source: azure_iot_hub_f767zi/trunk/asp_baseplatform/lwip/contrib-2.1.0/ports/unix/port/netif/fifo.c@ 457

/* Author: Magnus Ivarsson <magnus.ivarsson@volvo.com> */

/* ---------------------------------------------- */
/* --- fifo 4 unix ------------------------------ */
/* ---------------------------------------------- */
#include "lwip/err.h"
#include "netif/fifo.h"
#include "lwip/debug.h"
#include "lwip/def.h"
#include "lwip/sys.h"
#include "lwip/arch.h"
#include <unistd.h>

#ifndef TRUE
#define TRUE  1
#endif
#ifndef FALSE
#define FALSE 0
#endif

#ifndef SIO_FIFO_DEBUG
#define SIO_FIFO_DEBUG LWIP_DBG_OFF
#endif

u8_t fifoGet(fifo_t * fifo) 
{
        u8_t c;

        sys_sem_wait(&fifo->sem);      /* enter critical section */

        if (fifo->dataslot == fifo->emptyslot) 
        {
            fifo->getWaiting = TRUE;    /* tell putFifo to signal us when data is available */
            sys_sem_signal(&fifo->sem);  /* leave critical section (allow input from serial port..) */
            sys_sem_wait(&fifo->getSem); /* wait 4 data */
            sys_sem_wait(&fifo->sem);    /* reenter critical section */
        }

        c = fifo->data[fifo->dataslot++];
        fifo->len--;

        if (fifo->dataslot == FIFOSIZE) 
        {
                fifo->dataslot = 0; 
        }
        sys_sem_signal(&fifo->sem);    /* leave critical section */
        return c;
}


s16_t fifoGetNonBlock(fifo_t * fifo) 
{
        u16_t c;

        sys_sem_wait(&fifo->sem);      /* enter critical section */

        if (fifo->dataslot == fifo->emptyslot) 
        {
            /* empty fifo */
                c = -1;
        }
        else
        {
                c = fifo->data[fifo->dataslot++];
                fifo->len--;

                if (fifo->dataslot == FIFOSIZE) 
                {
                        fifo->dataslot = 0; 
                }
        }
        sys_sem_signal(&fifo->sem);    /* leave critical section */
        return c;
}


void fifoPut(fifo_t * fifo, int fd) 
{
        /* FIXME: mutex around struct data.. */
        int cnt=0;

        sys_sem_wait(&fifo->sem ); /* enter critical */

        LWIP_DEBUGF( SIO_FIFO_DEBUG,("fifoput: len%d dat%d empt%d --> ", fifo->len, fifo->dataslot, fifo->emptyslot ) );

        if ( fifo->emptyslot < fifo->dataslot )
        {
                cnt = read( fd, &fifo->data[fifo->emptyslot], fifo->dataslot - fifo->emptyslot );
        } 
        else
        {
                cnt = read( fd, &fifo->data[fifo->emptyslot], FIFOSIZE-fifo->emptyslot );
        }
        fifo->emptyslot += cnt;
        fifo->len += cnt;

        LWIP_DEBUGF( SIO_FIFO_DEBUG,("len%d dat%d empt%d\n", fifo->len, fifo->dataslot, fifo->emptyslot ) );

        if ( fifo->len > FIFOSIZE )
        {
                printf( "ERROR: fifo overrun detected len=%d, flushing\n", fifo->len );
                fifo->dataslot  = 0;
                fifo->emptyslot = 0;
                fifo->len = 0;
        }

        if ( fifo->emptyslot == FIFOSIZE )
        {
                fifo->emptyslot = 0;
                LWIP_DEBUGF( SIO_FIFO_DEBUG, ("(WRAP) ") );

                sys_sem_signal(&fifo->sem ); /* leave critical */
                fifoPut( fifo, fd );
                return;
        }
        if ( fifo->getWaiting )
        {
                fifo->getWaiting = FALSE;
                sys_sem_signal(&fifo->getSem );
        }

        sys_sem_signal(&fifo->sem ); /* leave critical */
        return;
}


void fifoInit(fifo_t * fifo)
{
  fifo->dataslot  = 0;
  fifo->emptyslot = 0;
  fifo->len       = 0;
  if(sys_sem_new(&fifo->sem, 1) != ERR_OK) {  /* critical section 1=free to enter */
    LWIP_ASSERT("Failed to create semaphore", 0);
  }
  if(sys_sem_new(&fifo->getSem, 0) != ERR_OK) {  /* 0 = no one waiting */
    LWIP_ASSERT("Failed to create semaphore", 0);
  }
  fifo->getWaiting = FALSE;
}