Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 622 insertions, 0 deletions

diff --git a/media/libjpeg/simd/arm/jcphuff-neon.c b/media/libjpeg/simd/arm/jcphuff-neon.c
new file mode 100644
index 0000000000..b91c5db478
--- /dev/null
+++ b/media/libjpeg/simd/arm/jcphuff-neon.c
@@ -0,0 +1,622 @@
+/*
+ * jcphuff-neon.c - prepare data for progressive Huffman encoding (Arm Neon)
+ *
+ * Copyright (C) 2020-2021, Arm Limited.  All Rights Reserved.
+ *
+ * This software is provided 'as-is', without any express or implied
+ * warranty.  In no event will the authors be held liable for any damages
+ * arising from the use of this software.
+ *
+ * Permission is granted to anyone to use this software for any purpose,
+ * including commercial applications, and to alter it and redistribute it
+ * freely, subject to the following restrictions:
+ *
+ * 1. The origin of this software must not be misrepresented; you must not
+ *    claim that you wrote the original software. If you use this software
+ *    in a product, an acknowledgment in the product documentation would be
+ *    appreciated but is not required.
+ * 2. Altered source versions must be plainly marked as such, and must not be
+ *    misrepresented as being the original software.
+ * 3. This notice may not be removed or altered from any source distribution.
+ */
+
+#define JPEG_INTERNALS
+#include "jconfigint.h"
+#include "../../jinclude.h"
+#include "../../jpeglib.h"
+#include "../../jsimd.h"
+#include "../../jdct.h"
+#include "../../jsimddct.h"
+#include "../jsimd.h"
+#include "neon-compat.h"
+
+#include <arm_neon.h>
+
+
+/* Data preparation for encode_mcu_AC_first().
+ *
+ * The equivalent scalar C function (encode_mcu_AC_first_prepare()) can be
+ * found in jcphuff.c.
+ */
+
+void jsimd_encode_mcu_AC_first_prepare_neon
+  (const JCOEF *block, const int *jpeg_natural_order_start, int Sl, int Al,
+   JCOEF *values, size_t *zerobits)
+{
+  JCOEF *values_ptr = values;
+  JCOEF *diff_values_ptr = values + DCTSIZE2;
+
+  /* Rows of coefficients to zero (since they haven't been processed) */
+  int i, rows_to_zero = 8;
+
+  for (i = 0; i < Sl / 16; i++) {
+    int16x8_t coefs1 = vld1q_dup_s16(block + jpeg_natural_order_start[0]);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[1], coefs1, 1);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[2], coefs1, 2);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[3], coefs1, 3);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[4], coefs1, 4);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[5], coefs1, 5);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[6], coefs1, 6);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[7], coefs1, 7);
+    int16x8_t coefs2 = vld1q_dup_s16(block + jpeg_natural_order_start[8]);
+    coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[9], coefs2, 1);
+    coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[10], coefs2, 2);
+    coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[11], coefs2, 3);
+    coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[12], coefs2, 4);
+    coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[13], coefs2, 5);
+    coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[14], coefs2, 6);
+    coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[15], coefs2, 7);
+
+    /* Isolate sign of coefficients. */
+    int16x8_t sign_coefs1 = vshrq_n_s16(coefs1, 15);
+    int16x8_t sign_coefs2 = vshrq_n_s16(coefs2, 15);
+    /* Compute absolute value of coefficients and apply point transform Al. */
+    int16x8_t abs_coefs1 = vabsq_s16(coefs1);
+    int16x8_t abs_coefs2 = vabsq_s16(coefs2);
+    coefs1 = vshlq_s16(abs_coefs1, vdupq_n_s16(-Al));
+    coefs2 = vshlq_s16(abs_coefs2, vdupq_n_s16(-Al));
+
+    /* Compute diff values. */
+    int16x8_t diff1 = veorq_s16(coefs1, sign_coefs1);
+    int16x8_t diff2 = veorq_s16(coefs2, sign_coefs2);
+
+    /* Store transformed coefficients and diff values. */
+    vst1q_s16(values_ptr, coefs1);
+    vst1q_s16(values_ptr + DCTSIZE, coefs2);
+    vst1q_s16(diff_values_ptr, diff1);
+    vst1q_s16(diff_values_ptr + DCTSIZE, diff2);
+    values_ptr += 16;
+    diff_values_ptr += 16;
+    jpeg_natural_order_start += 16;
+    rows_to_zero -= 2;
+  }
+
+  /* Same operation but for remaining partial vector */
+  int remaining_coefs = Sl % 16;
+  if (remaining_coefs > 8) {
