap_bit=PIb.TRAP):
 354         print("TRAP:", hex(trap_addr), hex(self.namespace['MSR'].value))
 355         # store CIA(+4?) in SRR0, set NIA to 0x700
 356         # store MSR in SRR1, set MSR to um errr something, have to check spec
 357         self.spr['SRR0'].value = self.pc.CIA.value
 358         self.spr['SRR1'].value = self.namespace['MSR'].value
 359         self.trap_nia = SelectableInt(trap_addr, 64)
 360         self.spr['SRR1'][trap_bit] = 1  # change *copy* of MSR in SRR1
 361
 362         # set exception bits.  TODO: this should, based on the address
 363         # in figure 66 p1065 V3.0B and the table figure 65 p1063 set these
 364         # bits appropriately.  however it turns out that *for now* in all
 365         # cases (all trap_addrs) the exact same thing is needed.
 366         self.msr[MSRb.IR] = 0
 367         self.msr[MSRb.DR] = 0
 368         self.msr[MSRb.FE0] = 0
 369         self.msr[MSRb.FE1] = 0
 370         self.msr[MSRb.EE] = 0
 371         self.msr[MSRb.RI] = 0
 372         self.msr[MSRb.SF] = 1
 373         self.msr[MSRb.TM] = 0
 374         self.msr[MSRb.VEC] = 0
 375         self.msr[MSRb.VSX] = 0
 376         self.msr[MSRb.PR] = 0
 377         self.msr[MSRb.FP] = 0
 378         self.msr[MSRb.PMM] = 0
 379         self.msr[MSRb.TEs] = 0
 380         self.msr[MSRb.TEe] = 0
 381         self.msr[MSRb.UND] = 0
 382         self.msr[MSRb.LE] = 1
 383
 384     def memassign(self, ea, sz, val):
 385         self.mem.memassign(ea, sz, val)
 386
 387     def prep_namespace(self, formname, op_fields):
 388         # TODO: get field names from form in decoder*1* (not decoder2)
 389         # decoder2 is hand-created, and decoder1.sigform is auto-generated
 390         # from spec
 391         # then "yield" fields only from op_fields rather than hard-coded
 392         # list, here.
 393         fields = self.decoder.sigforms[formname]
 394         for name in op_fields:
 395             if name == 'spr':
 396                 sig = getattr(fields, name.upper())
 397             else:
 398                 sig = getattr(fields, name)
 399             val = yield sig
 400             # these are all opcode fields involved in index-selection of CR,
 401             # and need to do "standard" arithmetic.  CR[BA+32] for example
 402             # would, if using SelectableInt, only be 5-bit.
 403             if name in ['BF', 'BFA', 'BC', 'BA', 'BB', 'BT', 'BI']:
 404                 self.namespace[name] = val
 405             else:
 406                 self.namespace[name] = SelectableInt(val, sig.width)
 407
 408         self.namespace['XER'] = self.spr['XER']
 409         self.namespace['CA'] = self.spr['XER'][XER_bits['CA']].value
 410         self.namespace['CA32'] = self.spr['XER'][XER_bits['CA32']].value
 411
 412     def handle_carry_(self, inputs, outputs, already_done):
 413         inv_a = yield self.dec2.e.do.invert_in
 414         if inv_a:
 415             inputs[0] = ~inputs[0]
 416
 417         imm_ok = yield self.dec2.e.do.imm_data.ok
 418         if imm_ok:
 419             imm = yield self.dec2.e.do.imm_data.data
 420             inputs.append(SelectableInt(imm, 64))
 421         assert len(outputs) >= 1
 422         print("outputs", repr(outputs))
 423         if isinstance(outputs, list) or isinstance(outputs, tuple):
 424             output = outputs[0]
 425         else:
 426             output = outputs
 427         gts = []
 428         for x in inputs:
 429             print("gt input", x, output)
 430             gt = (gtu(x, output))
 431             gts.append(gt)
 432         print(gts)
 433         cy = 1 if any(gts) else 0
 434         print ("CA", cy, gts)
 435         if not (1 & already_done):
 436             self.spr['XER'][XER_bits['CA']] = cy
 437
 438         print("inputs", already_done, inputs)
 439         # 32 bit carry
 440         # ARGH... different for OP_ADD... *sigh*...
