tif_fax3.h

一个国人自己实现图像库的程序（有参考价值）

		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_ */