/* ------------------------------------------------------------------------ */
/*                                                                          */
/*      These are the decompression algorithms.                             */
/*      Don't change here anything (apart from memory allocation perhaps).  */
/*      Any changes will very likely cause bugs!                            */
/*                                                                          */
/* ------------------------------------------------------------------------ */

#include "os.h"

#if defined(AMIGA)
 #include <string.h> // mem*()
#endif
#if defined(DOS) || defined(WIN16) || defined(WINNT) || defined(OS2) || defined(UNIX)
#if !defined(__CYGWIN__)
 #include <mem.h>    // mem*()
#endif 
#endif

#include <stdio.h>   // printf()
#include <stdlib.h>  // malloc()
#include <string.h>


#include "globals.h"
#include "portable.h"
#include "uac_comm.h"
#include "uac_crc.h"
#include "uac_dcpr.h"
#include "uac_sys.h"
#ifdef CRYPT
 #include "unace_ps.h"
#endif /* CRYPT */


//------------------------------ QUICKSORT ---------------------------------//
#define xchg_def(v1,v2) {INT dummy;\
                         dummy=v1; \
                         v1=v2;    \
                         v2=dummy;}

void sortrange(INT left, INT right)
{
	INT  zl = left,
	zr = right,
	hyphen;

	hyphen = sort_freq[right];

	//divides by hyphen the given range into 2 parts
	do
	{
		while (sort_freq[zl] > hyphen)
			zl++;
		while (sort_freq[zr] < hyphen)
			zr--;
		//found a too small (left side) and
		//a too big (right side) element-->exchange them
		if (zl <= zr)
		{
			xchg_def(sort_freq[zl], sort_freq[zr]);
			xchg_def(sort_org[zl], sort_org[zr]);
			zl++;
			zr--;
		}
	}
	while (zl < zr);

	//sort partial ranges - when very small, sort directly
	if (left < zr)
	{
		if (left < zr - 1)
			sortrange(left, zr);
		else if (sort_freq[left] < sort_freq[zr])
		{
			xchg_def(sort_freq[left], sort_freq[zr]);
			xchg_def(sort_org[left], sort_org[zr]);
		}
	}

	if (right > zl)
	{
		if (zl < right - 1)
			sortrange(zl, right);
		else if (sort_freq[zl] < sort_freq[right])
		{
			xchg_def(sort_freq[zl], sort_freq[right]);
			xchg_def(sort_org[zl], sort_org[right]);
		}
	}
}

void quicksort(INT n)
{
	INT  i;

	for (i = n + 1; i--;)
		sort_org[i] = i;
	sortrange(0, n);
}

//------------------------------ read bits ---------------------------------//
void readdat(void)
{
	UINT i;

	i = (size_rdb - 2) << 2;
	rpos -= size_rdb - 2;
	buf_rd[0] = buf_rd[size_rdb - 2];
	buf_rd[1] = buf_rd[size_rdb - 1];
	read_adds_blk((CHAR *) & buf_rd[2], i);
#ifdef HI_LO_BYTE_ORDER
	{
		ULONG *p;
		i>>=2;    // count LONGs not BYTEs
		p=&buf_rd[2];
		while (i--)
		{
			LONGswap(p);
			p++;
		}
	}
#endif
}

#define addbits(bits)                                   \
{                                                       \
	rpos+=(bits_rd+=bits)>>5;                             \
	bits_rd&=31;                                          \
	if (rpos==(size_rdb-2)) readdat();                    \
	code_rd=(buf_rd[rpos] << bits_rd)                     \
	+((buf_rd[rpos+1] >> (32-bits_rd))&(!bits_rd-1));   \
	}


//---------------------- COMMENT DECOMPRESSION -----------------------------//

#define comm_cpr_hf(a,b) (a+b)

void dcpr_comm_init(void)
{
	INT  i;

	i = comm_cpr_size > size_rdb * sizeof(LONG) ? size_rdb * sizeof(LONG) : comm_cpr_size;
	if (!f_err)
		memcpy(buf_rd, comm, i);
#ifdef HI_LO_BYTE_ORDER
	{
		ULONG *p;
		i>>=2;    // count LONGs not BYTEs
		p=buf_rd;
		while (i--)
		{
			LONGswap(p);
			p++;
		}
	}
#endif
	code_rd = buf_rd[0];
	rpos = bits_rd = 0;
}

void dcpr_comm(INT comm_size)
{
	SHORT hash[comm_cpr_hf(255, 255) + 1];
	INT  dpos = 0,
		c,
	pos = 0,
	len,
	hs;

	memset(&hash, 0, sizeof(hash));
	if (comm_cpr_size)
	{
		dcpr_comm_init();
		len = code_rd >> (32 - 15);
		addbits(15);
		if (len >= comm_size)
			len = comm_size - 1;
		if (read_wd(maxwd_mn, dcpr_code_mn, dcpr_wd_mn, max_cd_mn))
			do
		{
			if (dpos > 1)
			{
				pos = hash[hs = comm_cpr_hf(comm[dpos - 1], comm[dpos - 2])];
				hash[hs] = dpos;
			}
			addbits(dcpr_wd_mn[(c = dcpr_code_mn[code_rd >> (32 - maxwd_mn)])]);
			if (rpos == size_rdb - 3)
				rpos = 0;
			if (c > 255)
			{
				c -= 256;
				c += 2;
				while (c--)
					comm[dpos++] = comm[pos++];
			}
			else
			{
				comm[dpos++] = c;
			}
		}
		while (dpos < len);
		comm[len] = 0;
	}
}

