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
  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} memaddr 0x{:x}/{:x}".format(v,
 116                         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)
 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)
 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 class PC:
 182     def __init__(self, pc_init=0):
 183         self.CIA = SelectableInt(pc_init, 64)
 184         self.NIA = self.CIA + SelectableInt(4, 64)
 185
 186     def update(self, namespace):
 187         self.CIA = namespace['NIA'].narrow(64)
 188         self.NIA = self.CIA + SelectableInt(4, 64)
 189         namespace['CIA'] = self.CIA
 190         namespace['NIA'] = self.NIA
 191
 192
 193 class SPR(dict):
 194     def __init__(self, dec2, initial_sprs={}):
 195         self.sd = dec2
 196         dict.__init__(self)
 197         for key, v in initial_sprs.items():
 198             if isinstance(key, SelectableInt):
 199                 key = key.value
 200             key = special_sprs.get(key, key)
 201             if isinstance(key, int):
 202                 info = spr_dict[key]
 203             else:
 204                 info = spr_byname[key]
 205             if not isinstance(v, SelectableInt):
 206                 v = SelectableInt(v, info.length)
 207             self[key] = v
 208
 209     def __getitem__(self, key):
 210         print ("get spr", key)
 211         print ("dict", self.items())
 212         # if key in special_sprs get the special spr, otherwise return key
 213         if isinstance(key, SelectableInt):
 214             key = key.value
 215         if isinstance(key, int):
 216             key = spr_dict[key].SPR
 217         key = special_sprs.get(key, key)
 218         if key in self:
 219             res = dict.__getitem__(self, key)
 220         else:
 221             if isinstance(key, int):
 222                 info = spr_dict[key]
 223             else:
 224                 info = spr_byname[key]
 225             dict.__setitem__(self, key, SelectableInt(0, info.length))
 226             res = dict.__getitem__(self, key)
 227         print ("spr returning", key, res)
 228         return res
 229
 230     def __setitem__(self, key, value):
 231         if isinstance(key, SelectableInt):
 232             key = key.value
 233         if isinstance(key, int):
 234             key = spr_dict[key].SPR
 235             print ("spr key", key)
 236         key = special_sprs.get(key, key)
 237         print ("setting spr", key, value)
 238         dict.__setitem__(self, key, value)
 239
 240     def __call__(self, ridx):
 241         return self[ridx]
 242
 243
 244 class ISACaller:
 245     # decoder2 - an instance of power_decoder2
 246     # regfile - a list of initial values for the registers
 247     # initial_{etc} - initial values for SPRs, Condition Register, Mem, MSR
 248     # respect_pc - tracks the program counter.  requires initial_insns
 249     def __init__(self, decoder2, regfile, initial_sprs=None, initial_cr=0,
 250                        initial_mem=None, initial_msr=0,
 251                        initial_insns=None, respect_pc=False,
 252                        disassembly=None,
 253                        initial_pc=0,
 254                        bigendian=False):
 255
 256         self.bigendian = bigendian
 257         self.halted = False
 258         self.respect_pc = respect_pc
 259         if initial_sprs is None:
 260             initial_sprs = {}
 261         if initial_mem is None:
 262             initial_mem = {}
 263         if initial_insns is None:
 264             initial_insns = {}
 265             assert self.respect_pc == False, "instructions required to honor pc"
 266
 267         print ("ISACaller insns", respect_pc, initial_insns, disassembly)
 268         print ("ISACaller initial_msr", initial_msr)
 269
 270         # "fake program counter" mode (for unit testing)
 271         self.fake_pc = 0
 272         disasm_start = 0
 273         if not respect_pc:
 274             if isinstance(initial_mem, tuple):
 275                 self.fake_pc = initial_mem[0]
 276                 disasm_start = self.fake_pc
 277         else:
 278             disasm_start = initial_pc
 279
 280         # disassembly: we need this for now (not given from the decoder)
 281         self.disassembly = {}
 282         if disassembly:
