http_file.h

来自「AMLOGIC DPF source code」· C头文件 代码 · 共 87 行

/*******************************************************************
 * 
 *  Copyright C 2005 by Amlogic, Inc. All Rights Reserved.
 *
 *  Description: 
 *
 *  Author: LiChao
 *  Created: Thu Aug 26 2005
 *
 *******************************************************************/
#ifndef _HTTP_FILE_H_
#define _HTTP_FILE_H_

/**
 * @brief This is a call back function for WMC file read. Because WMC file is on server, it don't like
 * local file, we can read any data in a constant time, we cannot know how long time to receive the request 
 * data from WMC server. So we design this call back function, when we call http_file_get_data to read 
 * data from WMC server, if request data in system buffer, return it at once; otherwise send request to 
 * WMC server and return failure at once. When the system receive the data from WMC server, system will 
 * call this call back function to wake up the user blocked read process.
 * @param [in] buf_addr the data pointer which user requested by http_file_get_data.
 * @param [in] len the return data length. 
 * @param [in] arg the callback argument. 
 */
typedef void (*HTTP_FILE_CB)(void *buf_addr, int len, unsigned arg) ;

/**
 * @brief Following struct is basic information to store the UPnP http download information. 
 * It'll saved read offset and current download buffer size and download offset for http_file_read.
 */
typedef struct http_file_s http_file_t ;

/**
 * Open a media file which got by UPnP protocal and download by http protocal.
 * @param [in] file_uri the URL of download media file.
 * @param [in] buffer_size The amount of data to buffer.
 * @param [in] callback User callback, check user operation during reading data.
 *                                 
 * @returns handle of http connection when success, otherwise NULL.
*/
http_file_t* http_file_open(char *file_uri, unsigned buffer_size, unsigned callback) ;

/**
 * Get the address of the \a pbuf buffer chain for \a http_file_t.
 */
extern int
http_file_get_chain(http_file_t* file_handle, struct pbuf **pbuf, 
                    int len);

/**
 * @brief Same as http_file_read, just don't copy to user buf, only return data point.
 * @param [in] file_handle Define the handle of the media file we want to read.
 * @param [out] buf_addr return the data point which user want to get.
 * @param [in|out] len Read size(bytes) as input parameter, and reuturn actural read size as output parameter.
 * if actural read size less than request size and biger than -1, that means end of file.
 * if return size is -1, that means read file error.
 * @param [in] async_cb If DATA_NOT_READY, we will send data request to http server, when we get the data, we'll 
 * call the call back function to notify user data is ready.
 * @param [in] async_cb_arg argument for async_cb.
 *                                 
 * @returns -2 if len > file_buffer_size;
 *          -1(DATA_NOT_READY) if not more data to read. 
 *          0 success(DATA_READY).
*/
int http_file_get_data(http_file_t* file_handle, char **buf_addr, int len);

/**
 * Allow user set read offset of media file.
 * @param [in] file_handle Define the handle of the media file we want to set read offset.
 * @param [in] offset Define data of read offset.
 * @param [in] fromwhere If fromwhere is 0, seek from current offset. if fromwhere is 2, from the 
 * begining of file.
 *                                 
 * @returns -1 if failed, otherwise 0.
*/
int http_file_seek(http_file_t* file_handle, long offset, int fromwhere);
    
/**
 * Close a download media file and free all relate resource.
 * @param [in] file_handle Define the handle of the media file we want to close.
 *                                 
 * @returns -1 if failed, otherwise 0.
*/
int http_file_close(http_file_t* file_handle) ;

#endif//_HTTP_FILE_H_