//------------------------- LZW1 DECOMPRESSION -----------------------------//
void wrchar(CHAR ch)
{
	dcpr_do++;

	dcpr_text[dcpr_dpos] = ch;
	dcpr_dpos++;
	dcpr_dpos &= dcpr_dican;
}

void copystr(LONG d, INT l)
{
	INT  mpos;

	dcpr_do += l;

	mpos = dcpr_dpos - d;
	mpos &= dcpr_dican;

	if ((mpos >= dcpr_dicsiz - maxlength) || (dcpr_dpos >= dcpr_dicsiz - maxlength))
	{
		while (l--)
		{
			dcpr_text[dcpr_dpos] = dcpr_text[mpos];
			dcpr_dpos++;
			dcpr_dpos &= dcpr_dican;
			mpos++;
			mpos &= dcpr_dican;
		}
	}
	else
	{
		while (l--)
			dcpr_text[dcpr_dpos++] = dcpr_text[mpos++];
		dcpr_dpos &= dcpr_dican;
	}
}

void decompress(void)
{
	INT  c,
	lg,
	i,
	k;
	ULONG dist;

	while (dcpr_do < dcpr_do_max)
	{
		if (!blocksize)
			if (!calc_dectabs())
				return;

		addbits(dcpr_wd_mn[(c = dcpr_code_mn[code_rd >> (32 - maxwd_mn)])]);
		blocksize--;
		if (c > 255)
		{
			if (c > 259)
			{
				if ((c -= 260) > 1)
				{
					dist = (code_rd >> (33 - c)) + (1L << (c - 1));
					addbits(c - 1);
				}
				else
					dist = c;
				dcpr_olddist[(dcpr_oldnum = (dcpr_oldnum + 1) & 3)] = dist;
				i = 2;
				if (dist > maxdis2)
				{
					i++;
					if (dist > maxdis3)
						i++;
				}
			}
			else
			{
				dist = dcpr_olddist[(dcpr_oldnum - (c &= 255)) & 3];
				for (k = c + 1; k--;)
					dcpr_olddist[(dcpr_oldnum - k) & 3] = dcpr_olddist[(dcpr_oldnum - k + 1) & 3];
				dcpr_olddist[dcpr_oldnum] = dist;
				i = 2;
				if (c > 1)
					i++;
			}
			addbits(dcpr_wd_lg[(lg = dcpr_code_lg[code_rd >> (32 - maxwd_lg)])]);
			dist++;
			lg += i;
			copystr(dist, lg);
		}
		else
			wrchar(c);
	}
}

//-------------------------- HUFFMAN ROUTINES ------------------------------//
INT  makecode(UINT maxwd, UINT size1_t, UCHAR * wd, USHORT * code)
{
	UINT maxc,
	size2_t,
	l,
	c,
	i,
	max_make_code;

	memcpy(&sort_freq, wd, (size1_t + 1) * sizeof(CHAR));
	if (size1_t)
		quicksort(size1_t);
	else
		sort_org[0] = 0;
	sort_freq[size1_t + 1] = size2_t = c = 0;
	while (sort_freq[size2_t])
		size2_t++;
	if (size2_t < 2)
	{
		i = sort_org[0];
		wd[i] = 1;
		size2_t += (size2_t == 0);
	}
	size2_t--;

	max_make_code = 1 << maxwd;
	for (i = size2_t + 1; i-- && c < max_make_code;)
	{
		maxc = 1 << (maxwd - sort_freq[i]);
		l = sort_org[i];
		if (c + maxc > max_make_code)
		{
			dcpr_do = dcpr_do_max;
			return (0);
		}
		memset16(&code[c], l, maxc);
		c += maxc;
	}
	return (1);
}

INT  read_wd(UINT maxwd, USHORT * code, UCHAR * wd, INT max_el)
{
	UINT c,
	i,
	j,
	num_el,
	l,
	uplim,
	lolim;

	memset(wd, 0, max_el * sizeof(CHAR));
	memset(code, 0, (1 << maxwd) * sizeof(SHORT));

	num_el = code_rd >> (32 - 9);
	addbits(9);
	if (num_el > max_el)
		num_el = max_el;

	lolim = code_rd >> (32 - 4);
	addbits(4);
	uplim = code_rd >> (32 - 4);
	addbits(4);

	for (i = -1; ++i <= uplim;)
	{
		wd_svwd[i] = code_rd >> (32 - 3);
		addbits(3);
	}
	if (!makecode(maxwd_svwd, uplim, wd_svwd, code))
		return (0);
	j = 0;
	while (j <= num_el)
	{
		c = code[code_rd >> (32 - maxwd_svwd)];
		addbits(wd_svwd[c]);
		if (c < uplim)
			wd[j++] = c;
		else
		{
			l = (code_rd >> 28) + 4;
			addbits(4);
			while (l-- && j <= num_el)
				wd[j++] = 0;
		}
	}
	if (uplim)
		for (i = 0; ++i <= num_el;)
			wd[i] = (wd[i] + wd[i - 1]) % uplim;
	for (i = -1; ++i <= num_el;)
		if (wd[i])
			wd[i] += lolim;

	return (makecode(maxwd, num_el, wd, code));

