FreeBSD/Linux Kernel Cross Reference
sys/dev/drm2/drm_buffer.h

     /**************************************************************************
      *
      * 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>
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #ifndef _DRM_BUFFER_H_
    #define _DRM_BUFFER_H_
    
    #include <dev/drm2/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

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