+    int16x8_t coefs1 = vld1q_dup_s16(block + jpeg_natural_order_start[0]);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[1], coefs1, 1);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[2], coefs1, 2);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[3], coefs1, 3);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[4], coefs1, 4);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[5], coefs1, 5);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[6], coefs1, 6);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[7], coefs1, 7);
+    int16x8_t coefs2 = vdupq_n_s16(0);
+    switch (remaining_coefs) {
+    case 15:
+      coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[14], coefs2, 6);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 14:
+      coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[13], coefs2, 5);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 13:
+      coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[12], coefs2, 4);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 12:
+      coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[11], coefs2, 3);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 11:
+      coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[10], coefs2, 2);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 10:
+      coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[9], coefs2, 1);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 9:
+      coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[8], coefs2, 0);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    default:
+      break;
+    }
+
+    /* Isolate sign of coefficients. */
+    int16x8_t sign_coefs1 = vshrq_n_s16(coefs1, 15);
+    int16x8_t sign_coefs2 = vshrq_n_s16(coefs2, 15);
+    /* Compute absolute value of coefficients and apply point transform Al. */
+    int16x8_t abs_coefs1 = vabsq_s16(coefs1);
+    int16x8_t abs_coefs2 = vabsq_s16(coefs2);
+    coefs1 = vshlq_s16(abs_coefs1, vdupq_n_s16(-Al));
+    coefs2 = vshlq_s16(abs_coefs2, vdupq_n_s16(-Al));
+
+    /* Compute diff values. */
+    int16x8_t diff1 = veorq_s16(coefs1, sign_coefs1);
+    int16x8_t diff2 = veorq_s16(coefs2, sign_coefs2);
+
+    /* Store transformed coefficients and diff values. */
+    vst1q_s16(values_ptr, coefs1);
+    vst1q_s16(values_ptr + DCTSIZE, coefs2);
+    vst1q_s16(diff_values_ptr, diff1);
+    vst1q_s16(diff_values_ptr + DCTSIZE, diff2);
+    values_ptr += 16;
+    diff_values_ptr += 16;
+    rows_to_zero -= 2;
+
+  } else if (remaining_coefs > 0) {
+    int16x8_t coefs = vdupq_n_s16(0);
+
+    switch (remaining_coefs) {
+    case 8:
+      coefs = vld1q_lane_s16(block + jpeg_natural_order_start[7], coefs, 7);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 7:
+      coefs = vld1q_lane_s16(block + jpeg_natural_order_start[6], coefs, 6);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 6:
+      coefs = vld1q_lane_s16(block + jpeg_natural_order_start[5], coefs, 5);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 5:
+      coefs = vld1q_lane_s16(block + jpeg_natural_order_start[4], coefs, 4);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 4:
+      coefs = vld1q_lane_s16(block + jpeg_natural_order_start[3], coefs, 3);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 3:
+      coefs = vld1q_lane_s16(block + jpeg_natural_order_start[2], coefs, 2);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 2:
+      coefs = vld1q_lane_s16(block + jpeg_natural_order_start[1], coefs, 1);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 1:
+      coefs = vld1q_lane_s16(block + jpeg_natural_order_start[0], coefs, 0);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    default:
+      break;
+    }
+
+    /* Isolate sign of coefficients. */
+    int16x8_t sign_coefs = vshrq_n_s16(coefs, 15);
+    /* Compute absolute value of coefficients and apply point transform Al. */
+    int16x8_t abs_coefs = vabsq_s16(coefs);
+    coefs = vshlq_s16(abs_coefs, vdupq_n_s16(-Al));
+
+    /* Compute diff values. */
+    int16x8_t diff = veorq_s16(coefs, sign_coefs);
+
+    /* Store transformed coefficients and diff values. */
+    vst1q_s16(values_ptr, coefs);
+    vst1q_s16(diff_values_ptr, diff);
+    values_ptr += 8;
+    diff_values_ptr += 8;
+    rows_to_zero--;
+  }
+
+  /* Zero remaining memory in the values and diff_values blocks. */
+  for (i = 0; i < rows_to_zero; i++) {
+    vst1q_s16(values_ptr, vdupq_n_s16(0));
+    vst1q_s16(diff_values_ptr, vdupq_n_s16(0));
+    values_ptr += 8;
+    diff_values_ptr += 8;
+  }
+
+  /* Construct zerobits bitmap.  A set bit means that the corresponding
+   * coefficient != 0.
