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/** \file
 * \brief Shufti: character class acceleration.
 *
 * Utilises the SSSE3 pshufb shuffle instruction
 */

#include "shufti.h"
#include "ue2common.h"
#include "util/arch.h"
#include "util/bitutils.h"
#include "util/unaligned.h"

#include "util/simd/types.hpp"

#define GET1_LO_4(chars, low4bits) and128(chars, low4bits)
#define GET1_HI_4(chars, low4bits) and128(rshift64_m128(chars, 4), low4bits)

template <uint16_t S>
static really_inline
typename SuperVector<S>::movemask_type block(SuperVector<S> mask_lo, SuperVector<S> mask_hi,
            SuperVector<S> chars, const SuperVector<S> low4bits) {
    SuperVector<S> c_lo = chars & low4bits;
    print_m128_16x8("c_lo", c_lo.u.v128[0]);
    c_lo = mask_lo.pshufb(c_lo);
    print_m128_16x8("c_lo", c_lo.u.v128[0]);
    SuperVector<S> c_hi = mask_hi.pshufb(chars.rshift64(4) & low4bits);
    SuperVector<S> t = c_lo & c_hi;

    print_m128_16x8("low4bits", low4bits.u.v128[0]);
    print_m128_16x8("mask_lo", mask_lo.u.v128[0]);
    print_m128_16x8("mask_hi", mask_hi.u.v128[0]);
    print_m128_16x8("chars", chars.u.v128[0]);
    print_m128_16x8("c_lo", c_lo.u.v128[0]);
    print_m128_16x8("c_hi", c_hi.u.v128[0]);
    print_m128_16x8("t", t.u.v128[0]);

    return t.eqmask(SuperVector<S>::Zeroes());
}

template <uint16_t S>
const u8 *firstMatch(const u8 *buf, typename SuperVector<S>::movemask_type z);

template <uint16_t S>
const u8 *lastMatch(const u8 *buf, typename SuperVector<S>::movemask_type z);


template <>
really_inline
const u8 *firstMatch<16>(const u8 *buf, typename SuperVector<16>::movemask_type z) {
    DEBUG_PRINTF("buf %p z %08x \n", buf, z);
    DEBUG_PRINTF("z %08x\n", z);
    if (unlikely(z != 0xffff)) {
        u32 pos = ctz32(~z & 0xffff);
        DEBUG_PRINTF("~z %08x\n", ~z);
        DEBUG_PRINTF("match @ pos %u\n", pos);
        assert(pos < 16);
        return buf + pos;
    } else {
        return NULL; // no match
    }
}

template <>
really_inline
const u8 *firstMatch<64>(const u8 *buf, typename SuperVector<64>::movemask_type z) {
    DEBUG_PRINTF("z 0x%016llx\n", z);
    if (unlikely(z != ~0ULL)) {
        u32 pos = ctz64(~z);
        DEBUG_PRINTF("match @ pos %u\n", pos);
        assert(pos < 64);
        return buf + pos;
    } else {
        return NULL; // no match
    }
}

template <uint16_t S>
static really_inline
const u8 *fwdBlock(SuperVector<S> mask_lo, SuperVector<S> mask_hi, SuperVector<S> chars, 
                      const SuperVector<S> low4bits, const u8 *buf) {
    typename SuperVector<S>::movemask_type z = block(mask_lo, mask_hi, chars, low4bits);
    DEBUG_PRINTF("z %08x\n", z);

    return firstMatch<S>(buf, z);
}

template <uint16_t S>
static really_inline
const u8 *shortShufti(SuperVector<S> mask_lo, SuperVector<S> mask_hi, const u8 *buf,
                         const u8 *buf_end, const SuperVector<S> low4bits) {
    DEBUG_PRINTF("short shufti %p len %zu\n", buf, buf_end - buf);
    uintptr_t len = buf_end - buf;
    assert(len <= S);

    SuperVector<S> chars = SuperVector<S>::loadu_maskz(buf, static_cast<uint8_t>(len));
    print_m128_16x8("chars", chars.u.v128[0]);
    uint8_t alignment = (uintptr_t)(buf) & 15;
    typename SuperVector<S>::movemask_type maskb = 1 << alignment;
    typename SuperVector<S>::movemask_type maske = SINGLE_LOAD_MASK(len - alignment);
    typename SuperVector<S>::movemask_type z = block(mask_lo, mask_hi, chars, low4bits);
    // reuse the load mask to indicate valid bytes
    DEBUG_PRINTF("z %08x\n", z);
    z &= maskb | maske;
    DEBUG_PRINTF("z %08x\n", z);
    
