pqclean/crypto_sign/falcon-1024/aarch64/util.c

/*
 * Utils function
 *
 * =============================================================================
 * Copyright (c) 2023 by Cryptographic Engineering Research Group (CERG)
 * ECE Department, George Mason University
 * Fairfax, VA, U.S.A.
 * Author: Duc Tri Nguyen
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *     http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * =============================================================================
 * @author   Duc Tri Nguyen <[email protected]>, <[email protected]>
 */

#include "inner.h"
#include "macrofx4.h"
#include "util.h"

/*
 * Convert an integer polynomial (with small values) into the
 * representation with complex numbers.
 */
void PQCLEAN_FALCON1024_AARCH64_smallints_to_fpr(fpr *r, const int8_t *t, const unsigned logn) {
    float64x2x4_t neon_flo64, neon_fhi64;
    int64x2x4_t neon_lo64, neon_hi64;
    int32x4_t neon_lo32[2], neon_hi32[2];
    int16x8_t neon_lo16, neon_hi16;
    int8x16_t neon_8;

    const unsigned falcon_n =  1 << logn;

    for (unsigned i = 0; i < falcon_n; i += 16) {
        neon_8 = vld1q_s8(&t[i]);

        // Extend from 8 to 16 bit
        // x7 | x6 | x5 | x5 - x3 | x2 | x1 | x0
        neon_lo16 = vmovl_s8(vget_low_s8(neon_8));
        neon_hi16 = vmovl_high_s8(neon_8);

        // Extend from 16 to 32 bit
        // xxx3 | xxx2 | xxx1 | xxx0
        neon_lo32[0] = vmovl_s16(vget_low_s16(neon_lo16));
        neon_lo32[1] = vmovl_high_s16(neon_lo16);
        neon_hi32[0] = vmovl_s16(vget_low_s16(neon_hi16));
        neon_hi32[1] = vmovl_high_s16(neon_hi16);

        // Extend from 32 to 64 bit
        neon_lo64.val[0] = vmovl_s32(vget_low_s32(neon_lo32[0]));
        neon_lo64.val[1] = vmovl_high_s32(neon_lo32[0]);
        neon_lo64.val[2] = vmovl_s32(vget_low_s32(neon_lo32[1]));
        neon_lo64.val[3] = vmovl_high_s32(neon_lo32[1]);

        neon_hi64.val[0] = vmovl_s32(vget_low_s32(neon_hi32[0]));
        neon_hi64.val[1] = vmovl_high_s32(neon_hi32[0]);
        neon_hi64.val[2] = vmovl_s32(vget_low_s32(neon_hi32[1]));
        neon_hi64.val[3] = vmovl_high_s32(neon_hi32[1]);

        vfcvtx4(neon_flo64, neon_lo64);
        vfcvtx4(neon_fhi64, neon_hi64);

        vstorex4(&r[i], neon_flo64);
        vstorex4(&r[i + 8], neon_fhi64);
    }
}