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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 <drm/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 |
149 |
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