将十六进制值拆分为单个组件 [英] Split hex value into individual components

问题描述

我如何将一个十六进制值分成单独的值。

假设我有一个字节0xFF。我怎么会得到一个值是F，第二个是F在Objective-C？我试图在Objective-C中实现SubBytes（）过程，显然，SubBytes（）步骤包含一个矩阵，其中输出取决于字节的第一个和第二个十六进制表示形式。

解决方案

下面是一个如何屏蔽/移动要查找的十六进制字节部分的示例：

 字节exampleValue = 0x23; 
 Byte nibble1 = 0x0F& exampleValue; 
 Byte nibble2 =（0xF0& exampleValue）>> 4; 
 
 NSLog（@nibble2 =％d，nibble1 =％d，nibble2，nibble1）; 
  

这个例子会给出一个输出：nibble2 = 2，nibble1 = 3

How do I split a hex value into individual values.

Suppose I have a byte, 0xFF. How would I get one value being F and a second being F in Objective-C?

I'm trying to implement the SubBytes() procedure in Objective-C and obviously, the SubBytes() step involves a matrix where the output is dependent on the first and second hex representations of the byte.

解决方案

Here's an example of how you can mask out / shift the portion of the hex bytes that you're looking for:

Byte exampleValue = 0x23;
Byte nibble1 = 0x0F & exampleValue;
Byte nibble2 = (0xF0 & exampleValue)>>4;

NSLog(@"nibble2 = %d, nibble1 = %d", nibble2, nibble1);

This example will give an output: nibble2 = 2, nibble1 = 3

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