 283             for i, code in enumerate(disassembly):
 284                 self.disassembly[i*4 + disasm_start] = code
 285
 286         # set up registers, instruction memory, data memory, PC, SPRs, MSR
 287         self.gpr = GPR(decoder2, regfile)
 288         self.mem = Mem(row_bytes=8, initial_mem=initial_mem)
 289         self.imem = Mem(row_bytes=4, initial_mem=initial_insns)
 290         self.pc = PC()
 291         self.spr = SPR(decoder2, initial_sprs)
 292         self.msr = SelectableInt(initial_msr, 64) # underlying reg
 293
 294         # TODO, needed here:
 295         # FPR (same as GPR except for FP nums)
 296         # 4.2.2 p124 FPSCR (definitely "separate" - not in SPR)
 297         #            note that mffs, mcrfs, mtfsf "manage" this FPSCR
 298         # 2.3.1 CR (and sub-fields CR0..CR6 - CR0 SO comes from XER.SO)
 299         #         note that mfocrf, mfcr, mtcr, mtocrf, mcrxrx "manage" CRs
 300         #         -- Done
 301         # 2.3.2 LR   (actually SPR #8) -- Done
 302         # 2.3.3 CTR  (actually SPR #9) -- Done
 303         # 2.3.4 TAR  (actually SPR #815)
 304         # 3.2.2 p45 XER  (actually SPR #1) -- Done
 305         # 3.2.3 p46 p232 VRSAVE (actually SPR #256)
 306
 307         # create CR then allow portions of it to be "selectable" (below)
 308         self._cr = SelectableInt(initial_cr, 64) # underlying reg
 309         self.cr = FieldSelectableInt(self._cr, list(range(32,64)))
 310
 311         # "undefined", just set to variable-bit-width int (use exts "max")
 312         self.undefined = SelectableInt(0, 256) # TODO, not hard-code 256!
 313
 314         self.namespace = {}
 315         self.namespace.update(self.spr)
 316         self.namespace.update({'GPR': self.gpr,
 317                           'MEM': self.mem,
 318                           'SPR': self.spr,
 319                           'memassign': self.memassign,
 320                           'NIA': self.pc.NIA,
 321                           'CIA': self.pc.CIA,
 322                           'CR': self.cr,
 323                           'MSR': self.msr,
 324                           'undefined': self.undefined,
 325                           'mode_is_64bit': True,
 326                           'SO': XER_bits['SO']
 327                           })
 328
 329         # update pc to requested start point
 330         self.set_pc(initial_pc)
 331
 332         # field-selectable versions of Condition Register TODO check bitranges?
 333         self.crl = []
 334         for i in range(8):
 335             bits = tuple(range(i*4, (i+1)*4))# errr... maybe?
 336             _cr = FieldSelectableInt(self.cr, bits)
 337             self.crl.append(_cr)
 338             self.namespace["CR%d" % i] = _cr
 339
 340         self.decoder = decoder2.dec
 341         self.dec2 = decoder2
 342
 343     def TRAP(self, trap_addr=0x700, trap_bit=PIb.TRAP):
 344         print ("TRAP:", hex(trap_addr), hex(self.namespace['MSR'].value))
 345         # store CIA(+4?) in SRR0, set NIA to 0x700
 346         # store MSR in SRR1, set MSR to um errr something, have to check spec
 347         self.spr['SRR0'].value = self.pc.CIA.value
 348         self.spr['SRR1'].value = self.namespace['MSR'].value
 349         self.trap_nia = SelectableInt(trap_addr, 64)
 350         self.spr['SRR1'][trap_bit] = 1 # change *copy* of MSR in SRR1
 351
 352         # set exception bits.  TODO: this should, based on the address
 353         # in figure 66 p1065 V3.0B and the table figure 65 p1063 set these
 354         # bits appropriately.  however it turns out that *for now* in all
 355         # cases (all trap_addrs) the exact same thing is needed.
 356         self.msr[MSRb.SF] = 1
 357         self.msr[MSRb.EE] = 0
 358         self.msr[MSRb.PR] = 0
 359         self.msr[MSRb.IR] = 0
 360         self.msr[MSRb.DR] = 0
 361         self.msr[MSRb.RI] = 0
 362         self.msr[MSRb.LE] = 1
 363
 364     def memassign(self, ea, sz, val):
 365         self.mem.memassign(ea, sz, val)
 366
 367     def prep_namespace(self, formname, op_fields):
 368         # TODO: get field names from form in decoder*1* (not decoder2)
 369         # decoder2 is hand-created, and decoder1.sigform is auto-generated
 370         # from spec
 371         # then "yield" fields only from op_fields rather than hard-coded
 372         # list, here.
