225 lines
3.4 KiB
NASM
225 lines
3.4 KiB
NASM
extern NR_write
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extern strlen
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extern strcat
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extern itoa
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section .rodata
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NL db 0xA
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bufferLength equ 4096
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ERR_buffLen db "<!> ERROR: Failed to complete printf(), reached buffer length!",0xA,0x0
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lERR_buffLen equ $-ERR_buffLen-1
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section .bss
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printfBuff resb bufferLength
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printfNBuff resb 32
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section .text
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global print
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global puts
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global printf
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;----- print (char* string) -----;
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; return value: N/A
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print:
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push rbp
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mov rbp, rsp
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call strlen
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mov rdx, rax
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mov rax, NR_write
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mov rsi, rdi
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mov rdi, 1
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syscall
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leave
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ret
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;----- puts (char* string) -----;
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; return value: N/A
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puts:
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push rbp
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mov rbp, rsp
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mov r10, rdi
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call print
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mov rdi, r10
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mov rax, NR_write
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mov rdi, 1
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mov rsi, NL
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mov rdx, 1
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syscall
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leave
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ret
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;----- printf(const char* string, ...) -----;
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; Currently only supports specifiers: %d, %c, %s, %%
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; Return value: Amount of printed characters
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printf:
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push rbp
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mov rbp, rsp
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push r12
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push r14
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xor r10, r10
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xor r14, r14
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lea r11, [rel printfBuff]
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.makeStr:
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cmp byte [rdi], 0x0
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je .finish
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cmp r14, bufferLength-1
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je .finish
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cmp byte [rdi], '%'
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je .replaceArg
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mov r12b, byte [rdi]
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mov byte [r11], r12b
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inc r14
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jmp .continue
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.replaceArg:
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cmp byte [rdi+1], 0x0
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je .continue
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push rdi
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cmp byte [rdi+1], 'd'
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je .rep_d
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cmp byte [rdi+1], '%'
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je .rep_pct
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cmp byte [rdi+1], 'c'
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je .rep_c
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cmp byte [rdi+1], 's'
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je .rep_s
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;--- invalid specifier ---;
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mov byte [r11], '%'
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inc r14
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inc r10
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jmp .continue
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;--- %d ---;
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.rep_d:
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cmp r10, 0
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cmove rdi, rsi
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je .convertInt
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cmp r10, 1
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cmove rdi, rdx
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je .convertInt
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cmp r10, 2
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cmove rdi, rcx
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je .convertInt
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cmp r10, 3
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cmove rdi, r8
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je .convertInt
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cmp r10, 4
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cmove rdi, r9
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je .convertInt
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mov rdi, qword [rbp + 16 + (r10-5)*8]
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.convertInt:
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lea rsi, [rel printfNBuff]
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push rcx
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push rdx
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push r8
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push r10
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call itoa
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pop r10
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pop r8
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pop rdx
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pop rcx
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mov rsi, rax
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jmp .insertLoop
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;--- %% ---;
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.rep_pct:
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mov rdi, '%'
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dec r10
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jmp .charToStr
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;--- %c ---;
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.rep_c:
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cmp r10, 0
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cmove rdi, rsi
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je .charToStr
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cmp r10, 1
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cmove rdi, rdx
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je .charToStr
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cmp r10, 2
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cmove rdi, rcx
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je .charToStr
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cmp r10, 3
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cmove rdi, r8
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je .charToStr
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cmp r10, 4
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cmove rdi, r9
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je .charToStr
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mov rdi, qword [rbp + 16 + (r10-5)*8]
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.charToStr:
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mov [printfNBuff], dil
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mov dil, 0
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mov [printfNBuff+1], dil
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lea rsi, [rel printfNBuff]
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jmp .insertLoop
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;--- %s ---;
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.rep_s:
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cmp r10, 0
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je .insertLoop
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cmp r10, 1
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cmove rsi, rdx
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je .insertLoop
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cmp r10, 2
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cmove rsi, rcx
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je .insertLoop
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cmp r10, 3
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cmove rsi, r8
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je .insertLoop
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cmp r10, 4
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cmove rsi, r9
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je .insertLoop
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mov rsi, qword [rbp + 16 + (r10-5)*8]
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;--- Move fetched data to buffer ---;
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.insertLoop:
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cmp r14, bufferLength-1
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je .finish
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cmp byte [rsi], 0x0
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je .s0f
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mov r12b, byte [rsi]
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mov byte [r11], r12b
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inc r14
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inc rsi
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inc r11
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jmp .insertLoop
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.s0f:
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inc r10
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pop rdi
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add rdi, 2
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jmp .makeStr
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.continue:
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inc rdi
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inc r11
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jmp .makeStr
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.finish:
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mov byte [r11], 0x0
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mov rax, NR_write
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mov rdi, 1
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lea rsi, [rel printfBuff]
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mov rdx, r14
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syscall
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mov rax, r14
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cmp r14, bufferLength-1
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jl .final
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mov rax, NR_write
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mov rdi, 2
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lea rsi, [rel ERR_buffLen]
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mov rdx, lERR_buffLen
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syscall
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.final:
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pop r14
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pop r12
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leave
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ret
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