archival/libarchive/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 source tree.
  */
 #include "libbb.h"
 #include "bb_archive.h"

 #if ENABLE_FEATURE_LZMA_FAST
 #  define speed_inline ALWAYS_INLINE
 #  define size_inline
 #else
 #  define speed_inline
 #  define size_inline ALWAYS_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 once in rc_do_normalize() */
 static void rc_read(rc_t *rc)
 {
 	int buffer_size = safe_read(rc->fd, RC_BUFFER, RC_BUFFER_SIZE);
 //TODO: return -1 instead
 //This will make unlzma delete broken unpacked file on unpack errors
 	if (buffer_size <= 0)
 		bb_error_msg_and_die("unexpected EOF");
 	rc->buffer_end = RC_BUFFER + buffer_size;
 	rc->ptr = RC_BUFFER;
 }

 /* Called twice, but one callsite is in speed_inline'd rc_is_bit_1() */
 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);
 	}
 }

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

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

 	rc->fd = fd;
 	/* rc->ptr = rc->buffer_end; */

 	for (i = 0; i < 5; i++) {
 		rc_do_normalize(rc);
 	}
 	rc->range = 0xffffffff;
 	return rc;
 }

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

 /* rc_is_bit_1 is called 9 times */
 static speed_inline int rc_is_bit_1(rc_t *rc, uint16_t *p)
 {
 	rc_normalize(rc);
 	rc->bound = *p * (rc->range >> RC_MODEL_TOTAL_BITS);
 	if (rc->code < rc->bound) {
 		rc->range = rc->bound;
 		*p += ((1 << RC_MODEL_TOTAL_BITS) - *p) >> RC_MOVE_BITS;
 		return 0;
 	}
 	rc->range -= rc->bound;
 	rc->code -= rc->bound;
 	*p -= *p >> RC_MOVE_BITS;
 	return 1;
 }

 /* Called 4 times in unlzma loop */
 static ALWAYS_INLINE int rc_get_bit(rc_t *rc, uint16_t *p, int *symbol)
 {
 	int ret = rc_is_bit_1(rc, p);
 	*symbol = *symbol * 2 + ret;
 	return ret;
 }

 /* 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;
 } 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),
 };


 IF_DESKTOP(long long) int FAST_FUNC
 unpack_lzma_stream(transformer_state_t *xstate)
 {
 	IF_DESKTOP(long long total_written = 0;)
 	lzma_header_t header;
 	int lc, pb, lp;
 	uint32_t pos_state_mask;
 	uint32_t literal_pos_mask;
 	uint16_t *p;
 	rc_t *rc;
 	int i;
 	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;

 	if (full_read(xstate->src_fd, &header, sizeof(header)) != sizeof(header)
 	 || header.pos >= (9 * 5 * 5)
 	) {
 		bb_error_msg("bad lzma header");
 		return -1;
 	}

 	i = header.pos / 9;
 	lc = header.pos % 9;
 	pb = i / 5;
 	lp = i % 5;
 	pos_state_mask = (1 << pb) - 1;
 	literal_pos_mask = (1 << lp) - 1;

 	/* Example values from linux-3.3.4.tar.lzma:
 	 * dict_size: 64M, dst_size: 2^64-1
 	 */
 	header.dict_size = SWAP_LE32(header.dict_size);
 	header.dst_size = SWAP_LE64(header.dst_size);

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

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

 	{
 		int num_probs;

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

 	rc = rc_init(xstate->src_fd); /*, RC_BUFFER_SIZE); */

 	while (global_pos + buffer_pos < header.dst_size) {
 		int pos_state = (buffer_pos + global_pos) & pos_state_mask;
 		uint16_t *prob = p + LZMA_IS_MATCH + (state << LZMA_NUM_POS_BITS_MAX) + pos_state;

 		if (!rc_is_bit_1(rc, prob)) {
 			static const char next_state[LZMA_NUM_STATES] =
 				{ 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 4, 5 };
 			int mi = 1;