+   */
+  int16x8_t row0 = vld1q_s16(values + 0 * DCTSIZE);
+  int16x8_t row1 = vld1q_s16(values + 1 * DCTSIZE);
+  int16x8_t row2 = vld1q_s16(values + 2 * DCTSIZE);
+  int16x8_t row3 = vld1q_s16(values + 3 * DCTSIZE);
+  int16x8_t row4 = vld1q_s16(values + 4 * DCTSIZE);
+  int16x8_t row5 = vld1q_s16(values + 5 * DCTSIZE);
+  int16x8_t row6 = vld1q_s16(values + 6 * DCTSIZE);
+  int16x8_t row7 = vld1q_s16(values + 7 * DCTSIZE);
+
+  uint8x8_t row0_eq0 = vmovn_u16(vceqq_s16(row0, vdupq_n_s16(0)));
+  uint8x8_t row1_eq0 = vmovn_u16(vceqq_s16(row1, vdupq_n_s16(0)));
+  uint8x8_t row2_eq0 = vmovn_u16(vceqq_s16(row2, vdupq_n_s16(0)));
+  uint8x8_t row3_eq0 = vmovn_u16(vceqq_s16(row3, vdupq_n_s16(0)));
+  uint8x8_t row4_eq0 = vmovn_u16(vceqq_s16(row4, vdupq_n_s16(0)));
+  uint8x8_t row5_eq0 = vmovn_u16(vceqq_s16(row5, vdupq_n_s16(0)));
+  uint8x8_t row6_eq0 = vmovn_u16(vceqq_s16(row6, vdupq_n_s16(0)));
+  uint8x8_t row7_eq0 = vmovn_u16(vceqq_s16(row7, vdupq_n_s16(0)));
+
+  /* { 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80 } */
+  const uint8x8_t bitmap_mask =
+    vreinterpret_u8_u64(vmov_n_u64(0x8040201008040201));
+
+  row0_eq0 = vand_u8(row0_eq0, bitmap_mask);
+  row1_eq0 = vand_u8(row1_eq0, bitmap_mask);
+  row2_eq0 = vand_u8(row2_eq0, bitmap_mask);
+  row3_eq0 = vand_u8(row3_eq0, bitmap_mask);
+  row4_eq0 = vand_u8(row4_eq0, bitmap_mask);
+  row5_eq0 = vand_u8(row5_eq0, bitmap_mask);
+  row6_eq0 = vand_u8(row6_eq0, bitmap_mask);
+  row7_eq0 = vand_u8(row7_eq0, bitmap_mask);
+
+  uint8x8_t bitmap_rows_01 = vpadd_u8(row0_eq0, row1_eq0);
+  uint8x8_t bitmap_rows_23 = vpadd_u8(row2_eq0, row3_eq0);
+  uint8x8_t bitmap_rows_45 = vpadd_u8(row4_eq0, row5_eq0);
+  uint8x8_t bitmap_rows_67 = vpadd_u8(row6_eq0, row7_eq0);
+  uint8x8_t bitmap_rows_0123 = vpadd_u8(bitmap_rows_01, bitmap_rows_23);
+  uint8x8_t bitmap_rows_4567 = vpadd_u8(bitmap_rows_45, bitmap_rows_67);
+  uint8x8_t bitmap_all = vpadd_u8(bitmap_rows_0123, bitmap_rows_4567);
+
+#if defined(__aarch64__) || defined(_M_ARM64)
+  /* Move bitmap to a 64-bit scalar register. */
+  uint64_t bitmap = vget_lane_u64(vreinterpret_u64_u8(bitmap_all), 0);
+  /* Store zerobits bitmap. */
+  *zerobits = ~bitmap;
+#else
+  /* Move bitmap to two 32-bit scalar registers. */
+  uint32_t bitmap0 = vget_lane_u32(vreinterpret_u32_u8(bitmap_all), 0);
+  uint32_t bitmap1 = vget_lane_u32(vreinterpret_u32_u8(bitmap_all), 1);
+  /* Store zerobits bitmap. */
+  zerobits[0] = ~bitmap0;
+  zerobits[1] = ~bitmap1;
+#endif
+}
+
+
+/* Data preparation for encode_mcu_AC_refine().
