![Our first program
org 0x7c00
mov ax,0xb800
mov ds,ax
;mov byte [ds:0],0x1b
here:
inc byte [ds:0]
jmp here
times 510 - ($-$$) db 0
dw 0xAA55
hello.asm bochsrc.bxrc
boot: floppy
floppya: 1_44=hello, status=inserted
megs: 16
#ata0-master: type=disk, mode=flat, path="30M.sample"
nasm hello.asm
ndisasm hello
bochs -q -f bochsrx.bxrc
Debugger:
bochsdbg -q -f bochsrx.bxrc
run](https://image.slidesharecdn.com/assembly-programming-i-180818154333/85/Assembly-programming-8-320.jpg)
![Size Directives
mov BYTE [ds:bx], 2 ; Move 2 into the single byte at the address stored in EBX.
mov WORD [ds:bx], 2
; Move the 16-bit integer representation of 2 into the 2 bytes
starting at the address in EBX.
mov DWORD [ds:bx], 2
; Move the 32-bit integer representation of 2 into the 4 bytes
starting at the address in EBX.](https://image.slidesharecdn.com/assembly-programming-i-180818154333/85/Assembly-programming-12-320.jpg)
Assembly programming
- 2. Peter Cheung • Programmer • Ask me quedtions at [email protected]
- 3. Today • Assembly programming jump start • Instruction Set
- 4. Learning Path • Book • Instruction • CPU Architecture (intel system programming guide) • Newsgroup • Alt.lang.asm • Alt.os.development
- 5. We need an Assembler • Assembler • Nasm/Fasm/Masm/Basm • Macro
- 6. We need an way to debug • http://bochs.sourceforge.net
- 7. We need an way to debug • https://x64dbg.com
- 8. Our first program org 0x7c00 mov ax,0xb800 mov ds,ax ;mov byte [ds:0],0x1b here: inc byte [ds:0] jmp here times 510 - ($-$$) db 0 dw 0xAA55 hello.asm bochsrc.bxrc boot: floppy floppya: 1_44=hello, status=inserted megs: 16 #ata0-master: type=disk, mode=flat, path="30M.sample" nasm hello.asm ndisasm hello bochs -q -f bochsrx.bxrc Debugger: bochsdbg -q -f bochsrx.bxrc run
- 9. Registers
- 10. Addressing
- 12. Size Directives mov BYTE [ds:bx], 2 ; Move 2 into the single byte at the address stored in EBX. mov WORD [ds:bx], 2 ; Move the 16-bit integer representation of 2 into the 2 bytes starting at the address in EBX. mov DWORD [ds:bx], 2 ; Move the 32-bit integer representation of 2 into the 4 bytes starting at the address in EBX.
- 13. Data Movement Instructions mov <reg>,<reg> mov <reg>,<mem> mov <mem>,<reg> mov <reg>,<const> mov <mem>,<const>
- 14. MOV DX, TAX_RATE MOV COUNT, CX MOV EAX, EBX
- 15. Immediate Addressing BYTE_VALUE DB 150 ; A byte value is defined WORD_VALUE DW 300 ; A word value is defined ADD BYTE_VALUE, 65 ; an immediate operand 65 is added MOV AX, 45H ; immediate constant 45H is transferred to AX
- 17. XOR Operand1: 0101 Operand2: 0011 ---------------------------- After XOR -> Operand1: 0110 XOR EAX, EAX
- 18. TEST Test al, 01h Jz even_number
- 19. CMP CMP DX, 00 ; compare the DX value with zero JE L7 ; if yes, then jump to label L7
- 20. CMP LP1: INC EDX CMP EDX, 10 ; Compares whether the counter has reached 10 JLE LP1 ; If it is less than or equal to 10, then jump to LP1
- 21. CMP