archival/libunarchive/decompress_unlzma.c - busybox - Git at Google

 /* vi: set sw=4 ts=4: */
 /*
  * Small lzma deflate implementation.
  * Copyright (C) 2006  Aurelien Jacobs <aurel@gnuage.org>
  *
  * Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
  * Copyright (C) 1999-2005  Igor Pavlov
  *
  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  */

 #include "libbb.h"
 #include "unarchive.h"

 #if ENABLE_FEATURE_LZMA_FAST
 #  define speed_inline ALWAYS_INLINE
 #else
 #  define speed_inline
 #endif


 typedef struct {
 	int fd;
 	uint8_t *ptr;

 /* Was keeping rc on stack in unlzma and separately allocating buffer,
  * but with "buffer 'attached to' allocated rc" code is smaller: */
 	/* uint8_t *buffer; */
 #define RC_BUFFER ((uint8_t*)(rc+1))

 	uint8_t *buffer_end;

 /* Had provisions for variable buffer, but we don't need it here */
 	/* int buffer_size; */
 #define RC_BUFFER_SIZE 0x10000

 	uint32_t code;
 	uint32_t range;
 	uint32_t bound;
 } rc_t;

 #define RC_TOP_BITS 24
 #define RC_MOVE_BITS 5
 #define RC_MODEL_TOTAL_BITS 11


 /* Called twice: once at startup and once in rc_normalize() */
 static void rc_read(rc_t *rc)
 {
 	int buffer_size = safe_read(rc->fd, RC_BUFFER, RC_BUFFER_SIZE);
 	if (buffer_size <= 0)
 		bb_error_msg_and_die("unexpected EOF");
 	rc->ptr = RC_BUFFER;
 	rc->buffer_end = RC_BUFFER + buffer_size;
 }

 /* Called once */
 static rc_t* rc_init(int fd) /*, int buffer_size) */
 {
 	int i;
 	rc_t *rc;

 	rc = xmalloc(sizeof(*rc) + RC_BUFFER_SIZE);

 	rc->fd = fd;
 	/* rc->buffer_size = buffer_size; */
 	rc->buffer_end = RC_BUFFER + RC_BUFFER_SIZE;
 	rc->ptr = rc->buffer_end;

 	rc->code = 0;
 	rc->range = 0xFFFFFFFF;
 	for (i = 0; i < 5; i++) {
 		if (rc->ptr >= rc->buffer_end)
 			rc_read(rc);
 		rc->code = (rc->code << 8) | *rc->ptr++;
 	}
 	return rc;
 }

 /* Called once  */
 static ALWAYS_INLINE void rc_free(rc_t *rc)
 {
 	free(rc);
 }

 /* Called twice, but one callsite is in speed_inline'd rc_is_bit_0_helper() */
 static void rc_do_normalize(rc_t *rc)
 {
 	if (rc->ptr >= rc->buffer_end)
 		rc_read(rc);
 	rc->range <<= 8;
 	rc->code = (rc->code << 8) | *rc->ptr++;
 }
 static ALWAYS_INLINE void rc_normalize(rc_t *rc)
 {
 	if (rc->range < (1 << RC_TOP_BITS)) {
 		rc_do_normalize(rc);
 	}
 }

 /* rc_is_bit_0 is called 9 times */
 /* Why rc_is_bit_0_helper exists?
  * Because we want to always expose (rc->code < rc->bound) to optimizer.
  * Thus rc_is_bit_0 is always inlined, and rc_is_bit_0_helper is inlined
  * only if we compile for speed.
  */
 static speed_inline uint32_t rc_is_bit_0_helper(rc_t *rc, uint16_t *p)
 {
 	rc_normalize(rc);
 	rc->bound = *p * (rc->range >> RC_MODEL_TOTAL_BITS);
 	return rc->bound;
 }
 static ALWAYS_INLINE int rc_is_bit_0(rc_t *rc, uint16_t *p)
 {
 	uint32_t t = rc_is_bit_0_helper(rc, p);
 	return rc->code < t;
 }

 /* Called ~10 times, but very small, thus inlined */
 static speed_inline void rc_update_bit_0(rc_t *rc, uint16_t *p)
 {
 	rc->range = rc->bound;
 	*p += ((1 << RC_MODEL_TOTAL_BITS) - *p) >> RC_MOVE_BITS;
 }
 static speed_inline void rc_update_bit_1(rc_t *rc, uint16_t *p)
 {
 	rc->range -= rc->bound;
 	rc->code -= rc->bound;
 	*p -= *p >> RC_MOVE_BITS;
 }

 /* Called 4 times in unlzma loop */
 static int rc_get_bit(rc_t *rc, uint16_t *p, int *symbol)
 {
 	if (rc_is_bit_0(rc, p)) {
 		rc_update_bit_0(rc, p);
 		*symbol *= 2;
 		return 0;
 	} else {
 		rc_update_bit_1(rc, p);
 		*symbol = *symbol * 2 + 1;
 		return 1;
 	}
 }