+ *
+ * The equivalent scalar C function (encode_mcu_AC_refine_prepare()) can be
+ * found in jcphuff.c.
+ */
+
+int jsimd_encode_mcu_AC_refine_prepare_neon
+  (const JCOEF *block, const int *jpeg_natural_order_start, int Sl, int Al,
+   JCOEF *absvalues, size_t *bits)
+{
+  /* Temporary storage buffers for data used to compute the signbits bitmap and
+   * the end-of-block (EOB) position
+   */
+  uint8_t coef_sign_bits[64];
+  uint8_t coef_eq1_bits[64];
+
+  JCOEF *absvalues_ptr = absvalues;
+  uint8_t *coef_sign_bits_ptr = coef_sign_bits;
+  uint8_t *eq1_bits_ptr = coef_eq1_bits;
+
+  /* Rows of coefficients to zero (since they haven't been processed) */
+  int i, rows_to_zero = 8;
+
+  for (i = 0; i < Sl / 16; i++) {
+    int16x8_t coefs1 = vld1q_dup_s16(block + jpeg_natural_order_start[0]);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[1], coefs1, 1);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[2], coefs1, 2);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[3], coefs1, 3);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[4], coefs1, 4);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[5], coefs1, 5);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[6], coefs1, 6);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[7], coefs1, 7);
+    int16x8_t coefs2 = vld1q_dup_s16(block + jpeg_natural_order_start[8]);
+    coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[9], coefs2, 1);
+    coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[10], coefs2, 2);
+    coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[11], coefs2, 3);
+    coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[12], coefs2, 4);
+    coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[13], coefs2, 5);
+    coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[14], coefs2, 6);
+    coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[15], coefs2, 7);
+
+    /* Compute and store data for signbits bitmap. */
+    uint8x8_t sign_coefs1 =
+      vmovn_u16(vreinterpretq_u16_s16(vshrq_n_s16(coefs1, 15)));
+    uint8x8_t sign_coefs2 =
+      vmovn_u16(vreinterpretq_u16_s16(vshrq_n_s16(coefs2, 15)));
+    vst1_u8(coef_sign_bits_ptr, sign_coefs1);
+    vst1_u8(coef_sign_bits_ptr + DCTSIZE, sign_coefs2);
+
+    /* Compute absolute value of coefficients and apply point transform Al. */
+    int16x8_t abs_coefs1 = vabsq_s16(coefs1);
+    int16x8_t abs_coefs2 = vabsq_s16(coefs2);
+    coefs1 = vshlq_s16(abs_coefs1, vdupq_n_s16(-Al));
+    coefs2 = vshlq_s16(abs_coefs2, vdupq_n_s16(-Al));
+    vst1q_s16(absvalues_ptr, coefs1);
+    vst1q_s16(absvalues_ptr + DCTSIZE, coefs2);
+
+    /* Test whether transformed coefficient values == 1 (used to find EOB
+     * position.)
