path: root/common/recipes-utils/jbi/files/code/jbicomp.c

/****************************************************************************/
/*																			*/
/*	Module:			jbicomp.c												*/
/*																			*/
/*					Copyright (C) Altera Corporation 1997-2001				*/
/*																			*/
/*	Description:	Contains the code for compressing and uncompressing		*/
/*					Boolean array data.										*/
/*																			*/
/*					This algorithm works by searching previous bytes in the */
/*					data that match the current data. If a match is found,	*/
/*					then the offset and length of the matching data can		*/
/*					replace the actual data in the output.					*/
/*																			*/
/*	Revisions:		2.2  fixed /W4 warnings									*/
/*																			*/
/****************************************************************************/

#include "jbiport.h"
#include "jbiexprt.h"
#include "jbicomp.h"

#define	SHORT_BITS			16
#define	CHAR_BITS			8
#define	DATA_BLOB_LENGTH	3
#define	MATCH_DATA_LENGTH	8192
#define JBI_ACA_REQUEST_SIZE 1024
#define JBI_ACA_BUFFER_SIZE	(MATCH_DATA_LENGTH + JBI_ACA_REQUEST_SIZE)

unsigned long jbi_in_length = 0L;
unsigned long jbi_in_index = 0L;	/* byte index into compressed array */
unsigned int jbi_bits_avail = CHAR_BITS;

#if PORT == DOS
int jbi_current_variable_id = -1;
int jbi_current_page = -1;
int jbi_version = 0;
unsigned long jbi_out_length = 0L;
unsigned int jbi_out_index = 0;	/* byte index into jbi_aca_out_buffer[] */
unsigned long jbi_aca_in_offset = 0L;
unsigned char jbi_aca_out_buffer[JBI_ACA_BUFFER_SIZE];
#endif

/****************************************************************************/
/*																			*/
/*	The following functions implement incremental decompression of Boolean	*/
/*	array data, using a small memory window.								*/
/*																			*/
/*	This algorithm works by searching previous bytes in the data that match	*/
/*	the current data. If a match is found, then the offset and length of	*/
/*	the matching data can replace the actual data in the output.			*/
/*																			*/
/*	Memory usage is reduced by maintaining a "window" buffer which contains	*/
/*	the uncompressed data for one 8K page, plus some extra amount specified	*/
/*	by JBI_ACA_REQUEST_SIZE.  The function jbi_uncompress_page() is used to	*/
/*	request a subrange of the uncompressed data, starting at a particular	*/
/*	bit position and extending a maximum of JBI_ACA_REQUEST_SIZE bytes.		*/
/*																			*/
/****************************************************************************/

/****************************************************************************/
/*																			*/

unsigned int jbi_bits_required(unsigned int n)

/*																			*/
/*	Description:	Calculate the minimum number of bits required to		*/
/*					represent n.											*/
/*																			*/
/*	Returns:		Number of bits.											*/
/*																			*/
/****************************************************************************/
{
	unsigned int result = SHORT_BITS;

	if (n == 0)
	{
		result = 1;
	}
	else
	{
		/* Look for the highest non-zero bit position */
		while ((n & (1 << (SHORT_BITS - 1))) == 0)
		{
			n <<= 1;
			--result;
		}
	}

	return (result);
}

/****************************************************************************/
/*																			*/

unsigned int jbi_read_packed
(
#if PORT!=DOS
	unsigned char *buffer,
#endif
	unsigned int bits
)

/*																			*/
/*	Description:	Read the next value from the input array "buffer".		*/
/*					Read only "bits" bits from the array. The amount of		*/
/*					bits that have already been read from "buffer" is		*/
/*					stored internally to this function.					 	*/
/*																			*/
/*	Returns:		Up to 16 bit value. -1 if buffer overrun.				*/
/*																			*/
/****************************************************************************/
{
	unsigned int result = 0;
	unsigned int shift = 0;
	unsigned int databyte = 0;

	while (bits > 0)
	{
#if PORT==DOS
		databyte = GET_BYTE(jbi_aca_in_offset + jbi_in_index);
#else
		databyte = buffer[jbi_in_index];
#endif
		result |= (((databyte >> (CHAR_BITS - jbi_bits_avail))
			& (0xFF >> (CHAR_BITS - jbi_bits_avail))) << shift);

		if (bits <= jbi_bits_avail)
		{
			result &= (0xFFFF >> (SHORT_BITS - (bits + shift)));
			jbi_bits_avail -= bits;
			bits = 0;
		}
		else
		{
			++jbi_in_index;
			shift += jbi_bits_avail;
			bits -= jbi_bits_avail;
			jbi_bits_avail = CHAR_BITS;
		}
	}

	return (result);
}

#if PORT==DOS

/****************************************************************************/
/*																			*/

void jbi_uncompress_next_page(int version)

