内存映射接口，进一步的问题

问题描述：

我仍然有我的C code，它与内存映射设备涉及的一些问题。
此刻，我申报寄存器我写挥发地址空间
指针，如下图所示将数据写入其中：

I still have some issues with my c code that deals with an memory mapped device. At the moment I declare the address space for the registers I write as volatile pointer and I write data to them as shown below:

volatile unsigned int *wr_register = (int *) 0x40000000;
volatile unsigned int *c_register =  (int *) 0x40000100;
...

main{

  *wr_register = 0x01234567;

  *c_register = 0x01234567;    
  *(c_register+1) = 0x89abcdef;  

}

本作品或多或少的罚款。不过，我想有特定的读取和
写与内存映射寄存器进行交互的功能。因此理想情况下，
它看起来是这样的：

This works more or less fine. However, I would like to have specific read and write functions that interact with the memory mapped registers. So ideally, it would look something like this:

const unsigned int wr_register = 0x40000000;
const unsigned int c_register  = 0x40000100;

function write_REG(unsigned int address, int offset, int data)
{
    (unsigned int*) (address + offset) = data;
}

main{

  *write_REG(0x40000000, 0, 0x01234567);

  *write_REG(0x40000100, 0, 0x01234567);
  *write_REG(0x40000100, 1, 0x89abcdef);  

}

我还没有尝试过了还没有说实话，但如果有人能我想知道
告诉我，如果这是做一个适当的方式？

I have not tried it out yet to be honest, but I am wondering if somebody could tell me if this is a proper way to do it?

编辑：也许这是用别人的，在这里我有我的功能，他们似乎工作。非常感谢为有益的意见！

Maybe it is of use for someone else, here I have my function and they seem to work. Many thanks for the helpful comments!

void reg_write(unsigned int address, int offset, int data)
{
    *((volatile unsigned int*)address + offset) = data;
}

int reg_read(unsigned int address, int offset)
{
    return(*((volatile unsigned int*)address + offset));
}

非常感谢

答

有您的code不少问题：

There are quite a few problems with your code:

我假设你的意思无效其中你写函数。

您应该使指针的函数内部是挥发性以及

您应该取消引用指针写数据之前。在 * 应该是里面的功能，而不是在调用点（ * WRITE_REG ），因为它是现在 - 这将是一个编译错误。

您应该添加的偏移量指针，而不是地址。这是因为偏移1，就是要在未来 INT 这可能是，比方说，4个字节了，但它添加到地址只会增加1个字节。

I assume you meant void where you wrote function.
You should make the pointer inside the function to be volatile as well.
You should dereference the pointer before writing the data. The * should be inside the function, not at the call site (*write_REG) as it is now - that would be a compile error.
You should add the offset to the pointer, not the address. This is because an offset of 1 is meant to be the next int which could be, say, 4 bytes away, but adding it to the address will only add 1 byte.

您纠正功能应该是这样的：

Your corrected function should look like this:

void write_REG(unsigned int address, int offset, int data)
{
    *((volatile unsigned int*)address + offset) = data;
}

和你这样调用它：

write_REG(0x40000000, 0, 0x01234567);

内存映射接口，进一步的问题

相关推荐