--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/dgif_lib.c	Mon Aug 13 10:42:44 2007 +0200
@@ -0,0 +1,965 @@
+/******************************************************************************
+*   "Gif-Lib" - Yet another gif library.				      *
+*									      *
+* Written by:  Gershon Elber			IBM PC Ver 1.1,	Aug. 1990     *
+*******************************************************************************
+* The kernel of the GIF Decoding process can be found here.		      *
+*******************************************************************************
+* History:								      *
+* 16 Jun 89 - Version 1.0 by Gershon Elber.				      *
+*  3 Sep 90 - Version 1.1 by Gershon Elber (Support for Gif89, Unique names). *
+* 19 Feb 98 - Version 1.2 by Jareth Hein (Support for user specified I/O)     *
+******************************************************************************/
+
+#ifdef __MSDOS__
+#include <io.h>
+#include <alloc.h>
+#include <stdlib.h>
+#include <sys\stat.h>
+#else
+#include <sys/types.h>
+#include <sys/stat.h>
+#endif /* __MSDOS__ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#ifdef HAVE_FCNTL_H
+#include <fcntl.h>
+#endif
+
+#include "gifrlib.h"
+
+#define PROGRAM_NAME	"GIFLIB"
+
+
+static void DGifGetWord(GifFileType *GifFile, int *Word);
+static void DGifSetupDecompress(GifFileType *GifFile);
+static void DGifDecompressLine(GifFileType *GifFile, GifPixelType *Line,
+								int LineLen);
+static int DGifGetPrefixChar(unsigned int *Prefix, int Code, int ClearCode);
+static void DGifDecompressInput(GifFileType *GifFile, int *Code);
+static void DGifBufferedInput(GifFileType *GifFile, GifByteType *NextByte);
+
+/******************************************************************************
+*   Open a new gif file for read, given by its name.			      *
+*   Returns GifFileType pointer dynamically allocated which serves as the gif *
+* info record. 								      *
+******************************************************************************/
+void DGifOpenFileName(GifFileType *GifFile, const char *FileName)
+{
+    FILE *f;
+
+    if ((f = fopen(FileName, 
+#ifdef __MSDOS__
+			     "rb"
+#else
+		             "r"
+#endif /* __MSDOS__ */
+			                     )) == NULL)
+	GifInternError(GifFile, D_GIF_ERR_OPEN_FAILED);
+
+    GifStdIOInit(GifFile, f, -1);
+    DGifInitRead(GifFile);
+}
+
+/******************************************************************************
+*   Update a new gif file, given its file handle.			      *
+*   Returns GifFileType pointer dynamically allocated which serves as the gif *
+* info record.								      *
+******************************************************************************/
+void DGifOpenFileHandle(GifFileType *GifFile, int FileHandle)
+{
+    FILE *f;
+
+#ifdef __MSDOS__
+    setmode(FileHandle, O_BINARY);	  /* Make sure it is in binary mode. */
+    f = fdopen(FileHandle, "rb");		   /* Make it into a stream: */
+    setvbuf(f, NULL, _IOFBF, GIF_FILE_BUFFER_SIZE);/* And inc. stream buffer.*/
+#else
+    f = fdopen(FileHandle, "r");		   /* Make it into a stream: */
+#endif /* __MSDOS__ */
+
+    GifStdIOInit(GifFile, f, -1);
+    DGifInitRead(GifFile);
+}
+
+/******************************************************************************
+*   Update a new gif file, given its file handle.			      *
+*   Returns GifFileType pointer dynamically allocated which serves as the gif *
+* info record. _GifError is cleared if succesfull.			      *
+******************************************************************************/
+void DGifInitRead(GifFileType *GifFile)
+{
+    GifByteType Buf[GIF_STAMP_LEN+1];
+    GifFilePrivateType *Private;
+
+    if ((Private = (GifFilePrivateType *) malloc(sizeof(GifFilePrivateType)))
+	== NULL) {
+	GifInternError(GifFile, D_GIF_ERR_NOT_ENOUGH_MEM);
+    }
+    memset(Private, '\0', sizeof(GifFilePrivateType));
+    GifFile->Private = (VoidPtr) Private;
+
+    Private->FileState = 0;   /* Make sure bit 0 = 0 (File open for read). */
+
+    /* Lets see if this is a GIF file: */
+    GifRead(Buf, GIF_STAMP_LEN, GifFile);
+
+    /* The GIF Version number is ignored at this time. Maybe we should do    */
+    /* something more useful with it.					     */
+    Buf[GIF_STAMP_LEN] = 0;
+    if (strncmp(GIF_STAMP, Buf, GIF_VERSION_POS) != 0) {
+	GifInternError(GifFile, D_GIF_ERR_NOT_GIF_FILE);
+    }
+
+    DGifGetScreenDesc(GifFile);