 			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;
 				uint32_t 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;
 					bit ^= (rc_get_bit(rc, prob + 0x100 + bit + mi, &mi) << 8); /* 0x100 or 0 */
 					if (bit)
 						break;
 				} while (mi < 0x100);
 			}
 			while (mi < 0x100) {
 				rc_get_bit(rc, prob + mi, &mi);
 			}

 			state = next_state[state];

 			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 (transformer_write(xstate, buffer, header.dict_size) != (ssize_t)header.dict_size)
 					goto bad;
 				IF_DESKTOP(total_written += header.dict_size;)
 			}
 #else
 			len = 1;
 			goto one_byte2;
 #endif
 		} else {
 			int num_bits;
 			int offset;
 			uint16_t *prob2;
 #define prob_len prob2

 			prob2 = p + LZMA_IS_REP + state;
 			if (!rc_is_bit_1(rc, prob2)) {
 				rep3 = rep2;
 				rep2 = rep1;
 				rep1 = rep0;
 				state = state < LZMA_NUM_LIT_STATES ? 0 : 3;
 				prob2 = p + LZMA_LEN_CODER;
 			} else {
 				prob2 += LZMA_IS_REP_G0 - LZMA_IS_REP;
 				if (!rc_is_bit_1(rc, prob2)) {
 					prob2 = (p + LZMA_IS_REP_0_LONG
 					        + (state << LZMA_NUM_POS_BITS_MAX)
 					        + pos_state
 					);
 					if (!rc_is_bit_1(rc, prob2)) {
 #if ENABLE_FEATURE_LZMA_FAST
 						uint32_t pos = buffer_pos - rep0;
 						state = state < LZMA_NUM_LIT_STATES ? 9 : 11;
 						while (pos >= header.dict_size)
 							pos += header.dict_size;
 						previous_byte = buffer[pos];
 						goto one_byte1;
 #else
 						state = state < LZMA_NUM_LIT_STATES ? 9 : 11;
 						len = 1;
 						goto string;
 #endif
 					}
 				} else {
 					uint32_t distance;

 					prob2 += LZMA_IS_REP_G1 - LZMA_IS_REP_G0;
 					distance = rep1;
 					if (rc_is_bit_1(rc, prob2)) {
 						prob2 += LZMA_IS_REP_G2 - LZMA_IS_REP_G1;
 						distance = rep2;
 						if (rc_is_bit_1(rc, prob2)) {
 							distance = rep3;
 							rep3 = rep2;
 						}
 						rep2 = rep1;
 					}
 					rep1 = rep0;
 					rep0 = distance;
 				}
 				state = state < LZMA_NUM_LIT_STATES ? 8 : 11;
 				prob2 = p + LZMA_REP_LEN_CODER;
 			}

 			prob_len = prob2 + LZMA_LEN_CHOICE;
 			num_bits = LZMA_LEN_NUM_LOW_BITS;
 			if (!rc_is_bit_1(rc, prob_len)) {
 				prob_len += LZMA_LEN_LOW - LZMA_LEN_CHOICE
 				            + (pos_state << LZMA_LEN_NUM_LOW_BITS);
 				offset = 0;
 			} else {
 				prob_len += LZMA_LEN_CHOICE_2 - LZMA_LEN_CHOICE;
 				if (!rc_is_bit_1(rc, prob_len)) {
 					prob_len += LZMA_LEN_MID - LZMA_LEN_CHOICE_2
 					            + (pos_state << LZMA_LEN_NUM_MID_BITS);
 					offset = 1 << LZMA_LEN_NUM_LOW_BITS;
 					num_bits += LZMA_LEN_NUM_MID_BITS - LZMA_LEN_NUM_LOW_BITS;
 				} else {
 					prob_len += LZMA_LEN_HIGH - LZMA_LEN_CHOICE_2;
 					offset = ((1 << LZMA_LEN_NUM_LOW_BITS)
 					          + (1 << LZMA_LEN_NUM_MID_BITS));
 					num_bits += LZMA_LEN_NUM_HIGH_BITS - LZMA_LEN_NUM_LOW_BITS;
 				}
 			}
 			rc_bit_tree_decode(rc, prob_len, num_bits, &len);
 			len += offset;

 			if (state < 4) {
 				int pos_slot;
 				uint16_t *prob3;

