// SPDX-License-Identifier: GPL-2.0-only
/*
 *  LZO1X Compressor from LZO
 *
 *  Copyright (C) 1996-2012 Markus F.X.J. Oberhumer <markus@oberhumer.com>
 *
 *  The full LZO package can be found at:
 *  http://www.oberhumer.com/opensource/lzo/
 *
 *  Changed for Linux kernel use by:
 *  Nitin Gupta <nitingupta910@gmail.com>
 *  Richard Purdie <rpurdie@openedhand.com>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/unaligned.h>
#include <linux/lzo.h>
#include "lzodefs.h"

#undef LZO_UNSAFE

#ifndef LZO_SAFE
#define LZO_UNSAFE 1
#define LZO_SAFE(name) name
#define HAVE_OP(x) 1
#endif

#define NEED_OP(x) if (unlikely(!HAVE_OP(x))) goto output_overrun

static noinline int
LZO_SAFE(lzo1x_1_do_compress)(const unsigned char *in, size_t in_len,
                              unsigned char **out, unsigned char *op_end,
                              size_t *tp, void *wrkmem,
                              signed char *state_offset,
                              const unsigned char bitstream_version)
{
        const unsigned char *ip;
        unsigned char *op;
        const unsigned char * const in_end = in + in_len;
        const unsigned char * const ip_end = in + in_len - 20;
        const unsigned char *ii;
        lzo_dict_t * const dict = (lzo_dict_t *) wrkmem;
        size_t ti = *tp;

        op = *out;
        ip = in;
        ii = ip;
        ip += ti < 4 ? 4 - ti : 0;

        for (;;) {
                const unsigned char *m_pos = NULL;
                size_t t, m_len, m_off;
                u32 dv;
                u32 run_length = 0;
literal:
                ip += 1 + ((ip - ii) >> 5);
next:
                if (unlikely(ip >= ip_end))
                        break;
                dv = get_unaligned_le32(ip);

                if (dv == 0 && bitstream_version) {
                        const unsigned char *ir = ip + 4;
                        const unsigned char *limit = min(ip_end, ip + MAX_ZERO_RUN_LENGTH + 1);
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && \
        defined(LZO_FAST_64BIT_MEMORY_ACCESS)
                        u64 dv64;

                        for (; (ir + 32) <= limit; ir += 32) {
                                dv64 = get_unaligned((u64 *)ir);
                                dv64 |= get_unaligned((u64 *)ir + 1);
                                dv64 |= get_unaligned((u64 *)ir + 2);
                                dv64 |= get_unaligned((u64 *)ir + 3);
                                if (dv64)
                                        break;
                        }
                        for (; (ir + 8) <= limit; ir += 8) {
                                dv64 = get_unaligned((u64 *)ir);
                                if (dv64) {
#  if defined(__LITTLE_ENDIAN)
                                        ir += __builtin_ctzll(dv64) >> 3;
#  elif defined(__BIG_ENDIAN)
                                        ir += __builtin_clzll(dv64) >> 3;
#  else
#    error "missing endian definition"
#  endif
                                        break;
                                }
                        }
#else
                        while ((ir < (const unsigned char *)
                                        ALIGN((uintptr_t)ir, 4)) &&
                                        (ir < limit) && (*ir == 0))
                                ir++;
                        if (IS_ALIGNED((uintptr_t)ir, 4)) {
                                for (; (ir + 4) <= limit; ir += 4) {
                                        dv = *((u32 *)ir);
                                        if (dv) {
#  if defined(__LITTLE_ENDIAN)
                                                ir += __builtin_ctz(dv) >> 3;
#  elif defined(__BIG_ENDIAN)
                                                ir += __builtin_clz(dv) >> 3;
#  else
#    error "missing endian definition"
#  endif
                                                break;
                                        }
                                }
                        }
#endif
                        while (likely(ir < limit) && unlikely(*ir == 0))
                                ir++;
                        run_length = ir - ip;
                        if (run_length > MAX_ZERO_RUN_LENGTH)
                                run_length = MAX_ZERO_RUN_LENGTH;
                } else {
                        t = ((dv * 0x1824429d) >> (32 - D_BITS)) & D_MASK;
                        m_pos = in + dict[t];
                        dict[t] = (lzo_dict_t) (ip - in);
                        if (unlikely(dv != get_unaligned_le32(m_pos)))
                                goto literal;
                }

                ii -= ti;
                ti = 0;
                t = ip - ii;
                if (t != 0) {
                        if (t <= 3) {
                                op[*state_offset] |= t;
                                NEED_OP(4);
                                COPY4(op, ii);
                                op += t;
                        } else if (t <= 16) {
                                NEED_OP(17);
                                *op++ = (t - 3);
                                COPY8(op, ii);
                                COPY8(op + 8, ii + 8);
                                op += t;
                        } else {
                                if (t <= 18) {
                                        NEED_OP(1);
                                        *op++ = (t - 3);
                                } else {
                                        size_t tt = t - 18;
                                        NEED_OP(1);
                                        *op++ = 0;
                                        while (unlikely(tt > 255)) {
                                                tt -= 255;
                                                NEED_OP(1);
                                                *op++ = 0;
                                        }
                                        NEED_OP(1);
                                        *op++ = tt;
                                }
                                NEED_OP(t);
                                do {
                                        COPY8(op, ii);
                                        COPY8(op + 8, ii + 8);
                                        op += 16;
                                        ii += 16;
                                        t -= 16;
                                } while (t >= 16);
                                if (t > 0) do {
                                        *op++ = *ii++;
                                } while (--t > 0);
                        }
                }