+}
+
+/******************************************************************************
+*   This routine should be called before any other DGif calls. Note that      *
+* this routine is called automatically from DGif file open routines.	      *
+******************************************************************************/
+void DGifGetScreenDesc(GifFileType *GifFile)
+{
+    int i, BitsPerPixel;
+    GifByteType Buf[3];
+    GifFilePrivateType *Private = (GifFilePrivateType*) GifFile->Private;
+
+    if (!IS_READABLE(Private)) {
+	/* This file was NOT open for reading: */
+	GifInternError(GifFile, D_GIF_ERR_NOT_READABLE);
+    }
+
+    /* Put the screen descriptor into the file: */
+    DGifGetWord(GifFile, &GifFile->SWidth);
+    DGifGetWord(GifFile, &GifFile->SHeight);
+
+    GifRead(Buf, 3, GifFile);
+    GifFile->SColorResolution = (((Buf[0] & 0x70) + 1) >> 4) + 1;
+    BitsPerPixel = (Buf[0] & 0x07) + 1;
+    GifFile->SBackGroundColor = Buf[1];
+    if (Buf[0] & 0x80) {		     /* Do we have global color map? */
+
+	GifFile->SColorMap = MakeMapObject(1 << BitsPerPixel, NULL);
+
+	/* Get the global color map: */
+	for (i = 0; i < GifFile->SColorMap->ColorCount; i++) {
+	    GifRead(Buf, 3, GifFile);
+	    GifFile->SColorMap->Colors[i].Red = Buf[0];
+	    GifFile->SColorMap->Colors[i].Green = Buf[1];
+	    GifFile->SColorMap->Colors[i].Blue = Buf[2];
+	}
+    } else {
+	/* We should always have a colormap */
+	GifFile->SColorMap = MakeMapObject(2, NULL);
+	GifFile->SColorMap->Colors[0].Red = 0;
+	GifFile->SColorMap->Colors[0].Green = 0;
+	GifFile->SColorMap->Colors[0].Blue = 0;
+	GifFile->SColorMap->Colors[1].Red = 0xff;
+	GifFile->SColorMap->Colors[1].Green = 0xff;
+	GifFile->SColorMap->Colors[1].Blue = 0xff;
+    }
+}
+
+/******************************************************************************
+*   This routine should be called before any attemp to read an image.         *
+******************************************************************************/
+void DGifGetRecordType(GifFileType *GifFile, GifRecordType *Type)
+{
+    GifByteType Buf;
+    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
+    
+    if (!IS_READABLE(Private)) {
+	/* This file was NOT open for reading: */
+	GifInternError(GifFile, D_GIF_ERR_NOT_READABLE);
+    }
+
+    GifRead(&Buf, 1, GifFile);
+
+    switch (Buf) {
+	case ',':
+	    *Type = IMAGE_DESC_RECORD_TYPE;
+	    break;
+	case '!':
+	    *Type = EXTENSION_RECORD_TYPE;
+	    break;
+	case ';':
+	    *Type = TERMINATE_RECORD_TYPE;
+	    break;
+	default:
+	    *Type = UNDEFINED_RECORD_TYPE;
+	    GifInternError(GifFile, D_GIF_ERR_WRONG_RECORD);
+    }
+}
+
+/******************************************************************************
+*   This routine should be called before any attemp to read an image.         *
+*   Note it is assumed the Image desc. header (',') has been read.	      *
+******************************************************************************/
+void DGifGetImageDesc(GifFileType *GifFile)
+{
+    int i, BitsPerPixel;
+    GifByteType Buf[3];
+    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
+
+    if (!IS_READABLE(Private)) {
+	/* This file was NOT open for reading: */
+	GifInternError(GifFile, D_GIF_ERR_NOT_READABLE);
+    }
+
+    DGifGetWord(GifFile, &GifFile->Image.Left);
+    DGifGetWord(GifFile, &GifFile->Image.Top);
+    DGifGetWord(GifFile, &GifFile->Image.Width);
+    DGifGetWord(GifFile, &GifFile->Image.Height);
+
+    GifRead(Buf, 1, GifFile);
+    BitsPerPixel = (Buf[0] & 0x07) + 1;
+    GifFile->Image.Interlace = (Buf[0] & 0x40);
+    if (Buf[0] & 0x80) {	    /* Does this image have local color map? */
+
+	if (GifFile->Image.ColorMap && GifFile->SavedImages == NULL)
+	    FreeMapObject(GifFile->Image.ColorMap);
+
+	GifFile->Image.ColorMap = MakeMapObject(1 << BitsPerPixel, NULL);
+    
+	/* Get the image local color map: */
+	for (i = 0; i < GifFile->Image.ColorMap->ColorCount; i++) {
+	    GifRead(Buf, 3, GifFile);
+	    GifFile->Image.ColorMap->Colors[i].Red = Buf[0];
+	    GifFile->Image.ColorMap->Colors[i].Green = Buf[1];
+	    GifFile->Image.ColorMap->Colors[i].Blue = Buf[2];
+	}
+    }
+
+    if (GifFile->SavedImages) {
+	SavedImage	*sp;
+
+	if ((GifFile->SavedImages = (SavedImage *)realloc(GifFile->SavedImages,
+		    sizeof(SavedImage) * (GifFile->ImageCount + 1))) == NULL) {
+	    GifInternError(GifFile, D_GIF_ERR_NOT_ENOUGH_MEM);
