#include "utils.h"

u16_t chksum(u16_t sum, const u8_t *data, u16_t len)
{
  u16_t t;
  const u8_t *dataptr;
  const u8_t *last_byte;

  dataptr = data;
  last_byte = data + len - 1;
  
  while(dataptr < last_byte) 
  {  /* At least two more bytes */
    t = (dataptr[0] << 8) + dataptr[1];
    sum += t;
    if(sum < t) 
    {
      sum++;    /* carry */
    }
    dataptr += 2;
  }
  
  if(dataptr == last_byte) 
  {
    t = (dataptr[0] << 8) + 0;
    sum += t;
    if(sum < t) 
    {
      sum++;    /* carry */
    }
  }

  /* Return sum in host byte order. */
  return sum;
}


char *uip_ntoa(uip_ipaddr_t addr, char *buf, int buflen)
{
    u32_t s_addr;
    char inv[3];
    char *rp;
    u8_t *ap;
    u8_t rem;
    u8_t n;
    u8_t i;
    int len = 0;

    s_addr = *(u32_t *)addr;

    rp = buf;
    ap = (u8_t *) &s_addr;
    for (n = 0; n < 4; n++)
    {
        i = 0;
        do
        {
            rem = *ap % (u8_t) 10;
            *ap /= (u8_t) 10;
            inv[i++] = (char) ('0' + rem);
        } while (*ap);
        while (i--)
        {
            if (len++ >= buflen)
            {
                return NULL;
            }
            *rp++ = inv[i];
        }
        if (len++ >= buflen)
        {
            return NULL;
        }
        *rp++ = '.';
        ap++;
    }
    *--rp = 0;
    return buf;
}

u8_t uip_aton(const char *addrstr, u8_t *ipaddr)
{
  u8_t tmp;
  char c;
  u8_t i, j;

  tmp = 0;
  
  for(i = 0; i < 4; ++i) 
  {
    j = 0;
    do 
    {
      c = *addrstr;
      
      ++j;
      
      if(j > 4) 
      {
        return 0;
      }
      
      if(c == '.' || c == 0) 
      {
        *ipaddr = tmp;
        ++ipaddr;
        tmp = 0;
      } 
      else if(c >= '0' && c <= '9') 
      {
        tmp = (tmp * 10) + (c - '0');
      } 
      else 
      {
        return 0;
      }
      
      ++addrstr;
      
    } while(c != '.' && c != 0);
  }
  return 1;
}