| /* | 
 |  * Copyright (c) 2021, Alliance for Open Media. All rights reserved | 
 |  * | 
 |  * This source code is subject to the terms of the BSD 3-Clause Clear License | 
 |  * and the Alliance for Open Media Patent License 1.0. If the BSD 3-Clause Clear | 
 |  * License was not distributed with this source code in the LICENSE file, you | 
 |  * can obtain it at aomedia.org/license/software-license/bsd-3-c-c/.  If the | 
 |  * Alliance for Open Media Patent License 1.0 was not distributed with this | 
 |  * source code in the PATENTS file, you can obtain it at | 
 |  * aomedia.org/license/patent-license/. | 
 |  */ | 
 |  | 
 | #include <assert.h> | 
 |  | 
 | #include <arm_neon.h> | 
 |  | 
 | #include "aom_ports/system_state.h" | 
 |  | 
 | #include "av1/encoder/rdopt.h" | 
 | #include "config/av1_rtcd.h" | 
 |  | 
 | // Process horizontal and vertical correlations in a 4x4 block of pixels. | 
 | // We actually use the 4x4 pixels to calculate correlations corresponding to | 
 | // the top-left 3x3 pixels, so this function must be called with 1x1 overlap, | 
 | // moving the window along/down by 3 pixels at a time. | 
 | INLINE static void horver_correlation_4x4(const int16_t *diff, int stride, | 
 |                                           int32x4_t *xy_sum_32, | 
 |                                           int32x4_t *xz_sum_32, | 
 |                                           int32x4_t *x_sum_32, | 
 |                                           int32x4_t *x2_sum_32) { | 
 |   // Pixels in this 4x4   [ a b c d ] | 
 |   // are referred to as:  [ e f g h ] | 
 |   //                      [ i j k l ] | 
 |   //                      [ m n o p ] | 
 |  | 
 |   const int16x4_t pixelsa_2_lo = vld1_s16(diff + (0 * stride)); | 
 |   const int16x4_t pixelsa_2_sli = | 
 |       vreinterpret_s16_s64(vshl_n_s64(vreinterpret_s64_s16(pixelsa_2_lo), 16)); | 
 |   const int16x4_t pixelsb_2_lo = vld1_s16(diff + (1 * stride)); | 
 |   const int16x4_t pixelsb_2_sli = | 
 |       vreinterpret_s16_s64(vshl_n_s64(vreinterpret_s64_s16(pixelsb_2_lo), 16)); | 
 |   const int16x4_t pixelsa_1_lo = vld1_s16(diff + (2 * stride)); | 
 |   const int16x4_t pixelsa_1_sli = | 
 |       vreinterpret_s16_s64(vshl_n_s64(vreinterpret_s64_s16(pixelsa_1_lo), 16)); | 
 |   const int16x4_t pixelsb_1_lo = vld1_s16(diff + (3 * stride)); | 
 |   const int16x4_t pixelsb_1_sli = | 
 |       vreinterpret_s16_s64(vshl_n_s64(vreinterpret_s64_s16(pixelsb_1_lo), 16)); | 
 |  | 
 |   const int16x8_t slli_a = vcombine_s16(pixelsa_1_sli, pixelsa_2_sli); | 
 |  | 
 |   *xy_sum_32 = vmlal_s16(*xy_sum_32, pixelsa_1_lo, pixelsa_1_sli); | 
 |   *xy_sum_32 = vmlal_s16(*xy_sum_32, pixelsa_2_lo, pixelsa_2_sli); | 
 |   *xy_sum_32 = vmlal_s16(*xy_sum_32, pixelsb_2_lo, pixelsb_2_sli); | 
 |  | 
 |   *xz_sum_32 = vmlal_s16(*xz_sum_32, pixelsa_1_sli, pixelsb_1_sli); | 
 |   *xz_sum_32 = vmlal_s16(*xz_sum_32, pixelsa_2_sli, pixelsb_2_sli); | 
 |   *xz_sum_32 = vmlal_s16(*xz_sum_32, pixelsa_1_sli, pixelsb_2_sli); | 
 |  | 
 |   // Now calculate the straight sums, x_sum += a+b+c+e+f+g+i+j+k | 