                if (unlikely(run_length)) {
                        ip += run_length;
                        run_length -= MIN_ZERO_RUN_LENGTH;
                        NEED_OP(4);
                        put_unaligned_le32((run_length << 21) | 0xfffc18
                                           | (run_length & 0x7), op);
                        op += 4;
                        run_length = 0;
                        *state_offset = -3;
                        goto finished_writing_instruction;
                }

                m_len = 4;
                {
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && defined(LZO_USE_CTZ64)
                u64 v;
                v = get_unaligned((const u64 *) (ip + m_len)) ^
                    get_unaligned((const u64 *) (m_pos + m_len));
                if (unlikely(v == 0)) {
                        do {
                                m_len += 8;
                                v = get_unaligned((const u64 *) (ip + m_len)) ^
                                    get_unaligned((const u64 *) (m_pos + m_len));
                                if (unlikely(ip + m_len >= ip_end))
                                        goto m_len_done;
                        } while (v == 0);
                }
#  if defined(__LITTLE_ENDIAN)
                m_len += (unsigned) __builtin_ctzll(v) / 8;
#  elif defined(__BIG_ENDIAN)
                m_len += (unsigned) __builtin_clzll(v) / 8;
#  else
#    error "missing endian definition"
#  endif
#elif defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && defined(LZO_USE_CTZ32)
                u32 v;
                v = get_unaligned((const u32 *) (ip + m_len)) ^
                    get_unaligned((const u32 *) (m_pos + m_len));
                if (unlikely(v == 0)) {
                        do {
                                m_len += 4;
                                v = get_unaligned((const u32 *) (ip + m_len)) ^
                                    get_unaligned((const u32 *) (m_pos + m_len));
                                if (v != 0)
                                        break;
                                m_len += 4;
                                v = get_unaligned((const u32 *) (ip + m_len)) ^
                                    get_unaligned((const u32 *) (m_pos + m_len));
                                if (unlikely(ip + m_len >= ip_end))
                                        goto m_len_done;
                        } while (v == 0);
                }
#  if defined(__LITTLE_ENDIAN)
                m_len += (unsigned) __builtin_ctz(v) / 8;
#  elif defined(__BIG_ENDIAN)
                m_len += (unsigned) __builtin_clz(v) / 8;
#  else
#    error "missing endian definition"
#  endif
#else
                if (unlikely(ip[m_len] == m_pos[m_len])) {
                        do {
                                m_len += 1;
                                if (ip[m_len] != m_pos[m_len])
                                        break;
                                m_len += 1;
                                if (ip[m_len] != m_pos[m_len])
                                        break;
                                m_len += 1;
                                if (ip[m_len] != m_pos[m_len])
                                        break;
                                m_len += 1;
                                if (ip[m_len] != m_pos[m_len])
                                        break;
                                m_len += 1;
                                if (ip[m_len] != m_pos[m_len])
                                        break;
                                m_len += 1;
                                if (ip[m_len] != m_pos[m_len])
                                        break;
                                m_len += 1;
                                if (ip[m_len] != m_pos[m_len])
                                        break;
                                m_len += 1;
                                if (unlikely(ip + m_len >= ip_end))
                                        goto m_len_done;
                        } while (ip[m_len] == m_pos[m_len]);
                }
#endif
                }
m_len_done:

                m_off = ip - m_pos;
                ip += m_len;
                if (m_len <= M2_MAX_LEN && m_off <= M2_MAX_OFFSET) {
                        m_off -= 1;
                        NEED_OP(2);
                        *op++ = (((m_len - 1) << 5) | ((m_off & 7) << 2));
                        *op++ = (m_off >> 3);
                } else if (m_off <= M3_MAX_OFFSET) {
                        m_off -= 1;
                        NEED_OP(1);
                        if (m_len <= M3_MAX_LEN)
                                *op++ = (M3_MARKER | (m_len - 2));
                        else {
                                m_len -= M3_MAX_LEN;
                                *op++ = M3_MARKER | 0;
                                while (unlikely(m_len > 255)) {
                                        m_len -= 255;
                                        NEED_OP(1);
                                        *op++ = 0;
                                }
                                NEED_OP(1);
                                *op++ = (m_len);
                        }
                        NEED_OP(2);
                        *op++ = (m_off << 2);
                        *op++ = (m_off >> 6);
                } else {
                        m_off -= 0x4000;
                        NEED_OP(1);
                        if (m_len <= M4_MAX_LEN)
                                *op++ = (M4_MARKER | ((m_off >> 11) & 8)
                                                | (m_len - 2));
                        else {
                                if (unlikely(((m_off & 0x403f) == 0x403f)
                                                && (m_len >= 261)
                                                && (m_len <= 264))
                                                && likely(bitstream_version)) {
                                        // Under lzo-rle, block copies
                                        // for 261 <= length <= 264 and
                                        // (distance & 0x80f3) == 0x80f3
                                        // can result in ambiguous
                                        // output. Adjust length
                                        // to 260 to prevent ambiguity.
                                        ip -= m_len - 260;
                                        m_len = 260;
                                }
                                m_len -= M4_MAX_LEN;
                                *op++ = (M4_MARKER | ((m_off >> 11) & 8));
                                while (unlikely(m_len > 255)) {
                                        NEED_OP(1);
                                        m_len -= 255;
                                        *op++ = 0;
                                }
                                NEED_OP(1);
                                *op++ = (m_len);
                        }
                        NEED_OP(2);
                        *op++ = (m_off << 2);
                        *op++ = (m_off >> 6);
                }
                *state_offset = -2;
finished_writing_instruction:
                ii = ip;
                goto next;
        }
        *out = op;
        *tp = in_end - (ii - ti);
        return LZO_E_OK;