+	}
+
+	sp = &GifFile->SavedImages[GifFile->ImageCount];
+	memcpy(&sp->ImageDesc, &GifFile->Image, sizeof(GifImageDesc));
+	if (GifFile->Image.ColorMap)
+	  {
+	    sp->ImageDesc.ColorMap =
+	      MakeMapObject (GifFile->Image.ColorMap->ColorCount,
+			     GifFile->Image.ColorMap->Colors);
+	  }
+	sp->RasterBits = (GifPixelType *)NULL;
+	sp->ExtensionBlockCount = 0;
+	sp->ExtensionBlocks = (ExtensionBlock *)NULL;
+    }
+
+    GifFile->ImageCount++;
+
+    Private->PixelCount = (long) GifFile->Image.Width *
+			    (long) GifFile->Image.Height;
+
+    DGifSetupDecompress(GifFile);  /* Reset decompress algorithm parameters. */
+}
+
+/******************************************************************************
+*  Get one full scanned line (Line) of length LineLen from GIF file.	      *
+******************************************************************************/
+void DGifGetLine(GifFileType *GifFile, GifPixelType *Line, int LineLen)
+{
+    GifByteType *Dummy;
+    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
+
+    if (!IS_READABLE(Private)) {
+	/* This file was NOT open for reading: */
+	GifInternError(GifFile, D_GIF_ERR_NOT_READABLE);
+    }
+
+    if (!LineLen) LineLen = GifFile->Image.Width;
+
+#if defined(__MSDOS__) || defined(__GNUC__)
+    if ((Private->PixelCount -= LineLen) > 0xffff0000UL)
+#else
+    if ((Private->PixelCount -= LineLen) > 0xffff0000)
+#endif /* __MSDOS__ */
+    {    
+	GifInternError(GifFile, D_GIF_ERR_DATA_TOO_BIG);
+    }
+
+    DGifDecompressLine(GifFile, Line, LineLen);
+    if (Private->PixelCount == 0) {
+	/* We probably would not be called any more, so lets clean 	     */
+	/* everything before we return: need to flush out all rest of    */
+	/* image until empty block (size 0) detected. We use GetCodeNext.*/
+	do
+	    DGifGetCodeNext(GifFile, &Dummy);
+	while (Dummy != NULL);
+    }
+}
+
+/******************************************************************************
+* Put one pixel (Pixel) into GIF file.					      *
+******************************************************************************/
+void DGifGetPixel(GifFileType *GifFile, GifPixelType Pixel)
+{
+    GifByteType *Dummy;
+    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
+
+    if (!IS_READABLE(Private)) {
+	/* This file was NOT open for reading: */
+	GifInternError(GifFile, D_GIF_ERR_NOT_READABLE);
+    }
+
+#if defined(__MSDOS__) || defined(__GNUC__)
+    if (--Private->PixelCount > 0xffff0000UL)
+#else
+    if (--Private->PixelCount > 0xffff0000)
+#endif /* __MSDOS__ */
+    {
+	GifInternError(GifFile, D_GIF_ERR_DATA_TOO_BIG);
+    }
+
+    DGifDecompressLine(GifFile, &Pixel, 1);
+    if (Private->PixelCount == 0) {
+	/* We probably would not be called any more, so lets clean 	     */
+	/* everything before we return: need to flush out all rest of    */
+	/* image until empty block (size 0) detected. We use GetCodeNext.*/
+	do
+	    DGifGetCodeNext(GifFile, &Dummy);
+	while (Dummy != NULL);
+    }
+}
+
+/******************************************************************************
+*   Get an extension block (see GIF manual) from gif file. This routine only  *
+* returns the first data block, and DGifGetExtensionNext shouldbe called      *
+* after this one until NULL extension is returned.			      *
+*   The Extension should NOT be freed by the user (not dynamically allocated).*
+*   Note it is assumed the Extension desc. header ('!') has been read.	      *
+******************************************************************************/
+void DGifGetExtension(GifFileType *GifFile, int *ExtCode,
+						    GifByteType **Extension)
+{
+    GifByteType Buf;
+    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
+
+    if (!IS_READABLE(Private)) {
+	/* This file was NOT open for reading: */
+	GifInternError(GifFile, D_GIF_ERR_NOT_READABLE);
+    }
+
+    GifRead(&Buf, 1, GifFile);
+    *ExtCode = Buf;
+
+    DGifGetExtensionNext(GifFile, Extension);
+}
+
+/******************************************************************************
+*   Get a following extension block (see GIF manual) from gif file. This      *
+* routine sould be called until NULL Extension is returned.		      *
+*   The Extension should NOT be freed by the user (not dynamically allocated).*
+******************************************************************************/
+void DGifGetExtensionNext(GifFileType *GifFile, GifByteType **Extension)
