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tge/lib/lungif/dgif_lib.c
Metario 9c6ff74f19 added everything
2017-04-17 06:17:10 -06:00

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/******************************************************************************
* "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). *
******************************************************************************/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#if defined(__MWERKS__)
#pragma warn_unusedarg off
#pragma warn_unusedvar off
#endif
#if defined (__MSDOS__) && !defined(__DJGPP__) && !defined(__GNUC__)
#include <io.h>
#include <alloc.h>
#include <stdlib.h>
#include <sys\stat.h>
#else
//#include <sys/types.h>
//#include <sys/stat.h>
#endif /* __MSDOS__ */
#ifndef __MSDOS__
#include <stdlib.h>
#endif
//#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include "gif_lib.h"
#include "gif_lib_private.h"
#define COMMENT_EXT_FUNC_CODE 0xfe /* Extension function code for comment. */
/* avoid extra function call in case we use fread (TVT) */
#define READ(_gif,_buf,_len) \
((GifFilePrivateType*)_gif->Private)->Read(_gif,(GifByteType*)_buf,_len)
// (((GifFilePrivateType*)_gif->Private)->Read ? \
// ((GifFilePrivateType*)_gif->Private)->Read(_gif,_buf,_len) : \
// fread(_buf,1,_len,((GifFilePrivateType*)_gif->Private)->File))
static int DGifGetWord(GifFileType *GifFile, int *Word);
static int DGifSetupDecompress(GifFileType *GifFile);
static int DGifDecompressLine(GifFileType *GifFile, GifPixelType *Line,
int LineLen);
static int DGifGetPrefixChar(unsigned int *Prefix, int Code, int ClearCode);
static int DGifDecompressInput(GifFileType *GifFile, int *Code);
static int DGifBufferedInput(GifFileType *GifFile, GifByteType *Buf,
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. _GifError is cleared if succesfull. *
******************************************************************************/
// GifFileType *DGifOpenFileName(const char *FileName)
// {
// int FileHandle;
// GifFileType *GifFile;
//
// if ((FileHandle = open(FileName, O_RDONLY
// #ifdef __MSDOS__
// | O_BINARY
// #endif /* __MSDOS__ */
// )) == -1) {
// _GifError = D_GIF_ERR_OPEN_FAILED;
// return NULL;
// }
//
// GifFile = DGifOpenFileHandle(FileHandle);
// if (GifFile == (GifFileType *)NULL)
// close(FileHandle);
// return 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. *
******************************************************************************/
// GifFileType *DGifOpenFileHandle(int FileHandle)
// {
// char Buf[GIF_STAMP_LEN+1];
// GifFileType *GifFile;
// GifFilePrivateType *Private;
// FILE *f;
//
// if ((GifFile = (GifFileType *) malloc(sizeof(GifFileType))) == NULL) {
// _GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
// return NULL;
// }
//
// memset(GifFile, '\0', sizeof(GifFileType));
//
// if ((Private = (GifFilePrivateType *) malloc(sizeof(GifFilePrivateType)))
// == NULL) {
// _GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
// free((char *) GifFile);
// return NULL;
// }
//
// #ifdef __MSDOS__
// setmode(FileHandle, O_BINARY); /* Make sure it is in binary mode. */
// #endif /* __MSDOS__ */
//
// f = fdopen(FileHandle, "rb"); /* Make it into a stream: */
//
// #ifdef __MSDOS__
// setvbuf(f, NULL, _IOFBF, GIF_FILE_BUFFER_SIZE);/* And inc. stream buffer.*/
// #endif /* __MSDOS__ */
//
// GifFile->Private = (VoidPtr) Private;
// Private->FileHandle = FileHandle;
// Private->File = f;
// Private->FileState = FILE_STATE_READ;
// Private->Read = 0; /* don't use alternate input method (TVT) */
// GifFile->UserData = 0; /* TVT */
//
// /* Lets see if this is a GIF file: */
// if (READ(GifFile,Buf, GIF_STAMP_LEN) != GIF_STAMP_LEN) {
// _GifError = D_GIF_ERR_READ_FAILED;
// fclose(f);
// free((char *) Private);
// free((char *) GifFile);
// return NULL;
// }
//
// /* 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) {
// _GifError = D_GIF_ERR_NOT_GIF_FILE;
// fclose(f);
// free((char *) Private);
// free((char *) GifFile);
// return NULL;
// }
//
// if (DGifGetScreenDesc(GifFile) == GIF_ERROR) {
// fclose(f);