 373         fields = self.decoder.sigforms[formname]
 374         for name in op_fields:
 375             if name == 'spr':
 376                 sig = getattr(fields, name.upper())
 377             else:
 378                 sig = getattr(fields, name)
 379             val = yield sig
 380             if name in ['BF', 'BFA']:
 381                 self.namespace[name] = val
 382             else:
 383                 self.namespace[name] = SelectableInt(val, sig.width)
 384
 385         self.namespace['XER'] = self.spr['XER']
 386         self.namespace['CA'] = self.spr['XER'][XER_bits['CA']].value
 387         self.namespace['CA32'] = self.spr['XER'][XER_bits['CA32']].value
 388
 389     def handle_carry_(self, inputs, outputs, already_done):
 390         inv_a = yield self.dec2.e.do.invert_a
 391         if inv_a:
 392             inputs[0] = ~inputs[0]
 393
 394         imm_ok = yield self.dec2.e.do.imm_data.ok
 395         if imm_ok:
 396             imm = yield self.dec2.e.do.imm_data.data
 397             inputs.append(SelectableInt(imm, 64))
 398         assert len(outputs) >= 1
 399         print ("outputs", repr(outputs))
 400         if isinstance(outputs, list) or isinstance(outputs, tuple):
 401             output = outputs[0]
 402         else:
 403             output = outputs
 404         gts = []
 405         for x in inputs:
 406             print ("gt input", x, output)
 407             gt = (x > output)
 408             gts.append(gt)
 409         print(gts)
 410         cy = 1 if any(gts) else 0
 411         if not (1 & already_done):
 412             self.spr['XER'][XER_bits['CA']] = cy
 413
 414         print ("inputs", inputs)
 415         # 32 bit carry
 416         gts = []
 417         for x in inputs:
 418             print ("input", x, output)
 419             gt = (x[32:64] > output[32:64]) == SelectableInt(1, 1)
 420             gts.append(gt)
 421         cy32 = 1 if any(gts) else 0
 422         if not (2 & already_done):
 423             self.spr['XER'][XER_bits['CA32']] = cy32
 424
 425     def handle_overflow(self, inputs, outputs, div_overflow):
 426         inv_a = yield self.dec2.e.do.invert_a
 427         if inv_a:
 428             inputs[0] = ~inputs[0]
 429
 430         imm_ok = yield self.dec2.e.do.imm_data.ok
 431         if imm_ok:
 432             imm = yield self.dec2.e.do.imm_data.data
 433             inputs.append(SelectableInt(imm, 64))
 434         assert len(outputs) >= 1
 435         print ("handle_overflow", inputs, outputs, div_overflow)
 436         if len(inputs) < 2 and div_overflow is None:
 437             return
 438
 439         # div overflow is different: it's returned by the pseudo-code
 440         # because it's more complex than can be done by analysing the output
 441         if div_overflow is not None:
 442             ov, ov32 = div_overflow, div_overflow
 443         # arithmetic overflow can be done by analysing the input and output
 444         elif len(inputs) >= 2:
 445             output = outputs[0]
 446
 447             # OV (64-bit)
 448             input_sgn = [exts(x.value, x.bits) < 0 for x in inputs]
 449             output_sgn = exts(output.value, output.bits) < 0
 450             ov = 1 if input_sgn[0] == input_sgn[1] and \
 451                 output_sgn != input_sgn[0] else 0
 452
 453             # OV (32-bit)
 454             input32_sgn = [exts(x.value, 32) < 0 for x in inputs]
 455             output32_sgn = exts(output.value, 32) < 0
 456             ov32 = 1 if input32_sgn[0] == input32_sgn[1] and \
 457                 output32_sgn != input32_sgn[0] else 0