+{
+    GifByteType Buf;
+    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
+
+    GifRead(&Buf, 1, GifFile);
+    if (Buf > 0) {
+	*Extension = Private->Buf;           /* Use private unused buffer. */
+	(*Extension)[0] = Buf;  /* Pascal strings notation (pos. 0 is len.). */
+	GifRead(&((*Extension)[1]), Buf, GifFile);
+    }
+    else
+	*Extension = NULL;
+}
+
+/******************************************************************************
+*   This routine should be called second to last, to close the GIF file.      *
+******************************************************************************/
+int DGifCloseFile(GifFileType *GifFile)
+{
+    GifFilePrivateType *Private = (GifFilePrivateType *)GifFile->Private;
+
+    if (GifFile == NULL) return -1;
+
+    if (!IS_READABLE(Private))
+    {
+	/* This file was NOT open for reading: */
+	GifInternError(GifFile, D_GIF_ERR_NOT_READABLE);
+    }
+
+    if (GifClose (GifFile))
+    {
+	GifInternError(GifFile, D_GIF_ERR_CLOSE_FAILED);
+    }
+    return 0;
+}
+
+/******************************************************************************
+*   Get 2 bytes (word) from the given file:				      *
+******************************************************************************/
+static void DGifGetWord(GifFileType *GifFile, int *Word)
+{
+    unsigned char c[2];
+
+    GifRead(c, 2, GifFile);
+
+    *Word = (((unsigned int) c[1]) << 8) + c[0];
+}
+
+/******************************************************************************
+*   Get the image code in compressed form.  his routine can be called if the  *
+* information needed to be piped out as is. Obviously this is much faster     *
+* than decoding and encoding again. This routine should be followed by calls  *
+* to DGifGetCodeNext, until NULL block is returned.			      *
+*   The block should NOT be freed by the user (not dynamically allocated).    *
+******************************************************************************/
+void DGifGetCode(GifFileType *GifFile, int *CodeSize, GifByteType **CodeBlock)
+{
+    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
+
+    if (!IS_READABLE(Private)) {
+	/* This file was NOT open for reading: */
+	GifInternError(GifFile, D_GIF_ERR_NOT_READABLE);
+    }
+
+    *CodeSize = Private->BitsPerPixel;
+
+    DGifGetCodeNext(GifFile, CodeBlock);
+}
+
+/******************************************************************************
+*   Continue to get the image code in compressed form. This routine should be *
+* called until NULL block is returned.					      *
+*   The block should NOT be freed by the user (not dynamically allocated).    *
+******************************************************************************/
+void DGifGetCodeNext(GifFileType *GifFile, GifByteType **CodeBlock)
+{
+    GifByteType Buf;
+    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
+
+    GifRead(&Buf, 1, GifFile);
+
+    if (Buf > 0) {
+	*CodeBlock = Private->Buf;	       /* Use private unused buffer. */
+	(*CodeBlock)[0] = Buf;  /* Pascal strings notation (pos. 0 is len.). */
+	GifRead(&((*CodeBlock)[1]), Buf, GifFile);
+    }
+    else {
+	*CodeBlock = NULL;
+	Private->Buf[0] = 0;		   /* Make sure the buffer is empty! */
+	Private->PixelCount = 0;   /* And local info. indicate image read. */
+    }
+
+}
+
+/******************************************************************************
+*   Setup the LZ decompression for this image:				      *
+******************************************************************************/
+static void DGifSetupDecompress(GifFileType *GifFile)
+{
+    int i, BitsPerPixel;
+    GifByteType CodeSize;
+    unsigned int *Prefix;
+    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
+
+    GifRead(&CodeSize, 1, GifFile);    /* Read Code size from file. */
+    BitsPerPixel = CodeSize;
+
+    Private->Buf[0] = 0;			      /* Input Buffer empty. */
+    Private->BitsPerPixel = BitsPerPixel;
+    Private->ClearCode = (1 << BitsPerPixel);
+    Private->EOFCode = Private->ClearCode + 1;
+    Private->RunningCode = Private->EOFCode + 1;
+    Private->RunningBits = BitsPerPixel + 1;	 /* Number of bits per code. */
+    Private->MaxCode1 = 1 << Private->RunningBits;     /* Max. code + 1. */
+    Private->StackPtr = 0;		    /* No pixels on the pixel stack. */
+    Private->LastCode = NO_SUCH_CODE;
+    Private->CrntShiftState = 0;	/* No information in CrntShiftDWord. */
