QNX/lib/lzo/lzo1f_d.ch

/*
Copyright 2002, QNX Software Systems Ltd. Unpublished Work All Rights
Reserved.

 
This source code contains confidential information of QNX Software Systems
Ltd. (QSSL). Any use, reproduction, modification, disclosure, distribution
or transfer of this software, or any software which includes or is based
upon any of this code, is only permitted under the terms of the QNX
Confidential Source License version 1.0 (see licensing.qnx.com for details)
or as otherwise expressly authorized by a written license agreement from
QSSL. For more information, please email licensing@qnx.com.
*/
/* lzo1f_d.ch -- implementation of the LZO1F decompression algorithm

   This file is part of the LZO real-time data compression library.

   Copyright (C) 1996-1999 Markus Franz Xaver Johannes Oberhumer

   Markus F.X.J. Oberhumer
   markus.oberhumer@jk.uni-linz.ac.at
 */


#include "lzo1_d.ch"


/***********************************************************************
// decompress a block of data.
************************************************************************/

LZO_PUBLIC(int)
DO_DECOMPRESS  ( const lzo_byte *in , lzo_uint  in_len,
                       lzo_byte *out, lzo_uint *out_len,
                       lzo_voidp wrkmem )
{
	register lzo_byte *op;
	register const lzo_byte *ip;
	register lzo_uint t;
	register const lzo_byte *m_pos;

	const lzo_byte * const ip_end = in + in_len;
#if defined(HAVE_ANY_OP)
	lzo_byte * const op_end = out + *out_len;
#endif

	LZO_UNUSED(wrkmem);

#if defined(__LZO_QUERY_DECOMPRESS)
	if (__LZO_IS_DECOMPRESS_QUERY(in,in_len,out,out_len,wrkmem))
		return __LZO_QUERY_DECOMPRESS(in,in_len,out,out_len,wrkmem,0,0);
#endif

	*out_len = 0;

	op = out;
	ip = in;

	while (TEST_IP && TEST_OP)
	{
		t = *ip++;
		if (t > 31)
			goto match;

		/* a literal run */
		if (t == 0)
		{
			NEED_IP(1);
			while (*ip == 0)
			{
				t += 255;
				ip++;
				NEED_IP(1);
			}
			t += 31 + *ip++;
		}
		/* copy literals */
		assert(t > 0); NEED_OP(t); NEED_IP(t+1);
#if defined(LZO_UNALIGNED_OK_4)
		if (t >= 4)
		{
			do {
				* (lzo_uint32p) op = * (const lzo_uint32p) ip;
				op += 4; ip += 4; t -= 4;
			} while (t >= 4);
			if (t > 0) do *op++ = *ip++; while (--t > 0);
		}
		else
#endif
		do *op++ = *ip++; while (--t > 0);

		t = *ip++;

		while (TEST_IP && TEST_OP)
		{
			/* handle matches */
			if (t < 32)
			{
				m_pos = op - 1 - 0x800;
				m_pos -= (t >> 2) & 7;
				m_pos -= *ip++ << 3;
				TEST_LOOKBEHIND(m_pos,out); NEED_OP(3);
				*op++ = *m_pos++; *op++ = *m_pos++; *op++ = *m_pos++;
			}
			else
			{
match:
				if (t < M3_MARKER)
				{
					m_pos = op - 1;
					m_pos -= (t >> 2) & 7;
					m_pos -= *ip++ << 3;
					t >>= 5;
					TEST_LOOKBEHIND(m_pos,out); assert(t > 0); NEED_OP(t+3-1);
					goto copy_match;
				}
				else
				{
					t &= 31;
					if (t == 0)
					{
						NEED_IP(1);
						while (*ip == 0)
						{
							t += 255;
							ip++;
							NEED_IP(1);
						}
						t += 31 + *ip++;
					}
					NEED_IP(2);
					m_pos = op;
#if defined(LZO_UNALIGNED_OK_2) && (LZO_BYTE_ORDER == LZO_LITTLE_ENDIAN)
                    m_pos -= (* (const lzo_ushortp) ip) >> 2;
					ip += 2;
#else
					m_pos -= *ip++ >> 2;
					m_pos -= *ip++ << 6;
#endif
					if (m_pos == op)
						goto eof_found;
				}

				/* copy match */
				TEST_LOOKBEHIND(m_pos,out); assert(t > 0); NEED_OP(t+3-1);
#if defined(LZO_UNALIGNED_OK_4)
				if (t >= 2 * 4 - (3 - 1) && (op - m_pos) >= 4)
				{
					* (lzo_uint32p) op = * (const lzo_uint32p) m_pos;
					op += 4; m_pos += 4; t -= 4 - (3 - 1);
					do {
						* (lzo_uint32p) op = * (const lzo_uint32p) m_pos;
						op += 4; m_pos += 4; t -= 4;
					} while (t >= 4);
					if (t > 0) do *op++ = *m_pos++; while (--t > 0);
				}
				else
#endif
				{
copy_match:
				*op++ = *m_pos++; *op++ = *m_pos++;
				do *op++ = *m_pos++; while (--t > 0);
				}
			}
			t = ip[-2] & 3;
			if (t == 0)
				break;

			/* copy literals */
			assert(t > 0); NEED_OP(t); NEED_IP(t+1);
			do *op++ = *ip++; while (--t > 0);
			t = *ip++;
		}
	}

#if defined(HAVE_TEST_IP) || defined(HAVE_TEST_OP)
	/* no EOF code was found */
	*out_len = op - out;
	return LZO_E_EOF_NOT_FOUND;
#endif

eof_found:
	assert(t == 1);
	*out_len = op - out;
	return (ip == ip_end ? LZO_E_OK :
	       (ip < ip_end  ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN));


#if defined(HAVE_NEED_IP)
input_overrun:
	*out_len = op - out;
	return LZO_E_INPUT_OVERRUN;
#endif

#if defined(HAVE_NEED_OP)
output_overrun:
	*out_len = op - out;
	return LZO_E_OUTPUT_OVERRUN;
#endif

#if defined(LZO_TEST_DECOMPRESS_OVERRUN_LOOKBEHIND)
lookbehind_overrun:
	*out_len = op - out;
	return LZO_E_LOOKBEHIND_OVERRUN;
#endif
}


/*
vi:ts=4
*/