 458
 459         self.spr['XER'][XER_bits['OV']] = ov
 460         self.spr['XER'][XER_bits['OV32']] = ov32
 461         so = self.spr['XER'][XER_bits['SO']]
 462         so = so | ov
 463         self.spr['XER'][XER_bits['SO']] = so
 464
 465     def handle_comparison(self, outputs):
 466         out = outputs[0]
 467         print ("handle_comparison", out.bits, hex(out.value))
 468         # TODO - XXX *processor* in 32-bit mode
 469         # https://bugs.libre-soc.org/show_bug.cgi?id=424
 470         #if is_32bit:
 471         #    o32 = exts(out.value, 32)
 472         #    print ("handle_comparison exts 32 bit", hex(o32))
 473         out = exts(out.value, out.bits)
 474         print ("handle_comparison exts", hex(out))
 475         zero = SelectableInt(out == 0, 1)
 476         positive = SelectableInt(out > 0, 1)
 477         negative = SelectableInt(out < 0, 1)
 478         SO = self.spr['XER'][XER_bits['SO']]
 479         print ("handle_comparison SO", SO)
 480         cr_field = selectconcat(negative, positive, zero, SO)
 481         self.crl[0].eq(cr_field)
 482
 483     def set_pc(self, pc_val):
 484         self.namespace['NIA'] = SelectableInt(pc_val, 64)
 485         self.pc.update(self.namespace)
 486
 487     def setup_one(self):
 488         """set up one instruction
 489         """
 490         if self.respect_pc:
 491             pc = self.pc.CIA.value
 492         else:
 493             pc = self.fake_pc
 494         self._pc = pc
 495         ins = self.imem.ld(pc, 4, False, True)
 496         if ins is None:
 497             raise KeyError("no instruction at 0x%x" % pc)
 498         print("setup: 0x%x 0x%x %s" % (pc, ins & 0xffffffff, bin(ins)))
 499         print ("CIA NIA", self.respect_pc, self.pc.CIA.value, self.pc.NIA.value)
 500
 501         yield self.dec2.dec.raw_opcode_in.eq(ins & 0xffffffff)
 502         yield self.dec2.dec.bigendian.eq(self.bigendian)
 503         yield self.dec2.msr.eq(self.msr.value)
 504         yield self.dec2.cia.eq(pc)
 505
 506     def execute_one(self):
 507         """execute one instruction
 508         """
 509         # get the disassembly code for this instruction
 510         code = self.disassembly[self._pc]
 511         print("sim-execute", hex(self._pc), code)
 512         opname = code.split(' ')[0]
 513         yield from self.call(opname)
 514
 515         if not self.respect_pc:
 516             self.fake_pc += 4
 517         print ("execute one, CIA NIA", self.pc.CIA.value, self.pc.NIA.value)
 518
 519     def get_assembly_name(self):
 520         # TODO, asmregs is from the spec, e.g. add RT,RA,RB
 521         # see http://bugs.libre-riscv.org/show_bug.cgi?id=282
 522         asmcode = yield self.dec2.dec.op.asmcode
 523         print ("get assembly name asmcode", asmcode)
 524         asmop = insns.get(asmcode, None)
 525         int_op = yield self.dec2.dec.op.internal_op
 526
 527         # sigh reconstruct the assembly instruction name
 528         ov_en = yield self.dec2.e.do.oe.oe
 529         ov_ok = yield self.dec2.e.do.oe.ok
 530         rc_en = yield self.dec2.e.do.rc.data
 531         rc_ok = yield self.dec2.e.do.rc.ok
 532         # grrrr have to special-case MUL op (see DecodeOE)
 533         print ("ov en rc en", ov_ok, ov_en, rc_ok, rc_en, int_op)
 534         if int_op in [MicrOp.OP_MUL_H64.value, MicrOp.OP_MUL_H32.value]:
 535             print ("mul op")
 536             if rc_en & rc_ok:
 537                 asmop += "."
 538         else:
 539             if ov_en & ov_ok:
 540                 asmop += "."
