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
 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