+    Private->CrntShiftDWord = 0;
+
+    Prefix = Private->Prefix;
+    for (i = 0; i <= LZ_MAX_CODE; i++) Prefix[i] = NO_SUCH_CODE;
+}
+
+/******************************************************************************
+*   The LZ decompression routine:					      *
+*   This version decompress the given gif file into Line of length LineLen.   *
+*   This routine can be called few times (one per scan line, for example), in *
+* order the complete the whole image.					      *
+******************************************************************************/
+static void DGifDecompressLine(GifFileType *GifFile, GifPixelType *Line,
+								int LineLen)
+{
+    int i = 0, j, CrntCode, EOFCode, ClearCode, CrntPrefix, LastCode, StackPtr;
+    GifByteType *Stack, *Suffix;
+    unsigned int *Prefix;
+    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
+
+    StackPtr = Private->StackPtr;
+    Prefix = Private->Prefix;
+    Suffix = Private->Suffix;
+    Stack = Private->Stack;
+    EOFCode = Private->EOFCode;
+    ClearCode = Private->ClearCode;
+    LastCode = Private->LastCode;
+
+    CrntPrefix = 0;
+    if (StackPtr != 0) {
+	/* Let pop the stack off before continueing to read the gif file: */
+	while (StackPtr != 0 && i < LineLen) Line[i++] = Stack[--StackPtr];
+    }
+
+    while (i < LineLen) {			    /* Decode LineLen items. */
+	DGifDecompressInput(GifFile, &CrntCode);
+
+	if (CrntCode == EOFCode) {
+	    /* Note however that usually we will not be here as we will stop */
+	    /* decoding as soon as we got all the pixel, or EOF code will    */
+	    /* not be read at all, and DGifGetLine/Pixel clean everything.   */
+	    if (i != LineLen - 1 || Private->PixelCount != 0) {
+		GifInternError(GifFile, D_GIF_ERR_EOF_TOO_SOON);
+	    }
+	    i++;
+	}
+	else if (CrntCode == ClearCode) {
+	    /* We need to start over again: */
+	    for (j = 0; j <= LZ_MAX_CODE; j++) Prefix[j] = NO_SUCH_CODE;
+	    Private->RunningCode = Private->EOFCode + 1;
+	    Private->RunningBits = Private->BitsPerPixel + 1;
+	    Private->MaxCode1 = 1 << Private->RunningBits;
+	    LastCode = Private->LastCode = NO_SUCH_CODE;
+	}
+	else {
+	    /* Its regular code - if in pixel range simply add it to output  */
+	    /* stream, otherwise trace to codes linked list until the prefix */
+	    /* is in pixel range:					     */
+	    if (CrntCode < ClearCode) {
+		/* This is simple - its pixel scalar, so add it to output:   */
+		Line[i++] = CrntCode;
+	    }
+	    else {
+		/* Its a code to needed to be traced: trace the linked list  */
+		/* until the prefix is a pixel, while pushing the suffix     */
+		/* pixels on our stack. If we done, pop the stack in reverse */
+		/* (thats what stack is good for!) order to output.	     */
+		if (Prefix[CrntCode] == NO_SUCH_CODE) {
+		    /* Only allowed if CrntCode is exactly the running code: */
+		    /* In that case CrntCode = XXXCode, CrntCode or the	     */
+		    /* prefix code is last code and the suffix char is	     */
+		    /* exactly the prefix of last code!			     */
+		    if (CrntCode == Private->RunningCode - 2) {
+			CrntPrefix = LastCode;
+			Suffix[Private->RunningCode - 2] =
+			Stack[StackPtr++] = DGifGetPrefixChar(Prefix,
+							LastCode, ClearCode);
+		    }
+		    else {
+			GifInternError(GifFile, D_GIF_ERR_IMAGE_DEFECT);
+		    }
+		}
+		else
+		    CrntPrefix = CrntCode;
+
+		/* Now (if image is O.K.) we should not get an NO_SUCH_CODE  */
+		/* During the trace. As we might loop forever, in case of    */
+		/* defective image, we count the number of loops we trace    */
+		/* and stop if we got LZ_MAX_CODE. obviously we can not      */
+		/* loop more than that.					     */
+		j = 0;
+		while (j++ <= LZ_MAX_CODE &&
+		       CrntPrefix > ClearCode &&
+		       CrntPrefix <= LZ_MAX_CODE) {
+		    Stack[StackPtr++] = Suffix[CrntPrefix];
+		    CrntPrefix = Prefix[CrntPrefix];
+		}
+		if (j >= LZ_MAX_CODE || CrntPrefix > LZ_MAX_CODE) {
+		    GifInternError(GifFile, D_GIF_ERR_IMAGE_DEFECT);
+		}
+		/* Push the last character on stack: */
+		Stack[StackPtr++] = CrntPrefix;
+
+		/* Now lets pop all the stack into output: */
+		while (StackPtr != 0 && i < LineLen)
+		    Line[i++] = Stack[--StackPtr];
+	    }
+	    if (LastCode != NO_SUCH_CODE) {
+		Prefix[Private->RunningCode - 2] = LastCode;
+
+		if (CrntCode == Private->RunningCode - 2) {
