Rotth is a stack based concatenative language highly inspired by Porth
Add print routine
Ivan Chinenov
(Mar 8, 2022, 10:25 PM +0300)
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print.asm
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print.asm
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section .data
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buffer times 32 db 0
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section .text
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global print
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print:
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call ft_itoa
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mov rdi, buffer
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call cstrlen
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mov rdi, 1 ; fd
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mov rsi, buffer ; buffer
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xor rdx, rdx
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mov rdx, rax ; count
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mov rax, 1 ; write(2)
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syscall
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ret
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;======================================================
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; https://tuttlem.github.io/2013/01/08/strlen-implementation-in-nasm.html
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cstrlen:
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push rbx ; save any registers that
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push rcx ; we will trash in here
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mov rbx, rdi ; rbx = rdi
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xor al, al ; the byte that the scan will
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; compare to is zero
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mov rcx, 0xffffffff ; the maximum number of bytes
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repne scasb ; while [rdi] != al, keep scanning
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sub rdi, rbx ; length = dist2 - dist1
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mov rax, rdi ; rax now holds our length
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pop rcx ; restore the saved registers
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pop rbx
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ret ; all done!
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;======================================================
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; https://stackoverflow.com/a/54381686/12015230
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ft_itoa:
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xor rcx, rcx ;initialize counter
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xor r9, r9 ;set neg flag to 0
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mov eax, edi ;move number in RAX for DIV instruction
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push rbx ;save RBX
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mov ebx, 10
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.check_negative:
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and edi, 0x80000000
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mov rdi, buffer
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jz .divide ;number is positive, proceed to main loop
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not eax ;else
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inc eax ;compute absolute value with binary complement
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inc r9 ;set neg flag
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.divide:
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xor edx, edx
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div ebx
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add edx, 48 ;convert int to char
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push rdx
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inc rcx
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cmp eax, 0
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jnz .divide
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.check_neg_flag:
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cmp r9, 1
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jne .buff_string
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mov byte[rdi], '-'
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.buff_string:
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pop rdx
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mov byte[rdi + r9], dl
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dec rcx
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inc r9
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cmp rcx, 0
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jnz .buff_string
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mov byte[rdi + r9], 10
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mov byte[rdi + r9 + 1], 0
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pop rbx ;restore RBX
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ret