Could someone please explain what the following code does. private int ReadInt32(byte[] _il, ref int position) { return (((il[position++] | (il[position++] << 8)) | (il[position++] << 0x10)) | (il[position++] << 0x18)); } I'm not sure I understand how the bitwise operators in this method work, could some please break it down for me? The integer is given as a byte arr
有人可以解释下面的代码是做什么的。 private int ReadInt32(byte[] _il, ref int position) { return (((il[position++] | (il[position++] << 8)) | (il[position++] << 0x10)) | (il[position++] << 0x18)); } 我不确定我是否明白这种方法中的按位运算符是如何工作的，有人可以为我分解它吗？ 整数以字节数组形式给出。 然后将每个字节左移0/8/16/24位，并将这些值相加得到整数值。 这是一个十
I have records with flexible array member typedef struct record { unsigned foo; signed bar; double number[]; } record; I have multiple records with the same amount of numbers so I can arrange them in array. I would like to allocate them into one continuous memory space. const unsigned numbers = ...; const unsigned records = ...; const size_t record_size = sizeof(record) + numbers*
我有灵活的阵列成员的records typedef struct record { unsigned foo; signed bar; double number[]; } record; 我有多个records与同量的numbers ，所以我可以在阵列排列。 我想将它们分配到一个连续的内存空间中。 const unsigned numbers = ...; const unsigned records = ...; const size_t record_size = sizeof(record) + numbers*sizeof(double); record *prec = malloc(records*record_size); 所以现在
How dangerous is accessing an array outside of its bounds (in C)? It can sometimes happen that I read from outside the array (I now understand I then access memory used by some other parts of my program or even beyond that) or I am trying to set a value to an index outside of the array. The program sometimes crashes, but sometimes just runs, only giving unexpected results. Now what I would li
访问数组之外的数组有多危险（C语言中）？ 有时候可能会发生，我从数组外读取（现在我明白了，然后访问我的程序的某些其他部分使用的内存，甚至超出了该范围），或者我试图将值设置为数组之外的索引。 该程序有时会崩溃，但有时只是运行，只会产生意想不到的结果。 现在我想知道的是，这真的有多危险？ 如果它损害我的程序，它并不坏。 另一方面，如果它在我的程序之外打破了某些东西，因为我设法访问了一些完全不相关的
Having some trouble figuring out the hit and miss rates of the following two snippets of code. Given info: we have a 1024 Byte direct-mapped cache with block sizes of 16 bytes. So that makes 64 lines (sets in this case) then. Assume the cache starts empty. Consider the following code: struct pos { int x; int y; }; struct pos grid[16][16]; int total_x = 0; int total_y = 0; void fun
在计算以下两段代码的命中率和缺失率时遇到一些困难。 给定信息：我们有一个1024字节的直接映射缓存，块大小为16字节。 这样就可以生成64行（这里是集合）。 假设缓存开始为空。 考虑下面的代码： struct pos { int x; int y; }; struct pos grid[16][16]; int total_x = 0; int total_y = 0; void function1() { int i, j; for (i = 0; i < 16; i++) { for (j = 0; j < 16; j++) {
I just finished a homework problem for Computer Science 1 (yes, it's homework, but hear me out!). Now, the assignment is 100% complete and working, so I don't need help on it. My question involves the efficiency of an algorithm I'm using (we aren't graded on algorithmic efficiency yet, I'm just really curious). The function I'm about to present currently uses a modifie
我刚刚完成了计算机科学1的作业问题（是的，这是作业，但听我说！）。 现在，这个任务已经完成并且工作了，所以我不需要帮助。 我的问题涉及到我使用的算法的效率（我们没有对算法效率进行评分，我只是很好奇）。 我要介绍的功能目前使用线性搜索算法的修改版本（我自己想出了这个算法！），以便检查给定彩票上的数字与获胜的数字相匹配，假设两者都是票上的号码和所画的号码按升序排列。 我想知道，有什么方法可以使这个算
