Import lwIP contrib rep

... from http://git.savannah.gnu.org/cgit/lwip/lwip-contrib.git/ into contrib/ subdir, STABLE-2_1_0_RELEASE tag
lwIP contrib is now officially frozen
TODO: Fix build

contrib/ports/unix/port/include/netif/fifo.h

@@ -0,0 +1,54 @@
+#ifndef FIFO_H
+#define FIFO_H
+
+#include "lwip/sys.h"
+
+/** How many bytes in fifo */
+#define FIFOSIZE 2048
+
+/** fifo data structure, this one is passed to all fifo functions */
+typedef struct fifo_t {
+  u8_t data[FIFOSIZE+10]; /* data segment, +10 is a hack probably not needed.. FIXME! */
+  int dataslot;			  /* index to next char to be read */
+  int emptyslot;		  /* index to next empty slot */
+  int len;				  /* len probably not needed, may be calculated from dataslot and emptyslot in conjunction with FIFOSIZE */
+
+  sys_sem_t sem;		/* semaphore protecting simultaneous data manipulation */
+  sys_sem_t getSem;		/* sepaphore used to signal new data if getWaiting is set */
+  u8_t getWaiting;		/* flag used to indicate that fifoget is waiting for data. fifoput is suposed to clear */
+  						/* this flag prior to signaling the getSem semaphore */
+} fifo_t;
+
+
+/**
+*   Get a character from fifo
+*   Blocking call.
+*	@param 	fifo pointer to fifo data structure
+*	@return	character read from fifo
+*/
+u8_t fifoGet(fifo_t * fifo);
+
+/**
+*   Get a character from fifo
+*   Non blocking call.
+*	@param 	fifo pointer to fifo data structure
+*	@return	character read from fifo, or < zero if non was available
+*/
+s16_t fifoGetNonBlock(fifo_t * fifo);
+
+/**
+*	fifoput is called by the signalhandler when new data has arrived (or some other event is indicated)
+*   fifoput reads directly from the serialport and is thus highly dependent on unix arch at this moment
+*	@param 	fifo pointer to fifo data structure
+*	@param	fd	unix file descriptor
+*/
+void fifoPut(fifo_t * fifo, int fd);
+
+/**
+*   fifoinit initiate fifo
+*	@param 	fifo	pointer to fifo data structure, allocated by the user
+*/
+void fifoInit(fifo_t * fifo);
+
+#endif
+