#include <immintrin.h>
#include <stdint.h>
#include <string.h>

#include "fips202.h"
#include "fips202x4.h"

#define NROUNDS 24
#define ROL(a, offset) (((a) << (offset)) ^ ((a) >> (64-(offset))))

static uint64_t load64(const unsigned char *x) {
    unsigned long long r = 0, i;

    for (i = 0; i < 8; ++i) {
        r |= (unsigned long long)x[i] << 8 * i;
    }
    return r;
}

static void store64(uint8_t *x, uint64_t u) {
    unsigned int i;

    for (i = 0; i < 8; ++i) {
        x[i] = (uint8_t)u;
        u >>= 8;
    }
}

/* Use implementation from the Keccak Code Package */
extern void KeccakP1600times4_PermuteAll_24rounds(__m256i *s);
#define KeccakF1600_StatePermute4x KeccakP1600times4_PermuteAll_24rounds

static void keccak_absorb4x(__m256i *s,
                            unsigned int r,
                            const unsigned char *m0,
                            const unsigned char *m1,
                            const unsigned char *m2,
                            const unsigned char *m3,
                            size_t mlen,
                            unsigned char p) {
    unsigned char t0[200] = {0};
    unsigned char t1[200] = {0};
    unsigned char t2[200] = {0};
    unsigned char t3[200] = {0};

    unsigned long long *ss = (unsigned long long *)s;


    while (mlen >= r) {
        for (size_t i = 0; i < r / 8; ++i) {
            ss[4 * i + 0] ^= load64(m0 + 8 * i);
            ss[4 * i + 1] ^= load64(m1 + 8 * i);
            ss[4 * i + 2] ^= load64(m2 + 8 * i);
            ss[4 * i + 3] ^= load64(m3 + 8 * i);
        }

        KeccakF1600_StatePermute4x(s);
        mlen -= r;
        m0 += r;
        m1 += r;
        m2 += r;
        m3 += r;
    }

    memcpy(t0, m0, mlen);
    memcpy(t1, m1, mlen);
    memcpy(t2, m2, mlen);
    memcpy(t3, m3, mlen);

    t0[mlen] = p;
    t1[mlen] = p;
    t2[mlen] = p;
    t3[mlen] = p;

    t0[r - 1] |= 128;
    t1[r - 1] |= 128;
    t2[r - 1] |= 128;
    t3[r - 1] |= 128;

    for (size_t i = 0; i < r / 8; ++i) {
        ss[4 * i + 0] ^= load64(t0 + 8 * i);
        ss[4 * i + 1] ^= load64(t1 + 8 * i);
        ss[4 * i + 2] ^= load64(t2 + 8 * i);
        ss[4 * i + 3] ^= load64(t3 + 8 * i);
    }
}


static void keccak_squeezeblocks4x(unsigned char *h0,
                                   unsigned char *h1,
                                   unsigned char *h2,
                                   unsigned char *h3,
                                   unsigned long long int nblocks,
                                   __m256i *s,
                                   unsigned int r) {
    unsigned int i;

    unsigned long long *ss = (unsigned long long *)s;

    while (nblocks > 0) {
        KeccakF1600_StatePermute4x(s);
        for (i = 0; i < (r >> 3); i++) {
            store64(h0 + 8 * i, ss[4 * i + 0]);
            store64(h1 + 8 * i, ss[4 * i + 1]);
            store64(h2 + 8 * i, ss[4 * i + 2]);
            store64(h3 + 8 * i, ss[4 * i + 3]);
        }
        h0 += r;
        h1 += r;
        h2 += r;
        h3 += r;
        nblocks--;
    }
}



void PQCLEAN_SPHINCSSHAKE256256SSIMPLE_AVX2_shake128x4(unsigned char *out0,
        unsigned char *out1,
        unsigned char *out2,
        unsigned char *out3,
        unsigned long long outlen,
        unsigned char *in0,
        unsigned char *in1,
        unsigned char *in2,
        unsigned char *in3,
        unsigned long long inlen) {
    __m256i s[25];
    unsigned char t0[SHAKE128_RATE];
    unsigned char t1[SHAKE128_RATE];
    unsigned char t2[SHAKE128_RATE];
    unsigned char t3[SHAKE128_RATE];
    unsigned int i;

    /* zero state */
    for (i = 0; i < 25; i++) {
        s[i] = _mm256_xor_si256(s[i], s[i]);
    }

    /* absorb 4 message of identical length in parallel */
    keccak_absorb4x(s, SHAKE128_RATE, in0, in1, in2, in3, (size_t)inlen, 0x1F);

    /* Squeeze output */
    keccak_squeezeblocks4x(out0, out1, out2, out3, outlen / SHAKE128_RATE, s, SHAKE128_RATE);

    out0 += (outlen / SHAKE128_RATE) * SHAKE128_RATE;
    out1 += (outlen / SHAKE128_RATE) * SHAKE128_RATE;
    out2 += (outlen / SHAKE128_RATE) * SHAKE128_RATE;
    out3 += (outlen / SHAKE128_RATE) * SHAKE128_RATE;

    if (outlen % SHAKE128_RATE) {
        keccak_squeezeblocks4x(t0, t1, t2, t3, 1, s, SHAKE128_RATE);
        for (i = 0; i < outlen % SHAKE128_RATE; i++) {
            out0[i] = t0[i];
            out1[i] = t1[i];
            out2[i] = t2[i];
            out3[i] = t3[i];
        }
    }
}


void PQCLEAN_SPHINCSSHAKE256256SSIMPLE_AVX2_shake256x4(unsigned char *out0,
        unsigned char *out1,
        unsigned char *out2,
        unsigned char *out3,
        unsigned long long outlen,
        unsigned char *in0,
        unsigned char *in1,
        unsigned char *in2,
        unsigned char *in3,
        unsigned long long inlen) {
    __m256i s[25];
    unsigned char t0[SHAKE256_RATE];
    unsigned char t1[SHAKE256_RATE];
    unsigned char t2[SHAKE256_RATE];
    unsigned char t3[SHAKE256_RATE];
    unsigned int i;

    /* zero state */
    for (i = 0; i < 25; i++) {
        s[i] = _mm256_xor_si256(s[i], s[i]);
    }

    /* absorb 4 message of identical length in parallel */
    keccak_absorb4x(s, SHAKE256_RATE, in0, in1, in2, in3, (size_t)inlen, 0x1F);

    /* Squeeze output */
    keccak_squeezeblocks4x(out0, out1, out2, out3, outlen / SHAKE256_RATE, s, SHAKE256_RATE);

    out0 += (outlen / SHAKE256_RATE) * SHAKE256_RATE;
    out1 += (outlen / SHAKE256_RATE) * SHAKE256_RATE;
    out2 += (outlen / SHAKE256_RATE) * SHAKE256_RATE;
    out3 += (outlen / SHAKE256_RATE) * SHAKE256_RATE;

    if (outlen % SHAKE256_RATE) {
        keccak_squeezeblocks4x(t0, t1, t2, t3, 1, s, SHAKE256_RATE);
        for (i = 0; i < outlen % SHAKE256_RATE; i++) {
            out0[i] = t0[i];
            out1[i] = t1[i];
            out2[i] = t2[i];
            out3[i] = t3[i];
        }
    }
}