Title here
Summary here
Enums in Assembly Language
Enumerated types (enums) are a special case of sum types. An enum is a type that has a fixed number of possible values, each with a distinct name. Assembly language doesn’t have a built-in enum type, but we can implement a similar concept using constants and macros.
; Define our ServerState enum using equates (constants)
StateIdle equ 0
StateConnected equ 1
StateError equ 2
StateRetrying equ 3
section .data
; Define string representations for our enum values
stateName db "idle", 0, "connected", 0, "error", 0, "retrying", 0
section .text
global _start
_start:
; Example usage of our enum
mov eax, StateIdle
call transition
call print_state
mov eax, eax ; The result of the previous transition
call transition
call print_state
; Exit the program
mov eax, 1
xor ebx, ebx
int 0x80
; transition function
; Input: eax - current state
; Output: eax - new state
transition:
cmp eax, StateIdle
je .to_connected
cmp eax, StateConnected
je .to_idle
cmp eax, StateRetrying
je .to_idle
cmp eax, StateError
je .stay_error
; If we reach here, it's an unknown state
jmp error
.to_connected:
mov eax, StateConnected
ret
.to_idle:
mov eax, StateIdle
ret
.stay_error:
mov eax, StateError
ret
; print_state function
; Input: eax - state to print
print_state:
push eax
mov ecx, stateName
mov edx, 0
.find_string:
cmp eax, 0
je .print
inc edx
.skip_string:
cmp byte [ecx + edx], 0
jne .skip_string
inc edx
dec eax
jmp .find_string
.print:
mov eax, 4 ; sys_write
mov ebx, 1 ; stdout
int 0x80
mov eax, 4
mov ebx, 1
mov ecx, newline
mov edx, 1
int 0x80
pop eax
ret
error:
; Print error message and exit
mov eax, 4
mov ebx, 1
mov ecx, error_msg
mov edx, error_msg_len
int 0x80
mov eax, 1
mov ebx, 1
int 0x80
section .data
newline db 10
error_msg db "Error: Unknown state", 10
error_msg_len equ $ - error_msgIn this Assembly Language implementation:
- We define our enum values as constants using
equ. - We create a string table (
stateName) to hold the string representations of our enum values. - The
transitionfunction simulates state transitions based on the current state. - The
print_statefunction prints the string representation of a given state. - We demonstrate the usage in the
_startfunction, which serves as our main entry point.
This implementation provides a way to work with enumerated types in Assembly Language, although it lacks the type safety and convenience features of higher-level languages. The concept of state transitions and string representations for enum values is preserved, albeit in a more low-level and manual fashion.
To run this program, you would need to assemble and link it using an assembler like NASM and a linker. The exact commands may vary depending on your system and toolchain.