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+/* $Id: tif_fax3.h,v 1.1 2008/10/17 06:16:07 scuri Exp $ */
+
+/*
+ * 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 pseduo tag TIFFTAG_FAXFILLFUNC.
+ * The routine must have the type signature given below;
+ * for example:
+ *
+ * fillruns(unsigned char* buf, uint32* runs, uint32* erun, uint32 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).
+ */
+typedef void (*TIFFFaxFillFunc)(unsigned char*, uint32*, uint32*, uint32);
+
+/*
+ * The default run filler; made external for other decoders.
+ */
+#if defined(__cplusplus)
+extern "C" {
+#endif
+extern void _TIFFFax3fillruns(unsigned char*, uint32*, uint32*, uint32);
+#if defined(__cplusplus)
+}
+#endif
+
+
+/* finite state machine codes */
+#define S_Null 0
+#define S_Pass 1
+#define S_Horiz 2
+#define S_V0 3
+#define S_VR 4
+#define S_VL 5
+#define S_Ext 6
+#define S_TermW 7
+#define S_TermB 8
+#define S_MakeUpW 9
+#define S_MakeUpB 10
+#define S_MakeUp 11
+#define S_EOL 12
+
+typedef struct { /* state table entry */
+ unsigned char State; /* see above */
+ unsigned char Width; /* width of code in bits */
+ uint32 Param; /* unsigned 32-bit run length in bits */
+} 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() (cp >= ep)
+#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) do { \
+ if (BitsAvail < (n)) { \
+ if (EndOfData()) { \
+ if (BitsAvail == 0) /* no valid bits */ \
+ goto eoflab; \
+ BitsAvail = (n); /* pad with zeros */ \
+ } else { \
+ BitAcc |= ((uint32) bitmap[*cp++])<<BitsAvail; \
+ BitsAvail += 8; \
+ } \
+ } \
+} while (0)
+#endif
+#ifndef NeedBits16
+#define NeedBits16(n,eoflab) do { \
+ if (BitsAvail < (n)) { \
+ if (EndOfData()) { \
+ if (BitsAvail == 0) /* no valid bits */ \
+ goto eoflab; \
+ BitsAvail = (n); /* pad with zeros */ \
+ } else { \
+ BitAcc |= ((uint32) bitmap[*cp++])<<BitsAvail; \
+ if ((BitsAvail += 8) < (n)) { \
+ if (EndOfData()) { \
+ /* NB: we know BitsAvail is non-zero here */ \
+ BitsAvail = (n); /* pad with zeros */ \
+ } else { \
+ BitAcc |= ((uint32) bitmap[*cp++])<<BitsAvail; \
+ BitsAvail += 8; \
+ } \
+ } \
+ } \
+ } \
+} while (0)
+#endif
+#define GetBits(n) (BitAcc & ((1<<(n))-1))
+#define ClrBits(n) do { \
+ BitsAvail -= (n); \
+ BitAcc >>= (n); \
+} while (0)
+
+#ifdef FAX3_DEBUG
+static const char* StateNames[] = {
+ "Null ",
+ "Pass ",
+ "Horiz ",
+ "V0 ",
+ "VR ",
+ "VL ",
+ "Ext ",
+ "TermW ",
+ "TermB ",
+ "MakeUpW",
+ "MakeUpB",
+ "MakeUp ",
+ "EOL ",
+};
+#define DEBUG_SHOW putchar(BitAcc & (1 << t) ? '1' : '0')
+#define LOOKUP8(wid,tab,eoflab) do { \
+ int t; \
+ NeedBits8(wid,eoflab); \
+ TabEnt = tab + GetBits(wid); \
+ printf("%08lX/%d: %s%5d\t", (long) BitAcc, BitsAvail, \
+ StateNames[TabEnt->State], TabEnt->Param); \
+ for (t = 0; t < TabEnt->Width; t++) \
+ DEBUG_SHOW; \
+ putchar('\n'); \
+ fflush(stdout); \
+ ClrBits(TabEnt->Width); \
+} while (0)
+#define LOOKUP16(wid,tab,eoflab) do { \
+ int t; \
+ NeedBits16(wid,eoflab); \
+ TabEnt = tab + GetBits(wid); \
+ printf("%08lX/%d: %s%5d\t", (long) BitAcc, BitsAvail, \
+ StateNames[TabEnt->State], TabEnt->Param); \
+ for (t = 0; t < TabEnt->Width; t++) \
+ DEBUG_SHOW; \
+ putchar('\n'); \
+ fflush(stdout); \
+ ClrBits(TabEnt->Width); \
+} while (0)
+
+#define SETVALUE(x) do { \
+ *pa++ = RunLength + (x); \
+ printf("SETVALUE: %d\t%d\n", RunLength + (x), a0); \
+ a0 += x; \
+ RunLength = 0; \
+} while (0)
+#else
+#define LOOKUP8(wid,tab,eoflab) do { \
+ NeedBits8(wid,eoflab); \
+ TabEnt = tab + GetBits(wid); \
+ ClrBits(TabEnt->Width); \
+} while (0)
+#define LOOKUP16(wid,tab,eoflab) do { \
+ NeedBits16(wid,eoflab); \
+ TabEnt = tab + GetBits(wid); \
+ ClrBits(TabEnt->Width); \
+} while (0)
+
+/*
+ * Append a run to the run length array for the
+ * current row and reset decoding state.
