drm_buffer.h
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/**************************************************************************
*
* Copyright 2010 Pauli Nieminen.
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sub license, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice (including the
* next paragraph) shall be included in all copies or substantial portions
* of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
* THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
* USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*
**************************************************************************/
/*
* Multipart buffer for coping data which is larger than the page size.
*
* Authors:
* Pauli Nieminen <suokkos-at-gmail-dot-com>
*/
#ifndef _DRM_BUFFER_H_
#define _DRM_BUFFER_H_
#include "drmP.h"
struct drm_buffer {
int iterator;
int size;
char *data[];
};
/**
* Return the index of page that buffer is currently pointing at.
*/
static inline int drm_buffer_page(struct drm_buffer *buf)
{
return buf->iterator / PAGE_SIZE;
}
/**
* Return the index of the current byte in the page
*/
static inline int drm_buffer_index(struct drm_buffer *buf)
{
return buf->iterator & (PAGE_SIZE - 1);
}
/**
* Return number of bytes that is left to process
*/
static inline int drm_buffer_unprocessed(struct drm_buffer *buf)
{
return buf->size - buf->iterator;
}
/**
* Advance the buffer iterator number of bytes that is given.
*/
static inline void drm_buffer_advance(struct drm_buffer *buf, int bytes)
{
buf->iterator += bytes;
}
/**
* Allocate the drm buffer object.
*
* buf: A pointer to a pointer where the object is stored.
* size: The number of bytes to allocate.
*/
extern int drm_buffer_alloc(struct drm_buffer **buf, int size);
/**
* Copy the user data to the begin of the buffer and reset the processing
* iterator.
*
* user_data: A pointer the data that is copied to the buffer.
* size: The Number of bytes to copy.
*/
extern int drm_buffer_copy_from_user(struct drm_buffer *buf,
void __user *user_data, int size);
/**
* Free the drm buffer object
*/
extern void drm_buffer_free(struct drm_buffer *buf);
/**
* Read an object from buffer that may be split to multiple parts. If object
* is not split function just returns the pointer to object in buffer. But in
* case of split object data is copied to given stack object that is suplied
* by caller.
*
* The processing location of the buffer is also advanced to the next byte
* after the object.
*
* objsize: The size of the objet in bytes.
* stack_obj: A pointer to a memory location where object can be copied.
*/
extern void *drm_buffer_read_object(struct drm_buffer *buf,
int objsize, void *stack_obj);
/**
* Returns the pointer to the dword which is offset number of elements from the
* current processing location.
*
* Caller must make sure that dword is not split in the buffer. This
* requirement is easily met if all the sizes of objects in buffer are
* multiples of dword and PAGE_SIZE is multiple dword.
*
* Call to this function doesn't change the processing location.
*
* offset: The index of the dword relative to the internat iterator.
*/
static inline void *drm_buffer_pointer_to_dword(struct drm_buffer *buffer,
int offset)
{
int iter = buffer->iterator + offset * 4;
return &buffer->data[iter / PAGE_SIZE][iter & (PAGE_SIZE - 1)];
}
/**
* Returns the pointer to the dword which is offset number of elements from
* the current processing location.
*
* Call to this function doesn't change the processing location.
*
* offset: The index of the byte relative to the internat iterator.
*/
static inline void *drm_buffer_pointer_to_byte(struct drm_buffer *buffer,
int offset)
{
int iter = buffer->iterator + offset;
return &buffer->data[iter / PAGE_SIZE][iter & (PAGE_SIZE - 1)];
}
#endif