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
40struct 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 */
50static 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 */
57static 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 */
64static 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 */
72static 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 */
83extern 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 */
92extern 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 */
98extern 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 */
112extern 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 */
127static 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 */
141static 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