+     */
+    uint8x8_t coefs_eq11 = vmovn_u16(vceqq_s16(coefs1, vdupq_n_s16(1)));
+    uint8x8_t coefs_eq12 = vmovn_u16(vceqq_s16(coefs2, vdupq_n_s16(1)));
+    vst1_u8(eq1_bits_ptr, coefs_eq11);
+    vst1_u8(eq1_bits_ptr + DCTSIZE, coefs_eq12);
+
+    absvalues_ptr += 16;
+    coef_sign_bits_ptr += 16;
+    eq1_bits_ptr += 16;
+    jpeg_natural_order_start += 16;
+    rows_to_zero -= 2;
+  }
+
+  /* Same operation but for remaining partial vector */
+  int remaining_coefs = Sl % 16;
+  if (remaining_coefs > 8) {
+    int16x8_t coefs1 = vld1q_dup_s16(block + jpeg_natural_order_start[0]);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[1], coefs1, 1);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[2], coefs1, 2);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[3], coefs1, 3);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[4], coefs1, 4);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[5], coefs1, 5);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[6], coefs1, 6);
+    coefs1 = vld1q_lane_s16(block + jpeg_natural_order_start[7], coefs1, 7);
+    int16x8_t coefs2 = vdupq_n_s16(0);
+    switch (remaining_coefs) {
+    case 15:
+      coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[14], coefs2, 6);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 14:
+      coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[13], coefs2, 5);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 13:
+      coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[12], coefs2, 4);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 12:
+      coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[11], coefs2, 3);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 11:
+      coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[10], coefs2, 2);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 10:
+      coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[9], coefs2, 1);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 9:
+      coefs2 = vld1q_lane_s16(block + jpeg_natural_order_start[8], coefs2, 0);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    default:
+      break;
+    }
+
+    /* Compute and store data for signbits bitmap. */
+    uint8x8_t sign_coefs1 =
+      vmovn_u16(vreinterpretq_u16_s16(vshrq_n_s16(coefs1, 15)));
+    uint8x8_t sign_coefs2 =
+      vmovn_u16(vreinterpretq_u16_s16(vshrq_n_s16(coefs2, 15)));
+    vst1_u8(coef_sign_bits_ptr, sign_coefs1);
+    vst1_u8(coef_sign_bits_ptr + DCTSIZE, sign_coefs2);
+
+    /* Compute absolute value of coefficients and apply point transform Al. */
+    int16x8_t abs_coefs1 = vabsq_s16(coefs1);
+    int16x8_t abs_coefs2 = vabsq_s16(coefs2);
+    coefs1 = vshlq_s16(abs_coefs1, vdupq_n_s16(-Al));
+    coefs2 = vshlq_s16(abs_coefs2, vdupq_n_s16(-Al));
+    vst1q_s16(absvalues_ptr, coefs1);
+    vst1q_s16(absvalues_ptr + DCTSIZE, coefs2);
+
+    /* Test whether transformed coefficient values == 1 (used to find EOB
+     * position.)
+     */
+    uint8x8_t coefs_eq11 = vmovn_u16(vceqq_s16(coefs1, vdupq_n_s16(1)));
+    uint8x8_t coefs_eq12 = vmovn_u16(vceqq_s16(coefs2, vdupq_n_s16(1)));
+    vst1_u8(eq1_bits_ptr, coefs_eq11);
+    vst1_u8(eq1_bits_ptr + DCTSIZE, coefs_eq12);
+
+    absvalues_ptr += 16;
+    coef_sign_bits_ptr += 16;
+    eq1_bits_ptr += 16;
+    jpeg_natural_order_start += 16;
+    rows_to_zero -= 2;
+
+  } else if (remaining_coefs > 0) {
+    int16x8_t coefs = vdupq_n_s16(0);
+
+    switch (remaining_coefs) {
+    case 8:
+      coefs = vld1q_lane_s16(block + jpeg_natural_order_start[7], coefs, 7);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 7:
+      coefs = vld1q_lane_s16(block + jpeg_natural_order_start[6], coefs, 6);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 6:
+      coefs = vld1q_lane_s16(block + jpeg_natural_order_start[5], coefs, 5);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 5:
+      coefs = vld1q_lane_s16(block + jpeg_natural_order_start[4], coefs, 4);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 4:
+      coefs = vld1q_lane_s16(block + jpeg_natural_order_start[3], coefs, 3);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 3:
+      coefs = vld1q_lane_s16(block + jpeg_natural_order_start[2], coefs, 2);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 2:
+      coefs = vld1q_lane_s16(block + jpeg_natural_order_start[1], coefs, 1);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    case 1:
+      coefs = vld1q_lane_s16(block + jpeg_natural_order_start[0], coefs, 0);
+      FALLTHROUGH               /*FALLTHROUGH*/
+    default:
+      break;
+    }
+
+    /* Compute and store data for signbits bitmap. */
+    uint8x8_t sign_coefs =
+      vmovn_u16(vreinterpretq_u16_s16(vshrq_n_s16(coefs, 15)));
+    vst1_u8(coef_sign_bits_ptr, sign_coefs);
+
+    /* Compute absolute value of coefficients and apply point transform Al. */
+    int16x8_t abs_coefs = vabsq_s16(coefs);
+    coefs = vshlq_s16(abs_coefs, vdupq_n_s16(-Al));
+    vst1q_s16(absvalues_ptr, coefs);
+
+    /* Test whether transformed coefficient values == 1 (used to find EOB
+     * position.)
