init

2026-08-01 19:47:43 -04:00
commit aebf8e7bf8
7 changed files with 446 additions and 0 deletions
@@ -0,0 +1,123 @@
+; Fibonacci number generator using AMD64 assembly with Windows syscalls
+; Uses lookup table for O(1) access
+; Author: Assistant
+
+global _main
+extern _ExitProcess@4
+extern _GetStdHandle@4
+extern _WriteConsoleA@16
+
+section .data
+    ; Precomputed Fibonacci numbers (first 50)
+    fib_table dd 1, 1, 2, 3, 5, 8, 13, 21, 34, 55
+    fib_table dd 89, 144, 233, 377, 610, 987, 1597, 2584, 4181, 6765
+    fib_table dd 10946, 17711, 28657, 46368, 75025, 121393, 196418, 317811, 514229, 832040
+    fib_table dd 1346269, 2178309, 3524578, 5702887, 9227465, 14930352, 24157817, 39088169, 63245986, 102334155
+    fib_table dd 165580141, 267914296, 433494437, 701408733, 1134903170, 1836311903
+    
+    ; Console handles
+    hStdOut dd 0
+    
+    ; Error messages
+    msg_error db 'Error: Index out of range', 0
+    msg_success db 'Fibonacci number: ', 0
+
+section .text
+; Function to get Fibonacci number at index n (0-based)
+; Input: RDI = index
+; Output: RAX = Fibonacci number
+get_fibonacci:
+    ; Validate input
+    cmp rdi, 0
+    jl invalid_input
+    
+    ; Check if index is within range (max 50)
+    cmp rdi, 49
+    jg invalid_input
+    
+    ; Calculate address in table
+    mov rax, rdi
+    shl rax, 2          ; Multiply by 4 (DWORD size)
+    
+    ; Load Fibonacci number from table
+    mov eax, [fib_table + rax]
+    ret
+    
+invalid_input:
+    xor rax, rax        ; Return 0 for invalid input
+    ret
+
+; Function to print a number to console
+print_number:
+    ; Input: RAX = number to print
+    push rax
+    push rbx
+    push rcx
+    push rdx
+    
+    ; Convert number to string and print
+    mov rbx, 10
+    mov rcx, 0          ; Digit count
+    
+    ; Special case for zero
+    cmp rax, 0
+    jne convert_loop
+    mov rcx, 1
+    jmp print_digits
+    
+convert_loop:
+    cmp rax, 0
+    je print_digits
+    
+    xor rdx, rdx        ; Clear high bits
+    div rbx             ; Divide by 10
+    push rdx            ; Push remainder (digit)
+    inc rcx             ; Increment digit count
+    jmp convert_loop
+    
+print_digits:
+    cmp rcx, 0
+    je done_printing
+    
+    pop rax             ; Get digit back
+    add rax, '0'        ; Convert to ASCII
+    push rax
+    
+    ; Write character to console
+    mov edx, esp
+    push 1              ; Number of characters
+    push edx            ; Address of character
+    push dword [hStdOut] ; Handle
+    call _WriteConsoleA@16
+    
+    add rsp, 12         ; Clean up stack
+    
+    dec rcx
+    jmp print_digits
+    
+done_printing:
+    pop rdx
+    pop rcx
+    pop rbx
+    pop rax
+    ret
+
+; Main program entry point
+_main:
+    ; Get console handle
+    mov rdi, -11        ; STD_OUTPUT_HANDLE
+    call _GetStdHandle@4
+    mov [hStdOut], eax
+    
+    ; Test Fibonacci numbers
+    mov rdi, 10         ; Get 11th Fibonacci number (0-indexed)
+    call get_fibonacci
+    
+    ; Print result
+    push rax
+    call print_number
+    add rsp, 8
+    
+    ; Exit program
+    mov rdi, 0
+    call _ExitProcess@4