 /* Called once */
 static ALWAYS_INLINE int rc_direct_bit(rc_t *rc)
 {
 	rc_normalize(rc);
 	rc->range >>= 1;
 	if (rc->code >= rc->range) {
 		rc->code -= rc->range;
 		return 1;
 	}
 	return 0;
 }

 /* Called twice */
 static speed_inline void
 rc_bit_tree_decode(rc_t *rc, uint16_t *p, int num_levels, int *symbol)
 {
 	int i = num_levels;

 	*symbol = 1;
 	while (i--)
 		rc_get_bit(rc, p + *symbol, symbol);
 	*symbol -= 1 << num_levels;
 }


 typedef struct {
 	uint8_t pos;
 	uint32_t dict_size;
 	uint64_t dst_size;
 } __attribute__ ((packed)) lzma_header_t;


 /* #defines will force compiler to compute/optimize each one with each usage.
  * Have heart and use enum instead. */
 enum {
 	LZMA_BASE_SIZE = 1846,
 	LZMA_LIT_SIZE  = 768,

 	LZMA_NUM_POS_BITS_MAX = 4,

 	LZMA_LEN_NUM_LOW_BITS  = 3,
 	LZMA_LEN_NUM_MID_BITS  = 3,
 	LZMA_LEN_NUM_HIGH_BITS = 8,

 	LZMA_LEN_CHOICE     = 0,
 	LZMA_LEN_CHOICE_2   = (LZMA_LEN_CHOICE + 1),
 	LZMA_LEN_LOW        = (LZMA_LEN_CHOICE_2 + 1),
 	LZMA_LEN_MID        = (LZMA_LEN_LOW \
 	                      + (1 << (LZMA_NUM_POS_BITS_MAX + LZMA_LEN_NUM_LOW_BITS))),
 	LZMA_LEN_HIGH       = (LZMA_LEN_MID \
 	                      + (1 << (LZMA_NUM_POS_BITS_MAX + LZMA_LEN_NUM_MID_BITS))),
 	LZMA_NUM_LEN_PROBS  = (LZMA_LEN_HIGH + (1 << LZMA_LEN_NUM_HIGH_BITS)),

 	LZMA_NUM_STATES     = 12,
 	LZMA_NUM_LIT_STATES = 7,

 	LZMA_START_POS_MODEL_INDEX = 4,
 	LZMA_END_POS_MODEL_INDEX   = 14,
 	LZMA_NUM_FULL_DISTANCES    = (1 << (LZMA_END_POS_MODEL_INDEX >> 1)),

 	LZMA_NUM_POS_SLOT_BITS = 6,
 	LZMA_NUM_LEN_TO_POS_STATES = 4,

 	LZMA_NUM_ALIGN_BITS = 4,

 	LZMA_MATCH_MIN_LEN  = 2,

 	LZMA_IS_MATCH       = 0,
 	LZMA_IS_REP         = (LZMA_IS_MATCH + (LZMA_NUM_STATES << LZMA_NUM_POS_BITS_MAX)),
 	LZMA_IS_REP_G0      = (LZMA_IS_REP + LZMA_NUM_STATES),
 	LZMA_IS_REP_G1      = (LZMA_IS_REP_G0 + LZMA_NUM_STATES),
 	LZMA_IS_REP_G2      = (LZMA_IS_REP_G1 + LZMA_NUM_STATES),
 	LZMA_IS_REP_0_LONG  = (LZMA_IS_REP_G2 + LZMA_NUM_STATES),
 	LZMA_POS_SLOT       = (LZMA_IS_REP_0_LONG \
 	                      + (LZMA_NUM_STATES << LZMA_NUM_POS_BITS_MAX)),
 	LZMA_SPEC_POS       = (LZMA_POS_SLOT \
 	                      + (LZMA_NUM_LEN_TO_POS_STATES << LZMA_NUM_POS_SLOT_BITS)),
 	LZMA_ALIGN          = (LZMA_SPEC_POS \
 	                      + LZMA_NUM_FULL_DISTANCES - LZMA_END_POS_MODEL_INDEX),
 	LZMA_LEN_CODER      = (LZMA_ALIGN + (1 << LZMA_NUM_ALIGN_BITS)),
 	LZMA_REP_LEN_CODER  = (LZMA_LEN_CODER + LZMA_NUM_LEN_PROBS),
 	LZMA_LITERAL        = (LZMA_REP_LEN_CODER + LZMA_NUM_LEN_PROBS),
 };