 541         lk = yield self.dec2.e.do.lk
 542         if lk:
 543             asmop += "l"
 544         print ("int_op", int_op)
 545         if int_op in [MicrOp.OP_B.value, MicrOp.OP_BC.value]:
 546             AA = yield self.dec2.dec.fields.FormI.AA[0:-1]
 547             print ("AA", AA)
 548             if AA:
 549                 asmop += "a"
 550         spr_msb = yield from self.get_spr_msb()
 551         if int_op == MicrOp.OP_MFCR.value:
 552             if spr_msb:
 553                 asmop = 'mfocrf'
 554             else:
 555                 asmop = 'mfcr'
 556         # XXX TODO: for whatever weird reason this doesn't work
 557         # https://bugs.libre-soc.org/show_bug.cgi?id=390
 558         if int_op == MicrOp.OP_MTCRF.value:
 559             if spr_msb:
 560                 asmop = 'mtocrf'
 561             else:
 562                 asmop = 'mtcrf'
 563         return asmop
 564
 565     def get_spr_msb(self):
 566         dec_insn = yield self.dec2.e.do.insn
 567         return dec_insn & (1<<20) != 0 # sigh - XFF.spr[-1]?
 568
 569     def call(self, name):
 570         name = name.strip() # remove spaces if not already done so
 571         if self.halted:
 572             print ("halted - not executing", name)
 573             return
 574
 575         # TODO, asmregs is from the spec, e.g. add RT,RA,RB
 576         # see http://bugs.libre-riscv.org/show_bug.cgi?id=282
 577         asmop = yield from self.get_assembly_name()
 578         print  ("call", name, asmop)
 579
 580         # check privileged
 581         int_op = yield self.dec2.dec.op.internal_op
 582         spr_msb = yield from self.get_spr_msb()
 583
 584         instr_is_privileged = False
 585         if int_op in [MicrOp.OP_ATTN.value,
 586                       MicrOp.OP_MFMSR.value,
 587                       MicrOp.OP_MTMSR.value,
 588                       MicrOp.OP_MTMSRD.value,
 589                       # TODO: OP_TLBIE
 590                       MicrOp.OP_RFID.value]:
 591             instr_is_privileged = True
 592         if int_op in [MicrOp.OP_MFSPR.value,
 593                       MicrOp.OP_MTSPR.value] and spr_msb:
 594             instr_is_privileged = True
 595
 596         print ("is priv", instr_is_privileged, hex(self.msr.value),
 597                           self.msr[MSRb.PR])
 598         # check MSR priv bit and whether op is privileged: if so, throw trap
 599         if instr_is_privileged and self.msr[MSRb.PR] == 1:
 600             self.TRAP(0x700, PIb.PRIV)
 601             self.namespace['NIA'] = self.trap_nia
 602             self.pc.update(self.namespace)
 603             return
 604
 605         # check halted condition
 606         if name == 'attn':
 607             self.halted = True
 608             return
 609
 610         # check illegal instruction
 611         illegal = False
 612         if name not in ['mtcrf', 'mtocrf']:
 613             illegal = name != asmop
 614
 615         if illegal:
 616             self.TRAP(0x700, PIb.ILLEG)
 617             self.namespace['NIA'] = self.trap_nia
 618             self.pc.update(self.namespace)
 619             print ("name %s != %s - calling ILLEGAL trap, PC: %x" % \
 620                     (name, asmop, self.pc.CIA.value))
 621             return
 622
 623         info = self.instrs[name]
 624         yield from self.prep_namespace(info.form, info.op_fields)
 625
 626         # preserve order of register names
 627         input_names = create_args(list(info.read_regs) +
 628                                   list(info.uninit_regs))
 629         print(input_names)
 630
 631         # main registers (RT, RA ...)
