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