/* Lzma decompressor for Linux kernel. Shamelessly snarfed
 *from busybox 1.1.1
 *
 *Linux kernel adaptation
 *Copyright (C) 2006  Alain < alain@knaff.lu >
 *
 *Based on small lzma deflate implementation/Small range coder
 *implementation for lzma.
 *Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
 *
 *Based on LzmaDecode.c from the LZMA SDK 4.22 (https://www.7-zip.org/)
 *Copyright (C) 1999-2005  Igor Pavlov
 *
 *Copyrights of the parts, see headers below.
 *
 *
 *This program is free software; you can redistribute it and/or
 *modify it under the terms of the GNU Lesser General Public
 *License as published by the Free Software Foundation; either
 *version 2.1 of the License, or (at your option) any later version.
 *
 *This program is distributed in the hope that it will be useful,
 *but WITHOUT ANY WARRANTY; without even the implied warranty of
 *MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *Lesser General Public License for more details.
 *
 *You should have received a copy of the GNU Lesser General Public
 *License along with this library; if not, write to the Free Software
 *Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#ifdef STATIC
#define PREBOOT
#else
#include <linux/decompress/unlzma.h>
#endif /* STATIC */

#include <linux/decompress/mm.h>

#ifndef MIN
#define MIN(a, b) (((a) < (b)) ? (a) : (b))
#endif

static long long INIT read_int(unsigned char *ptr, int size)
{
        int i;
        long long ret = 0;

        for (i = 0; i < size; i++)
                ret = (ret << 8) | ptr[size-i-1];
        return ret;
}

#define ENDIAN_CONVERT(x) \
  x = (typeof(x))read_int((unsigned char *)&x, sizeof(x))


/* Small range coder implementation for lzma.
 *Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
 *
 *Based on LzmaDecode.c from the LZMA SDK 4.22 (https://www.7-zip.org/)
 *Copyright (c) 1999-2005  Igor Pavlov
 */

#include <linux/compiler.h>

#define LZMA_IOBUF_SIZE 0x10000

struct rc {
        long (*fill)(void*, unsigned long);
        uint8_t *ptr;
        uint8_t *buffer;
        uint8_t *buffer_end;
        long buffer_size;
        uint32_t code;
        uint32_t range;
        uint32_t bound;
        void (*error)(char *);
};


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


static long INIT nofill(void *buffer, unsigned long len)
{
        return -1;
}

/* Called twice: once at startup and once in rc_normalize() */
static void INIT rc_read(struct rc *rc)
{
        rc->buffer_size = rc->fill((char *)rc->buffer, LZMA_IOBUF_SIZE);
        if (rc->buffer_size <= 0)
                rc->error("unexpected EOF");
        rc->ptr = rc->buffer;
        rc->buffer_end = rc->buffer + rc->buffer_size;
}

/* Called once */
static inline void INIT rc_init(struct rc *rc,
                                       long (*fill)(void*, unsigned long),
                                       char *buffer, long buffer_size)
{
        if (fill)
                rc->fill = fill;
        else
                rc->fill = nofill;
        rc->buffer = (uint8_t *)buffer;
        rc->buffer_size = buffer_size;
        rc->buffer_end = rc->buffer + rc->buffer_size;
        rc->ptr = rc->buffer;

        rc->code = 0;
        rc->range = 0xFFFFFFFF;
}

static inline void INIT rc_init_code(struct rc *rc)
{
        int i;

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


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

/* Called 9 times */
/* Why rc_is_bit_0_helper exists?
 *Because we want to always expose (rc->code < rc->bound) to optimizer
 */
static inline uint32_t INIT rc_is_bit_0_helper(struct rc *rc, uint16_t *p)
{
        rc_normalize(rc);
        rc->bound = *p * (rc->range >> RC_MODEL_TOTAL_BITS);
        return rc->bound;
}
static inline int INIT rc_is_bit_0(struct rc *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 inline void INIT rc_update_bit_0(struct rc *rc, uint16_t *p)
{
        rc->range = rc->bound;
        *p += ((1 << RC_MODEL_TOTAL_BITS) - *p) >> RC_MOVE_BITS;
}
static inline void INIT rc_update_bit_1(struct rc *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 INIT rc_get_bit(struct rc *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 inline int INIT rc_direct_bit(struct rc *rc)
{
        rc_normalize(rc);
        rc->range >>= 1;
        if (rc->code >= rc->range) {
                rc->code -= rc->range;
                return 1;
        }
        return 0;
}

