1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
|
#ifndef _GPXE_IOBUF_H
#define _GPXE_IOBUF_H
/** @file
*
* I/O buffers
*
*/
FILE_LICENCE ( GPL2_OR_LATER );
#include <stdint.h>
#include <assert.h>
#include <gpxe/list.h>
/**
* I/O buffer alignment
*
* I/O buffers allocated via alloc_iob() are guaranteed to be
* physically aligned to this boundary. Some cards cannot DMA across
* a 4kB boundary. With a standard Ethernet MTU, aligning to a 2kB
* boundary is sufficient to guarantee no 4kB boundary crossings. For
* a jumbo Ethernet MTU, a packet may be larger than 4kB anyway.
*/
#define IOB_ALIGN 2048
/**
* Minimum I/O buffer length
*
* alloc_iob() will round up the allocated length to this size if
* necessary. This is used on behalf of hardware that is not capable
* of auto-padding.
*/
#define IOB_ZLEN 64
/**
* A persistent I/O buffer
*
* This data structure encapsulates a long-lived I/O buffer. The
* buffer may be passed between multiple owners, queued for possible
* retransmission, etc.
*/
struct io_buffer {
/** List of which this buffer is a member
*
* The list must belong to the current owner of the buffer.
* Different owners may maintain different lists (e.g. a
* retransmission list for TCP).
*/
struct list_head list;
/** Start of the buffer */
void *head;
/** Start of data */
void *data;
/** End of data */
void *tail;
/** End of the buffer */
void *end;
};
/**
* Reserve space at start of I/O buffer
*
* @v iobuf I/O buffer
* @v len Length to reserve
* @ret data Pointer to new start of buffer
*/
static inline void * iob_reserve ( struct io_buffer *iobuf, size_t len ) {
iobuf->data += len;
iobuf->tail += len;
return iobuf->data;
}
#define iob_reserve( iobuf, len ) ( { \
void *__result; \
__result = iob_reserve ( (iobuf), (len) ); \
assert ( (iobuf)->tail <= (iobuf)->end ); \
__result; } )
/**
* Add data to start of I/O buffer
*
* @v iobuf I/O buffer
* @v len Length to add
* @ret data Pointer to new start of buffer
*/
static inline void * iob_push ( struct io_buffer *iobuf, size_t len ) {
iobuf->data -= len;
return iobuf->data;
}
#define iob_push( iobuf, len ) ( { \
void *__result; \
__result = iob_push ( (iobuf), (len) ); \
assert ( (iobuf)->data >= (iobuf)->head ); \
__result; } )
/**
* Remove data from start of I/O buffer
*
* @v iobuf I/O buffer
* @v len Length to remove
* @ret data Pointer to new start of buffer
*/
static inline void * iob_pull ( struct io_buffer *iobuf, size_t len ) {
iobuf->data += len;
assert ( iobuf->data <= iobuf->tail );
return iobuf->data;
}
#define iob_pull( iobuf, len ) ( { \
void *__result; \
__result = iob_pull ( (iobuf), (len) ); \
assert ( (iobuf)->data <= (iobuf)->tail ); \
__result; } )
/**
* Add data to end of I/O buffer
*
* @v iobuf I/O buffer
* @v len Length to add
* @ret data Pointer to newly added space
*/
static inline void * iob_put ( struct io_buffer *iobuf, size_t len ) {
void *old_tail = iobuf->tail;
iobuf->tail += len;
return old_tail;
}
#define iob_put( iobuf, len ) ( { \
void *__result; \
__result = iob_put ( (iobuf), (len) ); \
assert ( (iobuf)->tail <= (iobuf)->end ); \
__result; } )
/**
* Remove data from end of I/O buffer
*
* @v iobuf I/O buffer
* @v len Length to remove
*/
static inline void iob_unput ( struct io_buffer *iobuf, size_t len ) {
iobuf->tail -= len;
}
#define iob_unput( iobuf, len ) do { \
iob_unput ( (iobuf), (len) ); \
assert ( (iobuf)->tail >= (iobuf)->data ); \
} while ( 0 )
/**
* Empty an I/O buffer
*
* @v iobuf I/O buffer
*/
static inline void iob_empty ( struct io_buffer *iobuf ) {
iobuf->tail = iobuf->data;
}
/**
* Calculate length of data in an I/O buffer
*
* @v iobuf I/O buffer
* @ret len Length of data in buffer
*/
static inline size_t iob_len ( struct io_buffer *iobuf ) {
return ( iobuf->tail - iobuf->data );
}
/**
* Calculate available space at start of an I/O buffer
*
* @v iobuf I/O buffer
* @ret len Length of data available at start of buffer
*/
static inline size_t iob_headroom ( struct io_buffer *iobuf ) {
return ( iobuf->data - iobuf->head );
}
/**
* Calculate available space at end of an I/O buffer
*
* @v iobuf I/O buffer
* @ret len Length of data available at end of buffer
*/
static inline size_t iob_tailroom ( struct io_buffer *iobuf ) {
return ( iobuf->end - iobuf->tail );
}
/**
* Create a temporary I/O buffer
*
* @v iobuf I/O buffer
* @v data Data buffer
* @v len Length of data
* @v max_len Length of buffer
*
* It is sometimes useful to use the iob_xxx() methods on temporary
* data buffers.
*/
static inline void iob_populate ( struct io_buffer *iobuf,
void *data, size_t len, size_t max_len ) {
iobuf->head = iobuf->data = data;
iobuf->tail = ( data + len );
iobuf->end = ( data + max_len );
}
/**
* Disown an I/O buffer
*
* @v iobuf I/O buffer
*
* There are many functions that take ownership of the I/O buffer they
* are passed as a parameter. The caller should not retain a pointer
* to the I/O buffer. Use iob_disown() to automatically nullify the
* caller's pointer, e.g.:
*
* xfer_deliver_iob ( xfer, iob_disown ( iobuf ) );
*
* This will ensure that iobuf is set to NULL for any code after the
* call to xfer_deliver_iob().
*/
#define iob_disown( iobuf ) ( { \
struct io_buffer *__iobuf = (iobuf); \
(iobuf) = NULL; \
__iobuf; } )
extern struct io_buffer * __malloc alloc_iob ( size_t len );
extern void free_iob ( struct io_buffer *iobuf );
extern void iob_pad ( struct io_buffer *iobuf, size_t min_len );
extern int iob_ensure_headroom ( struct io_buffer *iobuf, size_t len );
#endif /* _GPXE_IOBUF_H */
|
