[lwip-users] RE:Re: Checksum problem with lwip_chksum()

[Chris WIlliams]

We all have our own way of coding. This is my routine at the moment.

I can't tell if this is faster of slower than John Taylors. If people
find this of use, could it be included properly?

Good luck.

static u16_t
lwip_chksum(void *dataptr, int len)
{
  u32_t acc = 0;
        unsigned char *dp = (unsigned char *)dataptr;
        int half_len;

        for(half_len = len / 2;half_len;half_len--){
                acc += ((u16_t)*dp++) << 8;
                acc += *dp++;
        }
        if(len & 1){
                acc += ((u16_t)*dp++) << 8;
        }

  acc = (acc >> 16) + (acc & 0xffffUL);

  if ((acc & 0xffff0000L) != 0) {
         acc = (acc >> 16) + (acc & 0xffffUL);
  }
  return (u16_t)acc;
}

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