下面是代码：
;*******************************************************
; PROGRAM NAME -
;
; PROGRAMMER -
;
; COMPILE - nasm -f elf64 -F dwarf -g Lab.asm
; ld -m elf_x86_64 -o lab Lab.o
;
; SYSTEM - Replit / Linux
;
; DATE - Started Jan. 12, 2023
;
; ISSUES - Don't use negative or decimal values when inputting numbers.
;
; DESCRIPTION - Simple mathematic algorithms including
; factoring, GCD, exponents, finding
; digits, printing digits, and counting
; digits.
; *******************************************************
global _start ;Linker instructions
section .text ;Main code
pnum: ;Number printing function
POP r15 ;Saving return adress in r15
POP r14 ;Saving number to be printed in r14
PUSH r14 ;Saving number to be printed on stack
call cdigits ;Counting digits of number
POP rbx ;Saving number of digits to rbx
dec rbx ;Decrementing it, so it functions well with power function
mov r8, 10 ;Saving 10 to r8
PUSH r8 ;Saving 10 to stack
PUSH rbx ;Saving number of digits to stack
call pow ;Getting 10^number of digits, for use in printing function
POP r8 ;Saving that number to r8
mov r9, 10 ;Saving 10 in r9
pnumwork: ;Recursive function for actually printing number
mov rax, r14 ;Saving number to print (r14) to rax
xor rdx, rdx ;Making rdx 0, so division doesnt mess up
div r8 ;Dividing rax by r8
mov r10, rax ;Saving result to r10
imul rax, r8 ;Multiplying result with r8, so we can subtract it from the number we're printing. EG: num is 123, r8 is 100, rax is 1, then subtracting 100 from 123, so we can recurse with 23 as num.
sub r14, rax ;Subtracting multiplication result from num
mov rax, r10 ;Moving result back to rax
add rax, 48 ;Adding 48 to rax for unicode, otherwise, printing, for example, 1, wouldent print one but unicode char with code 1
mov [temp_var], rax ;Save result of division to variable, for printing
mov rax, 1 ;System write
mov rdi, 1 ;Stdout
mov rsi, temp_var ;Message to be sent
mov rdx, temp_var_len ;Message length
syscall ;Printing message
xor rdx, rdx ;Making rdx 0
mov rax, r8 ;Making rax r8
div r9 ;Dividing r8 by 10
mov r8, rax ;Making r8 the division result, so when recursing we keep up with each digit in the number to print
mov rax, r14 ;Moving number to print to rax
cmp rax, 0 ;Comparing it with zero
jnz pnumwork ;If it is zero, stop recursing, else, recurse
PUSH r15 ;Pushing return address to top of stack
ret ;Return to location the function was called from
cdigits: ;Digit counting function
POP rbx ;Saving return adress to rbx
POP rax ;Getting number to count digits of, saving to rax
mov r8, 10 ;Making r8 10
mov r9, 0 ;Making r9 0
cdigitswork: ;Recursing function
xor rdx, rdx ;Making rdx 0
div r8 ;Dividing number to count digits of by 10
inc r9 ;Incrementing r9 (number of digits counter variable)
cmp rax, 0 ;Comparing division result with 0
jnz cdigitswork ;If rax is 0, exit recursive function, else, recurse.
PUSH r9 ;Push result number to stack
PUSH rbx ;Push return adress to stack
ret ;Return to location the function was called from
pow: ;Function to get a number to the power of another
POP r8 ;Save return adress to r8
POP r9 ;Save exponent to r9
dec r9 ;Decrement exponent, for compatibility with recursive function
POP r10 ;Save base to r10
mov r11, r10 ;Make r11 equal to r10
mov rcx, r9 ;Move rcx to r9 (most likely this is vestigial, im not messing with it just in case.)
powwork: ;Recursive function
imul r10, r11 ;Multiply base by copy of itself
dec r9 ;Decrement loop counter
cmp r9, 0 ;Compare loop counter with zero
jne powwork ;If so, exit recursive function, else, recurse
PUSH r10 ;Push result to stack
PUSH r8 ;Push return adress to stack
ret ;Return to location the function was called from
factors: ;Get factors of number (unfinished)
POP r8 ;Save return adress to r8
POP r9 ;Save number to r9
PUSH r8 ;Push return adress back onto stack
mov rax, 1 ;Print factors message one
mov rdi, 1 ; |
mov rsi, factors_msg_1 ; |
mov rdx, factors_msg_1_len ; |
syscall ;End print factors message one
PUSH r9 ;Save number on stack
PUSH r9 ;Push number (for printing) on to stack
call pnum ;Print number (issue here)
mov rax, 1 ;Print factors message two
mov rdi, 1 ; |
mov rsi, factors_msg_2 ; |
mov rdx, factors_msg_2_len ; |
syscall ;End print factors message two
POP r9 ;Save number to r9
ret ;Return to location the function was called from
_start: ;Linker instruction, code starts execution here
mov rax, 50 ;Save 50 to rax
PUSH rax ;Push rax onto stack, for factoring
call factors ;Factor number
;********************************************************
; System exit
;********************************************************
mov eax, 60 ;System exit code
mov rdi, 0 ;Success code
syscall ;Exit program
section .data ;Data for use in program
temp_var: times 256 db 0 ;Save number printing variable with a buffer
temp_var_len: equ $-temp_var ;Save the length of temp_var
factors_msg_1: db 0x0A, 'The factors of '
factors_msg_1_len: equ $-factors_msg_1
factors_msg_2: db ' are', 0x3A, 0x0A
factors_msg_2_len: equ $-factors_msg_2
factors_comma: db ','
factors_comma_len: equ $-factors_comma
factors_period: db ','
factors_period_len: equ $-factors_period当这个程序运行时，它打印消息："的因子"，然后插入符号停在原地。这让我想到它在数字打印函数中，很可能在某个地方陷入了循环。但我想知道的是问题出在哪里，因为我已经对打印函数做了独立测试。如果有人对这个问题有任何想法，那就很好地获得了一个不同于我自己的观点。
谢谢!
1条答案
按热度按时间evrscar21#
已解决：