
#include "constant.hpp"
#include "update_ops.hpp"
#include "utility.hpp"
#ifdef _OPENMP
#include <omp.h>
#endif

#ifdef _USE_SIMD
#ifdef _MSC_VER
#include <intrin.h>
#else
#include <x86intrin.h>
#endif
#endif

// void X_gate_old(UINT target_qubit_index, CTYPE *state, ITYPE dim);
// void X_gate_single(UINT target_qubit_index, CTYPE *state, ITYPE dim);
// void X_gate_parallel(UINT target_qubit_index, CTYPE *state, ITYPE dim);

void X_gate(UINT target_qubit_index, CTYPE* state, ITYPE dim) {
    // UINT threshold = 13;
    // X_gate_old(target_qubit_index, state, dim);
    // X_gate_single(target_qubit_index, state, dim);
    // X_gate_single_simd(target_qubit_index, state, dim);
    // X_gate_single_unroll(target_qubit_index, state, dim);
    // X_gate_parallel(target_qubit_index, state, dim);
    // return;

#ifdef _USE_SIMD
#ifdef _OPENMP
    UINT threshold = 13;
    if (dim < (((ITYPE)1) << threshold)) {
        X_gate_single_simd(target_qubit_index, state, dim);
    } else {
        X_gate_parallel_simd(target_qubit_index, state, dim);
    }
#else
    X_gate_single_simd(target_qubit_index, state, dim);
#endif
#else
#ifdef _OPENMP
    UINT threshold = 13;
    if (dim < (((ITYPE)1) << threshold)) {
        X_gate_single_unroll(target_qubit_index, state, dim);
    } else {
        X_gate_parallel_unroll(target_qubit_index, state, dim);
    }
#else
    X_gate_single_unroll(target_qubit_index, state, dim);
#endif
#endif
}

void X_gate_single_unroll(UINT target_qubit_index, CTYPE* state, ITYPE dim) {
    const ITYPE loop_dim = dim / 2;
    const ITYPE mask = (1ULL << target_qubit_index);
    const ITYPE mask_low = mask - 1;
    const ITYPE mask_high = ~mask_low;
    ITYPE state_index = 0;
    if (target_qubit_index == 0) {
        ITYPE basis_index = 0;
        for (basis_index = 0; basis_index < dim; basis_index += 2) {
            CTYPE temp = state[basis_index];
            state[basis_index] = state[basis_index + 1];
            state[basis_index + 1] = temp;
        }
    } else {
        for (state_index = 0; state_index < loop_dim; state_index += 2) {
            ITYPE basis_index_0 =
                (state_index & mask_low) + ((state_index & mask_high) << 1);
            ITYPE basis_index_1 = basis_index_0 + mask;
            CTYPE temp0 = state[basis_index_0];
            CTYPE temp1 = state[basis_index_0 + 1];
            state[basis_index_0] = state[basis_index_1];
            state[basis_index_0 + 1] = state[basis_index_1 + 1];
            state[basis_index_1] = temp0;
            state[basis_index_1 + 1] = temp1;
        }
    }
}

#ifdef _OPENMP
void X_gate_parallel_unroll(UINT target_qubit_index, CTYPE* state, ITYPE dim) {
    const ITYPE loop_dim = dim / 2;
    const ITYPE mask = (1ULL << target_qubit_index);
    const ITYPE mask_low = mask - 1;
    const ITYPE mask_high = ~mask_low;
    ITYPE state_index = 0;
    if (target_qubit_index == 0) {
        ITYPE basis_index = 0;
#pragma omp parallel for
        for (basis_index = 0; basis_index < dim; basis_index += 2) {
            CTYPE temp = state[basis_index];
            state[basis_index] = state[basis_index + 1];
            state[basis_index + 1] = temp;
        }
    } else {
#pragma omp parallel for
        for (state_index = 0; state_index < loop_dim; state_index += 2) {
            ITYPE basis_index_0 =
                (state_index & mask_low) + ((state_index & mask_high) << 1);
            ITYPE basis_index_1 = basis_index_0 + mask;
            CTYPE temp0 = state[basis_index_0];
            CTYPE temp1 = state[basis_index_0 + 1];
            state[basis_index_0] = state[basis_index_1];
            state[basis_index_0 + 1] = state[basis_index_1 + 1];
            state[basis_index_1] = temp0;
            state[basis_index_1 + 1] = temp1;
        }
    }
}
#endif

