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TOMOYO Linux Cross Reference
Linux/include/drm/drm_buffer.h

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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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