lodsb
Load byte from string
Loads the byte at [rsi] into al.
8086 and later
CFPFAFZFSFDFOF –––––––
- Changes no flag
- Reads DF
Forms
lodsb
The b suffix selects an element of 1 byte. After each element, the instruction increases rsi by 1 when DF = 0, or decreases rsi by 1 when DF = 1. In 64-bit mode the default addresses use rsi. The a32 address-size prefix instead uses esi; 16-bit string addressing is unavailable.
rep repeats until the counter reaches zero. The counter is rcx by default or ecx with a32. If it starts at zero, a repeated instruction accesses no element. The data width is independent of this address and counter width.
global _start
section .data
source: db 1, 2, 3, 4, 5, 6, 7, 8
destination: times 8 db 0
section .text
_start:
cld ; count upwards
mov rsi, source
mov rdi, destination
mov rax, 7
lodsb ; reads one byte from [rsi] into al
mov rax, 60 ; syscall 60: exit
xor rdi, rdi
syscall