pc: acpi: create Processor and Notify objects only for valid lapics
[qemu/ar7.git] / util / buffer.c
bloba6118bf5b25fbb50fcddfba7cb71d2fc80b02982
1 /*
2 * QEMU generic buffers
4 * Copyright (c) 2015 Red Hat, Inc.
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
21 #include "qemu/osdep.h"
22 #include "qemu/buffer.h"
23 #include "trace.h"
25 #define BUFFER_MIN_INIT_SIZE 4096
26 #define BUFFER_MIN_SHRINK_SIZE 65536
28 /* define the factor alpha for the expentional smoothing
29 * that is used in the average size calculation. a shift
30 * of 7 results in an alpha of 1/2^7. */
31 #define BUFFER_AVG_SIZE_SHIFT 7
33 static size_t buffer_req_size(Buffer *buffer, size_t len)
35 return MAX(BUFFER_MIN_INIT_SIZE,
36 pow2ceil(buffer->offset + len));
39 static void buffer_adj_size(Buffer *buffer, size_t len)
41 size_t old = buffer->capacity;
42 buffer->capacity = buffer_req_size(buffer, len);
43 buffer->buffer = g_realloc(buffer->buffer, buffer->capacity);
44 trace_buffer_resize(buffer->name ?: "unnamed",
45 old, buffer->capacity);
47 /* make it even harder for the buffer to shrink, reset average size
48 * to currenty capacity if it is larger than the average. */
49 buffer->avg_size = MAX(buffer->avg_size,
50 buffer->capacity << BUFFER_AVG_SIZE_SHIFT);
53 void buffer_init(Buffer *buffer, const char *name, ...)
55 va_list ap;
57 va_start(ap, name);
58 buffer->name = g_strdup_vprintf(name, ap);
59 va_end(ap);
62 static uint64_t buffer_get_avg_size(Buffer *buffer)
64 return buffer->avg_size >> BUFFER_AVG_SIZE_SHIFT;
67 void buffer_shrink(Buffer *buffer)
69 size_t new;
71 /* Calculate the average size of the buffer as
72 * avg_size = avg_size * ( 1 - a ) + required_size * a
73 * where a is 1 / 2 ^ BUFFER_AVG_SIZE_SHIFT. */
74 buffer->avg_size *= (1 << BUFFER_AVG_SIZE_SHIFT) - 1;
75 buffer->avg_size >>= BUFFER_AVG_SIZE_SHIFT;
76 buffer->avg_size += buffer_req_size(buffer, 0);
78 /* And then only shrink if the average size of the buffer is much
79 * too big, to avoid bumping up & down the buffers all the time.
80 * realloc() isn't exactly cheap ... */
81 new = buffer_req_size(buffer, buffer_get_avg_size(buffer));
82 if (new < buffer->capacity >> 3 &&
83 new >= BUFFER_MIN_SHRINK_SIZE) {
84 buffer_adj_size(buffer, buffer_get_avg_size(buffer));
87 buffer_adj_size(buffer, 0);
90 void buffer_reserve(Buffer *buffer, size_t len)
92 if ((buffer->capacity - buffer->offset) < len) {
93 buffer_adj_size(buffer, len);
97 gboolean buffer_empty(Buffer *buffer)
99 return buffer->offset == 0;
102 uint8_t *buffer_end(Buffer *buffer)
104 return buffer->buffer + buffer->offset;
107 void buffer_reset(Buffer *buffer)
109 buffer->offset = 0;
110 buffer_shrink(buffer);
113 void buffer_free(Buffer *buffer)
115 trace_buffer_free(buffer->name ?: "unnamed", buffer->capacity);
116 g_free(buffer->buffer);
117 g_free(buffer->name);
118 buffer->offset = 0;
119 buffer->capacity = 0;
120 buffer->buffer = NULL;
121 buffer->name = NULL;
124 void buffer_append(Buffer *buffer, const void *data, size_t len)
126 memcpy(buffer->buffer + buffer->offset, data, len);
127 buffer->offset += len;
130 void buffer_advance(Buffer *buffer, size_t len)
132 memmove(buffer->buffer, buffer->buffer + len,
133 (buffer->offset - len));
134 buffer->offset -= len;
135 buffer_shrink(buffer);
138 void buffer_move_empty(Buffer *to, Buffer *from)
140 trace_buffer_move_empty(to->name ?: "unnamed",
141 from->offset,
142 from->name ?: "unnamed");
143 assert(to->offset == 0);
145 g_free(to->buffer);
146 to->offset = from->offset;
147 to->capacity = from->capacity;
148 to->buffer = from->buffer;
150 from->offset = 0;
151 from->capacity = 0;
152 from->buffer = NULL;
155 void buffer_move(Buffer *to, Buffer *from)
157 if (to->offset == 0) {
158 buffer_move_empty(to, from);
159 return;
162 trace_buffer_move(to->name ?: "unnamed",
163 from->offset,
164 from->name ?: "unnamed");
165 buffer_reserve(to, from->offset);
166 buffer_append(to, from->buffer, from->offset);
168 g_free(from->buffer);
169 from->offset = 0;
170 from->capacity = 0;
171 from->buffer = NULL;