+ */
+#define SETVALUE(x) do { \
+ *pa++ = RunLength + (x); \
+ a0 += (x); \
+ RunLength = 0; \
+} while (0)
+#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) do { \
+ if (EOLcnt == 0) { \
+ for (;;) { \
+ NeedBits16(11,eoflab); \
+ if (GetBits(11) == 0) \
+ break; \
+ ClrBits(1); \
+ } \
+ } \
+ for (;;) { \
+ NeedBits8(8,eoflab); \
+ if (GetBits(8)) \
+ break; \
+ ClrBits(8); \
+ } \
+ while (GetBits(1) == 0) \
+ ClrBits(1); \
+ ClrBits(1); /* EOL bit */ \
+ EOLcnt = 0; /* reset EOL counter/flag */ \
+} while (0)
+
+/*
+ * 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() do { \
+ if (RunLength) \
+ SETVALUE(0); \
+ if (a0 != lastx) { \
+ badlength(a0, lastx); \
+ while (a0 > lastx && pa > thisrun) \
+ a0 -= *--pa; \
+ if (a0 < lastx) { \
+ if (a0 < 0) \
+ a0 = 0; \
+ if ((pa-thisrun)&1) \
+ SETVALUE(0); \
+ SETVALUE(lastx - a0); \
+ } else if (a0 > lastx) { \
+ SETVALUE(lastx); \
+ SETVALUE(0); \
+ } \
+ } \
+} while (0)
+
+/*
+ * 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) do { \
+ for (;;) { \
+ for (;;) { \
+ LOOKUP16(12, TIFFFaxWhiteTable, eof1d); \
+ switch (TabEnt->State) { \
+ case S_EOL: \
+ EOLcnt = 1; \
+ goto done1d; \
+ case S_TermW: \
+ SETVALUE(TabEnt->Param); \
+ goto doneWhite1d; \
+ case S_MakeUpW: \
+ case S_MakeUp: \
+ a0 += TabEnt->Param; \
+ RunLength += TabEnt->Param; \
+ break; \
+ default: \
+ unexpected("WhiteTable", a0); \
+ goto done1d; \
+ } \
+ } \
+ doneWhite1d: \
+ if (a0 >= lastx) \
+ goto done1d; \
+ for (;;) { \
+ LOOKUP16(13, TIFFFaxBlackTable, eof1d); \
+ switch (TabEnt->State) { \
+ case S_EOL: \
+ EOLcnt = 1; \
+ goto done1d; \
+ case S_TermB: \
+ SETVALUE(TabEnt->Param); \
+ goto doneBlack1d; \
+ case S_MakeUpB: \
+ case S_MakeUp: \
+ a0 += TabEnt->Param; \
+ RunLength += TabEnt->Param; \
+ break; \
+ default: \
+ unexpected("BlackTable", a0); \
+ goto done1d; \
+ } \
+ } \
+ doneBlack1d: \
+ if (a0 >= lastx) \
+ goto done1d; \
+ if( *(pa-1) == 0 && *(pa-2) == 0 ) \
+ pa -= 2; \
+ } \
+eof1d: \
+ prematureEOF(a0); \
+ CLEANUP_RUNS(); \
+ goto eoflab; \
+done1d: \
+ CLEANUP_RUNS(); \
+} while (0)
+
+/*
+ * Update the value of b1 using the array
+ * of runs for the reference line.
+ */
+#define CHECK_b1 do { \
+ if (pa != thisrun) while (b1 <= a0 && b1 < lastx) { \
+ b1 += pb[0] + pb[1]; \
+ pb += 2; \
+ } \
+} while (0)
+
+/*
+ * Expand a row of 2D-encoded data.