 |   // (sum up every element in slli_a and swap_b) | 
 |   *x_sum_32 = vpadalq_s16(*x_sum_32, slli_a); | 
 |   *x_sum_32 = vaddw_s16(*x_sum_32, pixelsb_2_sli); | 
 |  | 
 |   // Also sum their squares | 
 |   *x2_sum_32 = vmlal_s16(*x2_sum_32, pixelsa_1_sli, pixelsa_1_sli); | 
 |   *x2_sum_32 = vmlal_s16(*x2_sum_32, pixelsa_2_sli, pixelsa_2_sli); | 
 |   *x2_sum_32 = vmlal_s16(*x2_sum_32, pixelsb_2_sli, pixelsb_2_sli); | 
 | } | 
 |  | 
 | void av1_get_horver_correlation_full_neon(const int16_t *diff, int stride, | 
 |                                           int width, int height, float *hcorr, | 
 |                                           float *vcorr) { | 
 |   // The following notation is used: | 
 |   // x - current pixel | 
 |   // y - right neighbour pixel | 
 |   // z - below neighbour pixel | 
 |   // w - down-right neighbour pixel | 
 |   int64_t xy_sum = 0, xz_sum = 0; | 
 |   int64_t x_sum = 0, x2_sum = 0; | 
 |   int32x4_t zero = vdupq_n_s32(0); | 
 |   int64x2_t v_x_sum = vreinterpretq_s64_s32(zero); | 
 |   int64x2_t v_xy_sum = vreinterpretq_s64_s32(zero); | 
 |   int64x2_t v_xz_sum = vreinterpretq_s64_s32(zero); | 
 |   int64x2_t v_x2_sum = vreinterpretq_s64_s32(zero); | 
 |   // Process horizontal and vertical correlations through the body in 4x4 | 
 |   // blocks.  This excludes the final row and column and possibly one extra | 
 |   // column depending how 3 divides into width and height | 
 |  | 
 |   for (int i = 0; i <= height - 4; i += 3) { | 
 |     int32x4_t xy_sum_32 = zero; | 
 |     int32x4_t xz_sum_32 = zero; | 
 |     int32x4_t x_sum_32 = zero; | 
 |     int32x4_t x2_sum_32 = zero; | 
 |     for (int j = 0; j <= width - 4; j += 3) { | 
 |       horver_correlation_4x4(&diff[i * stride + j], stride, &xy_sum_32, | 
 |                              &xz_sum_32, &x_sum_32, &x2_sum_32); | 
 |     } | 
 |     v_xy_sum = vpadalq_s32(v_xy_sum, xy_sum_32); | 
 |     v_xz_sum = vpadalq_s32(v_xz_sum, xz_sum_32); | 
 |     v_x_sum = vpadalq_s32(v_x_sum, x_sum_32); | 
 |     v_x2_sum = vpadalq_s32(v_x2_sum, x2_sum_32); | 
 |   } | 
 | #if defined(__aarch64__) | 
 |   xy_sum = vaddvq_s64(v_xy_sum); | 
 |   xz_sum = vaddvq_s64(v_xz_sum); | 
 |   x2_sum = vaddvq_s64(v_x2_sum); | 
 |   x_sum = vaddvq_s64(v_x_sum); | 
 | #else | 
 |   xy_sum = vget_lane_s64( | 
 |       vadd_s64(vget_low_s64(v_xy_sum), vget_high_s64(v_xy_sum)), 0); | 
 |   xz_sum = vget_lane_s64( | 
 |       vadd_s64(vget_low_s64(v_xz_sum), vget_high_s64(v_xz_sum)), 0); | 
 |   x2_sum = vget_lane_s64( | 
 |       vadd_s64(vget_low_s64(v_x2_sum), vget_high_s64(v_x2_sum)), 0); | 
 |   x_sum = | 
 |       vget_lane_s64(vadd_s64(vget_low_s64(v_x_sum), vget_high_s64(v_x_sum)), 0); | 
 | #endif | 
 |   // x_sum now covers every pixel except the final 1-2 rows and 1-2 cols | 
 |   int64_t x_finalrow = 0, x_finalcol = 0, x2_finalrow = 0, x2_finalcol = 0; | 
 |  | 
 |   // Do we have 2 rows remaining or just the one?  Note that width and height | 
 |   // are powers of 2, so each modulo 3 must be 1 or 2. | 
