将存储在EDX：EAX中的64位数字打印为标准输出 [英] Print 64 bit number stored in EDX:EAX to standard out

问题描述

我在EDX：EAX中分别存储了64位大数字，分别为21C3677C：82B40000。我试图将数字以小数点形式输出到控制台2432902008176640000是否有系统调用可以实现此目的？

I have large 64 bit number stored in EDX:EAX as 21C3677C:82B40000 respectively. I'm trying to print the number out to the console as a decimal 2432902008176640000 Is there a system call that will allow me to accomplish this?

推荐答案

这里是一个如何使用printf打印64位数字的示例。

Here is an example how to print the 64 bit number with printf. This code works with YASM.

segment .data
    format db "Number %ld", 0x0a, 0 ; Format string for printf
    result dq 0                     ; Quad word to store the EDX:EAX result in 

segment .text
    global main
    extern printf

main:
    ; Store the 64 bit number in the quad word "result"
    mov edx, 0x21C3677C  ; Store the EDX value
    mov eax, 0x82B40000  ; Store the EAX value
    mov [result], eax    ; Lower half of "result" will be EAX
    mov [result+4], edx  ; Upper half of "result" will be EDX

    ; Print "result" with the printf function
    xor eax, eax         ; No float parameters for printf
    lea rdi, [format]    ; First parameter for printf (format string)
    mov rsi, [result]    ; Second parameter for printf ("result")
    call printf          ; Call printf

    ; End program
    xor     eax, eax     ; Return 0
    ret   

使用以下命令构建二进制文件：

Build the binary with the following commands:

yasm -f elf64 example.asm
gcc -o example example.o

更新：不使用内存的示例

segment .data
    format db "Number %ld", 0x0a, 0 ; Format string for printf

segment .text
    global main
    extern printf

main:
    ; Store the 64 bit number in register rsi
    mov edx, 0x21C3677C  ; Store the EDX value (upper half)
    mov eax, 0x82B40000  ; Store the EAX value (lower half)
    mov esi, edx         ; Place upper half in esi
    shl rsi, 32          ; Shift left 32 bits
    or  rsi, rax         ; Place the lower half in rsi

    ; Print "result" with the printf function
    xor eax, eax         ; No float parameters for printf
    lea rdi, [format]    ; First parameter for printf (format string)
    call printf          ; Call printf

    ; End program
    xor     eax, eax     ; Return 0
    ret   

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