1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * Copyright(c) 2010-2014 Intel Corporation.
4 */
5
6 #ifndef _KNI_FIFO_H_
7 #define _KNI_FIFO_H_
8
9 #include <rte_kni_common.h>
10
11 /* Skip some memory barriers on Linux < 3.14 */
12 #ifndef smp_load_acquire
13 #define smp_load_acquire(a) (*(a))
14 #endif
15 #ifndef smp_store_release
16 #define smp_store_release(a, b) *(a) = (b)
17 #endif
18
19 /**
20 * Adds num elements into the fifo. Return the number actually written
21 */
22 static inline uint32_t
kni_fifo_put(struct rte_kni_fifo * fifo,void ** data,uint32_t num)23 kni_fifo_put(struct rte_kni_fifo *fifo, void **data, uint32_t num)
24 {
25 uint32_t i = 0;
26 uint32_t fifo_write = fifo->write;
27 uint32_t fifo_read = smp_load_acquire(&fifo->read);
28 uint32_t new_write = fifo_write;
29
30 for (i = 0; i < num; i++) {
31 new_write = (new_write + 1) & (fifo->len - 1);
32
33 if (new_write == fifo_read)
34 break;
35 fifo->buffer[fifo_write] = data[i];
36 fifo_write = new_write;
37 }
38 smp_store_release(&fifo->write, fifo_write);
39
40 return i;
41 }
42
43 /**
44 * Get up to num elements from the fifo. Return the number actully read
45 */
46 static inline uint32_t
kni_fifo_get(struct rte_kni_fifo * fifo,void ** data,uint32_t num)47 kni_fifo_get(struct rte_kni_fifo *fifo, void **data, uint32_t num)
48 {
49 uint32_t i = 0;
50 uint32_t new_read = fifo->read;
51 uint32_t fifo_write = smp_load_acquire(&fifo->write);
52
53 for (i = 0; i < num; i++) {
54 if (new_read == fifo_write)
55 break;
56
57 data[i] = fifo->buffer[new_read];
58 new_read = (new_read + 1) & (fifo->len - 1);
59 }
60 smp_store_release(&fifo->read, new_read);
61
62 return i;
63 }
64
65 /**
66 * Get the num of elements in the fifo
67 */
68 static inline uint32_t
kni_fifo_count(struct rte_kni_fifo * fifo)69 kni_fifo_count(struct rte_kni_fifo *fifo)
70 {
71 uint32_t fifo_write = smp_load_acquire(&fifo->write);
72 uint32_t fifo_read = smp_load_acquire(&fifo->read);
73 return (fifo->len + fifo_write - fifo_read) & (fifo->len - 1);
74 }
75
76 /**
77 * Get the num of available elements in the fifo
78 */
79 static inline uint32_t
kni_fifo_free_count(struct rte_kni_fifo * fifo)80 kni_fifo_free_count(struct rte_kni_fifo *fifo)
81 {
82 uint32_t fifo_write = smp_load_acquire(&fifo->write);
83 uint32_t fifo_read = smp_load_acquire(&fifo->read);
84 return (fifo_read - fifo_write - 1) & (fifo->len - 1);
85 }
86
87 #endif /* _KNI_FIFO_H_ */
88