}

INT  calc_dectabs(void)
{
	if (!read_wd(maxwd_mn, dcpr_code_mn, dcpr_wd_mn, max_cd_mn)
		|| !read_wd(maxwd_lg, dcpr_code_lg, dcpr_wd_lg, max_cd_lg))
		return (0);

	blocksize = code_rd >> (32 - 15);
	addbits(15);

	return (1);
}

//---------------------------- BLOCK ROUTINES ------------------------------//
INT  decompress_blk(CHAR * buf, UINT len)
{
	LONG old_pos = dcpr_dpos;
	INT  i;

	dcpr_do = 0;
	if ((dcpr_do_max = len - maxlength) > dcpr_size)
		dcpr_do_max = dcpr_size;
	if ((LONG) dcpr_size > 0 && dcpr_do_max)
	{
		decompress();
		if (old_pos + dcpr_do > dcpr_dicsiz)
		{
			i = dcpr_dicsiz - old_pos;
			memcpy(buf, &dcpr_text[old_pos], i);
			memcpy(&buf[i], dcpr_text, dcpr_do - i);
		}
		else
			memcpy(buf, &dcpr_text[old_pos], dcpr_do);
	}
	dcpr_size -= dcpr_do;
	return (dcpr_do);
}

INT unstore(CHAR * buf, UINT len)
{
	UINT rd = 0,
	i,
	pos = 0;

#ifdef CRYPT
	len = crypt_len(len - 8);    /* because of decryption */
#endif /* CRYPT */

	while ((i = read_adds_blk((CHAR *) buf_rd, (INT) ((i = ((len > dcpr_size) ? dcpr_size : len)) > size_rdb ? size_rdb : i))) != 0)
	{
		rd += i;
		len -= i;
		memcpy(&buf[pos], buf_rd, i);
		pos += i;
	}
	dcpr_size -= rd;
	for (i = 0; i < rd; i++)
	{
		dcpr_text[dcpr_dpos] = buf[i];
		dcpr_dpos++;
		dcpr_dpos &= dcpr_dican;
	}
	return (INT)rd;
}

INT  dcpr_adds_blk(CHAR * buf, UINT len)
{
	INT  r;

	switch (fhead.TECH.TYPE)
	{
	case TYPE_STORE:
		r = unstore(buf, len);
		break;
	case TYPE_LZW1:
		r = decompress_blk(buf, len);
		break;
	default:
		error("\nFile compressed with unknown method. Decompression not possible.\n");
		f_err = ERR_OTHER;
		r = 0;
	}
	rd_crc = getcrc(rd_crc, (UCHAR*)buf, r);
	return r;
}


//----------------------------- INIT ROUTINES ------------------------------//
void dcpr_init(void)
{
	dcpr_frst_file = 1;

	dcpr_dic = 20;
	while ((dcpr_text = malloc(dcpr_dicsiz = (LONG) 1 << dcpr_dic))==NULL)
		dcpr_dic--;
	dcpr_dican = dcpr_dicsiz - 1;
}

void dcpr_init_file(void)
{
	UINT i;

#ifdef CRYPT

	reset_cryptkey();

#else /* CRYPT */

	if (head.HEAD_FLAGS & ACE_PASSW)
	{
		error("\nFound passworded file. Decryption not supported.\n");
		f_err = ERR_OTHER;
		return;
	}

#endif /* CRYPT */

	rd_crc = CRC_MASK;
	dcpr_size = fhead.SIZE;
	if (fhead.TECH.TYPE == TYPE_LZW1)
	{
		if ((fhead.TECH.PARM & 15) + 10 > dcpr_dic)
		{
			error("\nNot enough memory or dictionary of archive too large.\n");
			f_err = ERR_MEM;
			return;
		}

		i = size_rdb * sizeof(LONG);
		read_adds_blk((CHAR *) buf_rd, i);
#ifdef HI_LO_BYTE_ORDER
		{
			ULONG *p;
			i>>=2;    // count LONGs not BYTEs
			p=buf_rd;
			while (i--)
			{
				LONGswap(p);
				p++;
			}
		}
#endif
		code_rd = buf_rd[0];
		bits_rd = rpos = 0;

		blocksize = 0;
	}
	if (!adat.sol || dcpr_frst_file)
		dcpr_dpos = 0;

	dcpr_oldnum = 0;
	memset(&dcpr_olddist, 0, sizeof(dcpr_olddist));

	dcpr_frst_file = 0;
}