 441         op = yield self.dec2.e.do.insn_type
 442         if op == MicrOp.OP_ADD.value:
 443             res32 = (output.value & (1<<32)) != 0
 444             a32 = (inputs[0].value & (1<<32)) != 0
 445             if len(inputs) >= 2:
 446                 b32 = (inputs[1].value & (1<<32)) != 0
 447             else:
 448                 b32 = False
 449             cy32 = res32 ^ a32 ^ b32
 450             print ("CA32 ADD", cy32)
 451         else:
 452             gts = []
 453             for x in inputs:
 454                 print("input", x, output)
 455                 print("     x[32:64]", x, x[32:64])
 456                 print("     o[32:64]", output, output[32:64])
 457                 gt = (gtu(x[32:64], output[32:64])) == SelectableInt(1, 1)
 458                 gts.append(gt)
 459             cy32 = 1 if any(gts) else 0
 460             print ("CA32", cy32, gts)
 461         if not (2 & already_done):
 462             self.spr['XER'][XER_bits['CA32']] = cy32
 463
 464     def handle_overflow(self, inputs, outputs, div_overflow):
 465         inv_a = yield self.dec2.e.do.invert_in
 466         if inv_a:
 467             inputs[0] = ~inputs[0]
 468
 469         imm_ok = yield self.dec2.e.do.imm_data.ok
 470         if imm_ok:
 471             imm = yield self.dec2.e.do.imm_data.data
 472             inputs.append(SelectableInt(imm, 64))
 473         assert len(outputs) >= 1
 474         print("handle_overflow", inputs, outputs, div_overflow)
 475         if len(inputs) < 2 and div_overflow is None:
 476             return
 477
 478         # div overflow is different: it's returned by the pseudo-code
 479         # because it's more complex than can be done by analysing the output
 480         if div_overflow is not None:
 481             ov, ov32 = div_overflow, div_overflow
 482         # arithmetic overflow can be done by analysing the input and output
 483         elif len(inputs) >= 2:
 484             output = outputs[0]
 485
 486             # OV (64-bit)
 487             input_sgn = [exts(x.value, x.bits) < 0 for x in inputs]
 488             output_sgn = exts(output.value, output.bits) < 0
 489             ov = 1 if input_sgn[0] == input_sgn[1] and \
 490                 output_sgn != input_sgn[0] else 0
 491
 492             # OV (32-bit)
 493             input32_sgn = [exts(x.value, 32) < 0 for x in inputs]
 494             output32_sgn = exts(output.value, 32) < 0
 495             ov32 = 1 if input32_sgn[0] == input32_sgn[1] and \
 496                 output32_sgn != input32_sgn[0] else 0
 497
 498         self.spr['XER'][XER_bits['OV']] = ov
 499         self.spr['XER'][XER_bits['OV32']] = ov32
 500         so = self.spr['XER'][XER_bits['SO']]
 501         so = so | ov
 502         self.spr['XER'][XER_bits['SO']] = so
 503
 504     def handle_comparison(self, outputs):
 505         out = outputs[0]
 506         assert isinstance(out, SelectableInt), \
 507                           "out zero not a SelectableInt %s" % repr(outputs)
 508         print("handle_comparison", out.bits, hex(out.value))
 509         # TODO - XXX *processor* in 32-bit mode
 510         # https://bugs.libre-soc.org/show_bug.cgi?id=424
 511         # if is_32bit:
 512         #    o32 = exts(out.value, 32)
 513         #    print ("handle_comparison exts 32 bit", hex(o32))
 514         out = exts(out.value, out.bits)
 515         print("handle_comparison exts", hex(out))
 516         zero = SelectableInt(out == 0, 1)
 517         positive = SelectableInt(out > 0, 1)
 518         negative = SelectableInt(out < 0, 1)
 519         SO = self.spr['XER'][XER_bits['SO']]
 520         print("handle_comparison SO", SO)
 521         cr_field = selectconcat(negative, positive, zero, SO)
 522         self.crl[0].eq(cr_field)
 523