 				state += LZMA_NUM_LIT_STATES;
 				prob3 = 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, prob3,
 					LZMA_NUM_POS_SLOT_BITS, &pos_slot);
 				rep0 = pos_slot;
 				if (pos_slot >= LZMA_START_POS_MODEL_INDEX) {
 					int i2, mi2, num_bits2 = (pos_slot >> 1) - 1;
 					rep0 = 2 | (pos_slot & 1);
 					if (pos_slot < LZMA_END_POS_MODEL_INDEX) {
 						rep0 <<= num_bits2;
 						prob3 = p + LZMA_SPEC_POS + rep0 - pos_slot - 1;
 					} else {
 						for (; num_bits2 != LZMA_NUM_ALIGN_BITS; num_bits2--)
 							rep0 = (rep0 << 1) | rc_direct_bit(rc);
 						rep0 <<= LZMA_NUM_ALIGN_BITS;
 						prob3 = p + LZMA_ALIGN;
 					}
 					i2 = 1;
 					mi2 = 1;
 					while (num_bits2--) {
 						if (rc_get_bit(rc, prob3 + mi2, &mi2))
 							rep0 |= i2;
 						i2 <<= 1;
 					}
 				}
 				if (++rep0 == 0)
 					break;
 			}

 			len += LZMA_MATCH_MIN_LEN;
  IF_NOT_FEATURE_LZMA_FAST(string:)
 			do {
 				uint32_t pos = buffer_pos - rep0;
 				while (pos >= header.dict_size)
 					pos += header.dict_size;
 				previous_byte = buffer[pos];
  IF_NOT_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 (transformer_write(xstate, buffer, header.dict_size) != (ssize_t)header.dict_size)
 						goto bad;
 					IF_DESKTOP(total_written += header.dict_size;)
 				}
 				len--;
 			} while (len != 0 && buffer_pos < header.dst_size);
 			/* FIXME: ...........^^^^^
 			 * shouldn't it be "global_pos + buffer_pos < header.dst_size"?
 			 */
 		}
 	}

 	{
 		IF_NOT_DESKTOP(int total_written = 0; /* success */)
 		IF_DESKTOP(total_written += buffer_pos;)
 		if (transformer_write(xstate, 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 source tree.
	*/
	#include "libbb.h"
	#include "bb_archive.h"

	#if ENABLE_FEATURE_LZMA_FAST
	# define speed_inline ALWAYS_INLINE
	# define size_inline
	#else
	# define speed_inline
	# define size_inline ALWAYS_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 once in rc_do_normalize() */
	static void rc_read(rc_t *rc)
	{
	int buffer_size = safe_read(rc->fd, RC_BUFFER, RC_BUFFER_SIZE);
	//TODO: return -1 instead
	//This will make unlzma delete broken unpacked file on unpack errors
	if (buffer_size <= 0)
	bb_error_msg_and_die("unexpected EOF");
	rc->buffer_end = RC_BUFFER + buffer_size;
	rc->ptr = RC_BUFFER;
	}

	/* Called twice, but one callsite is in speed_inline'd rc_is_bit_1() */
	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);
	}
	}

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

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

	rc->fd = fd;
	/* rc->ptr = rc->buffer_end; */

	for (i = 0; i < 5; i++) {
	rc_do_normalize(rc);
	}
	rc->range = 0xffffffff;
	return rc;
	}

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

	/* rc_is_bit_1 is called 9 times */
	static speed_inline int rc_is_bit_1(rc_t rc, uint16_t p)
	{
	rc_normalize(rc);
	rc->bound = p (rc->range >> RC_MODEL_TOTAL_BITS);
	if (rc->code < rc->bound) {
	rc->range = rc->bound;
	p += ((1 << RC_MODEL_TOTAL_BITS) - p) >> RC_MOVE_BITS;
	return 0;
	}
	rc->range -= rc->bound;
	rc->code -= rc->bound;
	p -= p >> RC_MOVE_BITS;
	return 1;
	}