#ifdef _USE_SIMD
void X_gate_single_simd(UINT target_qubit_index, CTYPE* state, ITYPE dim) {
    const ITYPE loop_dim = dim / 2;
    const ITYPE mask = (1ULL << target_qubit_index);
    const ITYPE mask_low = mask - 1;
    const ITYPE mask_high = ~mask_low;
    ITYPE state_index = 0;
    // double* cast_state = (double*)state;
    if (target_qubit_index == 0) {
        ITYPE basis_index = 0;
        for (basis_index = 0; basis_index < dim; basis_index += 2) {
            double* ptr = (double*)(state + basis_index);
            __m256d data = _mm256_loadu_pd(ptr);
            data = _mm256_permute4x64_pd(data,
                78);  // (3210) -> (1032) : 1*2 + 4*3 + 16*0 + 64*1 = 2+12+64=78
            _mm256_storeu_pd(ptr, data);
        }
    } else {
        for (state_index = 0; state_index < loop_dim; state_index += 2) {
            ITYPE basis_index_0 =
                (state_index & mask_low) + ((state_index & mask_high) << 1);
            ITYPE basis_index_1 = basis_index_0 + mask;
            double* ptr0 = (double*)(state + basis_index_0);
            double* ptr1 = (double*)(state + basis_index_1);
            __m256d data0 = _mm256_loadu_pd(ptr0);
            __m256d data1 = _mm256_loadu_pd(ptr1);
            _mm256_storeu_pd(ptr1, data0);
            _mm256_storeu_pd(ptr0, data1);
        }
    }
}

#ifdef _OPENMP
void X_gate_parallel_simd(UINT target_qubit_index, CTYPE* state, ITYPE dim) {
    const ITYPE loop_dim = dim / 2;
    const ITYPE mask = (1ULL << target_qubit_index);
    const ITYPE mask_low = mask - 1;
    const ITYPE mask_high = ~mask_low;
    ITYPE state_index = 0;
    // double* cast_state = (double*)state;
    if (target_qubit_index == 0) {
        ITYPE basis_index = 0;
#pragma omp parallel for
        for (basis_index = 0; basis_index < dim; basis_index += 2) {
            double* ptr = (double*)(state + basis_index);
            __m256d data = _mm256_loadu_pd(ptr);
            data = _mm256_permute4x64_pd(data,
                78);  // (3210) -> (1032) : 1*2 + 4*3 + 16*0 + 64*1 = 2+12+64=78
            _mm256_storeu_pd(ptr, data);
        }
    } else {
#pragma omp parallel for
        for (state_index = 0; state_index < loop_dim; state_index += 2) {
            ITYPE basis_index_0 =
                (state_index & mask_low) + ((state_index & mask_high) << 1);
            ITYPE basis_index_1 = basis_index_0 + mask;
            double* ptr0 = (double*)(state + basis_index_0);
            double* ptr1 = (double*)(state + basis_index_1);
            __m256d data0 = _mm256_loadu_pd(ptr0);
            __m256d data1 = _mm256_loadu_pd(ptr1);
            _mm256_storeu_pd(ptr1, data0);
            _mm256_storeu_pd(ptr0, data1);
        }
    }
}
#endif
#endif

/*


void X_gate_old(UINT target_qubit_index, CTYPE *state, ITYPE dim) {
        const ITYPE loop_dim = dim / 2;
        const ITYPE mask = (1ULL << target_qubit_index);
        ITYPE state_index;
#ifdef _OPENMP
//#pragma omp parallel for
#endif
        for (state_index = 0; state_index < loop_dim; ++state_index) {
                ITYPE basis_index_0 = insert_zero_to_basis_index(state_index,
mask, target_qubit_index); ITYPE basis_index_1 = basis_index_0 ^ mask;
                swap_amplitude(state, basis_index_0, basis_index_1);
        }
}

void X_gate_single(UINT target_qubit_index, CTYPE *state, ITYPE dim) {
        const ITYPE loop_dim = dim / 2;
        const ITYPE mask = (1ULL << target_qubit_index);
        const ITYPE mask_low = mask - 1;
        const ITYPE mask_high = ~mask_low;
        ITYPE state_index = 0;
        for (state_index = 0; state_index < loop_dim; ++state_index) {
                ITYPE basis_index_0 = (state_index&mask_low) +
((state_index&mask_high) << 1); ITYPE basis_index_1 = basis_index_0 + mask;
                CTYPE temp = state[basis_index_0];
                state[basis_index_0] = state[basis_index_1];
                state[basis_index_1] = temp;
        }
}

#ifdef _OPENMP
void X_gate_parallel(UINT target_qubit_index, CTYPE *state, ITYPE dim) {
        const ITYPE loop_dim = dim / 2;
        const ITYPE mask = (1ULL << target_qubit_index);
        const ITYPE mask_low = mask - 1;
        const ITYPE mask_high = ~mask_low;
        ITYPE state_index = 0;
#pragma omp parallel for
        for (state_index = 0; state_index < loop_dim; ++state_index) {
                ITYPE basis_index_0 = (state_index&mask_low) +
((state_index&mask_high) << 1); ITYPE basis_index_1 = basis_index_0 + mask;
                CTYPE temp = state[basis_index_0];
                state[basis_index_0] = state[basis_index_1];
                state[basis_index_1] = temp;
        }
}
#endif

*/
