/* $Id: tif_fax3.h,v 1.9 2011-03-10 20:23:07 fwarmerdam 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; \ if (b1 <= (int) (a0 + TabEnt->Param)) { \ if (b1 < (int) (a0 + TabEnt->Param) || pa != thisrun) { \ unexpected("VL", a0); \ goto eol2d; \ } \ } \ 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_ */ /* * Local Variables: * mode: c * c-basic-offset: 8 * fill-column: 78 * End: */