 USE_DESKTOP(long long) int FAST_FUNC
 unpack_lzma_stream(int src_fd, int dst_fd)
 {
 	USE_DESKTOP(long long total_written = 0;)
 	lzma_header_t header;
 	int lc, pb, lp;
 	uint32_t pos_state_mask;
 	uint32_t literal_pos_mask;
 	uint32_t pos;
 	uint16_t *p;
 	uint16_t *prob;
 	uint16_t *prob_lit;
 	int num_bits;
 	int num_probs;
 	rc_t *rc;
 	int i, mi;
 	uint8_t *buffer;
 	uint8_t previous_byte = 0;
 	size_t buffer_pos = 0, global_pos = 0;
 	int len = 0;
 	int state = 0;
 	uint32_t rep0 = 1, rep1 = 1, rep2 = 1, rep3 = 1;

 	xread(src_fd, &header, sizeof(header));

 	if (header.pos >= (9 * 5 * 5))
 		bb_error_msg_and_die("bad header");
 	mi = header.pos / 9;
 	lc = header.pos % 9;
 	pb = mi / 5;
 	lp = mi % 5;
 	pos_state_mask = (1 << pb) - 1;
 	literal_pos_mask = (1 << lp) - 1;

 	header.dict_size = SWAP_LE32(header.dict_size);
 	header.dst_size = SWAP_LE64(header.dst_size);

 	if (header.dict_size == 0)
 		header.dict_size = 1;

 	buffer = xmalloc(MIN(header.dst_size, header.dict_size));

 	num_probs = LZMA_BASE_SIZE + (LZMA_LIT_SIZE << (lc + lp));
 	p = xmalloc(num_probs * sizeof(*p));
 	num_probs = LZMA_LITERAL + (LZMA_LIT_SIZE << (lc + lp));
 	for (i = 0; i < num_probs; i++)
 		p[i] = (1 << RC_MODEL_TOTAL_BITS) >> 1;

 	rc = rc_init(src_fd); /*, RC_BUFFER_SIZE); */

 	while (global_pos + buffer_pos < header.dst_size) {
 		int pos_state = (buffer_pos + global_pos) & pos_state_mask;

 		prob = p + LZMA_IS_MATCH + (state << LZMA_NUM_POS_BITS_MAX) + pos_state;
 		if (rc_is_bit_0(rc, prob)) {
 			mi = 1;
 			rc_update_bit_0(rc, prob);
 			prob = (p + LZMA_LITERAL
 			        + (LZMA_LIT_SIZE * ((((buffer_pos + global_pos) & literal_pos_mask) << lc)
 			                            + (previous_byte >> (8 - lc))
 			                           )
 			          )
 			);

 			if (state >= LZMA_NUM_LIT_STATES) {
 				int match_byte;

 				pos = buffer_pos - rep0;
 				while (pos >= header.dict_size)
 					pos += header.dict_size;
 				match_byte = buffer[pos];
 				do {
 					int bit;

 					match_byte <<= 1;
 					bit = match_byte & 0x100;
 					prob_lit = prob + 0x100 + bit + mi;
 					bit ^= (rc_get_bit(rc, prob_lit, &mi) << 8); /* 0x100 or 0 */
 					if (bit)
 						break;
 				} while (mi < 0x100);
 			}
 			while (mi < 0x100) {
 				prob_lit = prob + mi;
 				rc_get_bit(rc, prob_lit, &mi);
 			}

 			state -= 3;
 			if (state < 4-3)
 				state = 0;
 			if (state >= 10-3)
 				state -= 6-3;

 			previous_byte = (uint8_t) mi;
 #if ENABLE_FEATURE_LZMA_FAST
  one_byte1:
 			buffer[buffer_pos++] = previous_byte;
 			if (buffer_pos == header.dict_size) {
 				buffer_pos = 0;
 				global_pos += header.dict_size;
 				if (full_write(dst_fd, buffer, header.dict_size) != (ssize_t)header.dict_size)
 					goto bad;
 				USE_DESKTOP(total_written += header.dict_size;)
 			}
 #else
 			len = 1;
 			goto one_byte2;
 #endif
 		} else {
 			int offset;
 			uint16_t *prob_len;

 			rc_update_bit_1(rc, prob);
 			prob = p + LZMA_IS_REP + state;
 			if (rc_is_bit_0(rc, prob)) {
 				rc_update_bit_0(rc, prob);
 				rep3 = rep2;
 				rep2 = rep1;
 				rep1 = rep0;
 				state = state < LZMA_NUM_LIT_STATES ? 0 : 3;
 				prob = p + LZMA_LEN_CODER;
 			} else {
 				rc_update_bit_1(rc, prob);
 				prob = p + LZMA_IS_REP_G0 + state;
 				if (rc_is_bit_0(rc, prob)) {
 					rc_update_bit_0(rc, prob);
 					prob = (p + LZMA_IS_REP_0_LONG
 					        + (state << LZMA_NUM_POS_BITS_MAX)
 					        + pos_state
 					);
 					if (rc_is_bit_0(rc, prob)) {
 						rc_update_bit_0(rc, prob);

