Staging: speakup: i18n.c: cleaned up file
[linux-2.6/next.git] / samples / kfifo / bytestream-example.c
blob178061e87ffe47d39ac97a247071d896ff080e8a
1 /*
2 * Sample kfifo byte stream implementation
4 * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
6 * Released under the GPL version 2 only.
8 */
10 #include <linux/init.h>
11 #include <linux/module.h>
12 #include <linux/proc_fs.h>
13 #include <linux/mutex.h>
14 #include <linux/kfifo.h>
17 * This module shows how to create a byte stream fifo.
20 /* fifo size in elements (bytes) */
21 #define FIFO_SIZE 32
23 /* name of the proc entry */
24 #define PROC_FIFO "bytestream-fifo"
26 /* lock for procfs read access */
27 static DEFINE_MUTEX(read_lock);
29 /* lock for procfs write access */
30 static DEFINE_MUTEX(write_lock);
33 * define DYNAMIC in this example for a dynamically allocated fifo.
35 * Otherwise the fifo storage will be a part of the fifo structure.
37 #if 0
38 #define DYNAMIC
39 #endif
41 #ifdef DYNAMIC
42 static struct kfifo test;
43 #else
44 static DECLARE_KFIFO(test, unsigned char, FIFO_SIZE);
45 #endif
47 static const unsigned char expected_result[FIFO_SIZE] = {
48 3, 4, 5, 6, 7, 8, 9, 0,
49 1, 20, 21, 22, 23, 24, 25, 26,
50 27, 28, 29, 30, 31, 32, 33, 34,
51 35, 36, 37, 38, 39, 40, 41, 42,
54 static int __init testfunc(void)
56 unsigned char buf[6];
57 unsigned char i, j;
58 unsigned int ret;
60 printk(KERN_INFO "byte stream fifo test start\n");
62 /* put string into the fifo */
63 kfifo_in(&test, "hello", 5);
65 /* put values into the fifo */
66 for (i = 0; i != 10; i++)
67 kfifo_put(&test, &i);
69 /* show the number of used elements */
70 printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
72 /* get max of 5 bytes from the fifo */
73 i = kfifo_out(&test, buf, 5);
74 printk(KERN_INFO "buf: %.*s\n", i, buf);
76 /* get max of 2 elements from the fifo */
77 ret = kfifo_out(&test, buf, 2);
78 printk(KERN_INFO "ret: %d\n", ret);
79 /* and put it back to the end of the fifo */
80 ret = kfifo_in(&test, buf, ret);
81 printk(KERN_INFO "ret: %d\n", ret);
83 /* skip first element of the fifo */
84 printk(KERN_INFO "skip 1st element\n");
85 kfifo_skip(&test);
87 /* put values into the fifo until is full */
88 for (i = 20; kfifo_put(&test, &i); i++)
91 printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
93 /* show the first value without removing from the fifo */
94 if (kfifo_peek(&test, &i))
95 printk(KERN_INFO "%d\n", i);
97 /* check the correctness of all values in the fifo */
98 j = 0;
99 while (kfifo_get(&test, &i)) {
100 printk(KERN_INFO "item = %d\n", i);
101 if (i != expected_result[j++]) {
102 printk(KERN_WARNING "value mismatch: test failed\n");
103 return -EIO;
106 if (j != ARRAY_SIZE(expected_result)) {
107 printk(KERN_WARNING "size mismatch: test failed\n");
108 return -EIO;
110 printk(KERN_INFO "test passed\n");
112 return 0;
115 static ssize_t fifo_write(struct file *file, const char __user *buf,
116 size_t count, loff_t *ppos)
118 int ret;
119 unsigned int copied;
121 if (mutex_lock_interruptible(&write_lock))
122 return -ERESTARTSYS;
124 ret = kfifo_from_user(&test, buf, count, &copied);
126 mutex_unlock(&write_lock);
128 return ret ? ret : copied;
131 static ssize_t fifo_read(struct file *file, char __user *buf,
132 size_t count, loff_t *ppos)
134 int ret;
135 unsigned int copied;
137 if (mutex_lock_interruptible(&read_lock))
138 return -ERESTARTSYS;
140 ret = kfifo_to_user(&test, buf, count, &copied);
142 mutex_unlock(&read_lock);
144 return ret ? ret : copied;
147 static const struct file_operations fifo_fops = {
148 .owner = THIS_MODULE,
149 .read = fifo_read,
150 .write = fifo_write,
153 static int __init example_init(void)
155 #ifdef DYNAMIC
156 int ret;
158 ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
159 if (ret) {
160 printk(KERN_ERR "error kfifo_alloc\n");
161 return ret;
163 #else
164 INIT_KFIFO(test);
165 #endif
166 if (testfunc() < 0) {
167 #ifdef DYNAMIC
168 kfifo_free(&test);
169 #endif
170 return -EIO;
173 if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
174 #ifdef DYNAMIC
175 kfifo_free(&test);
176 #endif
177 return -ENOMEM;
179 return 0;
182 static void __exit example_exit(void)
184 remove_proc_entry(PROC_FIFO, NULL);
185 #ifdef DYNAMIC
186 kfifo_free(&test);
187 #endif
190 module_init(example_init);
191 module_exit(example_exit);
192 MODULE_LICENSE("GPL");
193 MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");