/* Called twice */
static inline void INIT
rc_bit_tree_decode(struct rc *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;
}


/*
 * Small lzma deflate implementation.
 * Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
 *
 * Based on LzmaDecode.c from the LZMA SDK 4.22 (https://www.7-zip.org/)
 * Copyright (C) 1999-2005  Igor Pavlov
 */


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


#define LZMA_BASE_SIZE 1846
#define LZMA_LIT_SIZE 768

#define LZMA_NUM_POS_BITS_MAX 4

#define LZMA_LEN_NUM_LOW_BITS 3
#define LZMA_LEN_NUM_MID_BITS 3
#define LZMA_LEN_NUM_HIGH_BITS 8

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

#define LZMA_NUM_STATES 12
#define LZMA_NUM_LIT_STATES 7

#define LZMA_START_POS_MODEL_INDEX 4
#define LZMA_END_POS_MODEL_INDEX 14
#define LZMA_NUM_FULL_DISTANCES (1 << (LZMA_END_POS_MODEL_INDEX >> 1))

#define LZMA_NUM_POS_SLOT_BITS 6
#define LZMA_NUM_LEN_TO_POS_STATES 4

#define LZMA_NUM_ALIGN_BITS 4

#define LZMA_MATCH_MIN_LEN 2

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


struct writer {
        uint8_t *buffer;
        uint8_t previous_byte;
        size_t buffer_pos;
        int bufsize;
        size_t global_pos;
        long (*flush)(void*, unsigned long);
        struct lzma_header *header;
};

struct cstate {
        int state;
        uint32_t rep0, rep1, rep2, rep3;
};

static inline size_t INIT get_pos(struct writer *wr)
{
        return
                wr->global_pos + wr->buffer_pos;
}

static inline uint8_t INIT peek_old_byte(struct writer *wr,
                                                uint32_t offs)
{
        if (!wr->flush) {
                int32_t pos;
                while (offs > wr->header->dict_size)
                        offs -= wr->header->dict_size;
                pos = wr->buffer_pos - offs;
                return wr->buffer[pos];
        } else {
                uint32_t pos = wr->buffer_pos - offs;
                while (pos >= wr->header->dict_size)
                        pos += wr->header->dict_size;
                return wr->buffer[pos];
        }

}

static inline int INIT write_byte(struct writer *wr, uint8_t byte)
{
        wr->buffer[wr->buffer_pos++] = wr->previous_byte = byte;
        if (wr->flush && wr->buffer_pos == wr->header->dict_size) {
                wr->buffer_pos = 0;
                wr->global_pos += wr->header->dict_size;
                if (wr->flush((char *)wr->buffer, wr->header->dict_size)
                                != wr->header->dict_size)
                        return -1;
        }
        return 0;
}


static inline int INIT copy_byte(struct writer *wr, uint32_t offs)
{
        return write_byte(wr, peek_old_byte(wr, offs));
}

static inline int INIT copy_bytes(struct writer *wr,
                                         uint32_t rep0, int len)
{
        do {
                if (copy_byte(wr, rep0))
                        return -1;
                len--;
        } while (len != 0 && wr->buffer_pos < wr->header->dst_size);

        return len;
}

static inline int INIT process_bit0(struct writer *wr, struct rc *rc,
                                     struct cstate *cst, uint16_t *p,
                                     int pos_state, uint16_t *prob,
                                     int lc, uint32_t literal_pos_mask) {
        int mi = 1;
        rc_update_bit_0(rc, prob);
        prob = (p + LZMA_LITERAL +
                (LZMA_LIT_SIZE
                 * (((get_pos(wr) & literal_pos_mask) << lc)
                    + (wr->previous_byte >> (8 - lc))))
                );

        if (cst->state >= LZMA_NUM_LIT_STATES) {
                int match_byte = peek_old_byte(wr, cst->rep0);
                do {
                        int bit;
                        uint16_t *prob_lit;

