//: Beginning of "level 2": tagging bytes with metadata around what field of //: an x86 instruction they're for. //: //: The x86 instruction set is variable-length, and how a byte is interpreted //: affects later instruction boundaries. A lot of the pain in programming machine code //: stems from computer and programmer going out of sync on what a byte //: means. The miscommunication is usually not immediately caught, and //: metastasizes at runtime into kilobytes of misinterpreted instructions. //: Tagging bytes with what the programmer expects them to be interpreted as //: helps the computer catch miscommunication immediately. //: //: This is one way SubX is going to be different from a 'language': we //: typically think of languages as less verbose than machine code. Here we're //: making machine code *more* verbose. //: //: --- //: //: While we're here, we'll also improve a couple of other things: //: //: a) Machine code often packs logically separate operands into bitfields of //: a single byte. We'll start writing out each operand separately, and the //: translator will construct the right bytes out of operands. //: //: SubX now gets still more verbose. What used to be a single byte, say 'c3', //: can now expand to '3/mod 0/subop 3/rm32'. //: //: b) Since each operand is tagged, we can loosen ordering restrictions and //: allow writing out the operands in any order, like keyword arguments. //: //: c) Operand values can be expressed in either decimal or hex (when prefixed //: with '0x'. Raw 2-character hex bytes without the '0x' are only valid when //: tagged without any operand metadata. (This may be a bad idea.) //: //: Coda: the actual opcodes (1-3 bytes) will continue to be at the start of //: each line, in hex, and untagged. The x86 instruction set is a mess, and //: instructions don't admit good names. :(before "End Help Texts") put(Help, "instructions", "Each x86 instruction consists of an instruction or opcode and some number\n" "of operands.\n" "Each operand has a type. An instruction won't have more than one operand of\n" "any type.\n" "Each instruction has some set of allowed operand types. It'll reject others.\n" "The complete list of operand types: mod, subop, r32 (register), rm32\n" "(register or memory), scale, index, base, disp8, disp16, disp32, imm8,\n" "imm32.\n" "Each of these has its own help page. Try reading 'subx help mod' next.\n" ); :(before "End Help Contents") cerr << " instructions\n"; //:: Check for 'syntax errors'; missing or unexpected operands. :(scenario check_missing_imm8_operand) % Hide_errors = true; == 0x1 # instruction effective address operand displacement immediate # op subop mod rm32 base index scale r32 # 1-3 bytes 3 bits 2 bits 3 bits 3 bits 3 bits 2 bits 2 bits 0/1/2/4 bytes 0/1/2/4 bytes cd # int ?? +error: 'cd' (software interrupt): missing imm8 operand :(before "End One-time Setup") Transform.push_back(check_operands); :(code) void check_operands(/*const*/ program& p) { if (p.segments.empty()) return; const segment& code = p.segments.at(0); for (int i = 0; i < SIZE(code.lines); ++i) { check_operands(code.lines.at(i)); if (trace_contains_errors()) return; // stop at the first mal-formed instruction } } void check_operands(const line& inst) { uint8_t op = hex_byte(inst.words.at(0).data); if (trace_contains_errors()) return; if (op == 0x0f) { check_operands_0f(inst); return; } if (op == 0xf3) { check_operands_f3(inst); return; } if (!contains_key(name, op)) { raise << "unknown opcode '" << HEXBYTE << NUM(op) << "'\n" << end(); return; } check_operands(op, inst); } //: To check the operands for an opcode, we'll track the permitted operands //: for each supported opcode in a bitvector. That way we can often compute the //: bitvector for each instruction's operands and compare it with the expected. :(before "End Types") enum operand_type { // start from the least significant bit