/* * Copyright (c) 1990-1997 Sam Leffler * Copyright (c) 1991-1997 Silicon Graphics, Inc. * * Permission to use, copy, modify, distribute, and sell this software and * its documentation for any purpose is hereby granted without fee, provided * that (i) the above copyright notices and this permission notice appear in * all copies of the software and related documentation, and (ii) the names of * Sam Leffler and Silicon Graphics may not be used in any advertising or * publicity relating to the software without the specific, prior written * permission of Sam Leffler and Silicon Graphics. * * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. * * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND, * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE * OF THIS SOFTWARE. */ #ifndef _FAX3_ #define _FAX3_ /* * TIFF Library. * * CCITT Group 3 (T.4) and Group 4 (T.6) Decompression Support. * * Decoder support is derived, with permission, from the code * in Frank Cringle's viewfax program; * Copyright (C) 1990, 1995 Frank D. Cringle. */ #include "tiff.h" /* * To override the default routine used to image decoded * spans one can use the pseudo tag TIFFTAG_FAXFILLFUNC. * The routine must have the type signature given below; * for example: * * fillruns(unsigned char* buf, uint32_t* runs, uint32_t* erun, uint32_t lastx) * * where buf is place to set the bits, runs is the array of b&w run * lengths (white then black), erun is the last run in the array, and * lastx is the width of the row in pixels. Fill routines can assume * the run array has room for at least lastx runs and can overwrite * data in the run array as needed (e.g. to append zero runs to bring * the count up to a nice multiple). */ TIFFFaxFillFunc; /* * The default run filler; made external for other decoders. */ #if defined(__cplusplus) extern "C" { #endif extern void _TIFFFax3fillruns(unsigned char *, uint32_t *, uint32_t *, uint32_t); #if defined(__cplusplus) } #endif /* finite state machine codes */ #define S_Null … #define S_Pass … #define S_Horiz … #define S_V0 … #define S_VR … #define S_VL … #define S_Ext … #define S_TermW … #define S_TermB … #define S_MakeUpW … #define S_MakeUpB … #define S_MakeUp … #define S_EOL … /* WARNING: do not change the layout of this structure as the HylaFAX software */ /* really depends on it. See http://bugzilla.maptools.org/show_bug.cgi?id=2636 */ TIFFFaxTabEnt; extern const TIFFFaxTabEnt TIFFFaxMainTable[]; extern const TIFFFaxTabEnt TIFFFaxWhiteTable[]; extern const TIFFFaxTabEnt TIFFFaxBlackTable[]; /* * The following macros define the majority of the G3/G4 decoder * algorithm using the state tables defined elsewhere. To build * a decoder you need some setup code and some glue code. Note * that you may also need/want to change the way the NeedBits* * macros get input data if, for example, you know the data to be * decoded is properly aligned and oriented (doing so before running * the decoder can be a big performance win). * * Consult the decoder in the TIFF library for an idea of what you * need to define and setup to make use of these definitions. * * NB: to enable a debugging version of these macros define FAX3_DEBUG * before including this file. Trace output goes to stdout. */ #ifndef EndOfData #define EndOfData() … #endif /* * Need <=8 or <=16 bits of input data. Unlike viewfax we * cannot use/assume a word-aligned, properly bit swizzled * input data set because data may come from an arbitrarily * aligned, read-only source such as a memory-mapped file. * Note also that the viewfax decoder does not check for * running off the end of the input data buffer. This is * possible for G3-encoded data because it prescans the input * data to count EOL markers, but can cause problems for G4 * data. In any event, we don't prescan and must watch for * running out of data since we can't permit the library to * scan past the end of the input data buffer. * * Finally, note that we must handle remaindered data at the end * of a strip specially. The coder asks for a fixed number of * bits when scanning for the next code. This may be more bits * than are actually present in the data stream. If we appear * to run out of data but still have some number of valid bits * remaining then we makeup the requested amount with zeros and * return successfully. If the returned data is incorrect then * we should be called again and get a premature EOF error; * otherwise we should get the right answer. */ #ifndef NeedBits8 #define NeedBits8(n, eoflab) … #endif #ifndef NeedBits16 #define NeedBits16(n, eoflab) … #endif #define GetBits(n) … #define ClrBits(n) … #ifdef FAX3_DEBUG static const char *StateNames[] = { "Null ", "Pass ", "Horiz ", "V0 ", "VR ", "VL ", "Ext ", "TermW ", "TermB ", "MakeUpW", "MakeUpB", "MakeUp ", "EOL ", }; #define DEBUG_SHOW … #define LOOKUP8 … #define LOOKUP16 … #define SETVALUE … #else #define LOOKUP8(wid, tab, eoflab) … #define LOOKUP16(wid, tab, eoflab) … /* * Append a run to the run length array for the * current row and reset decoding state. */ #define SETVALUE(x) … #endif /* * Synchronize input decoding at the start of each * row by scanning for an EOL (if appropriate) and * skipping any trash data that might be present * after a decoding error. Note that the decoding * done elsewhere that recognizes an EOL only consumes * 11 consecutive zero bits. This means that if EOLcnt * is non-zero then we still need to scan for the final flag * bit that is part of the EOL code. */ #define SYNC_EOL(eoflab) … /* * Cleanup the array of runs after decoding a row. * We adjust final runs to insure the user buffer is not * overwritten and/or undecoded area is white filled. */ #define CLEANUP_RUNS() … /* * Decode a line of 1D-encoded data. * * The line expanders are written as macros so that they can be reused * but still have direct access to the local variables of the "calling" * function. * * Note that unlike the original version we have to explicitly test for * a0 >= lastx after each black/white run is decoded. This is because * the original code depended on the input data being zero-padded to * insure the decoder recognized an EOL before running out of data. */ #define EXPAND1D(eoflab) … /* * Update the value of b1 using the array * of runs for the reference line. */ #define CHECK_b1 … /* * Expand a row of 2D-encoded data. */ #define EXPAND2D(eoflab) … #endif /* _FAX3_ */
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