/*																			*/
/*	Description:	Uncompresses one page of compressed data, using			*/
/*					data page as reference for repeated sections.			*/
/*					Overwrites previous page of data in buffer.				*/
/*																			*/
/*	Returns:		TRUE for success, FALSE if error encountered			*/
/*																			*/
/****************************************************************************/
{
	unsigned int i, j, offset, length;
	unsigned int end_index;
	unsigned long tmp_in_index = jbi_in_index;
	unsigned int tmp_out_index = jbi_out_index;
	unsigned int tmp_bits_avail = jbi_bits_avail;
	unsigned int prev[3];
	unsigned long long_end;
	unsigned int match_data_length = MATCH_DATA_LENGTH;

	if (version > 0) --match_data_length;

	if (jbi_current_page < 0)
	{
		/* this is the first page of the array */
		jbi_current_page = 0;
		jbi_in_index = 4;	/* skip over length field */
		jbi_out_index = 0;
		end_index = (jbi_out_length < JBI_ACA_BUFFER_SIZE) ?
			(unsigned int) jbi_out_length : JBI_ACA_BUFFER_SIZE;
	}
	else
	{
		/* this is not the first page */
		++jbi_current_page;
		jbi_out_index -= MATCH_DATA_LENGTH;
		long_end = jbi_out_length -
			((long) jbi_current_page * (long) MATCH_DATA_LENGTH);
		end_index = (long_end < JBI_ACA_BUFFER_SIZE) ?
			(unsigned int) long_end : JBI_ACA_BUFFER_SIZE;

		/* copy extra data from end of circular buffer to beginning */
		for (i = 0; i < jbi_out_index; ++i)
		{
			jbi_aca_out_buffer[i] = jbi_aca_out_buffer[i + MATCH_DATA_LENGTH];
		}
	}

	while (jbi_out_index < end_index)
	{
		/* save state so we can undo the last packet when we reach the end */
		tmp_in_index = jbi_in_index;
		tmp_out_index = jbi_out_index;
		tmp_bits_avail = jbi_bits_avail;

		/* A 0 bit indicates literal data. */
		if (jbi_read_packed(1) == 0)
		{
			for (i = 0; i < DATA_BLOB_LENGTH; ++i)
			{
				if (jbi_out_index < end_index)
				{
					if (version == 0)
					{
						prev[i] = jbi_aca_out_buffer[jbi_out_index] & 0xff;
					}
					jbi_aca_out_buffer[jbi_out_index++] =
						(unsigned char) jbi_read_packed(CHAR_BITS);
				}
			}
		}
		else
		{
			/* A 1 bit indicates offset/length to follow. */
			offset = jbi_read_packed(jbi_bits_required(
				(jbi_current_page > 0) ? match_data_length :
				(jbi_out_index > match_data_length ? match_data_length :
				jbi_out_index)));
			length = jbi_read_packed(CHAR_BITS);

			if ((version == 0) && (offset == match_data_length + 3))
			{
				jbi_aca_out_buffer[jbi_out_index++] = (unsigned char) prev[0];
				jbi_aca_out_buffer[jbi_out_index++] = (unsigned char) prev[1];
				jbi_aca_out_buffer[jbi_out_index++] = (unsigned char) prev[2];
				length -= 3;
			}

			for (i = 0; i < length; ++i)
			{
				if (jbi_out_index < end_index)
				{
					if (offset > jbi_out_index)
					{
						j = jbi_out_index + MATCH_DATA_LENGTH - offset;
					}
					else j = jbi_out_index - offset;
					jbi_aca_out_buffer[jbi_out_index] = jbi_aca_out_buffer[j];
					++jbi_out_index;
				}
			}

			if (version == 0)
			{
				prev[0] = jbi_aca_out_buffer[jbi_out_index - 3] & 0xff;
				prev[1] = jbi_aca_out_buffer[jbi_out_index - 2] & 0xff;
				prev[2] = jbi_aca_out_buffer[jbi_out_index - 1] & 0xff;
			}
		}
	}