+     */
+    uint8x8_t coefs_eq1 = vmovn_u16(vceqq_s16(coefs, vdupq_n_s16(1)));
+    vst1_u8(eq1_bits_ptr, coefs_eq1);
+
+    absvalues_ptr += 8;
+    coef_sign_bits_ptr += 8;
+    eq1_bits_ptr += 8;
+    rows_to_zero--;
+  }
+
+  /* Zero remaining memory in blocks. */
+  for (i = 0; i < rows_to_zero; i++) {
+    vst1q_s16(absvalues_ptr, vdupq_n_s16(0));
+    vst1_u8(coef_sign_bits_ptr, vdup_n_u8(0));
+    vst1_u8(eq1_bits_ptr, vdup_n_u8(0));
+    absvalues_ptr += 8;
+    coef_sign_bits_ptr += 8;
+    eq1_bits_ptr += 8;
+  }
+
+  /* Construct zerobits bitmap. */
+  int16x8_t abs_row0 = vld1q_s16(absvalues + 0 * DCTSIZE);
+  int16x8_t abs_row1 = vld1q_s16(absvalues + 1 * DCTSIZE);
+  int16x8_t abs_row2 = vld1q_s16(absvalues + 2 * DCTSIZE);
+  int16x8_t abs_row3 = vld1q_s16(absvalues + 3 * DCTSIZE);
+  int16x8_t abs_row4 = vld1q_s16(absvalues + 4 * DCTSIZE);
+  int16x8_t abs_row5 = vld1q_s16(absvalues + 5 * DCTSIZE);
+  int16x8_t abs_row6 = vld1q_s16(absvalues + 6 * DCTSIZE);
+  int16x8_t abs_row7 = vld1q_s16(absvalues + 7 * DCTSIZE);
+
+  uint8x8_t abs_row0_eq0 = vmovn_u16(vceqq_s16(abs_row0, vdupq_n_s16(0)));
+  uint8x8_t abs_row1_eq0 = vmovn_u16(vceqq_s16(abs_row1, vdupq_n_s16(0)));
+  uint8x8_t abs_row2_eq0 = vmovn_u16(vceqq_s16(abs_row2, vdupq_n_s16(0)));
+  uint8x8_t abs_row3_eq0 = vmovn_u16(vceqq_s16(abs_row3, vdupq_n_s16(0)));
+  uint8x8_t abs_row4_eq0 = vmovn_u16(vceqq_s16(abs_row4, vdupq_n_s16(0)));
+  uint8x8_t abs_row5_eq0 = vmovn_u16(vceqq_s16(abs_row5, vdupq_n_s16(0)));
+  uint8x8_t abs_row6_eq0 = vmovn_u16(vceqq_s16(abs_row6, vdupq_n_s16(0)));
+  uint8x8_t abs_row7_eq0 = vmovn_u16(vceqq_s16(abs_row7, vdupq_n_s16(0)));
+
+  /* { 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80 } */
+  const uint8x8_t bitmap_mask =
+    vreinterpret_u8_u64(vmov_n_u64(0x8040201008040201));
+
+  abs_row0_eq0 = vand_u8(abs_row0_eq0, bitmap_mask);
+  abs_row1_eq0 = vand_u8(abs_row1_eq0, bitmap_mask);
+  abs_row2_eq0 = vand_u8(abs_row2_eq0, bitmap_mask);
+  abs_row3_eq0 = vand_u8(abs_row3_eq0, bitmap_mask);
+  abs_row4_eq0 = vand_u8(abs_row4_eq0, bitmap_mask);
+  abs_row5_eq0 = vand_u8(abs_row5_eq0, bitmap_mask);
+  abs_row6_eq0 = vand_u8(abs_row6_eq0, bitmap_mask);
+  abs_row7_eq0 = vand_u8(abs_row7_eq0, bitmap_mask);
+
+  uint8x8_t bitmap_rows_01 = vpadd_u8(abs_row0_eq0, abs_row1_eq0);
+  uint8x8_t bitmap_rows_23 = vpadd_u8(abs_row2_eq0, abs_row3_eq0);
+  uint8x8_t bitmap_rows_45 = vpadd_u8(abs_row4_eq0, abs_row5_eq0);
+  uint8x8_t bitmap_rows_67 = vpadd_u8(abs_row6_eq0, abs_row7_eq0);
+  uint8x8_t bitmap_rows_0123 = vpadd_u8(bitmap_rows_01, bitmap_rows_23);
+  uint8x8_t bitmap_rows_4567 = vpadd_u8(bitmap_rows_45, bitmap_rows_67);
