f.c

来自「实现在ARM上的ICP/IP功能的源代码。」· C语言 代码 · 共 17 行

#include "typedef.h"
#include "utilities.h"
#include "ip.h"
u16_t chkum(u16_t *dataptr,u16_t len,u32_t acc)
{
for(;len>1;len-=2)
acc+=*(u16_t*)dataptr++;
if(len&1){
acc+=htons((u16_t)((*(u8_t*)dataptr)&0xff)<<8);
Uart_Printf("\nLWIPCS: there is an odd no...\n");
}
acc=(acc>>16)+(acc&0xffff);
acc+=(acc>>16);
return ((~acc)&0xffff);
}/*验证通过*/