// free((char *) Private);
// free((char *) GifFile);
// return NULL;
// }
//
// _GifError = 0;
//
// return GifFile;
// }
/******************************************************************************
* GifFileType constructor with user supplied input function (TVT) *
* *
******************************************************************************/
GifFileType *DGifOpen( void* userData, InputFunc readFunc )
{
char Buf[GIF_STAMP_LEN+1];
GifFileType *GifFile;
GifFilePrivateType *Private;
if ((GifFile = (GifFileType *) malloc(sizeof(GifFileType))) == NULL) {
_GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
return NULL;
}
memset(GifFile, '\0', sizeof(GifFileType));
if (!(Private = (GifFilePrivateType*) malloc(sizeof(GifFilePrivateType)))){
_GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
free((char *) GifFile);
return NULL;
}
GifFile->Private = (VoidPtr) Private;
Private->FileHandle = 0;
Private->File = 0;
Private->FileState = FILE_STATE_READ;
Private->Read = readFunc; /* TVT */
GifFile->UserData = userData; /* TVT */
/* Lets see if this is a GIF file: */
if ( READ( GifFile, Buf, GIF_STAMP_LEN) != GIF_STAMP_LEN) {
_GifError = D_GIF_ERR_READ_FAILED;
free((char *) Private);
free((char *) GifFile);
return NULL;
}
/* 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) {
_GifError = D_GIF_ERR_NOT_GIF_FILE;
free((char *) Private);
free((char *) GifFile);
return NULL;
}
if (DGifGetScreenDesc(GifFile) == GIF_ERROR) {
free((char *) Private);
free((char *) GifFile);
return NULL;
}
_GifError = 0;
return GifFile;
}
/******************************************************************************
* This routine should be called before any other DGif calls. Note that *
* this routine is called automatically from DGif file open routines. *
******************************************************************************/
int 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: */
_GifError = D_GIF_ERR_NOT_READABLE;
return GIF_ERROR;
}
/* Put the screen descriptor into the file: */
if (DGifGetWord(GifFile, &GifFile->SWidth) == GIF_ERROR ||
DGifGetWord(GifFile, &GifFile->SHeight) == GIF_ERROR)
return GIF_ERROR;
if (READ( GifFile, Buf, 3) != 3) {
_GifError = D_GIF_ERR_READ_FAILED;
return GIF_ERROR;
}
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++) {
if (READ(GifFile, Buf, 3) != 3) {
_GifError = D_GIF_ERR_READ_FAILED;
return GIF_ERROR;
}
GifFile->SColorMap->Colors[i].Red = Buf[0];
GifFile->SColorMap->Colors[i].Green = Buf[1];
GifFile->SColorMap->Colors[i].Blue = Buf[2];
}
}
return GIF_OK;
}
/******************************************************************************
* This routine should be called before any attemp to read an image. *
******************************************************************************/
int DGifGetRecordType(GifFileType *GifFile, GifRecordType *Type)
{
GifByteType Buf;
GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
if (!IS_READABLE(Private)) {
/* This file was NOT open for reading: */
_GifError = D_GIF_ERR_NOT_READABLE;
return GIF_ERROR;
}
if (READ( GifFile, &Buf, 1) != 1) {
_GifError = D_GIF_ERR_READ_FAILED;
return GIF_ERROR;
}
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;
_GifError = D_GIF_ERR_WRONG_RECORD;
return GIF_ERROR;
}
return GIF_OK;
}
/******************************************************************************
* This routine should be called before any attemp to read an image. *
* Note it is assumed the Image desc. header (',') has been read. *
******************************************************************************/
int DGifGetImageDesc(GifFileType *GifFile)
{
int i, BitsPerPixel;
GifByteType Buf[3];
GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
SavedImage *sp;
if (!IS_READABLE(Private)) {
/* This file was NOT open for reading: */
_GifError = D_GIF_ERR_NOT_READABLE;
return GIF_ERROR;
}
if (DGifGetWord(GifFile, &GifFile->Image.Left) == GIF_ERROR ||
DGifGetWord(GifFile, &GifFile->Image.Top) == GIF_ERROR ||
DGifGetWord(GifFile, &GifFile->Image.Width) == GIF_ERROR ||
DGifGetWord(GifFile, &GifFile->Image.Height) == GIF_ERROR)
return GIF_ERROR;