 						state = state < LZMA_NUM_LIT_STATES ? 9 : 11;
 #if ENABLE_FEATURE_LZMA_FAST
 						pos = buffer_pos - rep0;
 						while (pos >= header.dict_size)
 							pos += header.dict_size;
 						previous_byte = buffer[pos];
 						goto one_byte1;
 #else
 						len = 1;
 						goto string;
 #endif
 					} else {
 						rc_update_bit_1(rc, prob);
 					}
 				} else {
 					uint32_t distance;

 					rc_update_bit_1(rc, prob);
 					prob = p + LZMA_IS_REP_G1 + state;
 					if (rc_is_bit_0(rc, prob)) {
 						rc_update_bit_0(rc, prob);
 						distance = rep1;
 					} else {
 						rc_update_bit_1(rc, prob);
 						prob = p + LZMA_IS_REP_G2 + state;
 						if (rc_is_bit_0(rc, prob)) {
 							rc_update_bit_0(rc, prob);
 							distance = rep2;
 						} else {
 							rc_update_bit_1(rc, prob);
 							distance = rep3;
 							rep3 = rep2;
 						}
 						rep2 = rep1;
 					}
 					rep1 = rep0;
 					rep0 = distance;
 				}
 				state = state < LZMA_NUM_LIT_STATES ? 8 : 11;
 				prob = p + LZMA_REP_LEN_CODER;
 			}

 			prob_len = prob + LZMA_LEN_CHOICE;
 			if (rc_is_bit_0(rc, prob_len)) {
 				rc_update_bit_0(rc, prob_len);
 				prob_len = (prob + LZMA_LEN_LOW
 				            + (pos_state << LZMA_LEN_NUM_LOW_BITS));
 				offset = 0;
 				num_bits = LZMA_LEN_NUM_LOW_BITS;
 			} else {
 				rc_update_bit_1(rc, prob_len);
 				prob_len = prob + LZMA_LEN_CHOICE_2;
 				if (rc_is_bit_0(rc, prob_len)) {
 					rc_update_bit_0(rc, prob_len);
 					prob_len = (prob + LZMA_LEN_MID
 					            + (pos_state << LZMA_LEN_NUM_MID_BITS));
 					offset = 1 << LZMA_LEN_NUM_LOW_BITS;
 					num_bits = LZMA_LEN_NUM_MID_BITS;
 				} else {
 					rc_update_bit_1(rc, prob_len);
 					prob_len = prob + LZMA_LEN_HIGH;
 					offset = ((1 << LZMA_LEN_NUM_LOW_BITS)
 					          + (1 << LZMA_LEN_NUM_MID_BITS));
 					num_bits = LZMA_LEN_NUM_HIGH_BITS;
 				}
 			}
 			rc_bit_tree_decode(rc, prob_len, num_bits, &len);
 			len += offset;

 			if (state < 4) {
 				int pos_slot;

 				state += LZMA_NUM_LIT_STATES;
 				prob = p + LZMA_POS_SLOT +
 				       ((len < LZMA_NUM_LEN_TO_POS_STATES ? len :
 				         LZMA_NUM_LEN_TO_POS_STATES - 1)
 				         << LZMA_NUM_POS_SLOT_BITS);
 				rc_bit_tree_decode(rc, prob, LZMA_NUM_POS_SLOT_BITS,
 								   &pos_slot);
 				if (pos_slot >= LZMA_START_POS_MODEL_INDEX) {
 					num_bits = (pos_slot >> 1) - 1;
 					rep0 = 2 | (pos_slot & 1);
 					if (pos_slot < LZMA_END_POS_MODEL_INDEX) {
 						rep0 <<= num_bits;
 						prob = p + LZMA_SPEC_POS + rep0 - pos_slot - 1;
 					} else {
 						num_bits -= LZMA_NUM_ALIGN_BITS;
 						while (num_bits--)
 							rep0 = (rep0 << 1) | rc_direct_bit(rc);
 						prob = p + LZMA_ALIGN;
 						rep0 <<= LZMA_NUM_ALIGN_BITS;
 						num_bits = LZMA_NUM_ALIGN_BITS;
 					}
 					i = 1;
 					mi = 1;
 					while (num_bits--) {
 						if (rc_get_bit(rc, prob + mi, &mi))
 							rep0 |= i;
 						i <<= 1;
 					}
 				} else
 					rep0 = pos_slot;
 				if (++rep0 == 0)
 					break;
 			}

 			len += LZMA_MATCH_MIN_LEN;
  SKIP_FEATURE_LZMA_FAST(string:)
 			do {
 				pos = buffer_pos - rep0;
 				while (pos >= header.dict_size)
 					pos += header.dict_size;
 				previous_byte = buffer[pos];
  SKIP_FEATURE_LZMA_FAST(one_byte2:)
 				buffer[buffer_pos++] = previous_byte;
 				if (buffer_pos == header.dict_size) {
 					buffer_pos = 0;
 					global_pos += header.dict_size;
 					if (full_write(dst_fd, buffer, header.dict_size) != (ssize_t)header.dict_size)
 						goto bad;
 					USE_DESKTOP(total_written += header.dict_size;)
 				}
 				len--;
 			} while (len != 0 && buffer_pos < header.dst_size);
 		}
 	}