MODRM, // more complex, may also involve disp8 or disp32 SUBOP, DISP8, DISP16, DISP32, IMM8, IMM32, NUM_OPERAND_TYPES }; :(before "End Globals") vector Operand_type_name; map Operand_type; :(before "End One-time Setup") init_op_types(); :(code) void init_op_types() { assert(NUM_OPERAND_TYPES <= /*bits in a uint8_t*/8); Operand_type_name.resize(NUM_OPERAND_TYPES); #define DEF(type) Operand_type_name.at(type) = tolower(#type), put(Operand_type, tolower(#type), type); DEF(MODRM); DEF(SUBOP); DEF(DISP8); DEF(DISP16); DEF(DISP32); DEF(IMM8); DEF(IMM32); #undef DEF } :(before "End Globals") map Permitted_operands; const uint8_t INVALID_OPERANDS = 0xff; // no instruction uses all the operands :(before "End One-time Setup") init_permitted_operands(); :(code) void init_permitted_operands() { //// Class A: just op, no operands // halt put(Permitted_operands, 0xf4, 0x00); // push put(Permitted_operands, 0x50, 0x00); put(Permitted_operands, 0x51, 0x00); put(Permitted_operands, 0x52, 0x00); put(Permitted_operands, 0x53, 0x00); put(Permitted_operands, 0x54, 0x00); put(Permitted_operands, 0x55, 0x00); put(Permitted_operands, 0x56, 0x00); put(Permitted_operands, 0x57, 0x00); // pop put(Permitted_operands, 0x58, 0x00); put(Permitted_operands, 0x59, 0x00); put(Permitted_operands, 0x5a, 0x00); put(Permitted_operands, 0x5b, 0x00); put(Permitted_operands, 0x5c, 0x00); put(Permitted_operands, 0x5d, 0x00); put(Permitted_operands, 0x5e, 0x00); put(Permitted_operands, 0x5f, 0x00); // return put(Permitted_operands, 0xc3, 0x00); //// Class B: just op and disp8 // imm32 imm8 disp32 |disp16 disp8 subop modrm // 0 0 0 |0 1 0 0 // jump put(Permitted_operands, 0xeb, 0x04); put(Permitted_operands, 0x74, 0x04); put(Permitted_operands, 0x75, 0x04); put(Permitted_operands, 0x7c, 0x04); put(Permitted_operands, 0x7d, 0x04); put(Permitted_operands, 0x7e, 0x04); put(Permitted_operands, 0x7f, 0x04); //// Class C: just op and disp16 // imm32 imm8 disp32 |disp16 disp8 subop modrm // 0 0 0 |1 0 0 0 put(Permitted_operands, 0xe8, 0x08); // jump //// Class D: just op and disp32 // imm32 imm8 disp32 |disp16 disp8 subop modrm // 0 0 1 |0 0 0 0 put(Permitted_operands, 0xe9, 0x10); // call //// Class E: just op and imm8 // imm32 imm8 disp32 |disp16 disp8 subop modrm // 0 1 0 |0 0 0 0 put(Permitted_operands, 0xcd, 0x20); // software interrupt //// Class F: just op and imm32 // imm32 imm8 disp32 |disp16 disp8 subop modrm // 1 0 0 |0 0 0 0 put(Permitted_operands, 0x05, 0x40); // add put(Permitted_operands, 0x2d, 0x40); // subtract put(Permitted_operands, 0x25, 0x40); // and put(Permitted_operands, 0x0d, 0x40); // or put(Permitted_operands, 0x35, 0x40); // xor put(Permitted_operands, 0x3d, 0x40); // compare put(Permitted_operands, 0x68, 0x40); // push // copy put(Permitted_operands, 0xb8, 0x40); put(Permitted_operands, 0xb9, 0x40); put(Permitted_operands, 0xba, 0x40); put(Permitted_operands, 0xbb, 0x40); put(Permitted_operands, 0xbc, 0x40); put(Permitted_operands, 0xbd, 0x40); put(Permitted_operands, 0xbe, 0x40); put(Permitted_operands, 0xbf, 0x40); //// Class M: using ModR/M byte // imm32 imm8 disp32 |disp16 disp8 subop modrm // 0 0 0 |0 0 0 1 // add put(Permitted_operands, 0x01, 0x01); put(Permitted_operands, 0x03, 0x01); // subtract put(Permitted_operands, 0x29, 0x01); put(Permitted_operands, 0x2b, 0x01); // and put(Permitted_operands, 0x21, 0x01); put(Permitted_operands, 0x23, 0x01); // or put(Permitted_operands, 0x09, 0x01); put(Permitted_operands, 0x0b, 0x01); // complement put(Permitted_operands, 0xf7, 0x01); // xor put(Permitted_operands, 0x31, 0x01); put(Permitted_operands, 0x33, 0x01); // compare put(Permitted_operands, 0x39, 0x01); put(Permitted_operands, 0x3b, 0x01); // copy put(Permitted_operands, 0x89, 0x01); put(Permitted_operands, 0x8b, 0x01); // swap put(Permitted_operands, 0x87, 0x01); // pop put(Permitted_operands, 0x8f, 0x01); //// Class O: op, ModR/M and subop (not r32) // imm32 imm8 disp32 |disp16 disp8 subop modrm // 0 0 0 |0 0 1 1 put(Permitted_operands, 0xff, 0x03); // jump/push/call //// Class N: op, ModR/M and imm32 // imm32 imm8 disp32 |disp16 disp8 subop modrm // 1 0 0 |0 0 0 1 put(Permitted_operands, 0xc7, 0x41); // copy //// Class P: op, ModR/M, subop (not r32) and imm32 // imm32 imm8 disp32 |disp16 disp8 subop modrm // 1 0 0 |0 0 1 1 put(Permitted_operands, 0x81, 0x43); // combine // End Init Permitted Operands } :(before "End Includes") #define HAS(bitvector, bit) ((bitvector) & (1 << (bit))) #define SET(bitvector, bit) ((bitvector) | (1 << (bit))) #define CLEAR(bitvector, bit) ((bitvector) & (~(1 << (bit)))) :(code) void check_operands(uint8_t op, const line& inst) { uint8_t expected_bitvector = get(Permitted_operands, op); if (HAS(expected_bitvector, MODRM)) check_operands_modrm(inst, op); compare_bitvector(op, inst, CLEAR(expected_bitvector, MODRM)); } //: Many instructions can be checked just by comparing bitvectors. void compare_bitvector(uint8_t op, const line& inst, uint8_t expected) { if (all_raw_hex_bytes(inst) && has_operands(inst)) return; // deliberately programming in raw hex; we'll raise a warning elsewhere uint8_t bitvector = compute_operand_bitvector(inst); if (trace_contains_errors()) return; // duplicate operand type if (bitvector == expected) return; // all good with this instruction for (int i = 0; i < NUM_OPERAND_TYPES; ++i, bitvector >>= 1, expected >>= 1) { //? cerr << "comparing " << HEXBYTE << NUM(bitvector) << " with " << NUM(expected) << '\n'; if ((bitvector & 0x1) == (expected & 0x1)) continue; // all good with this operand const string& optype = Operand_type_name.at(i); if ((bitvector & 0x1) > (expected & 0x1)) raise << "'" << to_string(inst) << "' (" << get(name, op) << "): unexpected " << optype << " operand\n" << end(); else raise << "'" << to_string(inst) << "' (" << get(name, op) << "): missing " << optype << " operand\n" << end(); // continue giving all errors for a single instruction } // ignore settings in any unused bits } uint32_t compute_operand_bitvector(const line& inst) { uint32_t bitvector = 0; for (int i = /*skip op*/1; i < SIZE(inst.words); ++i) { bitvector = bitvector | bitvector_for_operand(inst.words.at(i)); if (trace_contains_errors()) return INVALID_OPERANDS; // duplicate operand type } return bitvector; } bool has_operands(const line& inst) { return SIZE(inst.words) > first_operand(inst); } int first_operand(const line& inst) { if (inst.words.at(0).data == "0f") return 2; if (inst.words.at(0).data == "f3") { if (inst.words.at(1).data == "0f") return 3; else return 2; } return 1; } bool all_raw_hex_bytes(const line& inst) { for (int i = 0; i < SIZE(inst.words); ++i) { const word& curr = inst.words.at(i); if (contains_any_operand_metadata(curr)) return false; if (SIZE(curr.data) != 2) return false; if (curr.data.find_first_not_of("0123456789abcdefABCDEF") != string::npos) return false; } return true; } bool contains_any_operand_metadata(const word& word) { for (int i = 0; i < SIZE(word.metadata); ++i) if (Instruction_operands.find(word.metadata.at(i)) != Instruction_operands.end()) return true; return false; } // Scan the metadata of 'w' and return the bit corresponding to any operand type. // Also raise an error if metadata contains multiple operand types. uint32_t bitvector_for_operand(const word& w) { uint32_t bv = 0; bool found = false; for (int i = 0; i < SIZE(w.metadata); ++i) { const string& curr = w.metadata.at(i); if (!contains_key(Operand_type, curr)) continue; // ignore unrecognized metadata if (found) { raise << "'" << w.original << "' has conflicting operand types; it should have only one\n" << end(); return INVALID_OPERANDS; } bv = (1 << get(Operand_type, curr)); found = true; } return bv; } :(scenario conflicting_operand_type) % Hide_errors = true; == 0x1 cd/software-interrupt 80/imm8/imm32 +error: '80/imm8/imm32' has conflicting operand types; it should have only one //: Instructions computing effective addresses have more complex rules, so //: we'll hard-code a common set of instruction-decoding rules. :(scenario check_missing_mod_operand) % Hide_errors = true; == 0x1 81 0/add/subop 3/rm32/ebx 1/imm32 +error: '81 0/add/subop 3/rm32/ebx 1/imm32' (combine rm32 with imm32 based on subop): missing mod operand :(before "End Globals") set Instruction_operands; :(before "End One-time Setup") Instruction_operands.insert("subop"); Instruction_operands.insert("mod"); Instruction_operands.insert("rm32"); Instruction_operands.insert("base"); Instruction_operands.insert("index"); Instruction_operands.insert("scale"); Instruction_operands.insert("r32"); Instruction_operands.insert("disp8"); Instruction_operands.insert("disp16"); Instruction_operands.insert("disp32"); Instruction_operands.insert("imm8"); Instruction_operands.insert("imm32"); :(code) void check_operands_modrm(const line& inst, uint8_t op) { if (all_raw_hex_bytes(inst)) return; // deliberately programming in raw hex; we'll raise a warning elsewhere check_metadata_present(inst, "mod", op); check_metadata_present(inst, "rm32", op); // no check for r32; some instructions don't use it; just assume it's 0 if missing if (op == 0x81 || op == 0x8f || op == 0xff) { // keep sync'd with 'help subop' check_metadata_present(inst, "subop", op); check_metadata_absent(inst, "r32", op, "should be replaced by subop"); } if (trace_contains_errors()) return; if (metadata(inst, "rm32").data != "4") return; // SIB byte checks uint8_t mod = hex_byte(metadata(inst, "mod").data); if (mod != /*direct*/3) { check_metadata_present(inst, "base", op); check_metadata_present(inst, "index", op); // otherwise why go to SIB? } else { check_metadata_absent(inst, "base", op, "direct mode"); check_metadata_absent(inst, "index", op, "direct mode"); } // no check for scale; 0 (2**0 = 1) by default } void check_metadata_present(const line& inst, const string& type, uint8_t op) { if (!has_metadata(inst, type)) raise << "'" << to_string(inst) << "' (" << get(name, op) << "): missing " << type << " operand\n" << end(); } void check_metadata_absent(const line& inst, const string& type, uint8_t op, const string& msg) { if (has_metadata(inst, type)) raise << "'" << to_string(inst) << "' (" << get(name, op) << "): unexpected " << type << " operand (" << msg << ")\n" << end(); } bool has_metadata(const line& inst, const string& m) { bool result = false; for (int i = 0; i < SIZE(inst.words); ++i) { if (!has_metadata(inst.words.at(i), m)) continue; if (result) { raise << "'" << to_string(inst) << "' has conflicting " << m << " operands\n" << end(); return false; } result = true; } return result; } bool has_metadata(const word& w, const string& m) { bool result = false; bool metadata_found = false; for (int i = 0; i < SIZE(w.metadata); ++i) { const string& curr = w.metadata.at(i); if (!contains_key(Instruction_operands, curr)) continue; // ignore unrecognized metadata if (metadata_found) { raise << "'" << w.original << "' has conflicting operand types; it should have only one\n" << end(); return false; } metadata_found = true; result = (curr == m); } return result; } word metadata(const line& inst, const string& m) { for (int i = 0; i < SIZE(inst.words); ++i) if (has_metadata(inst.words.at(i), m)) return inst.words.at(i); assert(false); } :(scenario conflicting_operands_in_modrm_instruction) % Hide_errors = true; == 0x1 01/add 0/mod 3/mod +error: '01/add 0/mod 3/mod' has conflicting mod operands :(scenario conflicting_operand_type_modrm) % Hide_errors = true; == 0x1 01/add 0/mod 3/rm32/r32 +error: '3/rm32/r32' has conflicting operand types; it should have only one :(scenario check_missing_rm32_operand) % Hide_errors = true; == 0x1 81 0/add/subop 0/mod 1/imm32 +error: '81 0/add/subop 0/mod 1/imm32' (combine rm32 with imm32 based