if (READ(GifFile,Buf, 1) != 1) {
_GifError = D_GIF_ERR_READ_FAILED;
return GIF_ERROR;
}
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++) {
if (READ(GifFile,Buf, 3) != 3) {
_GifError = D_GIF_ERR_READ_FAILED;
return GIF_ERROR;
}
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) {
if ((GifFile->SavedImages = (SavedImage *)realloc(GifFile->SavedImages,
sizeof(SavedImage) * (GifFile->ImageCount + 1))) == NULL) {
_GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
return GIF_ERROR;
}
} else {
if ((GifFile->SavedImages =
(SavedImage *)malloc(sizeof(SavedImage))) == NULL) {
_GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
return GIF_ERROR;
}
}
sp = &GifFile->SavedImages[GifFile->ImageCount];
memcpy(&sp->ImageDesc, &GifFile->Image, sizeof(GifImageDesc));
if (GifFile->Image.ColorMap != NULL) {
sp->ImageDesc.ColorMap = MakeMapObject(
GifFile->Image.ColorMap->ColorCount,
GifFile->Image.ColorMap->Colors);
}
sp->RasterBits = (char *)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. */
return GIF_OK;
}
/******************************************************************************
* Get one full scanned line (Line) of length LineLen from GIF file. *
******************************************************************************/
int 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: */
_GifError = D_GIF_ERR_NOT_READABLE;
return GIF_ERROR;
}
if (!LineLen) LineLen = GifFile->Image.Width;
#if defined(__MSDOS__) || defined(__GNUC__)
if ((Private->PixelCount -= LineLen) > 0xffff0000UL) {
#else
if ((Private->PixelCount -= LineLen) > 0xffff0000) {
#endif /* __MSDOS__ */
_GifError = D_GIF_ERR_DATA_TOO_BIG;
return GIF_ERROR;
}
if (DGifDecompressLine(GifFile, Line, LineLen) == GIF_OK) {
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 if (DGifGetCodeNext(GifFile, &Dummy) == GIF_ERROR)
return GIF_ERROR;
while (Dummy != NULL);
}
return GIF_OK;
}
else
return GIF_ERROR;
}
/******************************************************************************
* Put one pixel (Pixel) into GIF file. *
******************************************************************************/
int DGifGetPixel(GifFileType *GifFile, GifPixelType Pixel)
{
GifByteType *Dummy;
GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
if (!IS_READABLE(Private)) {
/* This file was NOT open for reading: */
_GifError = D_GIF_ERR_NOT_READABLE;
return GIF_ERROR;
}
#if defined(__MSDOS__) || defined(__GNUC__)
if (--Private->PixelCount > 0xffff0000UL)
#else
if (--Private->PixelCount > 0xffff0000)
#endif /* __MSDOS__ */
{
_GifError = D_GIF_ERR_DATA_TOO_BIG;
return GIF_ERROR;
}
if (DGifDecompressLine(GifFile, &Pixel, 1) == GIF_OK) {
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 if (DGifGetCodeNext(GifFile, &Dummy) == GIF_ERROR)
return GIF_ERROR;
while (Dummy != NULL);
}
return GIF_OK;
}
else
return GIF_ERROR;
}
/******************************************************************************
* 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. *
******************************************************************************/
int 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: */
_GifError = D_GIF_ERR_NOT_READABLE;
return GIF_ERROR;
}
if (READ(GifFile,&Buf, 1) != 1) {
_GifError = D_GIF_ERR_READ_FAILED;
return GIF_ERROR;
}
*ExtCode = Buf;
return DGifGetExtensionNext(GifFile, Extension);
}
/******************************************************************************
* Get a following extension block (see GIF manual) from gif file. This *
* routine should be called until NULL Extension is returned. *
* The Extension should NOT be freed by the user (not dynamically allocated).*
******************************************************************************/
int DGifGetExtensionNext(GifFileType *GifFile, GifByteType **Extension)
{
GifByteType Buf;
GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
if (READ(GifFile,&Buf, 1) != 1) {
_GifError = D_GIF_ERR_READ_FAILED;
return GIF_ERROR;
}
if (Buf > 0) {
*Extension = Private->Buf; /* Use private unused buffer. */
(*Extension)[0] = Buf; /* Pascal strings notation (pos. 0 is len.). */
if (READ(GifFile,&((*Extension)[1]), Buf) != Buf) {
