spandsp
0.0.6
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00001 /* 00002 * SpanDSP - a series of DSP components for telephony 00003 * 00004 * private/t4_t6_decode.h - definitions for T.4/T.6 fax decoding 00005 * 00006 * Written by Steve Underwood <steveu@coppice.org> 00007 * 00008 * Copyright (C) 2003, 2009 Steve Underwood 00009 * 00010 * All rights reserved. 00011 * 00012 * This program is free software; you can redistribute it and/or modify 00013 * it under the terms of the GNU Lesser General Public License version 2.1, 00014 * as published by the Free Software Foundation. 00015 * 00016 * This program is distributed in the hope that it will be useful, 00017 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00018 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00019 * GNU Lesser General Public License for more details. 00020 * 00021 * You should have received a copy of the GNU Lesser General Public 00022 * License along with this program; if not, write to the Free Software 00023 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 00024 */ 00025 00026 #if !defined(_SPANDSP_PRIVATE_T4_T6_DECODE_H_) 00027 #define _SPANDSP_PRIVATE_T4_T6_DECODE_H_ 00028 00029 /*! 00030 T.4 1D, T4 2D and T6 decompressor state. 00031 */ 00032 struct t4_t6_decode_state_s 00033 { 00034 /*! \brief The type of compression used between the FAX machines. */ 00035 //int encoding; 00036 /*! \brief Width of the current page, in pixels. */ 00037 //int image_width; 00038 00039 /*! \brief Callback function to write a row of pixels to the image destination. */ 00040 t4_row_write_handler_t row_write_handler; 00041 /*! \brief Opaque pointer passed to row_write_handler. */ 00042 void *row_write_user_data; 00043 00044 /*! \brief A pointer into the image buffer indicating where the last row begins */ 00045 int last_row_starts_at; 00046 00047 /*! \brief This variable is used to count the consecutive EOLS we have seen. If it 00048 reaches six, this is the end of the image. It is initially set to -1 for 00049 1D and 2D decoding, as an indicator that we must wait for the first EOL, 00050 before decoding any image data. */ 00051 int consecutive_eols; 00052 00053 /*! \brief The reference or starting changing element on the coding line. At the 00054 start of the coding line, a0 is set on an imaginary white changing element 00055 situated just before the first element on the line. During the coding of 00056 the coding line, the position of a0 is defined by the previous coding mode. 00057 (See T.4/4.2.1.3.2.). */ 00058 int a0; 00059 /*! \brief The first changing element on the reference line to the right of a0 and of 00060 opposite colour to a0. */ 00061 int b1; 00062 /*! \brief The length of the in-progress run of black or white. */ 00063 int run_length; 00064 /*! \brief 2D horizontal mode control. */ 00065 int black_white; 00066 /*! \brief TRUE if the current run is black */ 00067 int its_black; 00068 00069 /*! \brief The current step into the current row run-lengths buffer. */ 00070 int a_cursor; 00071 /*! \brief The current step into the reference row run-lengths buffer. */ 00072 int b_cursor; 00073 00074 /*! \brief Incoming bit buffer for decompression. */ 00075 uint32_t rx_bitstream; 00076 /*! \brief The number of bits currently in rx_bitstream. */ 00077 int rx_bits; 00078 /*! \brief The number of bits to be skipped before trying to match the next code word. */ 00079 int rx_skip_bits; 00080 00081 /*! \brief Decoded pixel buffer. */ 00082 //uint32_t pixel_stream; 00083 /*! \brief The number of bits currently in pixel_stream. */ 00084 //int tx_bits; 00085 00086 /*! \brief Current pixel row number. */ 00087 //int row; 00088 00089 /*! \brief The current number of consecutive bad rows. */ 00090 int curr_bad_row_run; 00091 /*! \brief The longest run of consecutive bad rows seen in the current page. */ 00092 int longest_bad_row_run; 00093 /*! \brief The total number of bad rows in the current page. */ 00094 int bad_rows; 00095 00096 /*! \brief Error and flow logging control */ 00097 //logging_state_t logging; 00098 }; 00099 00100 #endif 00101 /*- End of file ------------------------------------------------------------*/