例如,在嵌入式系统中访问设备寄存器: volatile unsigned int * const address = (unsigned int * const)0x12345678; // 将硬件寄存器地址赋值给指针*address = 0x1234; // 向硬件寄存器写入数据unsigned int value = *address; // 从硬件寄存器读取数据 多线程同步 在多线程编程中,如果多个线程同时访问某个共享...
volatile unsigned int* registerPtr = (volatile unsigned int*)REGISTER_ADDRESS; int main() { // 启动一个线程,不断读取寄存器的值并输出 std::thread readerThread([]{ while (true) { unsigned int value = *registerPtr; // 读取寄存器的值 std::cout << "Register value: " << value << std:...
把宏定义放入句中就是（*(volatile unsigned int *)）（0x4e000000），不知其何意？？好像是定义一指针，该指针指向的内容就是0x4e000000该寄存器的内容。网上查了资料，先看英文的,看看外国人怎么解释：Using C, I was trying to assign a variable name to a register address so that my code would be ...
voidAssembler::lock(){// 对应lock指令emit_int8((unsigned char)0xF0);// lock对应0x0F二进制代码}voidAssembler::addl(Address dst,int32_t imm32){// 对应addl指令InstructionMarkim(this);prefix(dst);emit_arith_operand(0x81,rax,dst,imm32);// add对应0x81} 在Java Hotspot VM中有多个重载的As...
unsigned int *p = GetMagicAddress(); unsigned int a, b; a = *p b = *p; 考虑上面的代码,假设GetMagicAddress()是获得内存的地址,那么a = *p, b = *p,会被编译器认为是相同的操作,假设a = *p 使得值缓存在寄存器中,那么为了速度优化,编译器可能会将最后一行的代码换成 ...
voidplatform_reset(void){volatileunsignedint* p = (void*)0xb8008000;/* *TODO:we should take care of TLB stuff here. Otherwise * board does not boots properly next time *//* Write 0x8000_0001 to the Reset register */*p =0x80000001; ...
unsigned int *p = GetMagicAddress(); unsigned int a, b; a = *p b = *p; 考虑上面的代码,假设GetMagicAddress()是获得内存的地址,那么a = *p, b = *p,会被编译器认为是相同的操作,假设a = *p 使得值缓存在寄存器中,那么为了速度优化,编译器可能会将最后一行的代码换成 ...
unsigned short __shrt; __asm__ ("mov %0,%%bx" : : "a"(__shrt)); 由于变量__shrt是16-bit short类型,则编译出来的汇编代码中,则会让此变量使用%ex寄存器。编译结果为: movw -2(%ebp), %ax # %ax = __shrt #APP movl %ax, %bx ...
/** Declare the device registers* Whether to use int or short* is implementation dependent*/struct devregs{unsigned short volatile csr;unsigned short const volatile data;};/* bit patterns in the csr */#define ERROR 0x1#define READY 0x2#define RESET 0x4/* absolute address of the device *...
defineGPIOB_ODR(*(volatileunsignedlong*)0x40010C10UL) example: GPIOB_ODR=1;GPIOB_ODR=2;GPIOB_ODR=3; 如果不使用volatile修饰符,并且开启 O3 优化,则编译器可能会将上面的代码优化成: // 编译器会任务前面两个只是中间过程,所以会被优化掉// 但是对寄存器的每一次操作都是有现实意义的GPIOB_ODR=3;...