 524     def set_pc(self, pc_val):
 525         self.namespace['NIA'] = SelectableInt(pc_val, 64)
 526         self.pc.update(self.namespace)
 527
 528     def setup_one(self):
 529         """set up one instruction
 530         """
 531         if self.respect_pc:
 532             pc = self.pc.CIA.value
 533         else:
 534             pc = self.fake_pc
 535         self._pc = pc
 536         ins = self.imem.ld(pc, 4, False, True)
 537         if ins is None:
 538             raise KeyError("no instruction at 0x%x" % pc)
 539         print("setup: 0x%x 0x%x %s" % (pc, ins & 0xffffffff, bin(ins)))
 540         print("CIA NIA", self.respect_pc, self.pc.CIA.value, self.pc.NIA.value)
 541
 542         yield self.dec2.dec.raw_opcode_in.eq(ins & 0xffffffff)
 543         yield self.dec2.dec.bigendian.eq(self.bigendian)
 544         yield self.dec2.state.msr.eq(self.msr.value)
 545         yield self.dec2.state.pc.eq(pc)
 546
 547     def execute_one(self):
 548         """execute one instruction
 549         """
 550         # get the disassembly code for this instruction
 551         code = self.disassembly[self._pc]
 552         print("sim-execute", hex(self._pc), code)
 553         opname = code.split(' ')[0]
 554         yield from self.call(opname)
 555
 556         if not self.respect_pc:
 557             self.fake_pc += 4
 558         print("execute one, CIA NIA", self.pc.CIA.value, self.pc.NIA.value)
 559
 560     def get_assembly_name(self):
 561         # TODO, asmregs is from the spec, e.g. add RT,RA,RB
 562         # see http://bugs.libre-riscv.org/show_bug.cgi?id=282
 563         dec_insn = yield self.dec2.e.do.insn
 564         asmcode = yield self.dec2.dec.op.asmcode
 565         print("get assembly name asmcode", asmcode, hex(dec_insn))
 566         asmop = insns.get(asmcode, None)
 567         int_op = yield self.dec2.dec.op.internal_op
 568
 569         # sigh reconstruct the assembly instruction name
 570         ov_en = yield self.dec2.e.do.oe.oe
 571         ov_ok = yield self.dec2.e.do.oe.ok
 572         rc_en = yield self.dec2.e.do.rc.rc
 573         rc_ok = yield self.dec2.e.do.rc.ok
 574         # grrrr have to special-case MUL op (see DecodeOE)
 575         print("ov %d en %d rc %d en %d op %d" % \
 576                         (ov_ok, ov_en, rc_ok, rc_en, int_op))
 577         if int_op in [MicrOp.OP_MUL_H64.value, MicrOp.OP_MUL_H32.value]:
 578             print("mul op")
 579             if rc_en & rc_ok:
 580                 asmop += "."
 581         else:
 582             if not asmop.endswith("."): # don't add "." to "andis."
 583                 if rc_en & rc_ok:
 584                     asmop += "."
 585         if hasattr(self.dec2.e.do, "lk"):
 586             lk = yield self.dec2.e.do.lk
 587             if lk:
 588                 asmop += "l"
 589         print("int_op", int_op)
 590         if int_op in [MicrOp.OP_B.value, MicrOp.OP_BC.value]:
 591             AA = yield self.dec2.dec.fields.FormI.AA[0:-1]
 592             print("AA", AA)
 593             if AA:
 594                 asmop += "a"
 595         spr_msb = yield from self.get_spr_msb()
 596         if int_op == MicrOp.OP_MFCR.value:
 597             if spr_msb:
 598                 asmop = 'mfocrf'
 599             else:
 600                 asmop = 'mfcr'
 601         # XXX TODO: for whatever weird reason this doesn't work
 602         # https://bugs.libre-soc.org/show_bug.cgi?id=390
 603         if int_op == MicrOp.OP_MTCRF.value:
 604             if spr_msb:
 605                 asmop = 'mtocrf'
 606             else:
 607                 asmop = 'mtcrf'
 608         return asmop
 609
 610     def get_spr_msb(self):
 611         dec_insn = yield self.dec2.e.do.insn
 612         return dec_insn & (1 << 20) != 0  # sigh - XFF.spr[-1]?