	/* restore the state before the previous packet */
	jbi_in_index = tmp_in_index;
	jbi_out_index = tmp_out_index;
	jbi_bits_avail = tmp_bits_avail;
}

/****************************************************************************/
/*																			*/

void jbi_uncompress_page
(
	int variable_id,
	int page,
	int version
)

/*																			*/
/*	Description:	Uncompress requested page of variable data.  Stores		*/
/*					uncompressed data in jbi_aca_out_buffer[].				*/
/*																			*/
/*	Returns:		TRUE if successful, otherwise FALSE if:					*/
/*						1) variable is not a compressed array				*/
/*						2) compressed data is illegal or corrupted			*/
/*						3) requested page is beyond the end of the array	*/
/*						4) internal error in the code						*/
/*																			*/
/****************************************************************************/
{
	unsigned long symbol_table;
	unsigned long data_section;
	unsigned long offset;
	unsigned long value;
	int delta = version * 2;

	if (variable_id != jbi_current_variable_id)
	{
		/* initialize to uncompress the desired variable */
		symbol_table = GET_DWORD(16 + (version * 8));
		data_section = GET_DWORD(20 + (version * 8));
		offset = symbol_table + ((11 + delta) * variable_id);
		value = GET_DWORD(offset + 3 + delta);
		jbi_current_variable_id = variable_id;
		jbi_current_page = -1;
		jbi_bits_avail = CHAR_BITS;
		jbi_in_length = GET_DWORD(offset + 7 + delta);
		jbi_out_length =
			(((unsigned long) GET_BYTE(data_section + value)) |
			(((unsigned long) GET_BYTE(data_section + value + 1)) << 8) |
			(((unsigned long) GET_BYTE(data_section + value + 2)) << 16) |
			(((unsigned long) GET_BYTE(data_section + value + 3)) << 24));
		jbi_in_index = 4;	/* skip over length field */
		jbi_out_index = 0;
		jbi_aca_in_offset = data_section + value;
	}

	/* to look back at an earlier page, start over at the beginning */
	if (page < jbi_current_page)
	{
		jbi_current_page = -1;
		jbi_in_index = 4;	/* skip over length field */
		jbi_bits_avail = CHAR_BITS;
	}

	/* uncompress sequentially up to the desired page */
	while (page > jbi_current_page)
	{
		jbi_uncompress_next_page(version);
	}
}

#else

/****************************************************************************/
/*																			*/

unsigned long jbi_uncompress
(
	unsigned char *in, 
	unsigned long in_length, 
	unsigned char *out, 
	unsigned long out_length,
	int version
)

/*																			*/
/*	Description:	Uncompress data in "in" and write result to	"out".		*/
/*																			*/
/*	Returns:		Length of uncompressed data. -1 if:						*/
/*						1) out_length is too small							*/
/*						2) Internal error in the code						*/
/*						3) in doesn't contain ACA compressed data.			*/
/*																			*/
/****************************************************************************/
{
	unsigned long i, j, data_length = 0L;
	unsigned int offset, length;
	unsigned int match_data_length = MATCH_DATA_LENGTH;

	if (version > 0) --match_data_length;

	jbi_in_length = in_length;
	jbi_bits_avail = CHAR_BITS;
	jbi_in_index = 0L;
	for (i = 0; i < out_length; ++i) out[i] = 0;

	/* Read number of bytes in data. */
	for (i = 0; i < sizeof (in_length); ++i) 
	{
		data_length = data_length | ((unsigned long)
			jbi_read_packed(in, CHAR_BITS) << (i * CHAR_BITS));
	}

	if (data_length > out_length)
	{
		data_length = 0L;
	}
	else
	{
		i = 0;
		while (i < data_length)
		{
			/* A 0 bit indicates literal data. */
			if (jbi_read_packed(in, 1) == 0)
			{
				for (j = 0; j < DATA_BLOB_LENGTH; ++j)
				{
					if (i < data_length)
					{
						out[i] = (unsigned char) jbi_read_packed(in, CHAR_BITS);
						i++;
					}
				}
			}
			else
			{
				/* A 1 bit indicates offset/length to follow. */
				offset = jbi_read_packed(in, jbi_bits_required((short) (i > match_data_length ? match_data_length : i)));
				length = jbi_read_packed(in, CHAR_BITS);

				for (j = 0; j < length; ++j)
				{
					if (i < data_length)
					{
						out[i] = out[i - offset];
						i++;
					}
				}
			}
		}
	}

	return (data_length);
}

#endif