LOWPAN_DISPATCH_FRAG1
if (frag_type == LOWPAN_DISPATCH_FRAG1)
if (frag_type == LOWPAN_DISPATCH_FRAG1) {
return (dispatch & LOWPAN_DISPATCH_FRAG_MASK) == LOWPAN_DISPATCH_FRAG1;
frag_hdr[0] = LOWPAN_DISPATCH_FRAG1 | ((dgram_size >> 8) & 0x07);
frag_hdr[0] &= ~LOWPAN_DISPATCH_FRAG1;