AOM/third_party/libyuv/source/compare_neon64.cc

/*
 *  Copyright 2012 The LibYuv Project Authors. All rights reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS. All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#include "libyuv/basic_types.h"

#include "libyuv/compare_row.h"
#include "libyuv/row.h"

#ifdef __cplusplus
namespace libyuv {
extern "C" {
#endif

#if !defined(LIBYUV_DISABLE_NEON) && defined(__aarch64__)

// 256 bits at a time
// uses short accumulator which restricts count to 131 KB
uint32_t HammingDistance_NEON(const uint8_t* src_a,
                              const uint8_t* src_b,
                              int count) {
  uint32_t diff;
  asm volatile(
      "movi        v4.8h, #0                     \n"

      "1:                                        \n"
      "ld1         {v0.16b, v1.16b}, [%0], #32   \n"
      "ld1         {v2.16b, v3.16b}, [%1], #32   \n"
      "eor         v0.16b, v0.16b, v2.16b        \n"
      "prfm        pldl1keep, [%0, 448]          \n"  // prefetch 7 lines ahead
      "eor         v1.16b, v1.16b, v3.16b        \n"
      "cnt         v0.16b, v0.16b                \n"
      "prfm        pldl1keep, [%1, 448]          \n"
      "cnt         v1.16b, v1.16b                \n"
      "subs        %w2, %w2, #32                 \n"
      "add         v0.16b, v0.16b, v1.16b        \n"
      "uadalp      v4.8h, v0.16b                 \n"
      "b.gt        1b                            \n"

      "uaddlv      s4, v4.8h                     \n"
      "fmov        %w3, s4                       \n"
      : "+r"(src_a), "+r"(src_b), "+r"(count), "=r"(diff)
      :
      : "cc", "v0", "v1", "v2", "v3", "v4");
  return diff;
}

uint32_t SumSquareError_NEON(const uint8_t* src_a,
                             const uint8_t* src_b,
                             int count) {
  uint32_t sse;
  asm volatile(
      "eor         v16.16b, v16.16b, v16.16b     \n"
      "eor         v18.16b, v18.16b, v18.16b     \n"
      "eor         v17.16b, v17.16b, v17.16b     \n"
      "eor         v19.16b, v19.16b, v19.16b     \n"

      "1:                                        \n"
      "ld1         {v0.16b}, [%0], #16           \n"
      "ld1         {v1.16b}, [%1], #16           \n"
      "subs        %w2, %w2, #16                 \n"
      "usubl       v2.8h, v0.8b, v1.8b           \n"
      "usubl2      v3.8h, v0.16b, v1.16b         \n"
      "prfm        pldl1keep, [%0, 448]          \n"  // prefetch 7 lines ahead
      "smlal       v16.4s, v2.4h, v2.4h          \n"
      "smlal       v17.4s, v3.4h, v3.4h          \n"
      "prfm        pldl1keep, [%1, 448]          \n"
      "smlal2      v18.4s, v2.8h, v2.8h          \n"
      "smlal2      v19.4s, v3.8h, v3.8h          \n"
      "b.gt        1b                            \n"

      "add         v16.4s, v16.4s, v17.4s        \n"
      "add         v18.4s, v18.4s, v19.4s        \n"
      "add         v19.4s, v16.4s, v18.4s        \n"
      "addv        s0, v19.4s                    \n"
      "fmov        %w3, s0                       \n"
      : "+r"(src_a), "+r"(src_b), "+r"(count), "=r"(sse)
      :
      : "cc", "v0", "v1", "v2", "v3", "v16", "v17", "v18", "v19");
  return sse;
}

#endif  // !defined(LIBYUV_DISABLE_NEON) && defined(__aarch64__)

#ifdef __cplusplus
}  // extern "C"
}  // namespace libyuv
#endif