A complete Game Boy assembly programming tutorial, providing resources for beginners and experts alike! Support Resistance, Pivot Points for Avino Silver and Gold Mines Ltd with Key Turning Points and Technical Indicators. ASAM Level of Care (LOC) Determination Guidelines (1 of 2) As emergency needs come first, the highest severity problem (with specific attention to Dimensions 1, 2 and 3) should guide the client’s entry point into the treatment continuum.
Registers
64 bit | 32 bit | 16 bit | 8 bit | |
---|---|---|---|---|
A (accumulator) | RAX | EAX | AX | AL |
B (base, addressing) | RBX | EBX | BX | BL |
C (counter, iterations) | RCX | ECX | CX | CL |
D (data) | RDX | EDX | DX | DL |
RDI | EDI | DI | DIL | |
RSI | ESI | SI | SIL | |
Numbered (n=8..15) | Rn | RnD | RnW | RnB |
Stack pointer | RSP | ESP | SP | SPL |
Frame pointer | RBP | EBP | BP | BPL |
As well as XMM0 .. XMM15 for 128 bit floating point numbers.
Calling C
Put function arguments (first to last) in the following registers (64 bitrepresentations): RDI, RSI, RDX, RCX, R8, R9, then push to stack (in reverse,has to be cleaned up by the caller!) XMM0 - XMM7 for floats
Return values are stored in RAX (int
) or XMM0 (float
)
RBP, RBX, R12, R13, R14, R15 will not be changed by the called function, allothers may be
Align stack pointer (RSP) to 16 byte, calling pushes 8 bytes!
Keep in mind that strings (in C) are 0-terminated
Like in a normal C program, the label that is (de facto) called first ismain
, with the args argc
(argcount) in RDI, and the char** argv
in RSI(the commandline arguments as in C's main function).
Data
Definition size | Definition instruction |
---|---|
8 bit | db |
16 bit | dw |
32 bit | dd |
64 bit | ddq /do |
float | dd |
double | dq |
extended precision | dt |
Intel Asm Cheat Sheet
Conditionals
cmp op1, op2
-> mimics sub op1, op2
but only changes the zero and carry flagfor comparing.
Prefixes:
j~ x
-> jump to x if ~cmov~ x, y
-> conditional mov x, y if ~setc~ x
-> set x to 1 if ~, x is 8 bit reg
Asm Commands Cheat Sheet
Many suffixes, including:
a
(above, >)ae
(above or equal, >=)b
(below, <)be
(below or equal, <=)e
(equal, =)ne
(not equal, !=)
Program structure
global <entry>
-> exposes entry pointextern <function>
-> declares a function in another linked .o file (e.g. Cfunction, other asm file)section <sectiontype>
-> sets section, usually:.text
-> program code.data
-> data
The program entry point of a standalone program is the label _start
. Whencompiled with gcc, C provides _start
, which inits and then jumps to main
,which should then be implemented by the program.
Syscalls
- put syscall number in EAX (e.g. on Linux: 60 for exit, 1 for write to stdout)
- put arguments in the registers (see above) like when calling a C function
- execute the
syscall
instruction
Assemble
- Assemble:
nasm -felf64 -o <object> <filename>
- Link with ld:
ld -o <output> <object>
- Link with gcc:
gcc -o <output> <object>
Sources
- Forked from: mpdrescher
- Main: NASM Tutorial
- Registers: Assembly registers
- Conditionals: Jumps and loops (de)