+		    /* Only allowed if CrntCode is exactly the running code: */
+		    /* In that case CrntCode = XXXCode, CrntCode or the	     */
+		    /* prefix code is last code and the suffix char is	     */
+		    /* exactly the prefix of last code!			     */
+		    Suffix[Private->RunningCode - 2] =
+			DGifGetPrefixChar(Prefix, LastCode, ClearCode);
+		}
+		else {
+		    Suffix[Private->RunningCode - 2] =
+			DGifGetPrefixChar(Prefix, CrntCode, ClearCode);
+		}
+	    }
+	    LastCode = CrntCode;
+	}
+    }
+
+    Private->LastCode = LastCode;
+    Private->StackPtr = StackPtr;
+}
+
+/******************************************************************************
+* Routine to trace the Prefixes linked list until we get a prefix which is    *
+* not code, but a pixel value (less than ClearCode). Returns that pixel value.*
+* If image is defective, we might loop here forever, so we limit the loops to *
+* the maximum possible if image O.k. - LZ_MAX_CODE times.		      *
+******************************************************************************/
+static int DGifGetPrefixChar(unsigned int *Prefix, int Code, int ClearCode)
+{
+    int i = 0;
+
+    while (Code > ClearCode && i++ <= LZ_MAX_CODE) Code = Prefix[Code];
+    return Code;
+}
+
+/******************************************************************************
+*   Interface for accessing the LZ codes directly. Set Code to the real code  *
+* (12bits), or to -1 if EOF code is returned.				      *
+******************************************************************************/
+void DGifGetLZCodes(GifFileType *GifFile, int *Code)
+{
+    GifByteType *CodeBlock;
+    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
+
+    if (!IS_READABLE(Private)) {
+	/* This file was NOT open for reading: */
+	GifInternError(GifFile, D_GIF_ERR_NOT_READABLE);
+    }
+
+    DGifDecompressInput(GifFile, Code);
+
+    if (*Code == Private->EOFCode) {
+	/* Skip rest of codes (hopefully only NULL terminating block): */
+	do
+	    DGifGetCodeNext(GifFile, &CodeBlock);
+	while (CodeBlock != NULL);
+
+	*Code = -1;
+    }
+    else if (*Code == Private->ClearCode) {
+	/* We need to start over again: */
+	Private->RunningCode = Private->EOFCode + 1;
+	Private->RunningBits = Private->BitsPerPixel + 1;
+	Private->MaxCode1 = 1 << Private->RunningBits;
+    }
+}
+
+/******************************************************************************
+*   The LZ decompression input routine:					      *
+*   This routine is responsable for the decompression of the bit stream from  *
+* 8 bits (bytes) packets, into the real codes.				      *
+*   Returns GIF_OK if read succesfully.					      *
+******************************************************************************/
+static void DGifDecompressInput(GifFileType *GifFile, int *Code)
+{
+    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
+    GifByteType NextByte;
+    static unsigned int CodeMasks[] = {
+	0x0000, 0x0001, 0x0003, 0x0007,
+	0x000f, 0x001f, 0x003f, 0x007f,
+	0x00ff, 0x01ff, 0x03ff, 0x07ff,
+	0x0fff
+    };
+
+    while (Private->CrntShiftState < Private->RunningBits) {
+	/* Needs to get more bytes from input stream for next code: */
+	DGifBufferedInput(GifFile, &NextByte);
+	Private->CrntShiftDWord |=
+		((unsigned long) NextByte) << Private->CrntShiftState;
+	Private->CrntShiftState += 8;
+    }
+    *Code = Private->CrntShiftDWord & CodeMasks[Private->RunningBits];
+
+    Private->CrntShiftDWord >>= Private->RunningBits;
+    Private->CrntShiftState -= Private->RunningBits;
+
+    /* If code cannt fit into RunningBits bits, must raise its size. Note */
+    /* however that codes above 4095 are used for special signaling.      */
+    if (++Private->RunningCode > Private->MaxCode1 &&
+	Private->RunningBits < LZ_BITS) {
+	Private->MaxCode1 <<= 1;
+	Private->RunningBits++;
+    }
+}
+
+/******************************************************************************
+*   This routines read one gif data block at a time and buffers it internally *
+* so that the decompression routine could access it.			      *
+*   The routine returns the next byte from its internal buffer (or read next  *
+* block in if buffer empty)						      *
+******************************************************************************/
+static void DGifBufferedInput(GifFileType *GifFile, GifByteType *NextByte)
+{
+    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