    return firstMatch<S>(buf, z);
}


template <>
really_inline
const u8 *lastMatch<16>(const u8 *buf, typename SuperVector<16>::movemask_type z) {
    DEBUG_PRINTF("buf %p z %08x \n", buf, z);
    DEBUG_PRINTF("z %08x\n", z);
    if (unlikely(z != 0xffff)) {
        u32 pos = clz32(~z & 0xffff);
        DEBUG_PRINTF("~z %08x\n", ~z);
        DEBUG_PRINTF("match @ pos %u\n", pos);
        assert(pos >= 16 && pos < 32);
        return buf + (31 - pos);
    } else {
        return NULL; // no match
    }
}

template <>
really_inline
const u8 *lastMatch<64>(const u8 *buf, typename SuperVector<64>::movemask_type z) {
    DEBUG_PRINTF("z 0x%016llx\n", z);
    if (unlikely(z != ~0ULL)) {
        u32 pos = clz64(~z);
        DEBUG_PRINTF("match @ pos %u\n", pos);
        assert(pos < 64);
        return buf + pos;
    } else {
        return NULL; // no match
    }
}

template <uint16_t S>
static really_inline
const u8 *revBlock(SuperVector<S> mask_lo, SuperVector<S> mask_hi, SuperVector<S> chars, 
                   const SuperVector<S> low4bits, const u8 *buf) {
    typename SuperVector<S>::movemask_type z = block(mask_lo, mask_hi, chars, low4bits);
    DEBUG_PRINTF("z %08x\n", z);

    return lastMatch<S>(buf, z);
}


template <uint16_t S>
const u8 *shuftiExecReal(m128 mask_lo, m128 mask_hi, const u8 *buf, const u8 *buf_end) {
    assert(buf && buf_end);
    assert(buf < buf_end);
    DEBUG_PRINTF("shufti %p len %zu\n", buf, buf_end - buf);
    DEBUG_PRINTF("b %s\n", buf);

    const SuperVector<S> low4bits = SuperVector<S>::set1u_16x8(0xf);
    const SuperVector<S> wide_mask_lo(mask_lo);
    const SuperVector<S> wide_mask_hi(mask_hi);

    const u8 *d = buf;
    const u8 *rv;

    DEBUG_PRINTF("start %p end %p \n", d, buf_end);
    assert(d < buf_end);
    if (d + S <= buf_end) {
        // peel off first part to cacheline boundary
        const u8 *d1 = ROUNDUP_PTR(d, S);
        DEBUG_PRINTF("until aligned %p \n", d1);
        if (d1 != d) {
            rv = shuftiFwdSlow((const u8 *)&mask_lo, (const u8 *)&mask_hi, d, d1);
            // rv = shortShufti(wide_mask_lo, wide_mask_hi, d, d1, low4bits);
            if (rv != d1) {
                return rv;
            }
            d = d1;
        }

        size_t loops = (buf_end - d) / S;
        DEBUG_PRINTF("loops %ld \n", loops);

        for (size_t i = 0; i < loops; i++, d+= S) {
            DEBUG_PRINTF("d %p \n", d);
            const u8 *base = ROUNDUP_PTR(d, S);
            // On large packet buffers, this prefetch appears to get us about 2%.
            __builtin_prefetch(base + 256);

            SuperVector<S> chars = SuperVector<S>::load(d);
            rv = fwdBlock(wide_mask_lo, wide_mask_hi, chars, low4bits, d);
            if (rv) return rv;
        }
    }

    DEBUG_PRINTF("d %p e %p \n", d, buf_end);
    // finish off tail

    rv = buf_end;
    if (d != buf_end) {
        rv = shuftiFwdSlow((const u8 *)&mask_lo, (const u8 *)&mask_hi, d, buf_end);
        // rv = shortShufti(wide_mask_lo, wide_mask_hi, buf_end - S, buf_end, low4bits);
        DEBUG_PRINTF("rv %p \n", rv);
    }
    
    return rv;
}

template <uint16_t S>
const u8 *rshuftiExecReal(m128 mask_lo, m128 mask_hi, const u8 *buf, const u8 *buf_end) {
    assert(buf && buf_end);
    assert(buf < buf_end);
    DEBUG_PRINTF("shufti %p len %zu\n", buf, buf_end - buf);
    DEBUG_PRINTF("b %s\n", buf);

    const SuperVector<S> low4bits = SuperVector<S>::set1u_16x8(0xf);
    const SuperVector<S> wide_mask_lo(mask_lo);
    const SuperVector<S> wide_mask_hi(mask_hi);

    const u8 *d = buf_end;
    const u8 *rv;

    DEBUG_PRINTF("start %p end %p \n", buf, d);
    assert(d > buf);
    if (d - S >= buf) {
        // peel off first part to cacheline boundary
        const u8 *d1 = ROUNDDOWN_PTR(d, S);
        DEBUG_PRINTF("until aligned %p \n", d1);
        if (d1 != d) {
            rv = shuftiRevSlow((const u8 *)&mask_lo, (const u8 *)&mask_hi, d1, d);
            DEBUG_PRINTF("rv %p \n", rv);
            // rv = shortShufti(wide_mask_lo, wide_mask_hi, d, d1, low4bits);
            if (rv != d1 - 1) return rv;
            d = d1;
        }

        while (d - S >= buf) {
            d -= S;
            DEBUG_PRINTF("d %p \n", d);
            const u8 *base = ROUNDDOWN_PTR(buf, S);
            // On large packet buffers, this prefetch appears to get us about 2%.
            __builtin_prefetch(base + 256);