	/* Called 4 times in unlzma loop */
	static ALWAYS_INLINE int rc_get_bit(rc_t rc, uint16_t p, int *symbol)
	{
	int ret = rc_is_bit_1(rc, p);
	symbol = symbol * 2 + ret;
	return ret;
	}

	/* 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;
	} 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),
	};


	IF_DESKTOP(long long) int FAST_FUNC
	unpack_lzma_stream(transformer_state_t *xstate)
	{
	IF_DESKTOP(long long total_written = 0;)
	lzma_header_t header;
	int lc, pb, lp;
	uint32_t pos_state_mask;
	uint32_t literal_pos_mask;
	uint16_t *p;
	rc_t *rc;
	int i;
	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;

	if (full_read(xstate->src_fd, &header, sizeof(header)) != sizeof(header)
	\|\| header.pos >= (9 * 5 * 5)
	) {
	bb_error_msg("bad lzma header");
	return -1;
	}

	i = header.pos / 9;
	lc = header.pos % 9;
	pb = i / 5;
	lp = i % 5;
	pos_state_mask = (1 << pb) - 1;
	literal_pos_mask = (1 << lp) - 1;

	/* Example values from linux-3.3.4.tar.lzma:
	* dict_size: 64M, dst_size: 2^64-1
	*/
	header.dict_size = SWAP_LE32(header.dict_size);
	header.dst_size = SWAP_LE64(header.dst_size);

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

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

	{
	int num_probs;

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

	rc = rc_init(xstate->src_fd); /, RC_BUFFER_SIZE); /

	while (global_pos + buffer_pos < header.dst_size) {
	int pos_state = (buffer_pos + global_pos) & pos_state_mask;
	uint16_t *prob = p + LZMA_IS_MATCH + (state << LZMA_NUM_POS_BITS_MAX) + pos_state;

	if (!rc_is_bit_1(rc, prob)) {
	static const char next_state[LZMA_NUM_STATES] =
	{ 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 4, 5 };
	int mi = 1;

	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;
	uint32_t 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;
	bit ^= (rc_get_bit(rc, prob + 0x100 + bit + mi, &mi) << 8); /* 0x100 or 0 */
	if (bit)
	break;
	} while (mi < 0x100);
	}
	while (mi < 0x100) {
	rc_get_bit(rc, prob + mi, &mi);
	}

	state = next_state[state];

	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 (transformer_write(xstate, buffer, header.dict_size) != (ssize_t)header.dict_size)
	goto bad;
	IF_DESKTOP(total_written += header.dict_size;)
	}
	#else
	len = 1;
	goto one_byte2;
	#endif
	} else {
	int num_bits;
	int offset;
	uint16_t *prob2;
	#define prob_len prob2

	prob2 = p + LZMA_IS_REP + state;
	if (!rc_is_bit_1(rc, prob2)) {
	rep3 = rep2;
	rep2 = rep1;
	rep1 = rep0;
	state = state < LZMA_NUM_LIT_STATES ? 0 : 3;
	prob2 = p + LZMA_LEN_CODER;
	} else {
	prob2 += LZMA_IS_REP_G0 - LZMA_IS_REP;
	if (!rc_is_bit_1(rc, prob2)) {
	prob2 = (p + LZMA_IS_REP_0_LONG
	+ (state << LZMA_NUM_POS_BITS_MAX)
	+ pos_state
	);
	if (!rc_is_bit_1(rc, prob2)) {
	#if ENABLE_FEATURE_LZMA_FAST
	uint32_t pos = buffer_pos - rep0;
	state = state < LZMA_NUM_LIT_STATES ? 9 : 11;
	while (pos >= header.dict_size)
	pos += header.dict_size;
	previous_byte = buffer[pos];
	goto one_byte1;
	#else
	state = state < LZMA_NUM_LIT_STATES ? 9 : 11;
	len = 1;
	goto string;
	#endif
	}
	} else {
	uint32_t distance;

	prob2 += LZMA_IS_REP_G1 - LZMA_IS_REP_G0;
	distance = rep1;
	if (rc_is_bit_1(rc, prob2)) {
	prob2 += LZMA_IS_REP_G2 - LZMA_IS_REP_G1;
	distance = rep2;
	if (rc_is_bit_1(rc, prob2)) {
	distance = rep3;
	rep3 = rep2;
	}
	rep2 = rep1;
	}
	rep1 = rep0;
	rep0 = distance;
	}
	state = state < LZMA_NUM_LIT_STATES ? 8 : 11;
	prob2 = p + LZMA_REP_LEN_CODER;
	}