 |   if (height % 3 == 1) {  // Just horiz corrs on the final row | 
 |     const int16_t x0 = diff[(height - 1) * stride]; | 
 |     x_sum += x0; | 
 |     x_finalrow += x0; | 
 |     x2_sum += x0 * x0; | 
 |     x2_finalrow += x0 * x0; | 
 |     if (width >= 8) { | 
 |       int32x4_t v_y_sum = zero; | 
 |       int32x4_t v_y2_sum = zero; | 
 |       int32x4_t v_xy_sum_a = zero; | 
 |       int k = width - 1; | 
 |       int j = 0; | 
 |       while ((k - 8) > 0) { | 
 |         const int16x8_t v_x = vld1q_s16(&diff[(height - 1) * stride + j]); | 
 |         const int16x8_t v_y = vld1q_s16(&diff[(height - 1) * stride + j + 1]); | 
 |         const int16x4_t v_x_lo = vget_low_s16(v_x); | 
 |         const int16x4_t v_x_hi = vget_high_s16(v_x); | 
 |         const int16x4_t v_y_lo = vget_low_s16(v_y); | 
 |         const int16x4_t v_y_hi = vget_high_s16(v_y); | 
 |         v_xy_sum_a = vmlal_s16(v_xy_sum_a, v_x_lo, v_y_lo); | 
 |         v_xy_sum_a = vmlal_s16(v_xy_sum_a, v_x_hi, v_y_hi); | 
 |         v_y2_sum = vmlal_s16(v_y2_sum, v_y_lo, v_y_lo); | 
 |         v_y2_sum = vmlal_s16(v_y2_sum, v_y_hi, v_y_hi); | 
 |         v_y_sum = vpadalq_s16(v_y_sum, v_y); | 
 |         k -= 8; | 
 |         j += 8; | 
 |       } | 
 |  | 
 |       const int16x8_t v_l = vld1q_s16(&diff[(height - 1) * stride] + j); | 
 |       const int16x8_t v_x = | 
 |           vextq_s16(vextq_s16(vreinterpretq_s16_s32(zero), v_l, 7), | 
 |                     vreinterpretq_s16_s32(zero), 1); | 
 |       const int16x8_t v_y = vextq_s16(v_l, vreinterpretq_s16_s32(zero), 1); | 
 |       const int16x4_t v_x_lo = vget_low_s16(v_x); | 
 |       const int16x4_t v_x_hi = vget_high_s16(v_x); | 
 |       const int16x4_t v_y_lo = vget_low_s16(v_y); | 
 |       const int16x4_t v_y_hi = vget_high_s16(v_y); | 
 |       v_xy_sum_a = vmlal_s16(v_xy_sum_a, v_x_lo, v_y_lo); | 
 |       v_xy_sum_a = vmlal_s16(v_xy_sum_a, v_x_hi, v_y_hi); | 
 |       v_y2_sum = vmlal_s16(v_y2_sum, v_y_lo, v_y_lo); | 
 |       v_y2_sum = vmlal_s16(v_y2_sum, v_y_hi, v_y_hi); | 
 |       const int32x4_t v_y_sum_a = vpadalq_s16(v_y_sum, v_y); | 
 |       const int64x2_t v_xy_sum2 = vpaddlq_s32(v_xy_sum_a); | 
 | #if defined(__aarch64__) | 
 |       const int64x2_t v_y2_sum_a = vpaddlq_s32(v_y2_sum); | 
 |       xy_sum += vaddvq_s64(v_xy_sum2); | 
 |       const int32_t y = vaddvq_s32(v_y_sum_a); | 
 |       const int64_t y2 = vaddvq_s64(v_y2_sum_a); | 
 | #else | 
 |       xy_sum += vget_lane_s64( | 
 |           vadd_s64(vget_low_s64(v_xy_sum2), vget_high_s64(v_xy_sum2)), 0); | 
 |       const int64x2_t v_y_a = vpaddlq_s32(v_y_sum_a); | 
 |       const int64_t y = | 
 |           vget_lane_s64(vadd_s64(vget_low_s64(v_y_a), vget_high_s64(v_y_a)), 0); | 
 |       const int64x2_t v_y2_sum_b = vpaddlq_s32(v_y2_sum); | 
 |       int64_t y2 = vget_lane_s64( | 
 |           vadd_s64(vget_low_s64(v_y2_sum_b), vget_high_s64(v_y2_sum_b)), 0); | 
 | #endif | 
 |       x_sum += y; | 
 |       x2_sum += y2; | 
 |       x_finalrow += y; | 
 |       x2_finalrow += y2; | 
 |     } else { | 
