1    :  // Copyright 2014 Google Inc. All Rights Reserved.
   2    :  //
   3    :  // Licensed under the Apache License, Version 2.0 (the "License");
   4    :  // you may not use this file except in compliance with the License.
   5    :  // You may obtain a copy of the License at
   6    :  //
   7    :  //     http://www.apache.org/licenses/LICENSE-2.0
   8    :  //
   9    :  // Unless required by applicable law or agreed to in writing, software
  10    :  // distributed under the License is distributed on an "AS IS" BASIS,
  11    :  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12    :  // See the License for the specific language governing permissions and
  13    :  // limitations under the License.
  14    :  
  15    :  #ifndef SYZYGY_ASSM_CONST_H_
  16    :  #define SYZYGY_ASSM_CONST_H_
  17    :  
  18    :  namespace assm {
  19    :  
  20    :  enum Mod {
  21    :    kReg1Ind = 0,  // Register indirect mode.
  22    :    kReg1ByteDisp = 1,  // Register + byte displacement.
  23    :    kReg1WordDisp = 2,  // Register + word displacement.
  24    :    kReg1 = 3,  // Register itself.
  25    :  };
  26    :  
  27    :  // The code that AL/AX/EAX/RAX registers all map to. There are special encodings
  28    :  // for arithmetic instructions with this register as the destination.
  29  E :  static const RegisterCode kAccumulatorCode = Register::Code(kRegisterEax);
  30    :  
  31    :  const uint8 kTwoByteOpCodePrefix = 0x0F;
  32    :  // Prefix group 2 (segment selection).
  33    :  const uint8 kFsSegmentPrefix = 0x64;
  34    :  // Prefix group 3 (operand size override).
  35    :  const uint8 kOperandSizePrefix = 0x66;
  36    :  
  37    :  // Some opcodes that are used repeatedly.
  38    :  const uint8 kNopOpCode = 0x1F;
  39    :  
  40    :  const size_t kShortBranchOpcodeSize = 1;
  41    :  const size_t kShortBranchSize = kShortBranchOpcodeSize + 1;
  42    :  
  43    :  const size_t kLongBranchOpcodeSize = 2;
  44    :  const size_t kLongBranchSize = kLongBranchOpcodeSize + 4;
  45    :  
  46    :  const size_t kShortJumpOpcodeSize = 1;
  47    :  const size_t kShortJumpSize = kShortJumpOpcodeSize + 1;
  48    :  
  49    :  const size_t kLongJumpOpcodeSize = 1;
  50    :  const size_t kLongJumpSize = kLongJumpOpcodeSize + 4;
  51    :  
  52    :  // The maximum length a single instruction will assemble to.
  53    :  // No instruction on x86 can exceed 15 bytes, per specs.
  54    :  static const size_t kMaxInstructionLength = 15;
  55    :  
  56    :  }  // namespace assm
  57    :  
  58    :  #endif  // SYZYGY_ASSM_CONST_H_