合并算法

来源：互联网发布：ubuntu 查看系统语言编辑：程序博客网时间：2024/05/18 22:16
编写该算法解决的是，在tcp报文里面有很多的块，需要合并成一整块进行处理。使用的是递归
#include <stdlib.h>#include <stdio.h>#include <string.h>#include <malloc.h>#include "list.h"typedef unsigned int uint32;#define HERE printf("HERE: %s %d\n", __FUNCTION__,__LINE__)#define debug #define debug2 printf#ifndef min#definemin(a, b)((a) < (b) ? (a) : (b))#definemax(a,b) (((a)>(b))?(a):(b))#endifstruct buff_fragment {struct list_head list;unsigned int start;unsigned int end;//[start, end)};int merging(struct buff_fragment *fa, struct buff_fragment *fb){int fa_len = fa->end - fa->start;int fb_len = fb->end - fb->start;int dist = fa_len + fb_len;int diff;int fb_is_rear = 0;if (fb->end >= fa->end) {diff = fb->end - fa->start;fb_is_rear = 1;} else {diff = fa->end - fb->start;}if (diff <= dist) {fa->start = min(fa->start, fb->start);fa->end = max(fa->end, fb->end);debug2("merging start=%d, end=%d\n", fa->start, fa->end);return 0;}return fb_is_rear?1:2;}int dpi_merge_fragment(struct list_head *head, uint32 start, uint32 end){struct buff_fragment *fa, *temp;struct buff_fragment *prev = NULL;;int rc;struct buff_fragment *fb = malloc(sizeof(struct buff_fragment));fb->start = start;fb->end = end;debug2("dpi_merge_fragment: start = %u, end = %u\n", start, end);if (!fb)return -1;if (list_empty(head)) {list_add(&fb->list, head);return 0;}list_for_each_entry(fa, head, list) {if (fa->end < fb->start) {prev = fa;continue;}rc = merging(fa, fb);if (0 == rc)  {list_del(&fa->list);start = fa->start;end = fa->end;free(fa);free(fb);return dpi_merge_fragment(head, start, end);}break;}if (!prev) {HERE;list_add(&fb->list, head);return 0;} if (rc == 1) {HERE;list_add(&fb->list, &fa->list);} else {HERE;list_add(&fb->list, &prev->list);}return 0;}void dpi_show_fragment(struct list_head *head){struct buff_fragment *fa;int id = 0;debug2("dpi_show_fragment\n");list_for_each_entry(fa, head, list) {debug2("fa[%d]->start=%d, end=%d\n", id++, fa->start, fa->end);}}LIST_HEAD(fhead);struct buff_fragment data[]={{.start = 1,.end = 6},{.start = 5,.end = 10},{.start = 14,.end = 19},{.start = 13,.end = 14},{.start = 3,.end = 13},{.start = 100,.end = 200},{.start = 50,.end = 70},};int main(void){int i =0;for (;i< (sizeof(data) / sizeof(struct buff_fragment)); i++) {dpi_merge_fragment(&fhead, data[i].start, data[i].end);}dpi_show_fragment(&fhead);            return 0;}
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