Answering to another Stack Overflow question (this one) I stumbled upon an interesting sub-problem. What is the fastest way to sort an array of 6 ints? As the question is very low level: we can't assume libraries are available (and the call itself has its cost), only plain C to avoid emptying instruction pipeline (that has a very high cost) we should probably minimize branches, jumps,
回答另一个堆栈溢出问题（这一个）我偶然发现了一个有趣的子问题。 对6个整数的数组进行排序的最快方法是什么？ 由于问题非常低： 我们不能假定图书馆可用（并且通话本身有其成本），只有普通的C 为避免清空指令流水线（成本非常高），我们应该尽量减少分支，跳转以及其他任何类型的控制流程中断（例如隐藏在&&或||序列点后面的流程）。 空间有限，尽量减少寄存器和内存的使用是一个问题，理想情况下，排序可能
I have been studying measuring memory bandwidth for Intel processors with various operations and one of them is memcpy . I have done this on Core2, Ivy Bridge, and Haswell. I did most of my tests using C/C++ with intrinsics (see the code below - but I'm currently rewriting my tests in assembly). To write your own efficient memcpy function it's important to know what the absolute best
我一直在研究用各种操作测量英特尔处理器的内存带宽，其中之一是memcpy 。 我在Core2，Ivy Bridge和Haswell上做了这个。 我使用带有内在函数的C / C ++进行了大部分测试（请参阅下面的代码 - 但我正在用汇编重写我的测试）。 要编写自己的高效memcpy函数，重要的是要知道绝对最佳带宽可能是什么。 该带宽是将被复制的数组大小的函数，因此对于小型和大型（以及可能在两者之间），高效的memcpy函数需要进行不同的优化。 为
Possible Duplicate: Can a local variable's memory be accessed outside its scope? Scope vs life of variable in C int *p; void foo() { int i = 5; p = &i; } void foo1() { printf("%dn", *p); } int main() { foo(); foo1(); return 0; } Output: 5 (foo1() print the value of i) Note: I am running this program on Linux According my knowledge, the scope of local auto
可能重复： 局部变量的内存是否可以在其范围之外访问？ 范围与C中变量的生命期 int *p; void foo() { int i = 5; p = &i; } void foo1() { printf("%dn", *p); } int main() { foo(); foo1(); return 0; } 输出：5（foo1（）打印i的值） 注意：我正在Linux上运行此程序 据我所知，本地自动变量的范围仅限于块/函数的寿命。 在foo（）中，这个变量在哪个内存段中存储？ 或者所有函数的
Possible Duplicate: Can a local variable's memory be accessed outside its scope? I was refreshing the knowledge about how memory internally works, and I faced the confusion. Here is sample code int * func(){ int retval = 3; return &retval; } int main(void){ int *ptr = func(); printf("address return from function %p and value %dn", ptr, *ptr); } My understanding regards
可能重复： 局部变量的内存是否可以在其范围之外访问？ 我正在刷新关于内存如何工作的知识，并且我遇到了困惑。 这里是示例代码 int * func(){ int retval = 3; return &retval; } int main(void){ int *ptr = func(); printf("address return from function %p and value %dn", ptr, *ptr); } 我的理解是关于堆栈内存在例程中的工作方式，是当函数被调用时，它被推入堆栈。 一旦函数返回，此例程中局
I can't find information, how create joystick with several buttons on it using uinput / suinput . Example on python using python-uinput : import uinput def main(): events = ( uinput.BTN_JOYSTICK, uinput.ABS_X + (0, 255, 0, 0), uinput.ABS_Y + (0, 255, 0, 0), ) with uinput.Device(events) as device: for i in range(20): # syn=False t
我找不到信息，如何使用uinput / suinput创建带有几个按钮的suinput 。 上实施例python用python-uinput ： import uinput def main(): events = ( uinput.BTN_JOYSTICK, uinput.ABS_X + (0, 255, 0, 0), uinput.ABS_Y + (0, 255, 0, 0), ) with uinput.Device(events) as device: for i in range(20): # syn=False to emit an "atomic" (5, 5) event.