	prob_len = prob2 + LZMA_LEN_CHOICE;
	num_bits = LZMA_LEN_NUM_LOW_BITS;
	if (!rc_is_bit_1(rc, prob_len)) {
	prob_len += LZMA_LEN_LOW - LZMA_LEN_CHOICE
	+ (pos_state << LZMA_LEN_NUM_LOW_BITS);
	offset = 0;
	} else {
	prob_len += LZMA_LEN_CHOICE_2 - LZMA_LEN_CHOICE;
	if (!rc_is_bit_1(rc, prob_len)) {
	prob_len += LZMA_LEN_MID - LZMA_LEN_CHOICE_2
	+ (pos_state << LZMA_LEN_NUM_MID_BITS);
	offset = 1 << LZMA_LEN_NUM_LOW_BITS;
	num_bits += LZMA_LEN_NUM_MID_BITS - LZMA_LEN_NUM_LOW_BITS;
	} else {
	prob_len += LZMA_LEN_HIGH - LZMA_LEN_CHOICE_2;
	offset = ((1 << LZMA_LEN_NUM_LOW_BITS)
	+ (1 << LZMA_LEN_NUM_MID_BITS));
	num_bits += LZMA_LEN_NUM_HIGH_BITS - LZMA_LEN_NUM_LOW_BITS;
	}
	}
	rc_bit_tree_decode(rc, prob_len, num_bits, &len);
	len += offset;

	if (state < 4) {
	int pos_slot;
	uint16_t *prob3;

	state += LZMA_NUM_LIT_STATES;
	prob3 = 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, prob3,
	LZMA_NUM_POS_SLOT_BITS, &pos_slot);
	rep0 = pos_slot;
	if (pos_slot >= LZMA_START_POS_MODEL_INDEX) {
	int i2, mi2, num_bits2 = (pos_slot >> 1) - 1;
	rep0 = 2 \| (pos_slot & 1);
	if (pos_slot < LZMA_END_POS_MODEL_INDEX) {
	rep0 <<= num_bits2;
	prob3 = p + LZMA_SPEC_POS + rep0 - pos_slot - 1;
	} else {
	for (; num_bits2 != LZMA_NUM_ALIGN_BITS; num_bits2--)
	rep0 = (rep0 << 1) \| rc_direct_bit(rc);
	rep0 <<= LZMA_NUM_ALIGN_BITS;
	prob3 = p + LZMA_ALIGN;
	}
	i2 = 1;
	mi2 = 1;
	while (num_bits2--) {
	if (rc_get_bit(rc, prob3 + mi2, &mi2))
	rep0 \|= i2;
	i2 <<= 1;
	}
	}
	if (++rep0 == 0)
	break;
	}

	len += LZMA_MATCH_MIN_LEN;
	IF_NOT_FEATURE_LZMA_FAST(string:)
	do {
	uint32_t pos = buffer_pos - rep0;
	while (pos >= header.dict_size)
	pos += header.dict_size;
	previous_byte = buffer[pos];
	IF_NOT_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 (transformer_write(xstate, buffer, header.dict_size) != (ssize_t)header.dict_size)
	goto bad;
	IF_DESKTOP(total_written += header.dict_size;)
	}
	len--;
	} while (len != 0 && buffer_pos < header.dst_size);
	/* FIXME: ...........^^^^^
	* shouldn't it be "global_pos + buffer_pos < header.dst_size"?
	*/
	}
	}

	{
	IF_NOT_DESKTOP(int total_written = 0; /* success */)
	IF_DESKTOP(total_written += buffer_pos;)
	if (transformer_write(xstate, buffer, buffer_pos) != (ssize_t)buffer_pos) {
	bad:
	total_written = -1; /* failure */
	}
	rc_free(rc);
	free(p);
	free(buffer);
	return total_written;
	}
	}