+ */
+#define EXPAND2D(eoflab) do { \
+ while (a0 < lastx) { \
+ LOOKUP8(7, TIFFFaxMainTable, eof2d); \
+ switch (TabEnt->State) { \
+ case S_Pass: \
+ CHECK_b1; \
+ b1 += *pb++; \
+ RunLength += b1 - a0; \
+ a0 = b1; \
+ b1 += *pb++; \
+ break; \
+ case S_Horiz: \
+ if ((pa-thisrun)&1) { \
+ for (;;) { /* black first */ \
+ LOOKUP16(13, TIFFFaxBlackTable, eof2d); \
+ switch (TabEnt->State) { \
+ case S_TermB: \
+ SETVALUE(TabEnt->Param); \
+ goto doneWhite2da; \
+ case S_MakeUpB: \
+ case S_MakeUp: \
+ a0 += TabEnt->Param; \
+ RunLength += TabEnt->Param; \
+ break; \
+ default: \
+ goto badBlack2d; \
+ } \
+ } \
+ doneWhite2da:; \
+ for (;;) { /* then white */ \
+ LOOKUP16(12, TIFFFaxWhiteTable, eof2d); \
+ switch (TabEnt->State) { \
+ case S_TermW: \
+ SETVALUE(TabEnt->Param); \
+ goto doneBlack2da; \
+ case S_MakeUpW: \
+ case S_MakeUp: \
+ a0 += TabEnt->Param; \
+ RunLength += TabEnt->Param; \
+ break; \
+ default: \
+ goto badWhite2d; \
+ } \
+ } \
+ doneBlack2da:; \
+ } else { \
+ for (;;) { /* white first */ \
+ LOOKUP16(12, TIFFFaxWhiteTable, eof2d); \
+ switch (TabEnt->State) { \
+ case S_TermW: \
+ SETVALUE(TabEnt->Param); \
+ goto doneWhite2db; \
+ case S_MakeUpW: \
+ case S_MakeUp: \
+ a0 += TabEnt->Param; \
+ RunLength += TabEnt->Param; \
+ break; \
+ default: \
+ goto badWhite2d; \
+ } \
+ } \
+ doneWhite2db:; \
+ for (;;) { /* then black */ \
+ LOOKUP16(13, TIFFFaxBlackTable, eof2d); \
+ switch (TabEnt->State) { \
+ case S_TermB: \
+ SETVALUE(TabEnt->Param); \
+ goto doneBlack2db; \
+ case S_MakeUpB: \
+ case S_MakeUp: \
+ a0 += TabEnt->Param; \
+ RunLength += TabEnt->Param; \
+ break; \
+ default: \
+ goto badBlack2d; \
+ } \
+ } \
+ doneBlack2db:; \
+ } \
+ CHECK_b1; \
+ break; \
+ case S_V0: \
+ CHECK_b1; \
+ SETVALUE(b1 - a0); \
+ b1 += *pb++; \
+ break; \
+ case S_VR: \
+ CHECK_b1; \
+ SETVALUE(b1 - a0 + TabEnt->Param); \
+ b1 += *pb++; \
+ break; \
+ case S_VL: \
+ CHECK_b1; \
+ SETVALUE(b1 - a0 - TabEnt->Param); \
+ b1 -= *--pb; \
+ break; \
+ case S_Ext: \
+ *pa++ = lastx - a0; \
+ extension(a0); \
+ goto eol2d; \
+ case S_EOL: \
+ *pa++ = lastx - a0; \
+ NeedBits8(4,eof2d); \
+ if (GetBits(4)) \
+ unexpected("EOL", a0); \
+ ClrBits(4); \
+ EOLcnt = 1; \
+ goto eol2d; \
+ default: \
+ badMain2d: \
+ unexpected("MainTable", a0); \
+ goto eol2d; \
+ badBlack2d: \
+ unexpected("BlackTable", a0); \
+ goto eol2d; \
+ badWhite2d: \
+ unexpected("WhiteTable", a0); \
+ goto eol2d; \
+ eof2d: \
+ prematureEOF(a0); \
+ CLEANUP_RUNS(); \
+ goto eoflab; \
+ } \
+ } \
+ if (RunLength) { \
+ if (RunLength + a0 < lastx) { \
+ /* expect a final V0 */ \
+ NeedBits8(1,eof2d); \
+ if (!GetBits(1)) \
+ goto badMain2d; \
+ ClrBits(1); \
+ } \
+ SETVALUE(0); \
+ } \
+eol2d: \
+ CLEANUP_RUNS(); \
+} while (0)
+#endif /* _FAX3_ */
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