n = sz;
if (packet_max - 5 < n)
n = packet_max - 5;
- sprintf(hdr, "%04x", n + 5);
- hdr[4] = band;
- safe_write(fd, hdr, 5);
+ if (0 <= band) {
+ sprintf(hdr, "%04x", n + 5);
+ hdr[4] = band;
+ safe_write(fd, hdr, 5);
+ } else {
+ sprintf(hdr, "%04x", n + 4);
+ safe_write(fd, hdr, 4);
+ }
safe_write(fd, p, n);
p += n;
sz -= n;