95 lines
3.5 KiB
NASM
95 lines
3.5 KiB
NASM
; THIS CODE HAS BEEN TESTED AND IS FULLY OPERATIONAL.
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; Problem Statement: Write X86/64 ALP to perform non-overlapped block transfer (WITH string specific instructions). Block containing data can be defined in the data segment.
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; Code from Microprocessor (SPPU - Second Year - Computer Engineering - Content) repository on KSKA Git: https://git.kska.io/sppu-se-comp-content/Microprocessor/
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; BEGINNING OF CODE
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%macro print 2
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mov rax,1 ; Standard output
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mov rdi,1 ; Input write
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mov rsi,%1 ; Display message address
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mov rdx,%2 ; Message length
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syscall ; Interrupt for kernel in 64-bit
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%endmacro
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section .data
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msg db 10, 'Block contents before transfer',10,13 ; Initializing the display message
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msglen equ $-msg ; Length of the message
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msg2 db 10, 'Block contents after transfer',10,13 ; Initializing the display message
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msg2len equ $-msg2 ; Length of the message
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msg3 db 10,13, 'Source block'
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msg3len equ $-msg3
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msg4 db 10,13, 'Destination block'
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msg4len equ $-msg4
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space db ' ' ; Space between the variables to be displayed
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spacelen equ $-space ; Initializing length of space
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srcblk db 10h,20h,30h,40h,50h ; Contents of the src block
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destblk db 0,0,0,0,0 ; Initial contents of dest block
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cnt equ 5 ; Count is equal to 5 as 5 variables declared
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section .bss ; Storing the array of data/reserving space for the data
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ans resb 4 ; Reserve buffer ans of 4-bytes(8-bits each)
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;destblk resb 5 ; Reserve buffer destblk of 5-bytes
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section .text
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global _start ; Starting of the main program
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_start:
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print msg,msglen ; Displaying the msg1
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mov rsi,srcblk ; Move contents of source blk to rsi
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call disp_block ; Calling procedure disp_block
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cld ; Clear direction flag
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mov rcx,05h ; Move 05h into rcx register
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mov rsi,srcblk ; Move contents of src block into rsi
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mov rdi,destblk ; Move contents of dest blok into rdi
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rep movsb ; Repeat move string byte
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print msg2,msg2len ; Displaying the msg2
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mov rsi,destblk ; Move contents of destblk into rsi
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call disp_block ; Calling procedure disp_block
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mov rax,60 ; Exit system call
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xor rdi,rdi ; Clearing rdi (by using xor) so that we get 0 in destblk
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syscall ; Interrupt for kernel in 64-bit
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disp_block: ; Procedure disp_block
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mov rbp,cnt ; Base pointers
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back:
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mov al,[rsi] ; Move contents of rsi to al
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push rsi ; Push contents of rsi
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call disp_8 ; Calling the disp_8 procedure
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print space,1 ; Intialize one byte for space
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pop rsi ; Pop contents of rsi
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inc rsi ; Increment rsi by 1
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dec rbp ; Decrement cnt through rbp
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jnz back ; Jump to loop back if not zero
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ret ; Return
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disp_8: ; Procedure disp_8
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mov rsi,ans+1 ; Move the contents of ans buffer into rsi
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mov rcx,2 ; Move 2 into the rcx register
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back1: ; Loop back1
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mov rdx,0 ; Clear rdx
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mov rbx,16 ; Move 16 into rbx register
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div rbx ; Divide rax register by rbx register
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cmp dl,09h ; Compare the contents of dl register with 09h
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jbe add_30 ; If compared value is below (less) than add 30h
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add dl ,07h ; Add 07h to dl register
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add_30: ; add_30 label
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add dl,30h ; Add 30h to the contents of dl register
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mov[rsi],dl ; Move contents of dl into rsi
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dec rsi ; Decrement rsi
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dec rcx ; Decrement rcx
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jnz back1 ; Jump if not zero to loop back1
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print ans,2 ; Print the result
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ret ; Return
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; END OF CODE
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