 |       for (int j = 0; j < width - 1; ++j) { | 
 |         const int16_t x = diff[(height - 1) * stride + j]; | 
 |         const int16_t y = diff[(height - 1) * stride + j + 1]; | 
 |         xy_sum += x * y; | 
 |         x_sum += y; | 
 |         x2_sum += y * y; | 
 |         x_finalrow += y; | 
 |         x2_finalrow += y * y; | 
 |       } | 
 |     } | 
 |   } else {  // Two rows remaining to do | 
 |     const int16_t x0 = diff[(height - 2) * stride]; | 
 |     const int16_t z0 = diff[(height - 1) * stride]; | 
 |     x_sum += x0 + z0; | 
 |     x2_sum += x0 * x0 + z0 * z0; | 
 |     x_finalrow += z0; | 
 |     x2_finalrow += z0 * z0; | 
 |     if (width >= 8) { | 
 |       int32x4_t v_y2_sum = zero; | 
 |       int32x4_t v_w2_sum = zero; | 
 |       int32x4_t v_xy_sum_a = zero; | 
 |       int32x4_t v_xz_sum_a = zero; | 
 |       int32x4_t v_x_sum_a = zero; | 
 |       int32x4_t v_w_sum = zero; | 
 |       int k = width - 1; | 
 |       int j = 0; | 
 |       while ((k - 8) > 0) { | 
 |         const int16x8_t v_x = vld1q_s16(&diff[(height - 2) * stride + j]); | 
 |         const int16x8_t v_y = vld1q_s16(&diff[(height - 2) * stride + j + 1]); | 
 |         const int16x8_t v_z = vld1q_s16(&diff[(height - 1) * stride + j]); | 
 |         const int16x8_t v_w = vld1q_s16(&diff[(height - 1) * stride + j + 1]); | 
 |  | 
 |         const int16x4_t v_x_lo = vget_low_s16(v_x); | 
 |         const int16x4_t v_y_lo = vget_low_s16(v_y); | 
 |         const int16x4_t v_z_lo = vget_low_s16(v_z); | 
 |         const int16x4_t v_w_lo = vget_low_s16(v_w); | 
 |         const int16x4_t v_x_hi = vget_high_s16(v_x); | 
 |         const int16x4_t v_y_hi = vget_high_s16(v_y); | 
 |         const int16x4_t v_z_hi = vget_high_s16(v_z); | 
 |         const int16x4_t v_w_hi = vget_high_s16(v_w); | 
 |  | 
 |         v_xy_sum_a = vmlal_s16(v_xy_sum_a, v_x_lo, v_y_lo); | 
 |         v_xy_sum_a = vmlal_s16(v_xy_sum_a, v_x_hi, v_y_hi); | 
 |         v_xy_sum_a = vmlal_s16(v_xy_sum_a, v_z_lo, v_w_lo); | 
 |         v_xy_sum_a = vmlal_s16(v_xy_sum_a, v_z_hi, v_w_hi); | 
 |  | 
 |         v_xz_sum_a = vmlal_s16(v_xz_sum_a, v_x_lo, v_z_lo); | 
 |         v_xz_sum_a = vmlal_s16(v_xz_sum_a, v_x_hi, v_z_hi); | 
 |  | 
 |         v_w2_sum = vmlal_s16(v_w2_sum, v_w_lo, v_w_lo); | 
 |         v_w2_sum = vmlal_s16(v_w2_sum, v_w_hi, v_w_hi); | 
 |         v_y2_sum = vmlal_s16(v_y2_sum, v_y_lo, v_y_lo); | 
 |         v_y2_sum = vmlal_s16(v_y2_sum, v_y_hi, v_y_hi); | 
 |  | 
 |         v_w_sum = vpadalq_s16(v_w_sum, v_w); | 
 |         v_x_sum_a = vpadalq_s16(v_x_sum_a, v_y); | 
 |         v_x_sum_a = vpadalq_s16(v_x_sum_a, v_w); | 
 |  | 
 |         k -= 8; | 
 |         j += 8; | 
 |       } | 
 |       const int16x8_t v_l = vld1q_s16(&diff[(height - 2) * stride] + j); | 
 |       const int16x8_t v_x = | 
 |           vextq_s16(vextq_s16(vreinterpretq_s16_s32(zero), v_l, 7), | 
 |                     vreinterpretq_s16_s32(zero), 1); | 
 |       const int16x8_t v_y = vextq_s16(v_l, vreinterpretq_s16_s32(zero), 1); | 
