1 /* SPDX-License-Identifier: BSD-3-Clause
2 *
3 * Copyright (c) 2010-2020 Intel Corporation
4 * Copyright (c) 2007-2009 Kip Macy kmacy@freebsd.org
5 * All rights reserved.
6 * Derived from FreeBSD's bufring.h
7 * Used as BSD-3 Licensed with permission from Kip Macy.
8 */
9
10 #ifndef _RTE_RING_PEEK_ELEM_PVT_H_
11 #define _RTE_RING_PEEK_ELEM_PVT_H_
12
13 /**
14 * @file rte_ring_peek_elem_pvt.h
15 * It is not recommended to include this file directly,
16 * include <rte_ring.h> instead.
17 * Contains internal helper functions for rte_ring peek API.
18 * For more information please refer to <rte_ring_peek.h>.
19 */
20
21 /**
22 * @internal get current tail value.
23 * This function should be used only for single thread producer/consumer.
24 * Check that user didn't request to move tail above the head.
25 * In that situation:
26 * - return zero, that will cause abort any pending changes and
27 * return head to its previous position.
28 * - throw an assert in debug mode.
29 */
30 static __rte_always_inline uint32_t
__rte_ring_st_get_tail(struct rte_ring_headtail * ht,uint32_t * tail,uint32_t num)31 __rte_ring_st_get_tail(struct rte_ring_headtail *ht, uint32_t *tail,
32 uint32_t num)
33 {
34 uint32_t h, n, t;
35
36 h = ht->head;
37 t = ht->tail;
38 n = h - t;
39
40 RTE_ASSERT(n >= num);
41 num = (n >= num) ? num : 0;
42
43 *tail = t;
44 return num;
45 }
46
47 /**
48 * @internal set new values for head and tail.
49 * This function should be used only for single thread producer/consumer.
50 * Should be used only in conjunction with __rte_ring_st_get_tail.
51 */
52 static __rte_always_inline void
__rte_ring_st_set_head_tail(struct rte_ring_headtail * ht,uint32_t tail,uint32_t num,uint32_t enqueue)53 __rte_ring_st_set_head_tail(struct rte_ring_headtail *ht, uint32_t tail,
54 uint32_t num, uint32_t enqueue)
55 {
56 uint32_t pos;
57
58 RTE_SET_USED(enqueue);
59
60 pos = tail + num;
61 ht->head = pos;
62 rte_atomic_store_explicit(&ht->tail, pos, rte_memory_order_release);
63 }
64
65 /**
66 * @internal get current tail value.
67 * This function should be used only for producer/consumer in MT_HTS mode.
68 * Check that user didn't request to move tail above the head.
69 * In that situation:
70 * - return zero, that will cause abort any pending changes and
71 * return head to its previous position.
72 * - throw an assert in debug mode.
73 */
74 static __rte_always_inline uint32_t
__rte_ring_hts_get_tail(struct rte_ring_hts_headtail * ht,uint32_t * tail,uint32_t num)75 __rte_ring_hts_get_tail(struct rte_ring_hts_headtail *ht, uint32_t *tail,
76 uint32_t num)
77 {
78 uint32_t n;
79 union __rte_ring_hts_pos p;
80
81 p.raw = rte_atomic_load_explicit(&ht->ht.raw, rte_memory_order_relaxed);
82 n = p.pos.head - p.pos.tail;
83
84 RTE_ASSERT(n >= num);
85 num = (n >= num) ? num : 0;
86
87 *tail = p.pos.tail;
88 return num;
89 }
90
91 /**
92 * @internal set new values for head and tail as one atomic 64 bit operation.
93 * This function should be used only for producer/consumer in MT_HTS mode.
94 * Should be used only in conjunction with __rte_ring_hts_get_tail.
95 */
96 static __rte_always_inline void
__rte_ring_hts_set_head_tail(struct rte_ring_hts_headtail * ht,uint32_t tail,uint32_t num,uint32_t enqueue)97 __rte_ring_hts_set_head_tail(struct rte_ring_hts_headtail *ht, uint32_t tail,
98 uint32_t num, uint32_t enqueue)
99 {
100 union __rte_ring_hts_pos p;
101
102 RTE_SET_USED(enqueue);
103
104 p.pos.head = tail + num;
105 p.pos.tail = p.pos.head;
106
107 rte_atomic_store_explicit(&ht->ht.raw, p.raw, rte_memory_order_release);
108 }
109
110 /**
111 * @internal This function moves prod head value.
112 */
113 static __rte_always_inline unsigned int
__rte_ring_do_enqueue_start(struct rte_ring * r,uint32_t n,enum rte_ring_queue_behavior behavior,uint32_t * free_space)114 __rte_ring_do_enqueue_start(struct rte_ring *r, uint32_t n,
115 enum rte_ring_queue_behavior behavior, uint32_t *free_space)
116 {
117 uint32_t free, head, next;
118
119 switch (r->prod.sync_type) {
120 case RTE_RING_SYNC_ST:
121 n = __rte_ring_move_prod_head(r, RTE_RING_SYNC_ST, n,
122 behavior, &head, &next, &free);
123 break;
124 case RTE_RING_SYNC_MT_HTS:
125 n = __rte_ring_hts_move_prod_head(r, n, behavior,
126 &head, &free);
127 break;
128 case RTE_RING_SYNC_MT:
129 case RTE_RING_SYNC_MT_RTS:
130 default:
131 /* unsupported mode, shouldn't be here */
132 RTE_ASSERT(0);
133 n = 0;
134 free = 0;
135 }
136
137 if (free_space != NULL)
138 *free_space = free - n;
139 return n;
140 }
141
142 /**
143 * @internal This function moves cons head value and copies up to *n*
144 * objects from the ring to the user provided obj_table.
145 */
146 static __rte_always_inline unsigned int
__rte_ring_do_dequeue_start(struct rte_ring * r,void * obj_table,uint32_t esize,uint32_t n,enum rte_ring_queue_behavior behavior,uint32_t * available)147 __rte_ring_do_dequeue_start(struct rte_ring *r, void *obj_table,
148 uint32_t esize, uint32_t n, enum rte_ring_queue_behavior behavior,
149 uint32_t *available)
150 {
151 uint32_t avail, head, next;
152
153 switch (r->cons.sync_type) {
154 case RTE_RING_SYNC_ST:
155 n = __rte_ring_move_cons_head(r, RTE_RING_SYNC_ST, n,
156 behavior, &head, &next, &avail);
157 break;
158 case RTE_RING_SYNC_MT_HTS:
159 n = __rte_ring_hts_move_cons_head(r, n, behavior,
160 &head, &avail);
161 break;
162 case RTE_RING_SYNC_MT:
163 case RTE_RING_SYNC_MT_RTS:
164 default:
165 /* unsupported mode, shouldn't be here */
166 RTE_ASSERT(0);
167 n = 0;
168 avail = 0;
169 }
170
171 if (n != 0)
172 __rte_ring_dequeue_elems(r, head, obj_table, esize, n);
173
174 if (available != NULL)
175 *available = avail - n;
176 return n;
177 }
178
179 #endif /* _RTE_RING_PEEK_ELEM_PVT_H_ */
180