on subop): missing rm32 operand :(scenario check_missing_subop_operand) % Hide_errors = true; == 0x1 81 0/mod 3/rm32/ebx 1/imm32 +error: '81 0/mod 3/rm32/ebx 1/imm32' (combine rm32 with imm32 based on subop): missing subop operand :(scenario check_missing_base_operand) % Hide_errors = true; == 0x1 81 0/add/subop 0/mod/indirect 4/rm32/use-sib 1/imm32 +error: '81 0/add/subop 0/mod/indirect 4/rm32/use-sib 1/imm32' (combine rm32 with imm32 based on subop): missing base operand :(scenario check_missing_index_operand) % Hide_errors = true; == 0x1 81 0/add/subop 0/mod/indirect 4/rm32/use-sib 0/base 1/imm32 +error: '81 0/add/subop 0/mod/indirect 4/rm32/use-sib 0/base 1/imm32' (combine rm32 with imm32 based on subop): missing index operand :(scenario check_missing_base_operand_2) % Hide_errors = true; == 0x1 81 0/add/subop 0/mod/indirect 4/rm32/use-sib 2/index 3/scale 1/imm32 +error: '81 0/add/subop 0/mod/indirect 4/rm32/use-sib 2/index 3/scale 1/imm32' (combine rm32 with imm32 based on subop): missing base operand :(scenario check_base_operand_not_needed_in_direct_mode) == 0x1 81 0/add/subop 3/mod/indirect 4/rm32/use-sib 1/imm32 $error: 0 //:: similarly handle multi-byte opcodes :(code) void check_operands_0f(const line& inst) { assert(inst.words.at(0).data == "0f"); if (SIZE(inst.words) == 1) { raise << "opcode '0f' requires a second opcode\n" << end(); return; } uint8_t op = hex_byte(inst.words.at(1).data); if (!contains_key(name_0f, op)) { raise << "unknown 2-byte opcode '0f " << HEXBYTE << NUM(op) << "'\n" << end(); return; } check_operands_0f(op, inst); } void check_operands_f3(const line& /*unused*/) { raise << "no supported opcodes starting with f3\n" << end(); } :(scenario check_missing_disp16_operand) % Hide_errors = true; == 0x1 # instruction effective address operand displacement immediate # op subop mod rm32 base index scale r32 # 1-3 bytes 3 bits 2 bits 3 bits 3 bits 3 bits 2 bits 2 bits 0/1/2/4 bytes 0/1/2/4 bytes 0f 84 # jmp if ZF to ?? +error: '0f 84' (jump disp16 bytes away if ZF is set): missing disp16 operand :(before "End Globals") map Permitted_operands_0f; :(before "End Init Permitted Operands") //// Class C: just op and disp16 // imm32 imm8 disp32 |disp16 disp8 subop modrm // 0 0 0 |1 0 0 0 put(Permitted_operands_0f, 0x84, 0x08); put(Permitted_operands_0f, 0x85, 0x08); put(Permitted_operands_0f, 0x8c, 0x08); put(Permitted_operands_0f, 0x8d, 0x08); put(Permitted_operands_0f, 0x8e, 0x08); put(Permitted_operands_0f, 0x8f, 0x08); :(code) void check_operands_0f(uint8_t op, const line& inst) { uint8_t expected_bitvector = get(Permitted_operands_0f, op); if (HAS(expected_bitvector, MODRM)) check_operands_modrm(inst, op); compare_bitvector_0f(op, inst, CLEAR(expected_bitvector, MODRM)); } void compare_bitvector_0f(uint8_t op, const line& inst, uint8_t expected) { if (all_raw_hex_bytes(inst) && has_operands(inst)) return; // deliberately programming in raw hex; we'll raise a warning elsewhere uint8_t bitvector = compute_operand_bitvector(inst); if (trace_contains_errors()) return; // duplicate operand type if (bitvector == expected) return; // all good with this instruction for (int i = 0; i < NUM_OPERAND_TYPES; ++i, bitvector >>= 1, expected >>= 1) { //? cerr << "comparing " << HEXBYTE << NUM(bitvector) << " with " << NUM(expected) << '\n'; if ((bitvector & 0x1) == (expected & 0x1)) continue; // all good with this operand const string& optype = Operand_type_name.at(i); if ((bitvector & 0x1) > (expected & 0x1)) raise << "'" << to_string(inst) << "' (" << get(name_0f, op) << "): unexpected " << optype << " operand\n" << end(); else raise << "'" << to_string(inst) << "' (" << get(name_0f, op) << "): missing " << optype << " operand\n" << end(); // continue giving all errors for a single instruction } // ignore settings in any unused bits } string to_string(const line& inst) { ostringstream out; for (int i = 0; i < SIZE(inst.words); ++i) { if (i > 0) out << ' '; out << inst.words.at(i).original; } return out.str(); } string tolower(const char* s) { ostringstream out; for (/*nada*/; *s; ++s) out << static_cast(tolower(*s)); return out.str(); } //:: docs on each operand type :(before "End Help Texts") init_operand_type_help(); :(code) void init_operand_type_help() { put(Help, "mod", "2-bit operand controlling the _addressing mode_ of many instructions,\n" "to determine how to compute the _effective address_ to look up memory at\n" "based on the 'rm32' operand and potentially others.