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#include <sys/cdefs.h>
36#ifndef _DRM_BUFFER_H_
37#define _DRM_BUFFER_H_
38
39#include <dev/drm2/drmP.h>
40
41struct drm_buffer {
42	int iterator;
43	int size;
44	char *data[];
45};
46
47
48/**
49 * Return the index of page that buffer is currently pointing at.
50 */
51static inline int drm_buffer_page(struct drm_buffer *buf)
52{
53	return buf->iterator / PAGE_SIZE;
54}
55/**
56 * Return the index of the current byte in the page
57 */
58static inline int drm_buffer_index(struct drm_buffer *buf)
59{
60	return buf->iterator & (PAGE_SIZE - 1);
61}
62/**
63 * Return number of bytes that is left to process
64 */
65static inline int drm_buffer_unprocessed(struct drm_buffer *buf)
66{
67	return buf->size - buf->iterator;
68}
69
70/**
71 * Advance the buffer iterator number of bytes that is given.
72 */
73static inline void drm_buffer_advance(struct drm_buffer *buf, int bytes)
74{
75	buf->iterator += bytes;
76}
77
78/**
79 * Allocate the drm buffer object.
80 *
81 *   buf: A pointer to a pointer where the object is stored.
82 *   size: The number of bytes to allocate.
83 */
84extern int drm_buffer_alloc(struct drm_buffer **buf, int size);
85
86/**
87 * Copy the user data to the begin of the buffer and reset the processing
88 * iterator.
89 *
90 *   user_data: A pointer the data that is copied to the buffer.
91 *   size: The Number of bytes to copy.
92 */
93extern int drm_buffer_copy_from_user(struct drm_buffer *buf,
94		void __user *user_data, int size);
95
96/**
97 * Free the drm buffer object
98 */
99extern void drm_buffer_free(struct drm_buffer *buf);
100
101/**
102 * Read an object from buffer that may be split to multiple parts. If object
103 * is not split function just returns the pointer to object in buffer. But in
104 * case of split object data is copied to given stack object that is suplied
105 * by caller.
106 *
107 * The processing location of the buffer is also advanced to the next byte
108 * after the object.
109 *
110 *   objsize: The size of the objet in bytes.
111 *   stack_obj: A pointer to a memory location where object can be copied.
112 */
113extern void *drm_buffer_read_object(struct drm_buffer *buf,
114		int objsize, void *stack_obj);
115
116/**
117 * Returns the pointer to the dword which is offset number of elements from the
118 * current processing location.
119 *
120 * Caller must make sure that dword is not split in the buffer. This
121 * requirement is easily met if all the sizes of objects in buffer are
122 * multiples of dword and PAGE_SIZE is multiple dword.
123 *
124 * Call to this function doesn't change the processing location.
125 *
126 *   offset: The index of the dword relative to the internat iterator.
127 */
128static inline void *drm_buffer_pointer_to_dword(struct drm_buffer *buffer,
129		int offset)
130{
131	int iter = buffer->iterator + offset * 4;
132	return &buffer->data[iter / PAGE_SIZE][iter & (PAGE_SIZE - 1)];
133}
134/**
135 * Returns the pointer to the dword which is offset number of elements from
136 * the current processing location.
137 *
138 * Call to this function doesn't change the processing location.
139 *
140 *   offset: The index of the byte relative to the internat iterator.
141 */
142static inline void *drm_buffer_pointer_to_byte(struct drm_buffer *buffer,
143		int offset)
144{
145	int iter = buffer->iterator + offset;
146	return &buffer->data[iter / PAGE_SIZE][iter & (PAGE_SIZE - 1)];
147}
148
149#endif
150