CS 208 Quick Reference
This quick reference guide is based on one created by Aaron Bauer and adapted by Jeff Ondich.
Bits and binary
Helpful conversions:
Assembly instructions
Instruction |
Description |
---|---|
mov a, b |
Copy from a to b . |
movs a, b |
Copy from a to b with sign extension. Needs two width specifiers. |
movz a, b |
Copy from a to b with zero extension. Needs two width specifiers. |
lea a, b |
Compute address and store in b . Note: the scaling parameter of memory operands can only be 1, 2, 4, or 8. |
push src |
Push src onto the stack and decrement the stack pointer. |
pop dst |
Pop from the stack into dst and increment the stack pointer. |
call <func> |
Push the return address on to the stack and jump to the first instruction of procedure <func> . |
ret |
Pop the return address from the stack and jump to that address. |
add a, b |
Store b+a in b . Set condition codes. |
sub a, b |
Store b-a in b . Set condition codes. |
imul a, b |
Store b*a in b . Set condition codes. |
neg a |
Store -a (according to 2’s complement) in a . Set condition codes. |
and a, b |
Store bitwise-AND of a and b in b . Set condition codes. |
or a, b |
Store bitwise-OR of a and b in b . Set condition codes. |
xor a, b |
Store bitwise-XOR of a and b in b . Set condition codes. |
sar a, b |
Shift value of b right (arithmetic) by a bits and store in b . Set condition codes. |
shr a, b |
Shift value of b right (logical) by a bits and store in b . Set condition codes. |
sal a, b |
Shift value of b left by a bits and store in b . Set condition codes. |
shl a, b |
Same as sal . |
cmp a, b |
Compare b:a . Set condition codes based on b-a , but do not store b-a anywhere. |
test a, b |
Compute bitwise-AND of a and b , but do not store a&b anywhere. Set condition codes based on a&b . |
jmp <label> |
Unconditional jump to address <label> . |
jCOND <label> |
Conditional jump based on condition codes. |
setCOND a |
Set byte a to 0 or 1 based on condition codes. |
Conditionals
Instruction | Meaning |
(op) s, d |
test a, b |
cmp a, b |
||
---|---|---|---|---|---|---|
je |
sete |
equal | d (op) s == 0 |
b & a == 0 |
b == a |
|
jne |
setne |
not equal | d (op) s != 0 |
b & a != 0 |
b != a |
|
js |
sets |
sign (negative) | d (op) s < 0 |
b & a < 0 |
b - a < 0 |
|
jns |
setns |
non-negative | d (op) s >= 0 |
b & a >= 0 |
b - a >= 0 |
|
jg |
setg |
greater | d (op) s > 0 |
b & a > 0 |
b > a |
|
jge |
setge |
greater or equal | d (op) s >= 0 |
b & a >= 0 |
b >= a |
|
jl |
setl |
less | d (op) s < 0 |
b & a < 0 |
b < a |
|
jle |
setle |
less or equal | d (op) s <= 0 |
b & a <= 0 |
b <= a |
|
ja |
seta |
above (unsigned > ) |
d (op) s > 0U |
b & a > 0U |
b - a > 0U |
|
jb |
setb |
below (unsigned < ) |
d (op) s < 0U |
b & a < 0U |
b - a < 0U |
Registers and sizes
Name |
Convention |
Lowest 4 bytes |
Lowest 2 bytes |
Lowest byte |
---|---|---|---|---|
%rax |
return value | %eax |
%ax |
%al |
%rbx |
%ebx |
%bx |
%bl |
|
%rdx |
argument #3 | %edx |
%dx |
%dl |
%rcx |
argument #4 | %ecx |
%cx |
%cl |
%rdi |
argument #1 | %edi |
%di |
%dil |
%rsi |
argument #2 | %esi |
%si |
%sil |
%rsp |
stack pointer | %esp |
%sp |
%spl |
%rbp |
%ebp |
%bp |
%bpl |
|
%r8 |
argument #5 | %r8d |
%r8w |
%r8b |
%r9 |
argument #6 | %r9d |
%r9w |
%r9b |
%r10 |
%r10d |
%r10w |
%r10b |
|
%r11 |
%r11d |
%r11w |
%r11b |
|
%r12 |
%r12d |
%r12w |
%r12b |
|
%r13 |
%r13d |
%r13w |
%r13b |
|
%r14 |
%r14d |
%r14w |
%r14b |
|
%r15 |
%r15d |
%r15w |
%r15b |
C type | x86-64 suffix | Size in bytes |
---|---|---|
char |
b |
1 |
short |
w |
2 |
int |
l |
4 |
long |
q |
8 |