+    GifByteType *Buf = Private->Buf;
+
+    if (Buf[0] == 0) {
+	/* Needs to read the next buffer - this one is empty: */
+	GifRead(Buf, 1, GifFile);
+	GifRead((Buf + 1), Buf[0], GifFile);
+	*NextByte = Buf[1];
+	Buf[1] = 2;	   /* We use now the second place as last char read! */
+	Buf[0]--;
+    }
+    else {
+	*NextByte = Buf[Buf[1]++];
+	Buf[0]--;
+    }
+}
+
+/******************************************************************************
+* This routine reads an entire GIF into core, hanging all its state info off  *
+* the GifFileType pointer.  Call DGifOpenFileName() or DGifOpenFileHandle()   *
+* first to initialize I/O.  Its inverse is EGifSpew().			      *
+******************************************************************************/
+void DGifSlurp(GifFileType *GifFile)
+{
+    int ImageSize;
+    GifRecordType RecordType;
+    SavedImage *sp;
+    GifByteType *ExtData;
+
+    /* Some versions of malloc dislike 0-length requests */
+    GifFile->SavedImages = (SavedImage *)malloc(sizeof(SavedImage));
+    memset(GifFile->SavedImages, 0, sizeof(SavedImage));
+    sp = &GifFile->SavedImages[0];
+
+    do {
+	DGifGetRecordType(GifFile, &RecordType);
+
+	switch (RecordType) {
+	    case IMAGE_DESC_RECORD_TYPE:
+		DGifGetImageDesc(GifFile);
+
+		sp = &GifFile->SavedImages[GifFile->ImageCount-1];
+		ImageSize = sp->ImageDesc.Width * sp->ImageDesc.Height;
+
+		sp->RasterBits
+		    = (GifPixelType*) malloc(ImageSize * sizeof(GifPixelType));
+
+		DGifGetLine(GifFile, sp->RasterBits, ImageSize);
+		break;
+
+	    case EXTENSION_RECORD_TYPE:
+		DGifGetExtension(GifFile,&sp->Function,&ExtData);
+		
+		do {
+    		    if (AddExtensionBlock(sp, ExtData[0], ExtData+1) == GIF_ERROR)
+			GifInternError(GifFile, D_GIF_ERR_NOT_ENOUGH_MEM);
+		    DGifGetExtensionNext(GifFile, &ExtData);
+		} while (ExtData != NULL);
+		break;
+
+	    case TERMINATE_RECORD_TYPE:
+		break;
+
+	    default:	/* Should be trapped by DGifGetRecordType */
+		break;
+	}
+    } while (RecordType != TERMINATE_RECORD_TYPE);
+}
+
+/******************************************************************************
+* Extension record functions						      *
+******************************************************************************/
+
+void MakeExtension(SavedImage *New, int Function)
+{
+    New->Function = Function;
+    /*
+     * Someday we might have to deal with multiple extensions.
+     */
+}
+
+int AddExtensionBlock(SavedImage *New, int Len, GifByteType *data)
+{
+    int size;
+    ExtensionBlock *ep;
+
+    if (New->ExtensionBlocks == NULL)
+	New->ExtensionBlocks = (ExtensionBlock *)malloc(sizeof(ExtensionBlock));
+    else
+	New->ExtensionBlocks =
+	    (ExtensionBlock *)realloc(New->ExtensionBlocks,
+		      sizeof(ExtensionBlock) * (New->ExtensionBlockCount + 1));
+
+    if (New->ExtensionBlocks == NULL)
+	return(GIF_ERROR);
+
+    ep = &New->ExtensionBlocks[New->ExtensionBlockCount++];
+    ep->ByteCount = Len;
+    size = Len * sizeof(GifByteType);
+    ep->Bytes = (GifByteType *)malloc(size);
+    memcpy(ep->Bytes, data, size);
+    return(GIF_OK);
+}
+
+void FreeExtension(SavedImage *Image)
+{
+    ExtensionBlock	*ep;
+
+    for (ep = Image->ExtensionBlocks;
+	 ep < Image->ExtensionBlocks + Image->ExtensionBlockCount;
+	 ep++)
+	(void) free((char *)ep->Bytes);
+    free((char *)Image->ExtensionBlocks);
+    Image->ExtensionBlocks = NULL;
+}
+
+/******************************************************************************
+* Image block allocation functions					      *
+******************************************************************************/
+SavedImage *MakeSavedImage(GifFileType *GifFile, SavedImage *CopyFrom)
+/*
+ * Append an image block to the SavedImages array  
+ */
+{
+    SavedImage	*sp;
+
+    if (GifFile->SavedImages == NULL)
+	GifFile->SavedImages = (SavedImage *)malloc(sizeof(SavedImage));
+    else
+	GifFile->SavedImages = (SavedImage *)realloc(GifFile->SavedImages,
+				sizeof(SavedImage) * (GifFile->ImageCount+1));
+
+    if (GifFile->SavedImages == NULL)
+	return((SavedImage *)NULL);
+    else
+    {
+	sp = &GifFile->SavedImages[GifFile->ImageCount++];
+	memset((char *)sp, '\0', sizeof(SavedImage));
+
+	if (CopyFrom)
+	{
+	    memcpy((char *)sp, CopyFrom, sizeof(SavedImage));
+
+	    /*
+	     * Make our own allocated copies of the heap fields in the
+	     * copied record.  This guards against potential aliasing
+	     * problems.