 	{
 		SKIP_DESKTOP(int total_written = 0; /* success */)
 		USE_DESKTOP(total_written += buffer_pos;)
 		if (full_write(dst_fd, buffer, buffer_pos) != (ssize_t)buffer_pos) {
  bad:
 			total_written = -1; /* failure */
 		}
 		rc_free(rc);
 		free(p);
 		free(buffer);
 		return total_written;
 	}
 }
	/* vi: set sw=4 ts=4: */
	/*
	* Small lzma deflate implementation.
	* Copyright (C) 2006 Aurelien Jacobs <aurel@gnuage.org>
	*
	* Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
	* Copyright (C) 1999-2005 Igor Pavlov
	*
	* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
	*/

	#include "libbb.h"
	#include "unarchive.h"

	#if ENABLE_FEATURE_LZMA_FAST
	# define speed_inline ALWAYS_INLINE
	#else
	# define speed_inline
	#endif


	typedef struct {
	int fd;
	uint8_t *ptr;

	/* Was keeping rc on stack in unlzma and separately allocating buffer,
	* but with "buffer 'attached to' allocated rc" code is smaller: */
	/* uint8_t buffer; /
	#define RC_BUFFER ((uint8_t*)(rc+1))

	uint8_t *buffer_end;

	/* Had provisions for variable buffer, but we don't need it here */
	/* int buffer_size; */
	#define RC_BUFFER_SIZE 0x10000

	uint32_t code;
	uint32_t range;
	uint32_t bound;
	} rc_t;

	#define RC_TOP_BITS 24
	#define RC_MOVE_BITS 5
	#define RC_MODEL_TOTAL_BITS 11


	/* Called twice: once at startup and once in rc_normalize() */
	static void rc_read(rc_t *rc)
	{
	int buffer_size = safe_read(rc->fd, RC_BUFFER, RC_BUFFER_SIZE);
	if (buffer_size <= 0)
	bb_error_msg_and_die("unexpected EOF");
	rc->ptr = RC_BUFFER;
	rc->buffer_end = RC_BUFFER + buffer_size;
	}

	/* Called once */
	static rc_t* rc_init(int fd) /, int buffer_size) /
	{
	int i;
	rc_t *rc;

	rc = xmalloc(sizeof(*rc) + RC_BUFFER_SIZE);

	rc->fd = fd;
	/* rc->buffer_size = buffer_size; */
	rc->buffer_end = RC_BUFFER + RC_BUFFER_SIZE;
	rc->ptr = rc->buffer_end;

	rc->code = 0;
	rc->range = 0xFFFFFFFF;
	for (i = 0; i < 5; i++) {
	if (rc->ptr >= rc->buffer_end)
	rc_read(rc);
	rc->code = (rc->code << 8) \| *rc->ptr++;
	}
	return rc;
	}

	/* Called once */
	static ALWAYS_INLINE void rc_free(rc_t *rc)
	{
	free(rc);
	}

	/* Called twice, but one callsite is in speed_inline'd rc_is_bit_0_helper() */
	static void rc_do_normalize(rc_t *rc)
	{
	if (rc->ptr >= rc->buffer_end)
	rc_read(rc);
	rc->range <<= 8;
	rc->code = (rc->code << 8) \| *rc->ptr++;
	}
	static ALWAYS_INLINE void rc_normalize(rc_t *rc)
	{
	if (rc->range < (1 << RC_TOP_BITS)) {
	rc_do_normalize(rc);
	}
	}

	/* rc_is_bit_0 is called 9 times */
	/* Why rc_is_bit_0_helper exists?
	* Because we want to always expose (rc->code < rc->bound) to optimizer.
	* Thus rc_is_bit_0 is always inlined, and rc_is_bit_0_helper is inlined
	* only if we compile for speed.
	*/
	static speed_inline uint32_t rc_is_bit_0_helper(rc_t rc, uint16_t p)
	{
	rc_normalize(rc);
	rc->bound = p (rc->range >> RC_MODEL_TOTAL_BITS);
	return rc->bound;
	}
	static ALWAYS_INLINE int rc_is_bit_0(rc_t rc, uint16_t p)
	{
	uint32_t t = rc_is_bit_0_helper(rc, p);
	return rc->code < t;
	}

	/* Called ~10 times, but very small, thus inlined */
	static speed_inline void rc_update_bit_0(rc_t rc, uint16_t p)
	{
	rc->range = rc->bound;
	p += ((1 << RC_MODEL_TOTAL_BITS) - p) >> RC_MOVE_BITS;
	}
	static speed_inline void rc_update_bit_1(rc_t rc, uint16_t p)
	{
	rc->range -= rc->bound;
	rc->code -= rc->bound;
	p -= p >> RC_MOVE_BITS;
	}