 |       const int16x8_t v_l_2 = vld1q_s16(&diff[(height - 1) * stride] + j); | 
 |       const int16x8_t v_z = | 
 |           vextq_s16(vextq_s16(vreinterpretq_s16_s32(zero), v_l_2, 7), | 
 |                     vreinterpretq_s16_s32(zero), 1); | 
 |       const int16x8_t v_w = vextq_s16(v_l_2, vreinterpretq_s16_s32(zero), 1); | 
 |  | 
 |       const int16x4_t v_x_lo = vget_low_s16(v_x); | 
 |       const int16x4_t v_y_lo = vget_low_s16(v_y); | 
 |       const int16x4_t v_z_lo = vget_low_s16(v_z); | 
 |       const int16x4_t v_w_lo = vget_low_s16(v_w); | 
 |       const int16x4_t v_x_hi = vget_high_s16(v_x); | 
 |       const int16x4_t v_y_hi = vget_high_s16(v_y); | 
 |       const int16x4_t v_z_hi = vget_high_s16(v_z); | 
 |       const int16x4_t v_w_hi = vget_high_s16(v_w); | 
 |  | 
 |       v_xy_sum_a = vmlal_s16(v_xy_sum_a, v_x_lo, v_y_lo); | 
 |       v_xy_sum_a = vmlal_s16(v_xy_sum_a, v_x_hi, v_y_hi); | 
 |       v_xy_sum_a = vmlal_s16(v_xy_sum_a, v_z_lo, v_w_lo); | 
 |       v_xy_sum_a = vmlal_s16(v_xy_sum_a, v_z_hi, v_w_hi); | 
 |  | 
 |       v_xz_sum_a = vmlal_s16(v_xz_sum_a, v_x_lo, v_z_lo); | 
 |       v_xz_sum_a = vmlal_s16(v_xz_sum_a, v_x_hi, v_z_hi); | 
 |  | 
 |       v_w2_sum = vmlal_s16(v_w2_sum, v_w_lo, v_w_lo); | 
 |       v_w2_sum = vmlal_s16(v_w2_sum, v_w_hi, v_w_hi); | 
 |       v_y2_sum = vmlal_s16(v_y2_sum, v_y_lo, v_y_lo); | 
 |       v_y2_sum = vmlal_s16(v_y2_sum, v_y_hi, v_y_hi); | 
 |  | 
 |       v_w_sum = vpadalq_s16(v_w_sum, v_w); | 
 |       v_x_sum_a = vpadalq_s16(v_x_sum_a, v_y); | 
 |       v_x_sum_a = vpadalq_s16(v_x_sum_a, v_w); | 
 |  | 
 | #if defined(__aarch64__) | 
 |       xy_sum += vaddvq_s64(vpaddlq_s32(v_xy_sum_a)); | 
 |       xz_sum += vaddvq_s64(vpaddlq_s32(v_xz_sum_a)); | 
 |       x_sum += vaddvq_s32(v_x_sum_a); | 
 |       x_finalrow += vaddvq_s32(v_w_sum); | 
 |       int64_t y2 = vaddvq_s64(vpaddlq_s32(v_y2_sum)); | 
 |       int64_t w2 = vaddvq_s64(vpaddlq_s32(v_w2_sum)); | 
 | #else | 
 |       const int64x2_t v_xy_sum2 = vpaddlq_s32(v_xy_sum_a); | 
 |       xy_sum += vget_lane_s64( | 
 |           vadd_s64(vget_low_s64(v_xy_sum2), vget_high_s64(v_xy_sum2)), 0); | 
 |       const int64x2_t v_xz_sum2 = vpaddlq_s32(v_xz_sum_a); | 
 |       xz_sum += vget_lane_s64( | 
 |           vadd_s64(vget_low_s64(v_xz_sum2), vget_high_s64(v_xz_sum2)), 0); | 
 |       const int64x2_t v_x_sum2 = vpaddlq_s32(v_x_sum_a); | 
 |       x_sum += vget_lane_s64( | 
 |           vadd_s64(vget_low_s64(v_x_sum2), vget_high_s64(v_x_sum2)), 0); | 
 |       const int64x2_t v_w_sum_a = vpaddlq_s32(v_w_sum); | 
 |       x_finalrow += vget_lane_s64( | 
 |           vadd_s64(vget_low_s64(v_w_sum_a), vget_high_s64(v_w_sum_a)), 0); | 
 |       const int64x2_t v_y2_sum_a = vpaddlq_s32(v_y2_sum); | 
 |       int64_t y2 = vget_lane_s64( | 
 |           vadd_s64(vget_low_s64(v_y2_sum_a), vget_high_s64(v_y2_sum_a)), 0); | 
 |       const int64x2_t v_w2_sum_a = vpaddlq_s32(v_w2_sum); | 
 |       int64_t w2 = vget_lane_s64( | 
 |           vadd_s64(vget_low_s64(v_w2_sum_a), vget_high_s64(v_w2_sum_a)), 0); | 
