Cookie's Notes

x86 Commands

Commands

mov <dest>, <src>

  • Moves src into dest, replacing old data

movsx <dest>, <src>

  • Moves src into dest, replacing old data
  • Extends bits to fit dest’s size
  • Destination must be a register
    (Signed)

movsxd <dest>, <src>

  • Moves src into dest, replacing old data
  • Extends bits to fit dest’s size
  • Destination must be a register
  • Converts 32-bit to 64-bit
    (Signed)

movzx <dest>, <src>

  • Moves src into dest, replacing old data
  • Extends bits to fit dest’s size
  • Destination must be a register
    (Unsigned)

inc <dest>

  • i.e.t. dest++

dec <dest>

  • i.e.t. dest—

add <dest>, <src>

  • i.e.t. dest = dest + src

sub <dest>, <src>

  • i.e.t. dest = dest - src

mul <src>

  • first register * src (Unsigned)
  • Result is stored in both registers
  • Cannot be multiplied by itself

imul <src>

  • first register * src (Signed)
  • Result is stored in both registers
  • Cannot be multiplied by itself

div <src>

  • first register / src (Unsigned)
  • Quotient is stored in the first register
  • Remainder is stored in the second register

idiv <src>

  • first register / src (Signed)
  • Quotient is stored in the first register
  • Remainder is stored in the second register

Conversion commands (for signed division):

  • cbw - Converts a byte to a word
  • cwd - Converts a word to a dword
  • cdq - Converts a dword to a qword
  • cqo - Converts a qword into a dqword (i.e.t. oword)
    cmp <op1>, <op2>
  • Compares op1 and op2, to be used with jumps

Always jumps to dest (label):

  • jmp <dest>-

Signed, jumps to dest (label):

  • jg <dest> ; >
  • jge <dest> ; >=
  • jl <dest> ; <
  • jle <dest> ; <=

Unsigned, jumps to dest (label):

  • ja <dest> ; >
  • jae <dest> ; >=
  • jb <dest> ; <
  • jbe <dest>- ; <=

Equalities, jumps to dest (label):

  • je <dest> ; ==
  • jne <dest> ; !=

%macro <macroName> <numOfParams>

  • When in the macro, each parameter is %
  • Make sure you know if its a variable like max or a value like byte[max]
    When creating labels in macros: %% :
    to make the label names unique

%endmacro

  • Ends the macro (i.e.t. closing bracket of a function)

call <functionName>

  • Calls a function, uses Standard Calling Convention (see table above)

ret

  • Returns from a function
    syscall
  • Calls a system function, rax holds call code, uses calling convention

movss <dest>, <src>

  • Move single precision value (float)

movsd <dest>, <src>

  • Move double precision value (double)

addss and addsd <dest>, <src>

  • Same as add but for floating point

subss and subsd <dest>, <src>

  • Same as sub but for floating point

divss and divsd <dest>, <src>

  • Same as add/sub but for floating point division

mulss and mulsd <dest>, <src>

  • Same as add/sub but for floating point multiplication

sqrtss <dest>, <src>

  • Square roots and stores in

ucomiss <op1>, <op2>

  • Same as cmp but for floating point

ucomisd <op1>, <op2>

  • Same as cmp but for floating point

cvtsi2ss <dest>, <src>

  • Converts an int to a float

cvtss2si <dest>, <src>

  • Converts a float to an int

cvtss2sd <dest>, <src>

  • Converts a float to a double

cvtsi2sd <dest>, <src>

  • Converts an int to a double

cvtsd2si <dest>, <src>-

  • Converts a double to an int

cvtsd2ss <dest>, <src>

  • Converts a double to a float