project2 - RDT3.0 구현

목차

[Rdt3.0_functions] 7.56kb
　　error.c
　　in_cksum.c
　　Makefile
　　np.h
　　packet.h
　　set_address.c
　　tselect.c
　　udp_server.c
　　udt_send.c


[receiver] 2.06MB
　　error.c
　　error.o
　　in_cksum.c
　　in_cksum.o
　　Makefile
　　np.h
　　packet.h
　　receiver
　　receiver.c
　　receiver.o
　　Result1.txt
　　Result2.jpg
　　set_address.c
　　set_address.o
　　tselect.c
　　tselect.o
　　udt_send.c
　　udt_send.o


[sender] 2.05MB
　　error.c
　　error.o
　　in_cksum.c
　　in_cksum.o
　　Makefile
　　np.h
　　packet.h
　　sender
　　sender.c
　　sender.o
　　set_address.c
　　set_address.o
　　Test1.txt
　　Test2.jpg
　　tselect.c
　　tselect.o
　　udt_send.c
　　udt_send.o

본문내용

#include "np.h"

uint16_t
in_cksum(uint16_t *addr, int len)
{
int nleft = len;
uint32_t sum = 0;
uint16_t *w = addr;
uint16_t answer = 0;

/*
* Our algorithm is simple, using a 32 bit accumulator (sum), we add
* sequential 16 bit words to it, and at the end, fold back all the
* carry bits from the top 16 bits into the lower 16 bits.
*/
while (nleft > 1) {
sum += *w++;
nleft -= 2;
}

/* 4mop up an odd byte, if necessary */
if (nleft == 1) {
*(unsigned char *)(&answer) = *(unsigned char *)w ;
sum += answer;
}

/* 4add back carry outs from top 16 bits to low 16 bits */
sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */
sum += (sum >> 16); /* add carry */
answer = ~sum; /* truncate to 16 bits */
return(answer);
}

키워드

RDT 3.0 설계 및 구현 소스코드 및 함수 파일들,   RDT3.0,   project2