 | #endif | 
 |       x2_sum += y2 + w2; | 
 |       x2_finalrow += w2; | 
 |     } else { | 
 |       for (int j = 0; j < width - 1; ++j) { | 
 |         const int16_t x = diff[(height - 2) * stride + j]; | 
 |         const int16_t y = diff[(height - 2) * stride + j + 1]; | 
 |         const int16_t z = diff[(height - 1) * stride + j]; | 
 |         const int16_t w = diff[(height - 1) * stride + j + 1]; | 
 |  | 
 |         // Horizontal and vertical correlations for the penultimate row: | 
 |         xy_sum += x * y; | 
 |         xz_sum += x * z; | 
 |  | 
 |         // Now just horizontal correlations for the final row: | 
 |         xy_sum += z * w; | 
 |  | 
 |         x_sum += y + w; | 
 |         x2_sum += y * y + w * w; | 
 |         x_finalrow += w; | 
 |         x2_finalrow += w * w; | 
 |       } | 
 |     } | 
 |   } | 
 |  | 
 |   // Do we have 2 columns remaining or just the one? | 
 |   if (width % 3 == 1) {  // Just vert corrs on the final col | 
 |     const int16_t x0 = diff[width - 1]; | 
 |     x_sum += x0; | 
 |     x_finalcol += x0; | 
 |     x2_sum += x0 * x0; | 
 |     x2_finalcol += x0 * x0; | 
 |     for (int i = 0; i < height - 1; ++i) { | 
 |       const int16_t x = diff[i * stride + width - 1]; | 
 |       const int16_t z = diff[(i + 1) * stride + width - 1]; | 
 |       xz_sum += x * z; | 
 |       x_finalcol += z; | 
 |       x2_finalcol += z * z; | 
 |       // So the bottom-right elements don't get counted twice: | 
 |       if (i < height - (height % 3 == 1 ? 2 : 3)) { | 
 |         x_sum += z; | 
 |         x2_sum += z * z; | 
 |       } | 
 |     } | 
 |   } else {  // Two cols remaining | 
 |     const int16_t x0 = diff[width - 2]; | 
 |     const int16_t y0 = diff[width - 1]; | 
 |     x_sum += x0 + y0; | 
 |     x2_sum += x0 * x0 + y0 * y0; | 
 |     x_finalcol += y0; | 
 |     x2_finalcol += y0 * y0; | 
 |     for (int i = 0; i < height - 1; ++i) { | 
 |       const int16_t x = diff[i * stride + width - 2]; | 
 |       const int16_t y = diff[i * stride + width - 1]; | 
 |       const int16_t z = diff[(i + 1) * stride + width - 2]; | 
 |       const int16_t w = diff[(i + 1) * stride + width - 1]; | 
 |  | 
 |       // Horizontal and vertical correlations for the penultimate col: | 
 |       // Skip these on the last iteration of this loop if we also had two | 
 |       // rows remaining, otherwise the final horizontal and vertical correlation | 
 |       // get erroneously processed twice | 
 |       if (i < height - 2 || height % 3 == 1) { | 
 |         xy_sum += x * y; | 
 |         xz_sum += x * z; | 
 |       } | 
 |  | 
 |       x_finalcol += w; | 
 |       x2_finalcol += w * w; | 
 |       // So the bottom-right elements don't get counted twice: | 
 |       if (i < height - (height % 3 == 1 ? 2 : 3)) { | 
 |         x_sum += z + w; | 
 |         x2_sum += z * z + w * w; | 
 |       } | 
 |  | 
 |       // Now just vertical correlations for the final column: | 
 |       xz_sum += y * w; | 
 |     } | 
 |   } | 
 |  | 
 |   // Calculate the simple sums and squared-sums | 
