for ( unsigned int address = 0x287; address < 0x28f; address++) {}这个为什么进不去循环
时间: 2023-08-04 16:03:02 浏览: 41
这段代码的循环条件 `address < 0x28f` 是使用无符号整数(unsigned int)进行比较的。在无符号整数的表示范围内,它的最大值是无符号整数能表示的最大值。如果 `address` 的初始值 `0x287` 已经大于或等于无符号整数的最大值,那么循环条件将始终为假,不会进入循环。
请确保 `address` 的初始值小于无符号整数的最大值,以确保循环条件可以满足。如果你需要在循环中使用无符号整数进行迭代,可以尝试将 `address` 的初始值修改为小于 `0x28f` 的值。例如,将初始值修改为 `0x286`。
另外,请确保循环体内有具体的语句或逻辑,否则循环体为空时可能会被编译器优化而被忽略。
相关问题
regmap_block_write() 写入 command code=0x32, slave address = 0x2461 的数据 实例
好的,下面是一个使用 regmap_block_write() 函数写入 command code=0x32,slave address=0x2461 的数据的示例:
```c
#include <linux/regmap.h>
// 假设已经定义了一个名为 my_regmap 的 regmap 结构体指针
unsigned int slave_addr = 0x2461;
unsigned int reg_addr = 0x00; // 假设要写入的寄存器地址为 0x00
unsigned char data[] = {0x01, 0x02, 0x03}; // 假设要写入的数据为 0x01, 0x02, 0x03
size_t data_count = sizeof(data); // 数据的数量
// 写入操作
int ret = regmap_block_write(my_regmap, (0x32 << 8) | slave_addr, ®_addr, 1);
if (ret != 0) {
printk(KERN_ERR "Failed to write command code\n");
return ret;
}
// 继续写入数据
ret = regmap_block_write(my_regmap, (0x32 << 8) | slave_addr, data, data_count);
if (ret != data_count) {
printk(KERN_ERR "Failed to write data\n");
return ret;
}
// 写入完成
printk(KERN_INFO "Data written successfully\n");
```
在上述示例中,我们首先将 command code 和 slave address 合并为一个 16 位的地址,然后通过 regmap_block_write() 函数先写入命令码,再写入数据。需要注意的是,命令码应该左移 8 位之后与 slave address 进行按位或运算。
如果写入操作成功,函数将返回写入的数据字节数(即 data_count)。如果出现错误,将返回一个负数。
*(unsigned int*)0x40010C00 =((1)<<(4*0))
This line of code is setting a specific bit in a register at memory address 0x40010C00.
The expression `((1)<<(4*0))` shifts the value 1 by 0 bits, which effectively leaves the value unchanged (since any number shifted by 0 bits is still the same number). The result is simply 1.
The outer parentheses are not strictly necessary, but they help clarify the order of operations.
The entire expression is then cast to an `unsigned int*`, which is a pointer to an unsigned integer. This pointer is then dereferenced and assigned the value of 1, effectively setting a specific bit in the register to 1.
The exact meaning of this operation depends on the specific hardware and register being accessed.