+  uint8x8_t bitmap_all = vpadd_u8(bitmap_rows_0123, bitmap_rows_4567);
+
+#if defined(__aarch64__) || defined(_M_ARM64)
+  /* Move bitmap to a 64-bit scalar register. */
+  uint64_t bitmap = vget_lane_u64(vreinterpret_u64_u8(bitmap_all), 0);
+  /* Store zerobits bitmap. */
+  bits[0] = ~bitmap;
+#else
+  /* Move bitmap to two 32-bit scalar registers. */
+  uint32_t bitmap0 = vget_lane_u32(vreinterpret_u32_u8(bitmap_all), 0);
+  uint32_t bitmap1 = vget_lane_u32(vreinterpret_u32_u8(bitmap_all), 1);
+  /* Store zerobits bitmap. */
+  bits[0] = ~bitmap0;
+  bits[1] = ~bitmap1;
+#endif
+
+  /* Construct signbits bitmap. */
+  uint8x8_t signbits_row0 = vld1_u8(coef_sign_bits + 0 * DCTSIZE);
+  uint8x8_t signbits_row1 = vld1_u8(coef_sign_bits + 1 * DCTSIZE);
+  uint8x8_t signbits_row2 = vld1_u8(coef_sign_bits + 2 * DCTSIZE);
+  uint8x8_t signbits_row3 = vld1_u8(coef_sign_bits + 3 * DCTSIZE);
+  uint8x8_t signbits_row4 = vld1_u8(coef_sign_bits + 4 * DCTSIZE);
+  uint8x8_t signbits_row5 = vld1_u8(coef_sign_bits + 5 * DCTSIZE);
+  uint8x8_t signbits_row6 = vld1_u8(coef_sign_bits + 6 * DCTSIZE);
+  uint8x8_t signbits_row7 = vld1_u8(coef_sign_bits + 7 * DCTSIZE);
+
+  signbits_row0 = vand_u8(signbits_row0, bitmap_mask);
+  signbits_row1 = vand_u8(signbits_row1, bitmap_mask);
+  signbits_row2 = vand_u8(signbits_row2, bitmap_mask);
+  signbits_row3 = vand_u8(signbits_row3, bitmap_mask);
+  signbits_row4 = vand_u8(signbits_row4, bitmap_mask);
+  signbits_row5 = vand_u8(signbits_row5, bitmap_mask);
+  signbits_row6 = vand_u8(signbits_row6, bitmap_mask);
+  signbits_row7 = vand_u8(signbits_row7, bitmap_mask);
+
+  bitmap_rows_01 = vpadd_u8(signbits_row0, signbits_row1);
+  bitmap_rows_23 = vpadd_u8(signbits_row2, signbits_row3);
+  bitmap_rows_45 = vpadd_u8(signbits_row4, signbits_row5);
+  bitmap_rows_67 = vpadd_u8(signbits_row6, signbits_row7);
+  bitmap_rows_0123 = vpadd_u8(bitmap_rows_01, bitmap_rows_23);
+  bitmap_rows_4567 = vpadd_u8(bitmap_rows_45, bitmap_rows_67);
+  bitmap_all = vpadd_u8(bitmap_rows_0123, bitmap_rows_4567);
+
+#if defined(__aarch64__) || defined(_M_ARM64)
+  /* Move bitmap to a 64-bit scalar register. */
+  bitmap = vget_lane_u64(vreinterpret_u64_u8(bitmap_all), 0);
+  /* Store signbits bitmap. */
+  bits[1] = ~bitmap;
+#else
+  /* Move bitmap to two 32-bit scalar registers. */
+  bitmap0 = vget_lane_u32(vreinterpret_u32_u8(bitmap_all), 0);
+  bitmap1 = vget_lane_u32(vreinterpret_u32_u8(bitmap_all), 1);
+  /* Store signbits bitmap. */
+  bits[2] = ~bitmap0;
+  bits[3] = ~bitmap1;
+#endif
+
+  /* Construct bitmap to find EOB position (the index of the last coefficient
+   * equal to 1.)