_GifError = D_GIF_ERR_READ_FAILED;
return GIF_ERROR;
}
}
else
*Extension = NULL;
return GIF_OK;
}
/******************************************************************************
* This routine should be called last, to close the GIF file. *
******************************************************************************/
int DGifCloseFile(GifFileType *GifFile)
{
GifFilePrivateType *Private;
int *File;
if (GifFile == NULL) return GIF_ERROR;
Private = (GifFilePrivateType *) GifFile->Private;
if (!IS_READABLE(Private)) {
/* This file was NOT open for reading: */
_GifError = D_GIF_ERR_NOT_READABLE;
return GIF_ERROR;
}
File = Private->File;
if (GifFile->Image.ColorMap)
{
FreeMapObject(GifFile->Image.ColorMap);
GifFile->Image.ColorMap = NULL;
}
if (GifFile->SColorMap)
{
FreeMapObject(GifFile->SColorMap);
GifFile->SColorMap = NULL;
}
if (Private)
{
free((char *) Private);
Private = NULL;
}
if (GifFile->SavedImages)
{
FreeSavedImages(GifFile);
GifFile = NULL;
}
free(GifFile);
// if ( File && (fclose(File) != 0)) {
// _GifError = D_GIF_ERR_CLOSE_FAILED;
// return GIF_ERROR;
// }
return GIF_OK;
}
/******************************************************************************
* Get 2 bytes (word) from the given file: *
******************************************************************************/
static int DGifGetWord(GifFileType *GifFile, int *Word)
{
unsigned char c[2];
if (READ(GifFile,c, 2) != 2) {
_GifError = D_GIF_ERR_READ_FAILED;
return GIF_ERROR;
}
*Word = (((unsigned int) c[1]) << 8) + c[0];
return GIF_OK;
}
/******************************************************************************
* 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). *
******************************************************************************/
int DGifGetCode(GifFileType *GifFile, int *CodeSize, GifByteType **CodeBlock)
{
GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
if (!IS_READABLE(Private)) {
/* This file was NOT open for reading: */
_GifError = D_GIF_ERR_NOT_READABLE;
return GIF_ERROR;
}
*CodeSize = Private->BitsPerPixel;
return 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). *
******************************************************************************/
int DGifGetCodeNext(GifFileType *GifFile, GifByteType **CodeBlock)
{
GifByteType Buf;
GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
if (READ(GifFile,&Buf, 1) != 1) {
_GifError = D_GIF_ERR_READ_FAILED;
return GIF_ERROR;
}
if (Buf > 0) {
*CodeBlock = Private->Buf; /* Use private unused buffer. */
(*CodeBlock)[0] = Buf; /* Pascal strings notation (pos. 0 is len.). */
if (READ(GifFile,&((*CodeBlock)[1]), Buf) != Buf) {
_GifError = D_GIF_ERR_READ_FAILED;
return GIF_ERROR;
}
}
else {
*CodeBlock = NULL;
Private->Buf[0] = 0; /* Make sure the buffer is empty! */
Private->PixelCount = 0; /* And local info. indicate image read. */
}
return GIF_OK;
}
/******************************************************************************
* Setup the LZ decompression for this image: *
******************************************************************************/
static int DGifSetupDecompress(GifFileType *GifFile)
{
int i, BitsPerPixel;
GifByteType CodeSize;
unsigned int *Prefix;
GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
READ(GifFile,&CodeSize, 1); /* 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;
return GIF_OK;
}
/******************************************************************************
* 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 int 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;
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. */
if (DGifDecompressInput(GifFile, &CrntCode) == GIF_ERROR)
return GIF_ERROR;
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) {
_GifError = D_GIF_ERR_EOF_TOO_SOON;
return GIF_ERROR;
}
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 {
_GifError = D_GIF_ERR_IMAGE_DEFECT;
return GIF_ERROR;
}
}
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) {
_GifError = D_GIF_ERR_IMAGE_DEFECT;
return GIF_ERROR;
}
/* 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;
return GIF_OK;
}