            SuperVector<S> chars = SuperVector<S>::load(d);
            rv = revBlock(wide_mask_lo, wide_mask_hi, chars, low4bits, d);
            if (rv) return rv;
        }
    }

    DEBUG_PRINTF("d %p e %p \n", buf, d);
    // finish off tail

    if (d != buf) {
        rv = shuftiRevSlow((const u8 *)&mask_lo, (const u8 *)&mask_hi, buf, d);
        // rv = shortShufti(wide_mask_lo, wide_mask_hi, buf_end - S, buf_end, low4bits);
        DEBUG_PRINTF("rv %p \n", rv);
        if (rv != d - 1) return rv;
    }
    
    return buf - 1;
}

template <uint16_t S>
static really_inline
const u8 *fwdBlockDouble(SuperVector<S> mask1_lo, SuperVector<S> mask1_hi, SuperVector<S> mask2_lo, SuperVector<S> mask2_hi,
                    SuperVector<S> chars, const SuperVector<S> low4bits, const u8 *buf) {
    SuperVector<S> chars_lo = chars & low4bits;
    SuperVector<S> chars_hi = chars.rshift64(4) & low4bits;
    SuperVector<S> c1_lo = mask1_lo.pshufb(chars_lo);
    SuperVector<S> c1_hi = mask1_hi.pshufb(chars_hi);
    SuperVector<S> t1 = c1_lo | c1_hi;

    SuperVector<S> c2_lo = mask2_lo.pshufb(chars_lo);
    SuperVector<S> c2_hi = mask2_hi.pshufb(chars_hi);
    SuperVector<S> t2 = c2_lo | c2_hi;
    SuperVector<S> t = t1 | (t2 >> 1);

    typename SuperVector<S>::movemask_type z = t.eqmask(SuperVector<S>::Ones());
    DEBUG_PRINTF("    z: 0x%08x\n", z);
    return firstMatch<S>(buf, z);
}

template <uint16_t S>
const u8 *shuftiDoubleExecReal(m128 mask1_lo, m128 mask1_hi,
                           m128 mask2_lo, m128 mask2_hi,
                           const u8 *buf, const u8 *buf_end) {
        assert(buf && buf_end);
    assert(buf < buf_end);
    DEBUG_PRINTF("shufti %p len %zu\n", buf, buf_end - buf);
    DEBUG_PRINTF("b %s\n", buf);

    const SuperVector<S> low4bits = SuperVector<S>::set1u_16x8(0xf);
    const SuperVector<S> wide_mask1_lo(mask1_lo);
    const SuperVector<S> wide_mask1_hi(mask1_hi);
    const SuperVector<S> wide_mask2_lo(mask2_lo);
    const SuperVector<S> wide_mask2_hi(mask2_hi);

    const u8 *d = buf;
    const u8 *rv;

    DEBUG_PRINTF("start %p end %p \n", d, buf_end);
    assert(d < buf_end);
    if (d + S <= buf_end) {
        // peel off first part to cacheline boundary
        const u8 *d1 = ROUNDUP_PTR(d, S);
        DEBUG_PRINTF("until aligned %p \n", d1);
        if (d1 != d) {
            SuperVector<S> chars = SuperVector<S>::loadu(d);
            rv = fwdBlockDouble(wide_mask1_lo, wide_mask1_hi, wide_mask2_lo, wide_mask2_hi, chars, low4bits, d);
            if (rv) return rv;
            d = d1;
        }

        size_t loops = (buf_end - d) / S;
        DEBUG_PRINTF("loops %ld \n", loops);

        for (size_t i = 0; i < loops; i++, d+= S) {
            DEBUG_PRINTF("d %p \n", d);
            const u8 *base = ROUNDUP_PTR(d, S);
            // On large packet buffers, this prefetch appears to get us about 2%.
            __builtin_prefetch(base + 256);

            SuperVector<S> chars = SuperVector<S>::load(d);
            rv = fwdBlockDouble(wide_mask1_lo, wide_mask1_hi, wide_mask2_lo, wide_mask2_hi, chars, low4bits, d);
            if (rv) return rv;
        }
    }

    DEBUG_PRINTF("d %p e %p \n", d, buf_end);
    // finish off tail

    if (d != buf_end) {
        SuperVector<S> chars = SuperVector<S>::loadu(buf_end - S);
        rv = fwdBlockDouble(wide_mask1_lo, wide_mask1_hi, wide_mask2_lo, wide_mask2_hi, chars, low4bits, buf_end - S);
        DEBUG_PRINTF("rv %p \n", rv);
        if (rv) return rv;
    }
    
    return buf_end;
}