1 files changed, 141 insertions, 0 deletions
diff --git a/drivers/staging/unisys/visorutil/charqueue.c b/drivers/staging/unisys/visorutil/charqueue.c
new file mode 100644
index 000000000000..0ceede129e87
--- /dev/null
+++ b/drivers/staging/unisys/visorutil/charqueue.c
@@ -0,0 +1,141 @@
+/* charqueue.c
+ *
+ * Copyright © 2010 - 2013 UNISYS CORPORATION
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ *
+ * 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, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ */
+
+/*
+ *  Simple character queue implementation for Linux kernel mode.
+ */
+
+#include "charqueue.h"
+
+#define MYDRVNAME "charqueue"
+
+#define IS_EMPTY(charqueue) (charqueue->head == charqueue->tail)
+
+
+
+struct CHARQUEUE_Tag {
+	int alloc_size;
+	int nslots;
+	spinlock_t lock;
+	int head, tail;
+	unsigned char buf[0];
+};
+
+
+
+CHARQUEUE *visor_charqueue_create(ulong nslots)
+{
+	int alloc_size = sizeof(CHARQUEUE) + nslots + 1;
+	CHARQUEUE *cq = kmalloc(alloc_size, GFP_KERNEL|__GFP_NORETRY);
+	if (cq == NULL) {
+		ERRDRV("visor_charqueue_create allocation failed (alloc_size=%d)",
+		       alloc_size);
+		return NULL;
+	}
+	cq->alloc_size = alloc_size;
+	cq->nslots = nslots;
+	cq->head = cq->tail = 0;
+	spin_lock_init(&cq->lock);
+	return cq;
+}
+EXPORT_SYMBOL_GPL(visor_charqueue_create);
+
+
+
+void visor_charqueue_enqueue(CHARQUEUE *charqueue, unsigned char c)
+{
+	int alloc_slots = charqueue->nslots+1;  /* 1 slot is always empty */
+
+	spin_lock(&charqueue->lock);
+	charqueue->head = (charqueue->head+1) % alloc_slots;
+	if (charqueue->head == charqueue->tail)
+		/* overflow; overwrite the oldest entry */
+		charqueue->tail = (charqueue->tail+1) % alloc_slots;
+	charqueue->buf[charqueue->head] = c;
+	spin_unlock(&charqueue->lock);
+}
+EXPORT_SYMBOL_GPL(visor_charqueue_enqueue);
+
+
+
+BOOL visor_charqueue_is_empty(CHARQUEUE *charqueue)
+{
+	BOOL b;
+	spin_lock(&charqueue->lock);
+	b = IS_EMPTY(charqueue);
+	spin_unlock(&charqueue->lock);
+	return b;
+}
+EXPORT_SYMBOL_GPL(visor_charqueue_is_empty);
+
+
+
+static int charqueue_dequeue_1(CHARQUEUE *charqueue)
+{
+	int alloc_slots = charqueue->nslots + 1;  /* 1 slot is always empty */
+
+	if (IS_EMPTY(charqueue))
+		return -1;
+	charqueue->tail = (charqueue->tail+1) % alloc_slots;
+	return charqueue->buf[charqueue->tail];
+}
+
+
+
+int charqueue_dequeue(CHARQUEUE *charqueue)
+{
+	int rc;
+
+	spin_lock(&charqueue->lock);
+	rc = charqueue_dequeue_1(charqueue);
+	spin_unlock(&charqueue->lock);
+	return rc;
+}
+
+
+
+int visor_charqueue_dequeue_n(CHARQUEUE *charqueue, unsigned char *buf, int n)
+{
+	int rc, counter = 0, c;
+
+	spin_lock(&charqueue->lock);
+	for (;;) {
+		if (n <= 0)
+			break;  /* no more buffer space */
+		c = charqueue_dequeue_1(charqueue);
+		if (c < 0)
+			break;  /* no more input */
+		*buf = (unsigned char)(c);
+		buf++;
+		n--;
+		counter++;
+	}
+	rc = counter;
+	spin_unlock(&charqueue->lock);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(visor_charqueue_dequeue_n);
+
+
+
+void visor_charqueue_destroy(CHARQUEUE *charqueue)
+{
+	if (charqueue == NULL)
+		return;
+	kfree(charqueue);
+}
+EXPORT_SYMBOL_GPL(visor_charqueue_destroy);