path: root/subx/opcodes

Opcodes currently supported by SubX:
  01: add r32 to rm32 (add)
  03: add rm32 to r32 (add)
  05: add imm32 to EAX (add)
  09: rm32 = bitwise OR of r32 with rm32 (or)
  0b: r32 = bitwise OR of r32 with rm32 (or)
  0d: EAX = bitwise OR of imm32 with EAX (or)
  21: rm32 = bitwise AND of r32 with rm32 (and)
  23: r32 = bitwise AND of r32 with rm32 (and)
  25: EAX = bitwise AND of imm32 with EAX (and)
  29: subtract r32 from rm32 (sub)
  2b: subtract rm32 from r32 (sub)
  2d: subtract imm32 from EAX (sub)
  31: rm32 = bitwise XOR of r32 with rm32 (xor)
  33: r32 = bitwise XOR of r32 with rm32 (xor)
  35: EAX = bitwise XOR of imm32 with EAX (xor)
  39: compare: set SF if rm32 < r32 (cmp)
  3b: compare: set SF if r32 < rm32 (cmp)
  3d: compare: set SF if EAX < imm32 (cmp)
  40: increment EAX (inc)
  41: increment ECX (inc)
  42: increment EDX (inc)
  43: increment EBX (inc)
  44: increment ESP (inc)
  45: increment EBP (inc)
  46: increment ESI (inc)
  47: increment EDI (inc)
  48: decrement EAX (dec)
  49: decrement ECX (dec)
  4a: decrement EDX (dec)
  4b: decrement EBX (dec)
  4c: decrement ESP (dec)
  4d: decrement EBP (dec)
  4e: decrement ESI (dec)
  4f: decrement EDI (dec)
  50: push EAX to stack (push)
  51: push ECX to stack (push)
  52: push EDX to stack (push)
  53: push EBX to stack (push)
  54: push ESP to stack (push)
  55: push EBP to stack (push)
  56: push ESI to stack (push)
  57: push EDI to stack (push)
  58: pop top of stack to EAX (pop)
  59: pop top of stack to ECX (pop)
  5a: pop top of stack to EDX (pop)
  5b: pop top of stack to EBX (pop)
  5c: pop top of stack to ESP (pop)
  5d: pop top of stack to EBP (pop)
  5e: pop top of stack to ESI (pop)
  5f: pop top of stack to EDI (pop)
  68: push imm32 to stack (push)
  74: jump disp8 bytes away if equal, if ZF is set (jcc/jz/je)
  75: jump disp8 bytes away if not equal, if ZF is not set (jcc/jnz/jne)
  7c: jump disp8 bytes away if lesser, if SF != OF (jcc/jl/jnge)
  7d: jump disp8 bytes away if greater or equal, if SF == OF (jcc/jge/jnl)
  7e: jump disp8 bytes away if lesser or equal, if ZF is set or SF != OF (jcc/jle/jng)
  7f: jump disp8 bytes away if greater, if ZF is unset and SF == OF (jcc/jg/jnle)
  81: combine rm32 with imm32 based on subop (add/sub/and/or/xor/cmp)
  87: swap the contents of r32 and rm32 (xchg)
  88: copy r8 to r8/m8-at-r32
  89: copy r32 to rm32 (mov)
  8a: copy r8/m8-at-r32 to r8
  8b: copy rm32 to r32 (mov)
  8d: copy address in rm32 into r32 (lea)
  8f: pop top of stack to rm32 (pop)
  b8: copy imm32 to EAX (mov)
  b9: copy imm32 to ECX (mov)
  ba: copy imm32 to EDX (mov)
  bb: copy imm32 to EBX (mov)
  bc: copy imm32 to ESP (mov)
  bd: copy imm32 to EBP (mov)
  be: copy imm32 to ESI (mov)
  bf: copy imm32 to EDI (mov)
  c3: return from most recent unfinished call (ret)
  c7: copy imm32 to rm32 (mov)
  cd: software interrupt (int)
  e8: call disp32 (call)
  e9: jump disp16 bytes away (jmp)
  eb: jump disp8 bytes away (jmp)
  f4: halt (hlt)
  f7: negate/multiply rm32 (with EAX if necessary) depending on subop (neg/mul)
  ff: increment/decrement/jump/push/call rm32 based on subop (inc/dec/jmp/push/call)
  0f 84: jump disp16 bytes away if equal, if ZF is set (jcc/jz/je)
  0f 85: jump disp16 bytes away if not equal, if ZF is not set (jcc/jnz/jne)
  0f 8c: jump disp16 bytes away if lesser, if SF != OF (jcc/jl/jnge)
  0f 8d: jump disp16 bytes away if greater or equal, if SF == OF (jcc/jge/jnl)
  0f 8e: jump disp16 bytes away if lesser or equal, if ZF is set or SF != OF (jcc/jle/jng)
  0f 8f: jump disp16 bytes away if greater, if ZF is unset and SF == OF (jcc/jg/jnle)
  0f af: multiply rm32 into r32 (imul)
Run `subx help instructions` for details on words like 'r32' and 'disp8'.
For complete details on these instructions, consult the IA-32 manual (volume 2).
There's various versions of it online, such as https://c9x.me/x86.
The mnemonics in brackets will help you locate each instruction.