/******************************************************************************
* 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. *
******************************************************************************/
int DGifGetLZCodes(GifFileType *GifFile, int *Code)
{
GifByteType *CodeBlock;
GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
if (!IS_READABLE(Private)) {
/* This file was NOT open for reading: */
_GifError = D_GIF_ERR_NOT_READABLE;
return GIF_ERROR;
}
if (DGifDecompressInput(GifFile, Code) == GIF_ERROR)
return GIF_ERROR;
if (*Code == Private->EOFCode) {
/* Skip rest of codes (hopefully only NULL terminating block): */
do if (DGifGetCodeNext(GifFile, &CodeBlock) == GIF_ERROR)
return GIF_ERROR;
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;
}
return GIF_OK;
}
/******************************************************************************
* 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 int 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: */
if (DGifBufferedInput(GifFile, Private->Buf, &NextByte)
== GIF_ERROR) {
return GIF_ERROR;
}
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++;
}
return GIF_OK;
}
/******************************************************************************
* 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) and returns GIF_OK if succesful. *
******************************************************************************/
static int DGifBufferedInput(GifFileType *GifFile, GifByteType *Buf,
GifByteType *NextByte)
{
if (Buf[0] == 0) {
/* Needs to read the next buffer - this one is empty: */
if (READ(GifFile, Buf, 1) != 1)
{
_GifError = D_GIF_ERR_READ_FAILED;
return GIF_ERROR;
}
if (READ(GifFile,&Buf[1], Buf[0]) != Buf[0])
{
_GifError = D_GIF_ERR_READ_FAILED;
return GIF_ERROR;
}
*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]--;
}
return GIF_OK;
}
/******************************************************************************
* 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(). *
*
******************************************************************************/
int DGifSlurp(GifFileType *GifFile)
{
int i, j, Error, ImageSize;
GifRecordType RecordType;
SavedImage *sp;
GifByteType *ExtData;
SavedImage temp_save;
temp_save.ExtensionBlocks=NULL;
temp_save.ExtensionBlockCount=0;
do {
if (DGifGetRecordType(GifFile, &RecordType) == GIF_ERROR)
return(GIF_ERROR);
switch (RecordType) {
case IMAGE_DESC_RECORD_TYPE:
if (DGifGetImageDesc(GifFile) == GIF_ERROR)
return(GIF_ERROR);
sp = &GifFile->SavedImages[GifFile->ImageCount-1];
ImageSize = sp->ImageDesc.Width * sp->ImageDesc.Height;
sp->RasterBits
= (char *) malloc(ImageSize * sizeof(GifPixelType));
if (DGifGetLine(GifFile, (GifByteType*)sp->RasterBits, ImageSize)
== GIF_ERROR)
return(GIF_ERROR);
if (temp_save.ExtensionBlocks) {
sp->ExtensionBlocks = temp_save.ExtensionBlocks;
sp->ExtensionBlockCount = temp_save.ExtensionBlockCount;
temp_save.ExtensionBlocks = NULL;
temp_save.ExtensionBlockCount=0;
/* FIXME: The following is wrong. It is left in only for backwards
* compatibility. Someday it should go away. Use the
* sp->ExtensionBlocks->Function variable instead.
*/
sp->Function = sp->ExtensionBlocks[0].Function;
}
break;
case EXTENSION_RECORD_TYPE:
if (DGifGetExtension(GifFile,&temp_save.Function,&ExtData)==GIF_ERROR)
return(GIF_ERROR);
while (ExtData != NULL) {
/* Create an extension block with our data */
if (AddExtensionBlock(&temp_save, ExtData[0], (char*)&ExtData[1])
== GIF_ERROR)
return (GIF_ERROR);
if (DGifGetExtensionNext(GifFile, &ExtData) == GIF_ERROR)
return(GIF_ERROR);
temp_save.Function = 0;
}
break;
case TERMINATE_RECORD_TYPE:
break;
default: /* Should be trapped by DGifGetRecordType */
break;
}
} while (RecordType != TERMINATE_RECORD_TYPE);
/* Just in case the Gif has an extension block without an associated
* image... (Should we save this into a savefile structure with no image
* instead? Have to check if the present writing code can handle that as
* well....
*/
if (temp_save.ExtensionBlocks)
FreeExtension(&temp_save);
return(GIF_OK);
}
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