	/* Called 4 times in unlzma loop */
	static int rc_get_bit(rc_t rc, uint16_t p, int *symbol)
	{
	if (rc_is_bit_0(rc, p)) {
	rc_update_bit_0(rc, p);
	symbol = 2;
	return 0;
	} else {
	rc_update_bit_1(rc, p);
	symbol = symbol * 2 + 1;
	return 1;
	}
	}

	/* Called once */
	static ALWAYS_INLINE int rc_direct_bit(rc_t *rc)
	{
	rc_normalize(rc);
	rc->range >>= 1;
	if (rc->code >= rc->range) {
	rc->code -= rc->range;
	return 1;
	}
	return 0;
	}

	/* Called twice */
	static speed_inline void
	rc_bit_tree_decode(rc_t rc, uint16_t p, int num_levels, int *symbol)
	{
	int i = num_levels;

	*symbol = 1;
	while (i--)
	rc_get_bit(rc, p + *symbol, symbol);
	*symbol -= 1 << num_levels;
	}


	typedef struct {
	uint8_t pos;
	uint32_t dict_size;
	uint64_t dst_size;
	} __attribute__ ((packed)) lzma_header_t;


	/* #defines will force compiler to compute/optimize each one with each usage.
	* Have heart and use enum instead. */
	enum {
	LZMA_BASE_SIZE = 1846,
	LZMA_LIT_SIZE = 768,

	LZMA_NUM_POS_BITS_MAX = 4,

	LZMA_LEN_NUM_LOW_BITS = 3,
	LZMA_LEN_NUM_MID_BITS = 3,
	LZMA_LEN_NUM_HIGH_BITS = 8,

	LZMA_LEN_CHOICE = 0,
	LZMA_LEN_CHOICE_2 = (LZMA_LEN_CHOICE + 1),
	LZMA_LEN_LOW = (LZMA_LEN_CHOICE_2 + 1),
	LZMA_LEN_MID = (LZMA_LEN_LOW \
	+ (1 << (LZMA_NUM_POS_BITS_MAX + LZMA_LEN_NUM_LOW_BITS))),
	LZMA_LEN_HIGH = (LZMA_LEN_MID \
	+ (1 << (LZMA_NUM_POS_BITS_MAX + LZMA_LEN_NUM_MID_BITS))),
	LZMA_NUM_LEN_PROBS = (LZMA_LEN_HIGH + (1 << LZMA_LEN_NUM_HIGH_BITS)),

	LZMA_NUM_STATES = 12,
	LZMA_NUM_LIT_STATES = 7,

	LZMA_START_POS_MODEL_INDEX = 4,
	LZMA_END_POS_MODEL_INDEX = 14,
	LZMA_NUM_FULL_DISTANCES = (1 << (LZMA_END_POS_MODEL_INDEX >> 1)),

	LZMA_NUM_POS_SLOT_BITS = 6,
	LZMA_NUM_LEN_TO_POS_STATES = 4,

	LZMA_NUM_ALIGN_BITS = 4,

	LZMA_MATCH_MIN_LEN = 2,

	LZMA_IS_MATCH = 0,
	LZMA_IS_REP = (LZMA_IS_MATCH + (LZMA_NUM_STATES << LZMA_NUM_POS_BITS_MAX)),
	LZMA_IS_REP_G0 = (LZMA_IS_REP + LZMA_NUM_STATES),
	LZMA_IS_REP_G1 = (LZMA_IS_REP_G0 + LZMA_NUM_STATES),
	LZMA_IS_REP_G2 = (LZMA_IS_REP_G1 + LZMA_NUM_STATES),
	LZMA_IS_REP_0_LONG = (LZMA_IS_REP_G2 + LZMA_NUM_STATES),
	LZMA_POS_SLOT = (LZMA_IS_REP_0_LONG \
	+ (LZMA_NUM_STATES << LZMA_NUM_POS_BITS_MAX)),
	LZMA_SPEC_POS = (LZMA_POS_SLOT \
	+ (LZMA_NUM_LEN_TO_POS_STATES << LZMA_NUM_POS_SLOT_BITS)),
	LZMA_ALIGN = (LZMA_SPEC_POS \
	+ LZMA_NUM_FULL_DISTANCES - LZMA_END_POS_MODEL_INDEX),
	LZMA_LEN_CODER = (LZMA_ALIGN + (1 << LZMA_NUM_ALIGN_BITS)),
	LZMA_REP_LEN_CODER = (LZMA_LEN_CODER + LZMA_NUM_LEN_PROBS),
	LZMA_LITERAL = (LZMA_REP_LEN_CODER + LZMA_NUM_LEN_PROBS),
	};