                        match_byte <<= 1;
                        bit = match_byte & 0x100;
                        prob_lit = prob + 0x100 + bit + mi;
                        if (rc_get_bit(rc, prob_lit, &mi)) {
                                if (!bit)
                                        break;
                        } else {
                                if (bit)
                                        break;
                        }
                } while (mi < 0x100);
        }
        while (mi < 0x100) {
                uint16_t *prob_lit = prob + mi;
                rc_get_bit(rc, prob_lit, &mi);
        }
        if (cst->state < 4)
                cst->state = 0;
        else if (cst->state < 10)
                cst->state -= 3;
        else
                cst->state -= 6;

        return write_byte(wr, mi);
}

static inline int INIT process_bit1(struct writer *wr, struct rc *rc,
                                            struct cstate *cst, uint16_t *p,
                                            int pos_state, uint16_t *prob) {
        int offset;
        uint16_t *prob_len;
        int num_bits;
        int len;

        rc_update_bit_1(rc, prob);
        prob = p + LZMA_IS_REP + cst->state;
        if (rc_is_bit_0(rc, prob)) {
                rc_update_bit_0(rc, prob);
                cst->rep3 = cst->rep2;
                cst->rep2 = cst->rep1;
                cst->rep1 = cst->rep0;
                cst->state = cst->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 + cst->state;
                if (rc_is_bit_0(rc, prob)) {
                        rc_update_bit_0(rc, prob);
                        prob = (p + LZMA_IS_REP_0_LONG
                                + (cst->state <<
                                   LZMA_NUM_POS_BITS_MAX) +
                                pos_state);
                        if (rc_is_bit_0(rc, prob)) {
                                rc_update_bit_0(rc, prob);

                                cst->state = cst->state < LZMA_NUM_LIT_STATES ?
                                        9 : 11;
                                return copy_byte(wr, cst->rep0);
                        } else {
                                rc_update_bit_1(rc, prob);
                        }
                } else {
                        uint32_t distance;

                        rc_update_bit_1(rc, prob);
                        prob = p + LZMA_IS_REP_G1 + cst->state;
                        if (rc_is_bit_0(rc, prob)) {
                                rc_update_bit_0(rc, prob);
                                distance = cst->rep1;
                        } else {
                                rc_update_bit_1(rc, prob);
                                prob = p + LZMA_IS_REP_G2 + cst->state;
                                if (rc_is_bit_0(rc, prob)) {
                                        rc_update_bit_0(rc, prob);
                                        distance = cst->rep2;
                                } else {
                                        rc_update_bit_1(rc, prob);
                                        distance = cst->rep3;
                                        cst->rep3 = cst->rep2;
                                }
                                cst->rep2 = cst->rep1;
                        }
                        cst->rep1 = cst->rep0;
                        cst->rep0 = distance;
                }
                cst->state = cst->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 (cst->state < 4) {
                int pos_slot;

                cst->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) {
                        int i, mi;
                        num_bits = (pos_slot >> 1) - 1;
                        cst->rep0 = 2 | (pos_slot & 1);
                        if (pos_slot < LZMA_END_POS_MODEL_INDEX) {
                                cst->rep0 <<= num_bits;
                                prob = p + LZMA_SPEC_POS +
                                        cst->rep0 - pos_slot - 1;
                        } else {
                                num_bits -= LZMA_NUM_ALIGN_BITS;
                                while (num_bits--)
                                        cst->rep0 = (cst->rep0 << 1) |
                                                rc_direct_bit(rc);
                                prob = p + LZMA_ALIGN;
                                cst->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))
                                        cst->rep0 |= i;
                                i <<= 1;
                        }
                } else
                        cst->rep0 = pos_slot;
                if (++(cst->rep0) == 0)
                        return 0;
                if (cst->rep0 > wr->header->dict_size
                                || cst->rep0 > get_pos(wr))
                        return -1;
        }

        len += LZMA_MATCH_MIN_LEN;

