Utils/Libs/GLib/BITS.CPP

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+//===========================================================================
+//
+//		BITS.CPP
+//
+//		Author:  Graeme Webb
+//		Created: 3rd August 1996
+//		Project: General C++ Library
+//		Purpose: Bit stream object
+//
+//		Copyright (c) 1996 Graeme Webb
+//
+//===========================================================================
+// Revision history:
+//===========================================================================
+
+#include "gtypes.h"
+#include "bits.hpp"
+
+//===========================================================================
+
+BitStream::BitStream(byte *ptr)
+{
+	baseptr = (byte *) ptr;
+	currptr = (byte *) ptr;
+	bitpos = 0;
+	mask = 0x01;
+}
+
+BitStream::~BitStream()
+{
+}
+
+void BitStream::IncCurPtr(void)
+{
+	currptr++;
+}
+
+
+void BitStream::PutBit(uint bit)
+{
+	if (mask == 0x01)
+	{
+		*currptr = (bit ? mask : 0);
+		bitpos++;
+		mask <<= 1;
+	}
+	else
+	{
+		*currptr |= (bit ? mask : 0);
+		bitpos++;
+		if (mask == 0x80)
+		{
+			IncCurPtr();
+			mask = 0x01;
+		}
+		else
+		{
+			mask <<= 1;
+		}
+	}
+}
+
+void BitStream::PutBits(ulong bits, uint len)
+{
+	uint i;
+
+	for (i = 0; i < len; i++)
+	{
+		PutBit(bits & 1);
+		bits >>= 1;
+	}
+}
+
+uint BitStream::GetBit()
+{
+	uint bit;
+
+	bit = (*currptr & mask) ? 1 : 0;
+	bitpos++;
+
+	if (mask == 0x80)
+	{
+		IncCurPtr();
+		mask = 0x01;
+	}
+	else
+	{
+		mask <<= 1;
+	}
+
+	return bit;
+}
+
+ulong BitStream::GetBits(uint len)
+{
+	uint i;
+	ulong bits, mbit;
+
+	bits = 0;
+	mbit = 1;
+
+	for (i = 0; i < len; i++)
+	{
+		if (GetBit())
+			bits |= mbit;
+		mbit <<= 1;
+	}
+
+	return bits;
+}
+
+static inline ulong RoundUp(ulong value, uint align)
+{
+	value += align - 1;
+	return (value - value % align);
+}
+
+void BitStream::Align(uint bytes)
+{
+	ulong bytepos, nextpos;
+
+	bytepos = ByteLength();
+	nextpos = RoundUp(bytepos,bytes);
+
+	currptr = baseptr + bytepos;
+
+	while (bytepos < nextpos)
+	{
+		*currptr=0;
+		IncCurPtr();
+		bytepos++;
+	}
+
+	bitpos = bytepos * 8;
+	mask = 0x01;
+}
+
+//===========================================================================