模拟网站建设软件有哪些,如果域名网站用来做违法,南阳网站优化排名,网站制作流程图实践了内核的数据结构kfifo记录下#xff0c;其特点分析看了下这篇博客写的很详细。https://blog.csdn.net/zhoutaopower/article/details/86491852
fifo.c 实现kfifo的主干函数接口#xff0c;但是很多有用的接口没有扩展#xff0c;需要的时候再扩展。
#includestdi… 实践了内核的数据结构kfifo记录下其特点分析看了下这篇博客写的很详细。https://blog.csdn.net/zhoutaopower/article/details/86491852
fifo.c 实现kfifo的主干函数接口但是很多有用的接口没有扩展需要的时候再扩展。
#includestdio.h
#includestdlib.h
#includemath.h
#includestring.h
#includefifo.h#define min(a, b) \
({ \typeof(a) _a (a); \typeof(b) _b (b); \_a _b ? _a : _b \
})static inline int fls(int x)
{int position;int i;if(0 ! x){for(i (x 1), position 0; i ! 0; position)i 1;}else{position -1;}return position1;
}static inline unsigned int roundup_pow_of_two(unsigned int x)
{return 1UL fls(x - 1);
}int __kfifo_alloc(struct __kfifo *fifo, unsigned int size, size_t esize)
{/** round up to the next power of 2, since our let the indices* wrap technique works only in this case.*/size roundup_pow_of_two(size);fifo-in 0;fifo-out 0;fifo-esize esize;if (size 2) {fifo-data NULL;fifo-mask 0;return -1;}// fifo-data kmalloc_array(esize, size, gfp_mask);fifo-data malloc(esize*size);if (!fifo-data) {fifo-mask 0;return -1;}fifo-mask size - 1;return 0;
}int __kfifo_init(struct __kfifo *fifo, void *buffer, unsigned int size, size_t esize)
{size / esize;size roundup_pow_of_two(size);fifo-in 0;fifo-out 0;fifo-esize esize;fifo-data buffer;if (size 2) {fifo-mask 0;return -1;}fifo-mask size - 1;return 0;
}void __kfifo_free(struct __kfifo *fifo)
{free(fifo-data);fifo-in 0;fifo-out 0;fifo-esize 0;fifo-data NULL;fifo-mask 0;
}/** internal helper to calculate the unused elements in a fifo*/
static inline unsigned int kfifo_unused(struct __kfifo *fifo)
{return (fifo-mask 1) - (fifo-in - fifo-out);
}static void kfifo_copy_in(struct __kfifo *fifo, const void *src, unsigned int len, unsigned int off)
{unsigned int size fifo-mask 1;unsigned int esize fifo-esize;unsigned int l;off fifo-mask;if (esize ! 1) {off * esize;size * esize;len * esize;}l min(len, size - off);memcpy(fifo-data off, src, l);memcpy(fifo-data, src l, len - l);/** make sure that the data in the fifo is up to date before* incrementing the fifo-in index counter*/
// smp_wmb();
}unsigned int __kfifo_in(struct __kfifo *fifo, const void *buf, unsigned int len)
{unsigned int l;l kfifo_unused(fifo);if (len l)len l;kfifo_copy_in(fifo, buf, len, fifo-in);fifo-in len;return len;
}static void kfifo_copy_out(struct __kfifo *fifo, void *dst,unsigned int len, unsigned int off)
{unsigned int size fifo-mask 1;unsigned int esize fifo-esize;unsigned int l;off fifo-mask;if (esize ! 1) {off * esize;size * esize;len * esize;}l min(len, size - off);memcpy(dst, fifo-data off, l);memcpy(dst l, fifo-data, len - l);/** make sure that the data is copied before* incrementing the fifo-out index counter*/
// smp_wmb();
}unsigned int __kfifo_out_peek(struct __kfifo *fifo,void *buf, unsigned int len)
{unsigned int l;l fifo-in - fifo-out;if (len l)len l;kfifo_copy_out(fifo, buf, len, fifo-out);return len;
}unsigned int __kfifo_out(struct __kfifo *fifo,void *buf, unsigned int len)
{len __kfifo_out_peek(fifo, buf, len);fifo-out len;return len;
}
fifo.h
#includestdio.h
#includestdlib.hstruct __kfifo {unsigned int in; // 入列的时候增加的位置unsigned int out; // 出列的时候增加的位置unsigned int mask; // 巧妙的 mask 设计同时包含了数据的个数信息unsigned int esize; // 元素的大小void *data; // 数据
};int __kfifo_alloc(struct __kfifo *fifo, unsigned int size, size_t esize);
int __kfifo_init(struct __kfifo *fifo, void *buffer,unsigned int size, size_t esize);
void __kfifo_free(struct __kfifo *fifo);
unsigned int __kfifo_in(struct __kfifo *fifo, const void *buf, unsigned int len);
unsigned int __kfifo_out(struct __kfifo *fifo, void *buf, unsigned int len);
test.c
2024-04-07 记录#includestdio.h
#includestdlib.h
#includefifo.htypedef struct node
{int a;int b;
}node;int main()
{int esize sizeof(node);int size 8;void *buf NULL;struct __kfifo fifo;int count;node aa;aa.a 12;aa.b 13;node bb;bb.a 0;bb.b 0;__kfifo_init(fifo, buf, size, esize);__kfifo_alloc(fifo, size, esize);count __kfifo_in(fifo, (void *)aa, 1); //注意这里传参是node的数量不是node的大小。一开始实践赋值了node的大小会有内存溢出。printf(in count: %d.\n, count);count __kfifo_out(fifo, (void *)bb, 1);printf(out count: %d.\n, count);printf(bb.a :%d, bb.b :%d.\n, bb.a, bb.b);return 0;
}
