isa-l/igzip/huffman.h

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#include <stdint.h>
#include <stdlib.h>
#include <assert.h>
#include "igzip_lib.h"
#include "unaligned.h"

#if __x86_64__ || __i386__ || _M_X64 || _M_IX86
#ifdef _MSC_VER
#include <intrin.h>
#define inline __inline
#else
#include <x86intrin.h>
#endif
#else
#define inline __inline
#endif //__x86_64__  || __i386__ || _M_X64 || _M_IX86

/**
 * @brief Calculate the bit offset of the msb.
 * @param val 32-bit unsigned integer input
 *
 * @returns bit offset of msb starting at 1 for first bit
 */
static inline uint32_t
bsr(uint32_t val)
{
        uint32_t msb;
#if defined(_MSC_VER)
        unsigned long ret = 0;
        if (val != 0) {
                _BitScanReverse(&ret, val);
                msb = ret + 1;
        } else
                msb = 0;
#elif defined(__LZCNT__)
        msb = 32 - __lzcnt32(val);
#elif defined(__x86_64__) || defined(__aarch64__)
        msb = (val == 0) ? 0 : 32 - __builtin_clz(val);
#else
        for (msb = 0; val > 0; val >>= 1)
                msb++;
#endif
        return msb;
}

static inline uint32_t
tzbytecnt(uint64_t val)
{
        uint32_t cnt;

#ifdef __BMI__
        cnt = __tzcnt_u64(val);
        cnt = cnt / 8;
#elif defined(__x86_64__) || defined(__aarch64__)

        cnt = (val == 0) ? 64 : __builtin_ctzll(val);
        cnt = cnt / 8;

#else
        for (cnt = 8; val > 0; val <<= 8)
                cnt -= 1;
#endif
        return cnt;
}

static void
compute_dist_code(struct isal_hufftables *hufftables, uint16_t dist, uint64_t *p_code,
                  uint64_t *p_len)
{
        assert(dist > IGZIP_DIST_TABLE_SIZE);

        dist -= 1;
        uint32_t msb;
        uint32_t num_extra_bits;
        uint32_t extra_bits;
        uint32_t sym;
        uint32_t len;
        uint32_t code;

        msb = bsr(dist);
        assert(msb >= 2);
        num_extra_bits = msb - 2;
        extra_bits = dist & ((1 << num_extra_bits) - 1);
        dist >>= num_extra_bits;
        sym = dist + 2 * num_extra_bits;
        assert(sym < 30);
        code = hufftables->dcodes[sym - IGZIP_DECODE_OFFSET];
        len = hufftables->dcodes_sizes[sym - IGZIP_DECODE_OFFSET];
        *p_code = code | (extra_bits << len);
        *p_len = len + num_extra_bits;
}

static inline void
get_dist_code(struct isal_hufftables *hufftables, uint32_t dist, uint64_t *code, uint64_t *len)
{
        assert(dist >= 1);
        assert(dist <= 32768);
        if (dist <= IGZIP_DIST_TABLE_SIZE) {
                uint64_t code_len;
                code_len = hufftables->dist_table[dist - 1];
                *code = code_len >> 5;
                *len = code_len & 0x1F;
        } else {
                compute_dist_code(hufftables, dist, code, len);
        }
}

static inline void
get_len_code(struct isal_hufftables *hufftables, uint32_t length, uint64_t *code, uint64_t *len)
{
        assert(length >= 3);
        assert(length <= 258);

        uint64_t code_len;
        code_len = hufftables->len_table[length - 3];
        *code = code_len >> 5;
        *len = code_len & 0x1F;
}

static inline void
get_lit_code(struct isal_hufftables *hufftables, uint32_t lit, uint64_t *code, uint64_t *len)
{
        assert(lit <= 256);

        *code = hufftables->lit_table[lit];
        *len = hufftables->lit_table_sizes[lit];
}

static void
compute_dist_icf_code(uint32_t dist, uint32_t *code, uint32_t *extra_bits)
{
        uint32_t msb;
        uint32_t num_extra_bits;

        dist -= 1;
        msb = bsr(dist);
        assert(msb >= 2);
        num_extra_bits = msb - 2;
        *extra_bits = dist & ((1 << num_extra_bits) - 1);
        dist >>= num_extra_bits;
        *code = dist + 2 * num_extra_bits;
        assert(*code < 30);
}

static inline void
get_dist_icf_code(uint32_t dist, uint32_t *code, uint32_t *extra_bits)
{
        assert(dist >= 1);
        assert(dist <= 32768);
        if (dist <= 2) {
                *code = dist - 1;
                *extra_bits = 0;
        } else {
                compute_dist_icf_code(dist, code, extra_bits);
        }
}

static inline void
get_len_icf_code(uint32_t length, uint32_t *code)
{
        assert(length >= 3);
        assert(length <= 258);