        return copy_bytes(wr, cst->rep0, len);
}



STATIC inline int INIT unlzma(unsigned char *buf, long in_len,
                              long (*fill)(void*, unsigned long),
                              long (*flush)(void*, unsigned long),
                              unsigned char *output,
                              long *posp,
                              void(*error)(char *x)
        )
{
        struct lzma_header header;
        int lc, pb, lp;
        uint32_t pos_state_mask;
        uint32_t literal_pos_mask;
        uint16_t *p;
        int num_probs;
        struct rc rc;
        int i, mi;
        struct writer wr;
        struct cstate cst;
        unsigned char *inbuf;
        int ret = -1;

        rc.error = error;

        if (buf)
                inbuf = buf;
        else
                inbuf = malloc(LZMA_IOBUF_SIZE);
        if (!inbuf) {
                error("Could not allocate input buffer");
                goto exit_0;
        }

        cst.state = 0;
        cst.rep0 = cst.rep1 = cst.rep2 = cst.rep3 = 1;

        wr.header = &header;
        wr.flush = flush;
        wr.global_pos = 0;
        wr.previous_byte = 0;
        wr.buffer_pos = 0;

        rc_init(&rc, fill, inbuf, in_len);

        for (i = 0; i < sizeof(header); i++) {
                if (rc.ptr >= rc.buffer_end)
                        rc_read(&rc);
                ((unsigned char *)&header)[i] = *rc.ptr++;
        }

        if (header.pos >= (9 * 5 * 5)) {
                error("bad header");
                goto exit_1;
        }

        mi = 0;
        lc = header.pos;
        while (lc >= 9) {
                mi++;
                lc -= 9;
        }
        pb = 0;
        lp = mi;
        while (lp >= 5) {
                pb++;
                lp -= 5;
        }
        pos_state_mask = (1 << pb) - 1;
        literal_pos_mask = (1 << lp) - 1;

        ENDIAN_CONVERT(header.dict_size);
        ENDIAN_CONVERT(header.dst_size);

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

        if (output)
                wr.buffer = output;
        else {
                wr.bufsize = MIN(header.dst_size, header.dict_size);
                wr.buffer = large_malloc(wr.bufsize);
        }
        if (wr.buffer == NULL)
                goto exit_1;

        num_probs = LZMA_BASE_SIZE + (LZMA_LIT_SIZE << (lc + lp));
        p = (uint16_t *) large_malloc(num_probs * sizeof(*p));
        if (p == NULL)
                goto exit_2;
        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_init_code(&rc);

        while (get_pos(&wr) < header.dst_size) {
                int pos_state = get_pos(&wr) & pos_state_mask;
                uint16_t *prob = p + LZMA_IS_MATCH +
                        (cst.state << LZMA_NUM_POS_BITS_MAX) + pos_state;
                if (rc_is_bit_0(&rc, prob)) {
                        if (process_bit0(&wr, &rc, &cst, p, pos_state, prob,
                                        lc, literal_pos_mask)) {
                                error("LZMA data is corrupt");
                                goto exit_3;
                        }
                } else {
                        if (process_bit1(&wr, &rc, &cst, p, pos_state, prob)) {
                                error("LZMA data is corrupt");
                                goto exit_3;
                        }
                        if (cst.rep0 == 0)
                                break;
                }
                if (rc.buffer_size <= 0)
                        goto exit_3;
        }

        if (posp)
                *posp = rc.ptr-rc.buffer;
        if (!wr.flush || wr.flush(wr.buffer, wr.buffer_pos) == wr.buffer_pos)
                ret = 0;
exit_3:
        large_free(p);
exit_2:
        if (!output)
                large_free(wr.buffer);
exit_1:
        if (!buf)
                free(inbuf);
exit_0:
        return ret;
}

#ifdef PREBOOT
STATIC int INIT __decompress(unsigned char *buf, long in_len,
                              long (*fill)(void*, unsigned long),
                              long (*flush)(void*, unsigned long),
                              unsigned char *output, long out_len,
                              long *posp,
                              void (*error)(char *x))
{
        return unlzma(buf, in_len - 4, fill, flush, output, posp, error);
}
#endif