/* Id */

/*
 * 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 SETVAL(x) do {                                                  \
    *pa++ = RunLength + (x);                                            \
    printf("SETVAL: %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 SETVAL(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)                                                      \
        SETVAL(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)                                         \
                SETVAL(0);                                              \
            SETVAL(lastx - a0);                                         \
        } else if (a0 > lastx) {                                        \
            SETVAL(lastx);                                              \
            SETVAL(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:                                               \
                SETVAL(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:                                               \
                SETVAL(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:                                 \
            SETVAL(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:                                 \
            SETVAL(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:                                 \
            SETVAL(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:                                 \
            SETVAL(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;                                         \
      SETVAL(b1 - a0);                                  \
      b1 += *pb++;                                      \
      break;                                            \
    case S_VR:                                          \
      CHECK_b1;                                         \
      SETVAL(b1 - a0 + TabEnt->Param);                  \
      b1 += *pb++;                                      \
      break;                                            \
    case S_VL:                                          \
      CHECK_b1;                                         \
      SETVAL(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);                                       \
    }                                                   \
    SETVAL(0);                                          \
  }                                                     \
eol2d:                                                  \
  CLEANUP_RUNS();                                       \
} while (0)

#endif /* _FAX3_ */
