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//-----------------------------------------------------------------------------
//
// ImageLib Sources
// Copyright (C) 2000-2008 by Denton Woods
// Last modified: 08/14/2004
//
// Filename: src-IL/src/il_bits.c
//
// Description: Implements a file class that reads/writes bits directly.
//
//-----------------------------------------------------------------------------
#include "il_internal.h"
#include "il_bits.h"
// Opens a BITFILE just like fopen opens a FILE.
/*BITFILE *bopen(const char *FileName, const char *Mode)
{
BITFILE *ToReturn = NULL;
if (FileName != NULL) {
ToReturn = (BITFILE*)ialloc(sizeof(BITFILE));
if (ToReturn != NULL) {
iopenr((char*)FileName);
ToReturn->File = iGetFile();
ToReturn->BitPos = 0;
ToReturn->ByteBitOff = 8;
ToReturn->Buff = 0;
}
}
return ToReturn;
}*/
// Converts a FILE to a BITFILE.
BITFILE *bfile(ILHANDLE File)
{
BITFILE *ToReturn = NULL;
if (File != NULL) {
ToReturn = (BITFILE*)ialloc(sizeof(BITFILE));
if (ToReturn != NULL) {
ToReturn->File = File;
ToReturn->BitPos = itell() << 3;
ToReturn->ByteBitOff = 8;
ToReturn->Buff = 0;
}
}
return ToReturn;
}
// Closes an open BITFILE and frees memory for it.
ILint bclose(BITFILE *BitFile)
{
if (BitFile == NULL || BitFile->File == NULL)
return IL_EOF;
// Removed 01-26-2008. The file will get closed later by
// the calling function.
//icloser(BitFile->File);
ifree(BitFile);
return 0;
}
// Returns the current bit position of a BITFILE.
ILint btell(BITFILE *BitFile)
{
return BitFile->BitPos;
}
// Seeks in a BITFILE just like fseek for FILE.
ILint bseek(BITFILE *BitFile, ILuint Offset, ILuint Mode)
{
ILint KeepPos, Len;
if (BitFile == NULL || BitFile->File == NULL)
return 1;
switch (Mode)
{
case IL_SEEK_SET:
if (!iseek(Offset >> 3, Mode)) {
BitFile->BitPos = Offset;
BitFile->ByteBitOff = BitFile->BitPos % 8;
}
break;
case IL_SEEK_CUR:
if (!iseek(Offset >> 3, Mode)) {
BitFile->BitPos += Offset;
BitFile->ByteBitOff = BitFile->BitPos % 8;
}
break;
case IL_SEEK_END:
KeepPos = itell();
iseek(0, IL_SEEK_END);
Len = itell();
iseek(0, IL_SEEK_SET);
if (!iseek(Offset >> 3, Mode)) {
BitFile->BitPos = (Len << 3) + Offset;
BitFile->ByteBitOff = BitFile->BitPos % 8;
}
break;
default:
return 1;
}
return 0;
}
// hehe, "bread". It reads data into Buffer from the BITFILE, just like fread for FILE.
ILint bread(void *Buffer, ILuint Size, ILuint Number, BITFILE *BitFile)
{
// Note that this function is somewhat useless: In binary image
// formats, there are some pad bits after each scanline. This
// function does not take that into account, so you must use bseek to
// skip the calculated value of bits.
ILuint BuffPos = 0, Count = Size * Number;
while (BuffPos < Count) {
if (BitFile->ByteBitOff < 0 || BitFile->ByteBitOff > 7) {
BitFile->ByteBitOff = 7;
if (iread(&BitFile->Buff, 1, 1) != 1) // Reached eof or error...
return BuffPos;
}
*((ILubyte*)(Buffer) + BuffPos) = (ILubyte)!!(BitFile->Buff & (1 << BitFile->ByteBitOff));
BuffPos++;
BitFile->ByteBitOff--;
}
return BuffPos;
}
// Reads bits and puts the first bit in the file as the highest in the return value.
ILuint breadVal(ILuint NumBits, BITFILE *BitFile)
{
ILuint BuffPos = 0;
ILuint Buffer = 0;
// Only returning up to 32 bits at one time
if (NumBits > 32) {
ilSetError(IL_INTERNAL_ERROR);
return 0;
}
while (BuffPos < NumBits) {
Buffer <<= 1;
if (BitFile->ByteBitOff < 0 || BitFile->ByteBitOff > 7) {
BitFile->ByteBitOff = 7;
if (iread(&BitFile->Buff, 1, 1) != 1) // Reached eof or error...
return BuffPos;
}
Buffer = Buffer + (ILubyte)!!(BitFile->Buff & (1 << BitFile->ByteBitOff));
BuffPos++;
BitFile->ByteBitOff--;
}
return BuffPos;
}
// Not implemented yet.
/*ILint bwrite(void *Buffer, ILuint Size, ILuint Number, BITFILE *BitFile)
{
return 0;
}*/
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