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
fifo8_reset(Fifo8 * fifo)19 void fifo8_reset(Fifo8 *fifo)
20 {
21 fifo->num = 0;
22 fifo->head = 0;
23 }
24
fifo8_create(Fifo8 * fifo,uint32_t capacity)25 void fifo8_create(Fifo8 *fifo, uint32_t capacity)
26 {
27 fifo->data = g_new(uint8_t, capacity);
28 fifo->capacity = capacity;
29 fifo8_reset(fifo);
30 }
31
fifo8_destroy(Fifo8 * fifo)32 void fifo8_destroy(Fifo8 *fifo)
33 {
34 g_free(fifo->data);
35 }
36
fifo8_push(Fifo8 * fifo,uint8_t data)37 void fifo8_push(Fifo8 *fifo, uint8_t data)
38 {
39 assert(fifo->num < fifo->capacity);
40 fifo->data[(fifo->head + fifo->num) % fifo->capacity] = data;
41 fifo->num++;
42 }
43
fifo8_push_all(Fifo8 * fifo,const uint8_t * data,uint32_t num)44 void fifo8_push_all(Fifo8 *fifo, const uint8_t *data, uint32_t num)
45 {
46 uint32_t start, avail;
47
48 assert(fifo->num + num <= fifo->capacity);
49
50 start = (fifo->head + fifo->num) % fifo->capacity;
51
52 if (start + num <= fifo->capacity) {
53 memcpy(&fifo->data[start], data, num);
54 } else {
55 avail = fifo->capacity - start;
56 memcpy(&fifo->data[start], data, avail);
57 memcpy(&fifo->data[0], &data[avail], num - avail);
58 }
59
60 fifo->num += num;
61 }
62
fifo8_pop(Fifo8 * fifo)63 uint8_t fifo8_pop(Fifo8 *fifo)
64 {
65 uint8_t ret;
66
67 assert(fifo->num > 0);
68 ret = fifo->data[fifo->head++];
69 fifo->head %= fifo->capacity;
70 fifo->num--;
71 return ret;
72 }
73
fifo8_peekpop_buf(Fifo8 * fifo,uint32_t max,uint32_t * numptr,bool do_pop)74 static const uint8_t *fifo8_peekpop_buf(Fifo8 *fifo, uint32_t max,
75 uint32_t *numptr, bool do_pop)
76 {
77 uint8_t *ret;
78 uint32_t num;
79
80 assert(max > 0 && max <= fifo->num);
81 num = MIN(fifo->capacity - fifo->head, max);
82 ret = &fifo->data[fifo->head];
83
84 if (do_pop) {
85 fifo->head += num;
86 fifo->head %= fifo->capacity;
87 fifo->num -= num;
88 }
89 if (numptr) {
90 *numptr = num;
91 }
92 return ret;
93 }
94
fifo8_peek_bufptr(Fifo8 * fifo,uint32_t max,uint32_t * numptr)95 const uint8_t *fifo8_peek_bufptr(Fifo8 *fifo, uint32_t max, uint32_t *numptr)
96 {
97 return fifo8_peekpop_buf(fifo, max, numptr, false);
98 }
99
fifo8_pop_bufptr(Fifo8 * fifo,uint32_t max,uint32_t * numptr)100 const uint8_t *fifo8_pop_bufptr(Fifo8 *fifo, uint32_t max, uint32_t *numptr)
101 {
102 return fifo8_peekpop_buf(fifo, max, numptr, true);
103 }
104
fifo8_pop_buf(Fifo8 * fifo,uint8_t * dest,uint32_t destlen)105 uint32_t fifo8_pop_buf(Fifo8 *fifo, uint8_t *dest, uint32_t destlen)
106 {
107 const uint8_t *buf;
108 uint32_t n1, n2 = 0;
109 uint32_t len;
110
111 if (destlen == 0) {
112 return 0;
113 }
114
115 len = destlen;
116 buf = fifo8_pop_bufptr(fifo, len, &n1);
117 if (dest) {
118 memcpy(dest, buf, n1);
119 }
120
121 /* Add FIFO wraparound if needed */
122 len -= n1;
123 len = MIN(len, fifo8_num_used(fifo));
124 if (len) {
125 buf = fifo8_pop_bufptr(fifo, len, &n2);
126 if (dest) {
127 memcpy(&dest[n1], buf, n2);
128 }
129 }
130
131 return n1 + n2;
132 }
133
fifo8_drop(Fifo8 * fifo,uint32_t len)134 void fifo8_drop(Fifo8 *fifo, uint32_t len)
135 {
136 len -= fifo8_pop_buf(fifo, NULL, len);
137 assert(len == 0);
138 }
139
fifo8_is_empty(Fifo8 * fifo)140 bool fifo8_is_empty(Fifo8 *fifo)
141 {
142 return (fifo->num == 0);
143 }
144
fifo8_is_full(Fifo8 * fifo)145 bool fifo8_is_full(Fifo8 *fifo)
146 {
147 return (fifo->num == fifo->capacity);
148 }
149
fifo8_num_free(Fifo8 * fifo)150 uint32_t fifo8_num_free(Fifo8 *fifo)
151 {
152 return fifo->capacity - fifo->num;
153 }
154
fifo8_num_used(Fifo8 * fifo)155 uint32_t fifo8_num_used(Fifo8 *fifo)
156 {
157 return fifo->num;
158 }
159
160 const VMStateDescription vmstate_fifo8 = {
161 .name = "Fifo8",
162 .version_id = 1,
163 .minimum_version_id = 1,
164 .fields = (const VMStateField[]) {
165 VMSTATE_VBUFFER_UINT32(data, Fifo8, 1, NULL, capacity),
166 VMSTATE_UINT32(head, Fifo8),
167 VMSTATE_UINT32(num, Fifo8),
168 VMSTATE_END_OF_LIST()
169 }
170 };
171