用汇编打印十六进制数字 [英] Printing Hexadecimal Digits with Assembly

问题描述

我正在尝试学习 NASM 汇编，但似乎只是在高级语言中遇到了困难.

I'm trying to learn NASM assembly, but I seem to be struggling with what seems to simply in high level languages.

我使用的所有教科书都讨论使用字符串——事实上，这似乎是他们最喜欢的东西之一.打印hello world，大写变小写等

All of the textbooks which I am using discuss using strings -- in fact, that seems to be one of their favorite things. Printing hello world, changing from uppercase to lowercase, etc.

但是，我试图了解如何在 NASM 程序集中增加和打印十六进制数字，但不知道如何继续.例如，如果我想在十六进制中打印 #1 - n，如果不使用 C 库(我已经能够找到使用的所有引用)，我该怎么做?

However, I'm trying to understand how to increment and print hexadecimal digits in NASM assembly and don't know how to proceed. For instance, if I want to print #1 - n in Hex, how would I do so without the use of C libraries (which all references I have been able to find use)?

我的主要想法是在 .data 部分有一个变量，我会继续增加它.但是如何从这个位置提取十六进制值呢?我好像需要先把它转换成字符串...?

My main idea would be to have a variable in the .data section which I would continue to increment. But how do I extract the hexadecimal value from this location? I seem to need to convert it to a string first...?

任何建议或示例代码将不胜感激.

Any advice or sample code would be appreciated.

推荐答案

首先编写一个简单的例程，它以 nybble 值 (0..15) 作为输入并输出一个十六进制字符 ('0'..'9','A'...'F').

First write a simple routine which takes a nybble value (0..15) as input and outputs a hex character ('0'..'9','A'..'F').

接下来编写一个以字节值作为输入的例程，然后调用上述例程两次以输出 2 个十六进制字符，即每个 nybble 一个.

Next write a routine which takes a byte value as input and then calls the above routine twice to output 2 hex characters, i.e. one for each nybble.

最后，对于 N 字节整数，您需要一个例程，该例程调用第二个例程 N 次，每个字节一次.

Finally, for an N byte integer you need a routine which calls this second routine N times, once for each byte.

您可能会发现先用伪代码或 HLL(如 C)表达这一点会有所帮助，然后再考虑如何将其转换为 asm，例如

You might find it helpful to express this in pseudo code or an HLL such as C first, then think about how to translate this into asm, e.g.

void print_nybble(uint8_t n)
{
    if (n < 10) // handle '0' .. '9'
        putchar(n + '0');
    else // handle 'A'..'F'
        putchar(n - 10 + 'A');
}

void print_byte(uint8_t n)
{
    print_nybble(n >> 4); // print hi nybble
    print_nybble(n & 15); // print lo nybble
}

print_int16(uint16_t n)
{
    print_byte(n >> 8); // print hi byte
    print_byte(n & 255); // print lo byte
}

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