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1 | /************************************************************************** |
2 | * | |
3 | * Copyright 2010 Pauli Nieminen. | |
4 | * All Rights Reserved. | |
5 | * | |
6 | * Permission is hereby granted, free of charge, to any person obtaining a | |
7 | * copy of this software and associated documentation files (the | |
8 | * "Software"), to deal in the Software without restriction, including | |
9 | * without limitation the rights to use, copy, modify, merge, publish, | |
10 | * distribute, sub license, and/or sell copies of the Software, and to | |
11 | * permit persons to whom the Software is furnished to do so, subject to | |
12 | * the following conditions: | |
13 | * | |
14 | * The above copyright notice and this permission notice (including the | |
15 | * next paragraph) shall be included in all copies or substantial portions | |
16 | * of the Software. | |
17 | * | |
18 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
19 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
20 | * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL | |
21 | * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, | |
22 | * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR | |
23 | * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE | |
24 | * USE OR OTHER DEALINGS IN THE SOFTWARE. | |
25 | * | |
26 | * | |
27 | **************************************************************************/ | |
28 | /* | |
29 | * Multipart buffer for coping data which is larger than the page size. | |
30 | * | |
31 | * Authors: | |
32 | * Pauli Nieminen <suokkos-at-gmail-dot-com> | |
33 | */ | |
34 | ||
35 | #ifndef _DRM_BUFFER_H_ | |
36 | #define _DRM_BUFFER_H_ | |
37 | ||
38 | #include "drmP.h" | |
39 | ||
40 | struct drm_buffer { | |
41 | int iterator; | |
42 | int size; | |
43 | char *data[]; | |
44 | }; | |
45 | ||
46 | ||
47 | /** | |
48 | * Return the index of page that buffer is currently pointing at. | |
49 | */ | |
50 | static inline int drm_buffer_page(struct drm_buffer *buf) | |
51 | { | |
52 | return buf->iterator / PAGE_SIZE; | |
53 | } | |
54 | /** | |
55 | * Return the index of the current byte in the page | |
56 | */ | |
57 | static inline int drm_buffer_index(struct drm_buffer *buf) | |
58 | { | |
59 | return buf->iterator & (PAGE_SIZE - 1); | |
60 | } | |
61 | /** | |
62 | * Return number of bytes that is left to process | |
63 | */ | |
64 | static inline int drm_buffer_unprocessed(struct drm_buffer *buf) | |
65 | { | |
66 | return buf->size - buf->iterator; | |
67 | } | |
68 | ||
69 | /** | |
70 | * Advance the buffer iterator number of bytes that is given. | |
71 | */ | |
72 | static inline void drm_buffer_advance(struct drm_buffer *buf, int bytes) | |
73 | { | |
74 | buf->iterator += bytes; | |
75 | } | |
76 | ||
77 | /** | |
78 | * Allocate the drm buffer object. | |
79 | * | |
80 | * buf: A pointer to a pointer where the object is stored. | |
81 | * size: The number of bytes to allocate. | |
82 | */ | |
83 | extern int drm_buffer_alloc(struct drm_buffer **buf, int size); | |
84 | ||
85 | /** | |
86 | * Copy the user data to the begin of the buffer and reset the processing | |
87 | * iterator. | |
88 | * | |
89 | * user_data: A pointer the data that is copied to the buffer. | |
90 | * size: The Number of bytes to copy. | |
91 | */ | |
92 | extern int drm_buffer_copy_from_user(struct drm_buffer *buf, | |
93 | void __user *user_data, int size); | |
94 | ||
95 | /** | |
96 | * Free the drm buffer object | |
97 | */ | |
98 | extern void drm_buffer_free(struct drm_buffer *buf); | |
99 | ||
100 | /** | |
101 | * Read an object from buffer that may be split to multiple parts. If object | |
102 | * is not split function just returns the pointer to object in buffer. But in | |
103 | * case of split object data is copied to given stack object that is suplied | |
104 | * by caller. | |
105 | * | |
106 | * The processing location of the buffer is also advanced to the next byte | |
107 | * after the object. | |
108 | * | |
109 | * objsize: The size of the objet in bytes. | |
110 | * stack_obj: A pointer to a memory location where object can be copied. | |
111 | */ | |
112 | extern void *drm_buffer_read_object(struct drm_buffer *buf, | |
113 | int objsize, void *stack_obj); | |
114 | ||
115 | /** | |
116 | * Returns the pointer to the dword which is offset number of elements from the | |
117 | * current processing location. | |
118 | * | |
119 | * Caller must make sure that dword is not split in the buffer. This | |
120 | * requirement is easily met if all the sizes of objects in buffer are | |
121 | * multiples of dword and PAGE_SIZE is multiple dword. | |
122 | * | |
123 | * Call to this function doesn't change the processing location. | |
124 | * | |
125 | * offset: The index of the dword relative to the internat iterator. | |
126 | */ | |
127 | static inline void *drm_buffer_pointer_to_dword(struct drm_buffer *buffer, | |
128 | int offset) | |
129 | { | |
130 | int iter = buffer->iterator + offset * 4; | |
131 | return &buffer->data[iter / PAGE_SIZE][iter & (PAGE_SIZE - 1)]; | |
132 | } | |
133 | /** | |
134 | * Returns the pointer to the dword which is offset number of elements from | |
135 | * the current processing location. | |
136 | * | |
137 | * Call to this function doesn't change the processing location. | |
138 | * | |
139 | * offset: The index of the byte relative to the internat iterator. | |
140 | */ | |
141 | static inline void *drm_buffer_pointer_to_byte(struct drm_buffer *buffer, | |
142 | int offset) | |
143 | { | |
144 | int iter = buffer->iterator + offset; | |
145 | return &buffer->data[iter / PAGE_SIZE][iter & (PAGE_SIZE - 1)]; | |
146 | } | |
147 | ||
148 | #endif |