From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Wed, 5 Aug 2015 17:04:01 -0300
Subject: Initial import

---
 drivers/staging/unisys/visorutil/charqueue.c | 127 +++++++++++++++++++++++++++
 1 file changed, 127 insertions(+)
 create mode 100644 drivers/staging/unisys/visorutil/charqueue.c

(limited to 'drivers/staging/unisys/visorutil/charqueue.c')

diff --git a/drivers/staging/unisys/visorutil/charqueue.c b/drivers/staging/unisys/visorutil/charqueue.c
new file mode 100644
index 000000000..c91752a2d
--- /dev/null
+++ b/drivers/staging/unisys/visorutil/charqueue.c
@@ -0,0 +1,127 @@
+/* charqueue.c
+ *
+ * Copyright (C) 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 {
+	int alloc_size;
+	int nslots;
+	spinlock_t lock; /* read/write lock for this structure */
+	int head, tail;
+	unsigned char buf[0];
+};
+
+struct charqueue *visor_charqueue_create(ulong nslots)
+{
+	int alloc_size = sizeof(struct charqueue) + nslots + 1;
+	struct charqueue *cq;
+
+	cq = kmalloc(alloc_size, GFP_KERNEL|__GFP_NORETRY);
+	if (cq == NULL)
+		return NULL;
+	cq->alloc_size = alloc_size;
+	cq->nslots = nslots;
+	cq->head = 0;
+	cq->tail = 0;
+	spin_lock_init(&cq->lock);
+	return cq;
+}
+EXPORT_SYMBOL_GPL(visor_charqueue_create);
+
+void visor_charqueue_enqueue(struct 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(struct 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(struct 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(struct charqueue *charqueue)
+{
+	int rc;
+
+	spin_lock(&charqueue->lock);
+	rc = charqueue_dequeue_1(charqueue);
+	spin_unlock(&charqueue->lock);
+	return rc;
+}
+
+int visor_charqueue_dequeue_n(struct 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(struct charqueue *charqueue)
+{
+	if (charqueue == NULL)
+		return;
+	kfree(charqueue);
+}
+EXPORT_SYMBOL_GPL(visor_charqueue_destroy);
-- 
cgit v1.2.3-54-g00ecf