	USE_DESKTOP(long long) int FAST_FUNC
	unpack_lzma_stream(int src_fd, int dst_fd)
	{
	USE_DESKTOP(long long total_written = 0;)
	lzma_header_t header;
	int lc, pb, lp;
	uint32_t pos_state_mask;
	uint32_t literal_pos_mask;
	uint32_t pos;
	uint16_t *p;
	uint16_t *prob;
	uint16_t *prob_lit;
	int num_bits;
	int num_probs;
	rc_t *rc;
	int i, mi;
	uint8_t *buffer;
	uint8_t previous_byte = 0;
	size_t buffer_pos = 0, global_pos = 0;
	int len = 0;
	int state = 0;
	uint32_t rep0 = 1, rep1 = 1, rep2 = 1, rep3 = 1;

	xread(src_fd, &header, sizeof(header));

	if (header.pos >= (9 * 5 * 5))
	bb_error_msg_and_die("bad header");
	mi = header.pos / 9;
	lc = header.pos % 9;
	pb = mi / 5;
	lp = mi % 5;
	pos_state_mask = (1 << pb) - 1;
	literal_pos_mask = (1 << lp) - 1;

	header.dict_size = SWAP_LE32(header.dict_size);
	header.dst_size = SWAP_LE64(header.dst_size);

	if (header.dict_size == 0)
	header.dict_size = 1;

	buffer = xmalloc(MIN(header.dst_size, header.dict_size));

	num_probs = LZMA_BASE_SIZE + (LZMA_LIT_SIZE << (lc + lp));
	p = xmalloc(num_probs * sizeof(*p));
	num_probs = LZMA_LITERAL + (LZMA_LIT_SIZE << (lc + lp));
	for (i = 0; i < num_probs; i++)
	p[i] = (1 << RC_MODEL_TOTAL_BITS) >> 1;

	rc = rc_init(src_fd); /, RC_BUFFER_SIZE); /

	while (global_pos + buffer_pos < header.dst_size) {
	int pos_state = (buffer_pos + global_pos) & pos_state_mask;

	prob = p + LZMA_IS_MATCH + (state << LZMA_NUM_POS_BITS_MAX) + pos_state;
	if (rc_is_bit_0(rc, prob)) {
	mi = 1;
	rc_update_bit_0(rc, prob);
	prob = (p + LZMA_LITERAL
	+ (LZMA_LIT_SIZE * ((((buffer_pos + global_pos) & literal_pos_mask) << lc)
	+ (previous_byte >> (8 - lc))
	)
	)
	);

	if (state >= LZMA_NUM_LIT_STATES) {
	int match_byte;

	pos = buffer_pos - rep0;
	while (pos >= header.dict_size)
	pos += header.dict_size;
	match_byte = buffer[pos];
	do {
	int bit;

	match_byte <<= 1;
	bit = match_byte & 0x100;
	prob_lit = prob + 0x100 + bit + mi;
	bit ^= (rc_get_bit(rc, prob_lit, &mi) << 8); /* 0x100 or 0 */
	if (bit)
	break;
	} while (mi < 0x100);
	}
	while (mi < 0x100) {
	prob_lit = prob + mi;
	rc_get_bit(rc, prob_lit, &mi);
	}

	state -= 3;
	if (state < 4-3)
	state = 0;
	if (state >= 10-3)
	state -= 6-3;

	previous_byte = (uint8_t) mi;
	#if ENABLE_FEATURE_LZMA_FAST
	one_byte1:
	buffer[buffer_pos++] = previous_byte;
	if (buffer_pos == header.dict_size) {
	buffer_pos = 0;
	global_pos += header.dict_size;
	if (full_write(dst_fd, buffer, header.dict_size) != (ssize_t)header.dict_size)
	goto bad;
	USE_DESKTOP(total_written += header.dict_size;)
	}
	#else
	len = 1;
	goto one_byte2;
	#endif
	} else {
	int offset;
	uint16_t *prob_len;

	rc_update_bit_1(rc, prob);
	prob = p + LZMA_IS_REP + state;
	if (rc_is_bit_0(rc, prob)) {
	rc_update_bit_0(rc, prob);
	rep3 = rep2;
	rep2 = rep1;
	rep1 = rep0;
	state = state < LZMA_NUM_LIT_STATES ? 0 : 3;
	prob = p + LZMA_LEN_CODER;
	} else {
	rc_update_bit_1(rc, prob);
	prob = p + LZMA_IS_REP_G0 + state;
	if (rc_is_bit_0(rc, prob)) {
	rc_update_bit_0(rc, prob);
	prob = (p + LZMA_IS_REP_0_LONG
	+ (state << LZMA_NUM_POS_BITS_MAX)
	+ pos_state
	);
	if (rc_is_bit_0(rc, prob)) {
	rc_update_bit_0(rc, prob);

	state = state < LZMA_NUM_LIT_STATES ? 9 : 11;
	#if ENABLE_FEATURE_LZMA_FAST
	pos = buffer_pos - rep0;
	while (pos >= header.dict_size)
	pos += header.dict_size;
	previous_byte = buffer[pos];
	goto one_byte1;
	#else
	len = 1;
	goto string;
	#endif
	} else {
	rc_update_bit_1(rc, prob);
	}
	} else {
	uint32_t distance;