 613
 614     def call(self, name):
 615         name = name.strip()  # remove spaces if not already done so
 616         if self.halted:
 617             print("halted - not executing", name)
 618             return
 619
 620         # TODO, asmregs is from the spec, e.g. add RT,RA,RB
 621         # see http://bugs.libre-riscv.org/show_bug.cgi?id=282
 622         asmop = yield from self.get_assembly_name()
 623         print("call", name, asmop)
 624
 625         # check privileged
 626         int_op = yield self.dec2.dec.op.internal_op
 627         spr_msb = yield from self.get_spr_msb()
 628
 629         instr_is_privileged = False
 630         if int_op in [MicrOp.OP_ATTN.value,
 631                       MicrOp.OP_MFMSR.value,
 632                       MicrOp.OP_MTMSR.value,
 633                       MicrOp.OP_MTMSRD.value,
 634                       # TODO: OP_TLBIE
 635                       MicrOp.OP_RFID.value]:
 636             instr_is_privileged = True
 637         if int_op in [MicrOp.OP_MFSPR.value,
 638                       MicrOp.OP_MTSPR.value] and spr_msb:
 639             instr_is_privileged = True
 640
 641         print("is priv", instr_is_privileged, hex(self.msr.value),
 642               self.msr[MSRb.PR])
 643         # check MSR priv bit and whether op is privileged: if so, throw trap
 644         if instr_is_privileged and self.msr[MSRb.PR] == 1:
 645             self.TRAP(0x700, PIb.PRIV)
 646             self.namespace['NIA'] = self.trap_nia
 647             self.pc.update(self.namespace)
 648             return
 649
 650         # check halted condition
 651         if name == 'attn':
 652             self.halted = True
 653             return
 654
 655         # check illegal instruction
 656         illegal = False
 657         if name not in ['mtcrf', 'mtocrf']:
 658             illegal = name != asmop
 659
 660         if illegal:
 661             print ("illegal", name, asmop)
 662             self.TRAP(0x700, PIb.ILLEG)
 663             self.namespace['NIA'] = self.trap_nia
 664             self.pc.update(self.namespace)
 665             print("name %s != %s - calling ILLEGAL trap, PC: %x" %
 666                   (name, asmop, self.pc.CIA.value))
 667             return
 668
 669         info = self.instrs[name]
 670         yield from self.prep_namespace(info.form, info.op_fields)
 671
 672         # preserve order of register names
 673         input_names = create_args(list(info.read_regs) +
 674                                   list(info.uninit_regs))
 675         print(input_names)
 676
 677         # main registers (RT, RA ...)