 |   int64_t x_firstrow = 0, x_firstcol = 0; | 
 |   int64_t x2_firstrow = 0, x2_firstcol = 0; | 
 |  | 
 |   if (width >= 8) { | 
 |     int32x4_t v_x_firstrow = zero; | 
 |     int32x4_t v_x2_firstrow = zero; | 
 |     for (int j = 0; j < width; j += 8) { | 
 |       const int16x8_t v_diff = vld1q_s16(diff + j); | 
 |       const int16x4_t v_diff_lo = vget_low_s16(v_diff); | 
 |       const int16x4_t v_diff_hi = vget_high_s16(v_diff); | 
 |       v_x_firstrow = vpadalq_s16(v_x_firstrow, v_diff); | 
 |       v_x2_firstrow = vmlal_s16(v_x2_firstrow, v_diff_lo, v_diff_lo); | 
 |       v_x2_firstrow = vmlal_s16(v_x2_firstrow, v_diff_hi, v_diff_hi); | 
 |     } | 
 | #if defined(__aarch64__) | 
 |     x_firstrow += vaddvq_s32(v_x_firstrow); | 
 |     x2_firstrow += vaddvq_s32(v_x2_firstrow); | 
 | #else | 
 |     const int64x2_t v_x_firstrow_64 = vpaddlq_s32(v_x_firstrow); | 
 |     x_firstrow += vget_lane_s64( | 
 |         vadd_s64(vget_low_s64(v_x_firstrow_64), vget_high_s64(v_x_firstrow_64)), | 
 |         0); | 
 |     const int64x2_t v_x2_firstrow_64 = vpaddlq_s32(v_x2_firstrow); | 
 |     x2_firstrow += vget_lane_s64(vadd_s64(vget_low_s64(v_x2_firstrow_64), | 
 |                                           vget_high_s64(v_x2_firstrow_64)), | 
 |                                  0); | 
 | #endif | 
 |   } else { | 
 |     for (int j = 0; j < width; ++j) { | 
 |       x_firstrow += diff[j]; | 
 |       x2_firstrow += diff[j] * diff[j]; | 
 |     } | 
 |   } | 
 |   for (int i = 0; i < height; ++i) { | 
 |     x_firstcol += diff[i * stride]; | 
 |     x2_firstcol += diff[i * stride] * diff[i * stride]; | 
 |   } | 
 |  | 
 |   int64_t xhor_sum = x_sum - x_finalcol; | 
 |   int64_t xver_sum = x_sum - x_finalrow; | 
 |   int64_t y_sum = x_sum - x_firstcol; | 
 |   int64_t z_sum = x_sum - x_firstrow; | 
 |   int64_t x2hor_sum = x2_sum - x2_finalcol; | 
 |   int64_t x2ver_sum = x2_sum - x2_finalrow; | 
 |   int64_t y2_sum = x2_sum - x2_firstcol; | 
 |   int64_t z2_sum = x2_sum - x2_firstrow; | 
 |  | 
 |   aom_clear_system_state(); | 
 |  | 
 |   const float num_hor = (float)(height * (width - 1)); | 
 |   const float num_ver = (float)((height - 1) * width); | 
 |  | 
 |   const float xhor_var_n = x2hor_sum - (xhor_sum * xhor_sum) / num_hor; | 
 |   const float xver_var_n = x2ver_sum - (xver_sum * xver_sum) / num_ver; | 
 |  | 
 |   const float y_var_n = y2_sum - (y_sum * y_sum) / num_hor; | 
 |   const float z_var_n = z2_sum - (z_sum * z_sum) / num_ver; | 
 |  | 
 |   const float xy_var_n = xy_sum - (xhor_sum * y_sum) / num_hor; | 
 |   const float xz_var_n = xz_sum - (xver_sum * z_sum) / num_ver; | 
 |  | 
 |   if (xhor_var_n > 0 && y_var_n > 0) { | 
 |     *hcorr = xy_var_n / sqrtf(xhor_var_n * y_var_n); | 
 |     *hcorr = *hcorr < 0 ? 0 : *hcorr; | 
 |   } else { | 
 |     *hcorr = 1.0; | 
 |   } | 
 |   if (xver_var_n > 0 && z_var_n > 0) { | 
 |     *vcorr = xz_var_n / sqrtf(xver_var_n * z_var_n); | 
 |     *vcorr = *vcorr < 0 ? 0 : *vcorr; | 
 |   } else { | 
 |     *vcorr = 1.0; | 
 |   } | 
 | } |