        *code = length + 254;
}

static inline void
get_lit_icf_code(uint32_t lit, uint32_t *code)
{
        assert(lit <= 256);

        *code = lit;
}

/**
 * @brief Returns a hash of the first 3 bytes of input data.
 */
static inline uint32_t
compute_hash(uint32_t data)
{
#ifdef __SSE4_2__

        return _mm_crc32_u32(0, data);

#else
        uint64_t hash;
        /* Use multiplication to create a hash, 0xBDD06057 is a prime number */
        hash = data;
        hash *= 0xB2D06057;
        hash >>= 16;
        hash *= 0xB2D06057;
        hash >>= 16;

        return hash;

#endif /* __SSE4_2__ */
}

#define PROD1 0xFFFFE84B
#define PROD2 0xFFFF97B1
static inline uint32_t
compute_hash_mad(uint32_t data)
{
        int16_t data_low;
        int16_t data_high;

        data_low = data;
        data_high = data >> 16;
        data = PROD1 * data_low + PROD2 * data_high;

        data_low = data;
        data_high = data >> 16;
        data = PROD1 * data_low + PROD2 * data_high;

        return data;
}

static inline uint32_t
compute_long_hash(uint64_t data)
{

        return compute_hash(data >> 32) ^ compute_hash(data);
}

/**
 * @brief Returns how long str1 and str2 have the same symbols.
 * @param str1: First input string.
 * @param str2: Second input string.
 * @param max_length: length of the smaller string.
 */
static inline int
compare258(uint8_t *str1, uint8_t *str2, uint32_t max_length)
{
        uint32_t count;
        uint64_t test;
        uint64_t loop_length;

        if (max_length > 258)
                max_length = 258;

        loop_length = max_length & ~0x7;

        for (count = 0; count < loop_length; count += 8) {
                test = load_le_u64(str1);
                test ^= load_le_u64(str2);
                if (test != 0)
                        return count + tzbytecnt(test);
                str1 += 8;
                str2 += 8;
        }

        switch (max_length % 8) {

        case 7:
                if (*str1++ != *str2++)
                        return count;
                count++;
        case 6:
                if (*str1++ != *str2++)
                        return count;
                count++;
        case 5:
                if (*str1++ != *str2++)
                        return count;
                count++;
        case 4:
                if (*str1++ != *str2++)
                        return count;
                count++;
        case 3:
                if (*str1++ != *str2++)
                        return count;
                count++;
        case 2:
                if (*str1++ != *str2++)
                        return count;
                count++;
        case 1:
                if (*str1 != *str2)
                        return count;
                count++;
        }

        return count;
}

/**
 * @brief Returns how long str1 and str2 have the same symbols.
 * @param str1: First input string.
 * @param str2: Second input string.
 * @param max_length: length of the smaller string.
 */
static inline int
compare(uint8_t *str1, uint8_t *str2, uint32_t max_length)
{
        uint32_t count;
        uint64_t test;
        uint64_t loop_length;

        loop_length = max_length & ~0x7;

        for (count = 0; count < loop_length; count += 8) {
                test = load_le_u64(str1);
                test ^= load_le_u64(str2);
                if (test != 0)
                        return count + tzbytecnt(test);
                str1 += 8;
                str2 += 8;
        }

        switch (max_length % 8) {

        case 7:
                if (*str1++ != *str2++)
                        return count;
                count++;
        case 6:
                if (*str1++ != *str2++)
                        return count;
                count++;
        case 5:
                if (*str1++ != *str2++)
                        return count;
                count++;
        case 4:
                if (*str1++ != *str2++)
                        return count;
                count++;
        case 3:
                if (*str1++ != *str2++)
                        return count;
                count++;
        case 2:
                if (*str1++ != *str2++)
                        return count;
                count++;
        case 1:
                if (*str1 != *str2)
                        return count;
                count++;
        }

        return count;
}