	rc_update_bit_1(rc, prob);
	prob = p + LZMA_IS_REP_G1 + state;
	if (rc_is_bit_0(rc, prob)) {
	rc_update_bit_0(rc, prob);
	distance = rep1;
	} else {
	rc_update_bit_1(rc, prob);
	prob = p + LZMA_IS_REP_G2 + state;
	if (rc_is_bit_0(rc, prob)) {
	rc_update_bit_0(rc, prob);
	distance = rep2;
	} else {
	rc_update_bit_1(rc, prob);
	distance = rep3;
	rep3 = rep2;
	}
	rep2 = rep1;
	}
	rep1 = rep0;
	rep0 = distance;
	}
	state = state < LZMA_NUM_LIT_STATES ? 8 : 11;
	prob = p + LZMA_REP_LEN_CODER;
	}

	prob_len = prob + LZMA_LEN_CHOICE;
	if (rc_is_bit_0(rc, prob_len)) {
	rc_update_bit_0(rc, prob_len);
	prob_len = (prob + LZMA_LEN_LOW
	+ (pos_state << LZMA_LEN_NUM_LOW_BITS));
	offset = 0;
	num_bits = LZMA_LEN_NUM_LOW_BITS;
	} else {
	rc_update_bit_1(rc, prob_len);
	prob_len = prob + LZMA_LEN_CHOICE_2;
	if (rc_is_bit_0(rc, prob_len)) {
	rc_update_bit_0(rc, prob_len);
	prob_len = (prob + LZMA_LEN_MID
	+ (pos_state << LZMA_LEN_NUM_MID_BITS));
	offset = 1 << LZMA_LEN_NUM_LOW_BITS;
	num_bits = LZMA_LEN_NUM_MID_BITS;
	} else {
	rc_update_bit_1(rc, prob_len);
	prob_len = prob + LZMA_LEN_HIGH;
	offset = ((1 << LZMA_LEN_NUM_LOW_BITS)
	+ (1 << LZMA_LEN_NUM_MID_BITS));
	num_bits = LZMA_LEN_NUM_HIGH_BITS;
	}
	}
	rc_bit_tree_decode(rc, prob_len, num_bits, &len);
	len += offset;

	if (state < 4) {
	int pos_slot;

	state += LZMA_NUM_LIT_STATES;
	prob = p + LZMA_POS_SLOT +
	((len < LZMA_NUM_LEN_TO_POS_STATES ? len :
	LZMA_NUM_LEN_TO_POS_STATES - 1)
	<< LZMA_NUM_POS_SLOT_BITS);
	rc_bit_tree_decode(rc, prob, LZMA_NUM_POS_SLOT_BITS,
	&pos_slot);
	if (pos_slot >= LZMA_START_POS_MODEL_INDEX) {
	num_bits = (pos_slot >> 1) - 1;
	rep0 = 2 \| (pos_slot & 1);
	if (pos_slot < LZMA_END_POS_MODEL_INDEX) {
	rep0 <<= num_bits;
	prob = p + LZMA_SPEC_POS + rep0 - pos_slot - 1;
	} else {
	num_bits -= LZMA_NUM_ALIGN_BITS;
	while (num_bits--)
	rep0 = (rep0 << 1) \| rc_direct_bit(rc);
	prob = p + LZMA_ALIGN;
	rep0 <<= LZMA_NUM_ALIGN_BITS;
	num_bits = LZMA_NUM_ALIGN_BITS;
	}
	i = 1;
	mi = 1;
	while (num_bits--) {
	if (rc_get_bit(rc, prob + mi, &mi))
	rep0 \|= i;
	i <<= 1;
	}
	} else
	rep0 = pos_slot;
	if (++rep0 == 0)
	break;
	}

	len += LZMA_MATCH_MIN_LEN;
	SKIP_FEATURE_LZMA_FAST(string:)
	do {
	pos = buffer_pos - rep0;
	while (pos >= header.dict_size)
	pos += header.dict_size;
	previous_byte = buffer[pos];
	SKIP_FEATURE_LZMA_FAST(one_byte2:)
	buffer[buffer_pos++] = previous_byte;
	if (buffer_pos == header.dict_size) {
	buffer_pos = 0;
	global_pos += header.dict_size;
	if (full_write(dst_fd, buffer, header.dict_size) != (ssize_t)header.dict_size)
	goto bad;
	USE_DESKTOP(total_written += header.dict_size;)
	}
	len--;
	} while (len != 0 && buffer_pos < header.dst_size);
	}
	}

	{
	SKIP_DESKTOP(int total_written = 0; /* success */)
	USE_DESKTOP(total_written += buffer_pos;)
	if (full_write(dst_fd, buffer, buffer_pos) != (ssize_t)buffer_pos) {
	bad:
	total_written = -1; /* failure */
	}
	rc_free(rc);
	free(p);
	free(buffer);
	return total_written;
	}
	}