+	     */
+
+	    /* first, the local color map */
+	    if (sp->ImageDesc.ColorMap)
+		sp->ImageDesc.ColorMap =
+		    MakeMapObject(CopyFrom->ImageDesc.ColorMap->ColorCount,
+				  CopyFrom->ImageDesc.ColorMap->Colors);
+
+	    /* next, the raster */
+	    sp->RasterBits = (char *)malloc(sizeof(GifPixelType)
+				* CopyFrom->ImageDesc.Height
+				* CopyFrom->ImageDesc.Width);
+	    memcpy(sp->RasterBits,
+		   CopyFrom->RasterBits,
+		   sizeof(GifPixelType)
+			* CopyFrom->ImageDesc.Height
+			* CopyFrom->ImageDesc.Width);
+
+	    /* finally, the extension blocks */
+	    if (sp->ExtensionBlocks)
+	    {
+		sp->ExtensionBlocks
+		    = (ExtensionBlock*)malloc(sizeof(ExtensionBlock)
+					      * CopyFrom->ExtensionBlockCount);
+		memcpy(sp->ExtensionBlocks,
+		   CopyFrom->ExtensionBlocks,
+		   sizeof(ExtensionBlock)
+		   	* CopyFrom->ExtensionBlockCount);
+
+		/*
+		 * For the moment, the actual blocks can take their
+		 * chances with free().  We'll fix this later. 
+		 */
+	    }
+	}
+
+	return(sp);
+    }
+}
+
+void FreeSavedImages(GifFileType *GifFile)
+{
+    SavedImage	*sp;
+
+    for (sp = GifFile->SavedImages;
+	 sp < GifFile->SavedImages + GifFile->ImageCount;
+	 sp++)
+    {
+	if (sp->ImageDesc.ColorMap)
+	    FreeMapObject(sp->ImageDesc.ColorMap);
+
+	if (sp->RasterBits)
+	    free((char *)sp->RasterBits);
+
+	if (sp->ExtensionBlocks)
+	    FreeExtension(sp);
+    }
+    free((char *) GifFile->SavedImages);
+}
+
+/******************************************************************************
+* Miscellaneous utility functions					      *
+******************************************************************************/
+
+int BitSize(int n)
+/* return smallest bitfield size n will fit in */
+{
+    register	int i;
+
+    for (i = 1; i <= 8; i++)
+	if ((1 << i) >= n)
+	    break;
+    return(i);
+}
+
+/******************************************************************************
+* Color map object functions						      *
+******************************************************************************/
+
+ColorMapObject *MakeMapObject(int ColorCount, GifColorType *ColorMap)
+/*
+ * Allocate a color map of given size; initialize with contents of
+ * ColorMap if that pointer is non-NULL.
+ */
+{
+    ColorMapObject *Object;
+
+    if (ColorCount != (1 << BitSize(ColorCount)))
+	return((ColorMapObject *)NULL);
+
+    Object = (ColorMapObject *)malloc(sizeof(ColorMapObject));
+    if (Object == (ColorMapObject *)NULL)
+	return((ColorMapObject *)NULL);
+
+    Object->Colors = (GifColorType *)calloc(ColorCount, sizeof(GifColorType));
+    if (Object->Colors == (GifColorType *)NULL)
+	return((ColorMapObject *)NULL);
+
+    Object->ColorCount = ColorCount;
+    Object->BitsPerPixel = BitSize(ColorCount);
+
+    if (ColorMap)
+	memcpy((char *)Object->Colors,
+	       (char *)ColorMap, ColorCount * sizeof(GifColorType));
+
+    return(Object);
+}
+
+void FreeMapObject(ColorMapObject *Object)
+/*
+ * Free a color map object
+ */
+{
+    free(Object->Colors);
+    free(Object);
+}