init

2026-08-01 19:47:43 -04:00
commit aebf8e7bf8
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+; Fibonacci number generator using AMD64 assembly with Windows syscalls
+; Uses lookup table for O(1) access
+; Author: Assistant
+
+.686p
+.xmm
+.model flat, C
+
+include kernel32.inc
+include user32.inc
+
+includelib kernel32.lib
+includelib user32.lib
+
+.data
+    ; Precomputed Fibonacci numbers (first 50)
+    fib_table DWORD 1, 1, 2, 3, 5, 8, 13, 21, 34, 55
+    fib_table DWORD 89, 144, 233, 377, 610, 987, 1597, 2584, 4181, 6765
+    fib_table DWORD 10946, 17711, 28657, 46368, 75025, 121393, 196418, 317811, 514229, 832040
+    fib_table DWORD 1346269, 2178309, 3524578, 5702887, 9227465, 14930352, 24157817, 39088169, 63245986, 102334155
+    fib_table DWORD 165580141, 267914296, 433494437, 701408733, 1134903170, 1836311903
+    
+    ; Error messages
+    msg_error DWORD 'Error: Index out of range', 0
+    msg_success DWORD 'Fibonacci number: ', 0
+    
+    ; Console handles
+    hStdOut HANDLE ?
+    
+.code
+
+; Function to get Fibonacci number at index n (0-based)
+; Input: EAX = index
+; Output: EAX = Fibonacci number
+get_fibonacci PROC
+    ; Validate input
+    cmp eax, 0
+    jl invalid_input
+    
+    ; Check if index is within range (max 50)
+    cmp eax, 49
+    jg invalid_input
+    
+    ; Calculate address in table
+    mov ebx, eax
+    shl ebx, 2          ; Multiply by 4 (DWORD size)
+    
+    ; Load Fibonacci number from table
+    mov eax, fib_table[ebx]
+    ret
+    
+invalid_input:
+    xor eax, eax        ; Return 0 for invalid input
+    ret
+get_fibonacci ENDP
+
+; Function to print a number to console
+print_number PROC
+    ; Input: EAX = number to print
+    push eax
+    push ebx
+    push ecx
+    push edx
+    
+    ; Convert number to string and print
+    mov ebx, 10
+    mov ecx, 0          ; Digit count
+    
+    ; Special case for zero
+    cmp eax, 0
+    jne convert_loop
+    mov ecx, 1
+    jmp print_digits
+    
+convert_loop:
+    cmp eax, 0
+    je print_digits
+    
+    xor edx, edx        ; Clear high bits
+    div ebx             ; Divide by 10
+    push edx            ; Push remainder (digit)
+    inc ecx             ; Increment digit count
+    jmp convert_loop
+    
+print_digits:
+    cmp ecx, 0
+    je done_printing
+    
+    pop eax             ; Get digit back
+    add eax, '0'        ; Convert to ASCII
+    push eax
+    
+    ; Write character to console
+    mov edx, esp
+    push 1              ; Number of characters
+    push edx            ; Address of character
+    push hStdOut        ; Handle
+    call WriteConsoleA
+    
+    add esp, 12         ; Clean up stack
+    
+    dec ecx
+    jmp print_digits
+    
+done_printing:
+    pop edx
+    pop ecx
+    pop ebx
+    pop eax
+    ret
+print_number ENDP
+
+; Main program entry point
+main PROC
+    ; Get console handle
+    push -11            ; STD_OUTPUT_HANDLE
+    call GetStdHandle
+    mov hStdOut, eax
+    
+    ; Test Fibonacci numbers
+    mov eax, 10         ; Get 11th Fibonacci number (0-indexed)
+    call get_fibonacci
+    
+    ; Print result
+    push eax
+    call print_number
+    add esp, 4
+    
+    ; Exit program
+    push 0
+    call ExitProcess
+main ENDP
+
+END main