Forecast Channel

Forecast Channel
Version	0.7 (7)
Type	General channel
Peripherals

The Forecast channel download data packages from Nintendo servers via plain http connection.

Some examples:

http://weather.wapp.wii.com/1/076/short.bin
http://weather.wapp.wii.com/1/076/forecast.bin

http://news.wapp.wii.com/ displays a Red Hat Enterprise Linux Test Page.

File structure:

$0000 - $003F: padding (00)
$0040 - $013F: rsa encrypted sha-1 signature of rest of the file
$0140 - $0143: header
$0144 - .....: compressed data

The compression is very simple:

1. Read one byte
2. For each bit of the byte, msb-to-lsb,
   • if 0, copy one byte to the output
   • if 1, read 16 bits msb first in v, copy n bytes at offset m from the end of the output, n=3+(v>>12), m=v & fff

Quick and very dirty C code:

  i = 0x144;
  j = 0;
  while(i < size) {
    int k;
    int v = data[i++];
    for(k=0; k<8; k++)
      if(!(v & (1 << (7-k)))) {
        result_data[j++] = data[i++];
      } else {
        int vv = (data[i] << 8) | data[i+1];
        int nb = 3+(vv >> 12);
        int off = (vv & 0xfff);
        int l;
        i+=2;
        for(l=0; l<nb; l++) {
          result_data[j] = result_data[j-off-1];
          j++;
        }
      }
  }