 678         inputs = []
 679         for name in input_names:
 680             regnum = yield getattr(self.decoder, name)
 681             regname = "_" + name
 682             self.namespace[regname] = regnum
 683             print('reading reg %d' % regnum)
 684             inputs.append(self.gpr(regnum))
 685
 686         # "special" registers
 687         for special in info.special_regs:
 688             if special in special_sprs:
 689                 inputs.append(self.spr[special])
 690             else:
 691                 inputs.append(self.namespace[special])
 692
 693         # clear trap (trap) NIA
 694         self.trap_nia = None
 695
 696         print(inputs)
 697         results = info.func(self, *inputs)
 698         print(results)
 699
 700         # "inject" decorator takes namespace from function locals: we need to
 701         # overwrite NIA being overwritten (sigh)
 702         if self.trap_nia is not None:
 703             self.namespace['NIA'] = self.trap_nia
 704
 705         print("after func", self.namespace['CIA'], self.namespace['NIA'])
 706
 707         # detect if CA/CA32 already in outputs (sra*, basically)
 708         already_done = 0
 709         if info.write_regs:
 710             output_names = create_args(info.write_regs)
 711             for name in output_names:
 712                 if name == 'CA':
 713                     already_done |= 1
 714                 if name == 'CA32':
 715                     already_done |= 2
 716
 717         print("carry already done?", bin(already_done))
 718         carry_en = yield self.dec2.e.do.output_carry
 719         if carry_en:
 720             yield from self.handle_carry_(inputs, results, already_done)
 721
 722         # detect if overflow was in return result
 723         overflow = None
 724         if info.write_regs:
 725             for name, output in zip(output_names, results):
 726                 if name == 'overflow':
 727                     overflow = output
 728
 729         ov_en = yield self.dec2.e.do.oe.oe
 730         ov_ok = yield self.dec2.e.do.oe.ok
 731         print("internal overflow", overflow, ov_en, ov_ok)
 732         if ov_en & ov_ok:
 733             yield from self.handle_overflow(inputs, results, overflow)
 734
 735         rc_en = yield self.dec2.e.do.rc.rc
 736         if rc_en:
 737             self.handle_comparison(results)
 738
 739         # any modified return results?
 740         if info.write_regs:
 741             for name, output in zip(output_names, results):
 742                 if name == 'overflow':  # ignore, done already (above)
 743                     continue
 744                 if isinstance(output, int):
 745                     output = SelectableInt(output, 256)
 746                 if name in ['CA', 'CA32']:
 747                     if carry_en:
 748                         print("writing %s to XER" % name, output)
 749                         self.spr['XER'][XER_bits[name]] = output.value
 750                     else:
 751                         print("NOT writing %s to XER" % name, output)
 752                 elif name in info.special_regs:
 753                     print('writing special %s' % name, output, special_sprs)
 754                     if name in special_sprs:
 755                         self.spr[name] = output
 756                     else:
 757                         self.namespace[name].eq(output)
 758                     if name == 'MSR':
 759                         print('msr written', hex(self.msr.value))
 760                 else:
 761                     regnum = yield getattr(self.decoder, name)
 762                     print('writing reg %d %s' % (regnum, str(output)))
 763                     if output.bits > 64:
 764                         output = SelectableInt(output.value, 64)
 765                     self.gpr[regnum] = output
 766
 767         print("end of call", self.namespace['CIA'], self.namespace['NIA'])
 768         # UPDATE program counter
 769         self.pc.update(self.namespace)
 770
 771
 772 def inject():
 773     """Decorator factory.
 774
 775     this decorator will "inject" variables into the function's namespace,
 776     from the *dictionary* in self.namespace.  it therefore becomes possible
 777     to make it look like a whole stack of variables which would otherwise
 778     need "self." inserted in front of them (*and* for those variables to be
 779     added to the instance) "appear" in the function.
 780
 781     "self.namespace['SI']" for example becomes accessible as just "SI" but
 782     *only* inside the function, when decorated.
 783     """
 784     def variable_injector(func):
 785         @wraps(func)
 786         def decorator(*args, **kwargs):
 787             try:
 788                 func_globals = func.__globals__  # Python 2.6+
 789             except AttributeError:
 790                 func_globals = func.func_globals  # Earlier versions.
 791
 792             context = args[0].namespace  # variables to be injected
 793             saved_values = func_globals.copy()  # Shallow copy of dict.
 794             func_globals.update(context)
 795             result = func(*args, **kwargs)
 796             print("globals after", func_globals['CIA'], func_globals['NIA'])
 797             print("args[0]", args[0].namespace['CIA'],
 798                   args[0].namespace['NIA'])
 799             args[0].namespace = func_globals
 800             #exec (func.__code__, func_globals)
 801
 802             # finally:
 803             #    func_globals = saved_values  # Undo changes.
 804
 805             return result
 806
 807         return decorator
 808
 809     return variable_injector