i've tested, now you can too

libs/libcodec2/src/fifo.c

@@ -0,0 +1,143 @@
+/*---------------------------------------------------------------------------*\
+                                                                             
+  FILE........: fifo.c
+  AUTHOR......: David Rowe
+  DATE CREATED: Oct 15 2012
+                                                                             
+  A FIFO design useful in gluing the FDMDV modem and codec together in
+  integrated applications.  The unittest/tfifo indicates these
+  routines are thread safe without the need for syncronisation
+  object, e.g. a different thread can read and write to a fifo at the
+  same time.
+
+\*---------------------------------------------------------------------------*/
+
+/*
+  Copyright (C) 2012 David Rowe
+
+  All rights reserved.
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License version 2.1, as
+  published by the Free Software Foundation.  This program is
+  distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or
+  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
+  License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with this program; if not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <assert.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include "fifo.h"
+
+struct FIFO {
+    short *buf;
+    short *pin;
+    short *pout;
+    int    nshort;
+};
+
+struct FIFO *fifo_create(int nshort) {
+    struct FIFO *fifo;
+
+    fifo = (struct FIFO *)malloc(sizeof(struct FIFO));
+    assert(fifo != NULL);
+
+    fifo->buf = (short*)malloc(sizeof(short)*nshort);
+    assert(fifo->buf != NULL);
+    fifo->pin = fifo->buf;
+    fifo->pout = fifo->buf;
+    fifo->nshort = nshort;
+
+    return fifo;
+}
+
+void fifo_destroy(struct FIFO *fifo) {
+    assert(fifo != NULL);
+    free(fifo->buf);
+    free(fifo);
+}
+
+int fifo_write(struct FIFO *fifo, short data[], int n) {
+    int            i;
+    int            fifo_free;
+    short         *pdata;
+    short         *pin = fifo->pin;
+
+    assert(fifo != NULL);
+    assert(data != NULL);
+
+    // available storage is one less than nshort as prd == pwr
+    // is reserved for empty rather than full
+
+    fifo_free = fifo->nshort - fifo_used(fifo) - 1;
+
+    if (n > fifo_free) {
+	return -1;
+    }
+    else {
+
+	/* This could be made more efficient with block copies
+	   using memcpy */
+
+	pdata = data;
+	for(i=0; i<n; i++) {
+	    *pin++ = *pdata++;
+	    if (pin == (fifo->buf + fifo->nshort))
+		pin = fifo->buf;
+	}
+	fifo->pin = pin;
+    }
+
+    return 0;
+}
+
+int fifo_read(struct FIFO *fifo, short data[], int n)
+{
+    int            i;
+    short         *pdata;
+    short         *pin = fifo->pin;
+    short         *pout = fifo->pout;
+
+    assert(fifo != NULL);
+    assert(data != NULL);
+ 
+    if (n > fifo_used(fifo)) {
+	return -1;
+    }
+    else {
+
+	/* This could be made more efficient with block copies
+	   using memcpy */
+
+	pdata = data;
+	for(i=0; i<n; i++) {
+	    *pdata++ = *pout++;
+	    if (pout == (fifo->buf + fifo->nshort))
+		pout = fifo->buf;
+	}
+	fifo->pout = pout;
+    }
+
+    return 0;
+}
+
+int fifo_used(struct FIFO *fifo)
+{
+    short         *pin = fifo->pin;
+    short         *pout = fifo->pout;
+    unsigned int   used;
+
+    assert(fifo != NULL);
+    if (pin >= pout)
+        used = pin - pout;
+    else
+        used = fifo->nshort + (unsigned int)(pin - pout);
+
+    return used;
+}
+