xref: /openbmc/qemu/util/fifo8.c (revision 135b03cb)
1 /*
2  * Generic FIFO component, implemented as a circular buffer.
3  *
4  * Copyright (c) 2012 Peter A. G. Crosthwaite
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License
8  * as published by the Free Software Foundation; either version
9  * 2 of the License, or (at your option) any later version.
10  *
11  * You should have received a copy of the GNU General Public License along
12  * with this program; if not, see <http://www.gnu.org/licenses/>.
13  */
14 
15 #include "qemu/osdep.h"
16 #include "migration/vmstate.h"
17 #include "qemu/fifo8.h"
18 
19 void fifo8_create(Fifo8 *fifo, uint32_t capacity)
20 {
21     fifo->data = g_new(uint8_t, capacity);
22     fifo->capacity = capacity;
23     fifo->head = 0;
24     fifo->num = 0;
25 }
26 
27 void fifo8_destroy(Fifo8 *fifo)
28 {
29     g_free(fifo->data);
30 }
31 
32 void fifo8_push(Fifo8 *fifo, uint8_t data)
33 {
34     if (fifo->num == fifo->capacity) {
35         abort();
36     }
37     fifo->data[(fifo->head + fifo->num) % fifo->capacity] = data;
38     fifo->num++;
39 }
40 
41 void fifo8_push_all(Fifo8 *fifo, const uint8_t *data, uint32_t num)
42 {
43     uint32_t start, avail;
44 
45     if (fifo->num + num > fifo->capacity) {
46         abort();
47     }
48 
49     start = (fifo->head + fifo->num) % fifo->capacity;
50 
51     if (start + num <= fifo->capacity) {
52         memcpy(&fifo->data[start], data, num);
53     } else {
54         avail = fifo->capacity - start;
55         memcpy(&fifo->data[start], data, avail);
56         memcpy(&fifo->data[0], &data[avail], num - avail);
57     }
58 
59     fifo->num += num;
60 }
61 
62 uint8_t fifo8_pop(Fifo8 *fifo)
63 {
64     uint8_t ret;
65 
66     if (fifo->num == 0) {
67         abort();
68     }
69     ret = fifo->data[fifo->head++];
70     fifo->head %= fifo->capacity;
71     fifo->num--;
72     return ret;
73 }
74 
75 const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *num)
76 {
77     uint8_t *ret;
78 
79     if (max == 0 || max > fifo->num) {
80         abort();
81     }
82     *num = MIN(fifo->capacity - fifo->head, max);
83     ret = &fifo->data[fifo->head];
84     fifo->head += *num;
85     fifo->head %= fifo->capacity;
86     fifo->num -= *num;
87     return ret;
88 }
89 
90 void fifo8_reset(Fifo8 *fifo)
91 {
92     fifo->num = 0;
93     fifo->head = 0;
94 }
95 
96 bool fifo8_is_empty(Fifo8 *fifo)
97 {
98     return (fifo->num == 0);
99 }
100 
101 bool fifo8_is_full(Fifo8 *fifo)
102 {
103     return (fifo->num == fifo->capacity);
104 }
105 
106 uint32_t fifo8_num_free(Fifo8 *fifo)
107 {
108     return fifo->capacity - fifo->num;
109 }
110 
111 uint32_t fifo8_num_used(Fifo8 *fifo)
112 {
113     return fifo->num;
114 }
115 
116 const VMStateDescription vmstate_fifo8 = {
117     .name = "Fifo8",
118     .version_id = 1,
119     .minimum_version_id = 1,
120     .fields = (VMStateField[]) {
121         VMSTATE_VBUFFER_UINT32(data, Fifo8, 1, NULL, capacity),
122         VMSTATE_UINT32(head, Fifo8),
123         VMSTATE_UINT32(num, Fifo8),
124         VMSTATE_END_OF_LIST()
125     }
126 };
127