TOSWeb/Net/NetFifo.HC

// Warning: terrible code ahead. this still needs a lot of work

// In the future we'll probably have 2 FIFOs (pending frames & empty buffers)
// TODO: check if FIFO implementation is suitable for high throughput

#define NET_FIFO_DEPTH 1024

#define ETHERNET_FRAME_SIZE 1548

#define ETHERTYPE_IPV4 0x0800
#define ETHERTYPE_ARP 0x0806

class CNetFifoEntry {
  I64 length;
  U8 frame[ETHERNET_FRAME_SIZE];
};

static CFifoI64 *netfifo;

static CNetFifoEntry *entries;
static I64 next_entry = 0;

CTask *netfifo_handler_task = NULL;

// TODO: asm optimization? or perhaps use EndianU*?
// These don't belong here in the first place,
// but it's convenient for Ethernet drivers
// We'll probably split it off along with ETHERTYPE_* constants

U16 htons(U16 h) { return ((h >> 8) | (h << 8)) & 0xffff; }

U16 ntohs(U16 h) { return ((h >> 8) | (h << 8)) & 0xffff; }

U32 htonl(U32 h) {
  return ((h >> 24) | ((h & 0x00ff0000) >> 8) | ((h & 0x0000ff00) << 8) |
          (h << 24)) &
         0xffffffff;
}

U32 ntohl(U32 h) {
  return ((h >> 24) | ((h & 0x00ff0000) >> 8) | ((h & 0x0000ff00) << 8) |
          (h << 24)) &
         0xffffffff;
}

CNetFifoEntry *NetFifoPull() {
  CNetFifoEntry *entry;

  if (FifoI64Rem(netfifo, &entry))
    return entry;
  else
    return NULL;
}

I64 NetFifoPushCopy(U8 *data, I64 length) {
  CNetFifoEntry *entry = &entries[next_entry];
  next_entry = (next_entry + 1) & (NET_FIFO_DEPTH - 1);

  entry->length = length;
  MemCpy(entry->frame, data, length);

  if (!FifoI64Ins(netfifo, entry))
    return -1;

  // Wake up Handler Task
  if (netfifo_handler_task)
    LBtr(&netfifo_handler_task->task_flags, TASKf_IDLE);

  return 0;
}

U0 NetFifoInit() {
  netfifo = FifoI64New(NET_FIFO_DEPTH);
  entries = MAlloc(NET_FIFO_DEPTH * sizeof(CNetFifoEntry));
}

NetFifoInit;