Time Formatting Parsing in Assembly Language

section .data
    time_format db "2006-01-02T15:04:05-07:00", 0
    time_str db "2012-11-01T22:08:41+00:00", 0
    custom_format1 db "3:04PM", 0
    custom_format2 db "Mon Jan _2 15:04:05 2006", 0
    custom_format3 db "2006-01-02T15:04:05.999999-07:00", 0
    custom_time db "8 41 PM", 0
    custom_format4 db "3 04 PM", 0
    format_str db "%d-%02d-%02dT%02d:%02d:%02d-00:00", 10, 0

section .text
    global _start

_start:
    ; Get current time
    mov eax, 13    ; sys_time syscall number
    int 0x80
    mov [current_time], eax

    ; Format current time (simplified)
    mov eax, [current_time]
    add eax, 946684800  ; Convert Unix time to years since 2000
    mov ecx, 365*24*60*60
    xor edx, edx
    div ecx
    add eax, 2000
    push eax  ; Year

    ; ... (similar calculations for month, day, hour, minute, second)

    ; Print formatted time
    push dword [second]
    push dword [minute]
    push dword [hour]
    push dword [day]
    push dword [month]
    push dword [year]
    push format_str
    call printf
    add esp, 28

    ; Exit program
    mov eax, 1    ; sys_exit syscall number
    xor ebx, ebx  ; Exit code 0
    int 0x80

section .bss
    current_time resq 1
    year resd 1
    month resd 1
    day resd 1
    hour resd 1
    minute resd 1
    second resd 1

This Assembly Language example demonstrates a simplified version of time formatting. Assembly doesn’t have built-in libraries for complex time operations, so we’ve focused on the basic concept of getting the current time and formatting it.

Key points:

We use the sys_time syscall to get the current Unix timestamp.
The time is then converted from Unix time (seconds since 1970) to components like year, month, day, etc. This involves some arithmetic operations.
We use a format string similar to the C printf function to output the formatted time.

Note that this is a very basic implementation. Real-world assembly programs for time formatting would likely use system libraries or more complex algorithms for accurate time calculations, especially for handling time zones, leap years, etc.

To run this program, you would typically:

Save it to a file (e.g., time_format.asm)
Assemble it: nasm -f elf time_format.asm
Link it: ld -m elf_i386 -o time_format time_format.o
Execute: ./time_format

This example provides a basic illustration of working with time in assembly, but it’s important to note that for complex time operations, higher-level languages or specialized libraries are typically more practical and accurate.

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Time Formatting Parsing in Assembly Language