\n" "\n" "If mod = 3, just operate on the contents of the register specified by rm32 (direct mode).\n" "If mod = 2, effective address is usually* rm32 + disp32 (indirect mode with displacement).\n" "If mod = 1, effective address is usually* rm32 + disp8 (indirect mode with displacement).\n" "If mod = 0, effective address is usually* rm32 (indirect mode).\n" "(* - The exception is when rm32 is '4'. Register 4 is the stack pointer (ESP). Using it as an address gets more involved.\n" " For more details, try reading the help pages for 'base', 'index' and 'scale'.)\n" "\n" "For complete details consult the IA-32 software developer's manual, table 2-2,\n" "\"32-bit addressing forms with the ModR/M byte\".\n" " https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf\n" ); put(Help, "subop", "Additional 3-bit operand for determining the instruction when the opcode is 81, 8f or ff.\n" "Can't coexist with operand of type 'r32' in a single instruction, because the two use the same bits.\n" ); put(Help, "r32", "3-bit operand specifying a register operand used directly, without any further addressing modes.\n" ); put(Help, "rm32", "3-bit operand specifying a register operand whose precise interpretation interacts with 'mod'.\n" "For complete details consult the IA-32 software developer's manual, table 2-2,\n" "\"32-bit addressing forms with the ModR/M byte\".\n" " https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf\n" ); put(Help, "base", "Additional 3-bit operand (when 'rm32' is 4 unless 'mod' is 3) specifying the register containing an address to look up.\n" "This address may be further modified by 'index' and 'scale' operands.\n" " effective address = base + index*scale + displacement (disp8 or disp32)\n" "For complete details consult the IA-32 software developer's manual, table 2-3,\n" "\"32-bit addressing forms with the SIB byte\".\n" " https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf\n" ); put(Help, "index", "Optional 3-bit operand (when 'rm32' is 4 unless 'mod' is 3) that can be added to the 'base' operand to compute the 'effective address' at which to look up memory.\n" " effective address = base + index*scale + displacement (disp8 or disp32)\n" "For complete details consult the IA-32 software developer's manual, table 2-3,\n" "\"32-bit addressing forms with the SIB byte\".\n" " https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf\n" ); put(Help, "scale", "Optional 2-bit operand (when 'rm32' is 4 unless 'mod' is 3) that can be multiplied to the 'index' operand before adding the result to the 'base' operand to compute the _effective address_ to operate on.\n" " effective address = base + index * scale + displacement (disp8 or disp32)\n" "For complete details consult the IA-32 software developer's manual, table 2-3,\n" "\"32-bit addressing forms with the SIB byte\".\n" " https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-instruction-set-reference-manual-325383.pdf\n" ); put(Help, "disp8", "8-bit value to be added in many instructions.\n" ); put(Help, "disp16", "16-bit value to be added in many instructions.\n" ); put(Help, "disp32", "32-bit value to be added in many instructions.\n" ); put(Help, "imm8", "8-bit value for many instructions.\n" ); put(Help, "imm32", "32-bit value for many instructions.\n" ); } :(before "End Includes") #include