output_overrun:
        return LZO_E_OUTPUT_OVERRUN;
}

static int LZO_SAFE(lzogeneric1x_1_compress)(
        const unsigned char *in, size_t in_len,
        unsigned char *out, size_t *out_len,
        void *wrkmem, const unsigned char bitstream_version)
{
        unsigned char * const op_end = out + *out_len;
        const unsigned char *ip = in;
        unsigned char *op = out;
        unsigned char *data_start;
        size_t l = in_len;
        size_t t = 0;
        signed char state_offset = -2;
        unsigned int m4_max_offset;

        // LZO v0 will never write 17 as first byte (except for zero-length
        // input), so this is used to version the bitstream
        if (bitstream_version > 0) {
                *op++ = 17;
                *op++ = bitstream_version;
                m4_max_offset = M4_MAX_OFFSET_V1;
        } else {
                m4_max_offset = M4_MAX_OFFSET_V0;
        }

        data_start = op;

        while (l > 20) {
                size_t ll = min_t(size_t, l, m4_max_offset + 1);
                uintptr_t ll_end = (uintptr_t) ip + ll;
                int err;

                if ((ll_end + ((t + ll) >> 5)) <= ll_end)
                        break;
                BUILD_BUG_ON(D_SIZE * sizeof(lzo_dict_t) > LZO1X_1_MEM_COMPRESS);
                memset(wrkmem, 0, D_SIZE * sizeof(lzo_dict_t));
                err = LZO_SAFE(lzo1x_1_do_compress)(
                        ip, ll, &op, op_end, &t, wrkmem,
                        &state_offset, bitstream_version);
                if (err != LZO_E_OK)
                        return err;
                ip += ll;
                l  -= ll;
        }
        t += l;

        if (t > 0) {
                const unsigned char *ii = in + in_len - t;

                if (op == data_start && t <= 238) {
                        NEED_OP(1);
                        *op++ = (17 + t);
                } else if (t <= 3) {
                        op[state_offset] |= t;
                } else if (t <= 18) {
                        NEED_OP(1);
                        *op++ = (t - 3);
                } else {
                        size_t tt = t - 18;
                        NEED_OP(1);
                        *op++ = 0;
                        while (tt > 255) {
                                tt -= 255;
                                NEED_OP(1);
                                *op++ = 0;
                        }
                        NEED_OP(1);
                        *op++ = tt;
                }
                NEED_OP(t);
                if (t >= 16) do {
                        COPY8(op, ii);
                        COPY8(op + 8, ii + 8);
                        op += 16;
                        ii += 16;
                        t -= 16;
                } while (t >= 16);
                if (t > 0) do {
                        *op++ = *ii++;
                } while (--t > 0);
        }

        NEED_OP(3);
        *op++ = M4_MARKER | 1;
        *op++ = 0;
        *op++ = 0;

        *out_len = op - out;
        return LZO_E_OK;

output_overrun:
        return LZO_E_OUTPUT_OVERRUN;
}

int LZO_SAFE(lzo1x_1_compress)(const unsigned char *in, size_t in_len,
                               unsigned char *out, size_t *out_len,
                               void *wrkmem)
{
        return LZO_SAFE(lzogeneric1x_1_compress)(
                in, in_len, out, out_len, wrkmem, 0);
}

int LZO_SAFE(lzorle1x_1_compress)(const unsigned char *in, size_t in_len,
                                  unsigned char *out, size_t *out_len,
                                  void *wrkmem)
{
        return LZO_SAFE(lzogeneric1x_1_compress)(
                in, in_len, out, out_len, wrkmem, LZO_VERSION);
}

EXPORT_SYMBOL_GPL(LZO_SAFE(lzo1x_1_compress));
EXPORT_SYMBOL_GPL(LZO_SAFE(lzorle1x_1_compress));

#ifndef LZO_UNSAFE
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("LZO1X-1 Compressor");
#endif