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Registers Basic Instructions Data Instructions Bitwise Instructions Logic Instructions Appendix
Purpose of Register
MIPS
NASM
Stack Pointer
$sp
esp
Stack Frame Pointer / Base Pointer
$fp
ebp
Return Value
$v0-$v1
eax
Return Value (floating point)
$f0
st0
Arguments
$a0-$a3
NONE - In stack
Free (32-bit integer)
$t0-$t9, $s0-$s8
eax, ecx, ebx, edx, esi, edi(ebx if not in a shared library)
Free (16-bit integer)
NONE
ax, bx, cd, dx
Free (8-bit integer)
NONE
ah, al, bh, bl, ch, cl, dh, dl
Free (floating point)
$f0-$f31
st0,st1,...,st?
Return Address
$ra
NONE - In stack
Product and Remainder
$LO, $HI
eax, edx
Quotient and High 32 Bits
$LO, $HI
eax, edx
Arbitrarily chosen names are shown in italics .
Description
MIPS
NASM
Load immediate value into register.
li $t0, 4
mov eax,4
Move value of one register into another.
move $t0, $t1
mov eax,ecx
Add 2 registers.
add $t0, $t1, $t2
add eax,ebx (Sum saved in first register)
Add register and immediate.
addi $t0, $t1, 4
add eax,4 (Sum saved in first register)
Subtract 2 registers.
sub $t0, $t1, $t2
sub eax,ebx (Difference saved in first register)
Subtract register and immediate.
subi $t0, $t1, 4
sub eax,4 (Difference saved in first register)
Multiply.
mult $t1, $t2 (Result in $HI and $LO)
mul ebx (Multiply eax by ebx and put product into eax .)
Multiply by an immediate.
multi $t1, 3 (Result in $HI and $LO)
imul ebx, 3 (Multiply ebx by 3 and put product into ebx .)
Divide.
div $t1, $t2 (Result in $HI and $LO)
div ebx (Divide eax by ebx and put quotient into eax .)
Divide by an immediate.
divi $t1, 3 (Result in $HI and $LO)
idiv ebx, 3 (Divide ebx by 3 and put quotient into ebx .)
Add 1 to a register.
addi $t1 , $t1 , 1
inc eax
Subtract 1 from a register.
subi $t1 , $t1 , 1
dec eax
Call a function.
jalr address of function
call name of function
Import an external function.
.global name of function
extern name of function
Return
jr $ra
ret (Returns to the last jump instruction called.)
Description
MIPS
NASM
Push a value into the stack.
subi $sp, $sp, 4; sw $t0 , ($sp)
push eax
Pop a value from the stack.
lw $t0 , ($sp); addi $sp, $sp, 4
pop eax
Declare initialized variable. (Word)
variableName : .word 3 variableName : dw 3
Declare uninitialized variable. (Word)
NONE - Must initialize.
variableName : resd 1 (1 is # of words)
Declare initialized variable. (Byte)
variableName : .byte 3 variableName : db 3
Declare uninitialized variable. (Byte)
NONE - Must initialize.
variableName : resb 1 (1 is # of bytes)
Declare initialized variable. (Array)
NONE - Initialize after.
variableName : db 3
Declare uninitialized variable. (Array)
variableName : .space 10 (Array of 10 words)variableName : resq 10 (Array of 10 reals)
Description
MIPS
NASM
Shift logical left <<
sll $t0 , $t0 , 4
shl eax, 4
Shift logical right >>
srl $t0 , $t0 , 4
shr eax, 4
Bitwise NOT
not $t0 , $t0
not eax
Bitwise AND
not $t0 , $t0 , $t1
not eax , ebx
Bitwise OR
xor $t0 , $t0 , $t1
xor eax , ebx
Bitwise XOR
or $t0 , $t0 , $t1
or eax , ebx
Instruction
Description
b label
Unconditional branch.
beq $t0, $t1 , label
Branch if $t0 = $t1
bgez $t0 , label
Branch if $t0 >= 0
bgezal $t0 , label
Branch if $t0 >= 0 and set $ra
bgtz $t0 , label
Branch if $t0 > 0
bgtz $t0 , label
Branch if $t0 < 0
bgtzal $t0 , label
Branch if $t0 < 0 and set $ra
bne $t0, $t1 , label
Branch if $t0 != $t1
j address
Jump to address.
jr $t0
Jump to address stored in register.
jal address
Jump to address and set $ra.
jalr $t0
Jump to address stored in register and set $ra.
labelname :Define a label.
Instruction
Description
cmp eax, ebx
Set comparison flags for two values.
jl label
Jump to label if eax < ebx
jle label
Jump to label if eax <= ebx
je label
Jump to label if eax = ebx
jge label
Jump to label if eax >= ebx
jg label
Jump to label if eax > ebx
jne label
Jump to label if eax != ebx
labelname :Define a label.
A - Getting the program counter in MIPS. bgezal $zero, getpc
getpc:
move $v0, $ra
j $ra
B - NASM setup instructions.
Instruction
Definition
pusha
Push all registers.
popa
Pop all registers.
enter
Create the stack frame. (Gives you a place to push)
leave
Destroy the stack frame. (Frees up the memory taken by enter)
C - NASM Calling Procedure push ARGUMENT#N ;Push arguments
;...
push ARGUMENT#3
push ARGUMENT#2
push ARGUMENT#1
call FUNCTION ;Call function
add esp, 4*N ;Essentially pops arguments.
enter 0,0 ;Create stack frame
mov ARGUMENT#1, dword [ebp+8] ;Load arguments.
mov ARGUMENT#2, dword [ebp+12]
mov ARGUMENT#3, dword [ebp+16]
;...
mov ARGUMENT#N, dword [ebp+4+N*4]
;YOUR FUNCTION CODE HERE!
leave ;Destroy stack frame
ret ;Return to caller
http://www.nasm.us/doc/nasmdoc3.html https://www.csee.umbc.edu/courses/undergraduate/CMSC313/fall04/burt_katz/lectures/ http://www.eecg.toronto.edu/~amza/www.mindsec.com/files/x86regs.html https://msdn.microsoft.com/en-us/library/ms253512(VS.80).aspx http://www.mrc.uidaho.edu/mrc/people/jff/digital/MIPSir.html https://www.cs.uaf.edu/2006/fall/cs301/support/x86/ http://home.myfairpoint.net/fbkotler/nasmdocc.html https://en.wikibooks.org/wiki/X86_Assembly/Other_Instructions http://www.nasm.us/doc/nasmdoc9.html https://en.wikipedia.org/wiki/MIPS_instruction_set#Pseudo_instructions