 632         inputs = []
 633         for name in input_names:
 634             regnum = yield getattr(self.decoder, name)
 635             regname = "_" + name
 636             self.namespace[regname] = regnum
 637             print('reading reg %d' % regnum)
 638             inputs.append(self.gpr(regnum))
 639
 640         # "special" registers
 641         for special in info.special_regs:
 642             if special in special_sprs:
 643                 inputs.append(self.spr[special])
 644             else:
 645                 inputs.append(self.namespace[special])
 646
 647         # clear trap (trap) NIA
 648         self.trap_nia = None
 649
 650         print(inputs)
 651         results = info.func(self, *inputs)
 652         print(results)
 653
 654         # "inject" decorator takes namespace from function locals: we need to
 655         # overwrite NIA being overwritten (sigh)
 656         if self.trap_nia is not None:
 657             self.namespace['NIA'] = self.trap_nia
 658
 659         print ("after func", self.namespace['CIA'], self.namespace['NIA'])
 660
 661         # detect if CA/CA32 already in outputs (sra*, basically)
 662         already_done = 0
 663         if info.write_regs:
 664             output_names = create_args(info.write_regs)
 665             for name in output_names:
 666                 if name == 'CA':
 667                     already_done |= 1
 668                 if name == 'CA32':
 669                     already_done |= 2
 670
 671         print ("carry already done?", bin(already_done))
 672         carry_en = yield self.dec2.e.do.output_carry
 673         if carry_en:
 674             yield from self.handle_carry_(inputs, results, already_done)
 675
 676         # detect if overflow was in return result
 677         overflow = None
 678         if info.write_regs:
 679             for name, output in zip(output_names, results):
 680                 if name == 'overflow':
 681                     overflow = output
 682
 683         ov_en = yield self.dec2.e.do.oe.oe
 684         ov_ok = yield self.dec2.e.do.oe.ok
 685         print ("internal overflow", overflow, ov_en, ov_ok)
 686         if ov_en & ov_ok:
 687             yield from self.handle_overflow(inputs, results, overflow)
 688
 689         rc_en = yield self.dec2.e.do.rc.data
 690         if rc_en:
 691             self.handle_comparison(results)
 692
 693         # any modified return results?
 694         if info.write_regs:
 695             for name, output in zip(output_names, results):
 696                 if name == 'overflow': # ignore, done already (above)
 697                     continue
 698                 if isinstance(output, int):
 699                     output = SelectableInt(output, 256)
 700                 if name in ['CA', 'CA32']:
 701                     if carry_en:
 702                         print ("writing %s to XER" % name, output)
 703                         self.spr['XER'][XER_bits[name]] = output.value
 704                     else:
 705                         print ("NOT writing %s to XER" % name, output)
 706                 elif name in info.special_regs:
 707                     print('writing special %s' % name, output, special_sprs)
 708                     if name in special_sprs:
 709                         self.spr[name] = output
 710                     else:
 711                         self.namespace[name].eq(output)
 712                     if name == 'MSR':
 713                         print ('msr written', hex(self.msr.value))
 714                 else:
 715                     regnum = yield getattr(self.decoder, name)
 716                     print('writing reg %d %s' % (regnum, str(output)))
 717                     if output.bits > 64:
 718                         output = SelectableInt(output.value, 64)
 719                     self.gpr[regnum] = output
 720
 721         print ("end of call", self.namespace['CIA'], self.namespace['NIA'])
 722         # UPDATE program counter
 723         self.pc.update(self.namespace)
 724
 725
 726 def inject():
 727     """Decorator factory.
 728
 729     this decorator will "inject" variables into the function's namespace,
 730     from the *dictionary* in self.namespace.  it therefore becomes possible
 731     to make it look like a whole stack of variables which would otherwise
 732     need "self." inserted in front of them (*and* for those variables to be
 733     added to the instance) "appear" in the function.
 734
 735     "self.namespace['SI']" for example becomes accessible as just "SI" but
 736     *only* inside the function, when decorated.
 737     """
 738     def variable_injector(func):
 739         @wraps(func)
 740         def decorator(*args, **kwargs):
 741             try:
 742                 func_globals = func.__globals__  # Python 2.6+
 743             except AttributeError:
 744                 func_globals = func.func_globals  # Earlier versions.
 745
 746             context = args[0].namespace # variables to be injected
 747             saved_values = func_globals.copy()  # Shallow copy of dict.
 748             func_globals.update(context)
 749             result = func(*args, **kwargs)
 750             print ("globals after", func_globals['CIA'], func_globals['NIA'])
 751             print ("args[0]", args[0].namespace['CIA'],
 752                               args[0].namespace['NIA'])
 753             args[0].namespace = func_globals
 754             #exec (func.__code__, func_globals)
 755
 756             #finally:
 757             #    func_globals = saved_values  # Undo changes.
 758
 759             return result
 760
 761         return decorator
 762
 763     return variable_injector
 764