+   */
+  uint8x8_t row0_eq1 = vld1_u8(coef_eq1_bits + 0 * DCTSIZE);
+  uint8x8_t row1_eq1 = vld1_u8(coef_eq1_bits + 1 * DCTSIZE);
+  uint8x8_t row2_eq1 = vld1_u8(coef_eq1_bits + 2 * DCTSIZE);
+  uint8x8_t row3_eq1 = vld1_u8(coef_eq1_bits + 3 * DCTSIZE);
+  uint8x8_t row4_eq1 = vld1_u8(coef_eq1_bits + 4 * DCTSIZE);
+  uint8x8_t row5_eq1 = vld1_u8(coef_eq1_bits + 5 * DCTSIZE);
+  uint8x8_t row6_eq1 = vld1_u8(coef_eq1_bits + 6 * DCTSIZE);
+  uint8x8_t row7_eq1 = vld1_u8(coef_eq1_bits + 7 * DCTSIZE);
+
+  row0_eq1 = vand_u8(row0_eq1, bitmap_mask);
+  row1_eq1 = vand_u8(row1_eq1, bitmap_mask);
+  row2_eq1 = vand_u8(row2_eq1, bitmap_mask);
+  row3_eq1 = vand_u8(row3_eq1, bitmap_mask);
+  row4_eq1 = vand_u8(row4_eq1, bitmap_mask);
+  row5_eq1 = vand_u8(row5_eq1, bitmap_mask);
+  row6_eq1 = vand_u8(row6_eq1, bitmap_mask);
+  row7_eq1 = vand_u8(row7_eq1, bitmap_mask);
+
+  bitmap_rows_01 = vpadd_u8(row0_eq1, row1_eq1);
+  bitmap_rows_23 = vpadd_u8(row2_eq1, row3_eq1);
+  bitmap_rows_45 = vpadd_u8(row4_eq1, row5_eq1);
+  bitmap_rows_67 = vpadd_u8(row6_eq1, row7_eq1);
+  bitmap_rows_0123 = vpadd_u8(bitmap_rows_01, bitmap_rows_23);
+  bitmap_rows_4567 = vpadd_u8(bitmap_rows_45, bitmap_rows_67);
+  bitmap_all = vpadd_u8(bitmap_rows_0123, bitmap_rows_4567);
+
+#if defined(__aarch64__) || defined(_M_ARM64)
+  /* Move bitmap to a 64-bit scalar register. */
+  bitmap = vget_lane_u64(vreinterpret_u64_u8(bitmap_all), 0);
+
+  /* Return EOB position. */
+  if (bitmap == 0) {
+    /* EOB position is defined to be 0 if all coefficients != 1. */
+    return 0;
+  } else {
+    return 63 - BUILTIN_CLZLL(bitmap);
+  }
+#else
+  /* Move bitmap to two 32-bit scalar registers. */
+  bitmap0 = vget_lane_u32(vreinterpret_u32_u8(bitmap_all), 0);
+  bitmap1 = vget_lane_u32(vreinterpret_u32_u8(bitmap_all), 1);
+
+  /* Return EOB position. */
+  if (bitmap0 == 0 && bitmap1 == 0) {
+    return 0;
+  } else if (bitmap1 != 0) {
+    return 63 - BUILTIN_CLZ(bitmap1);
+  } else {
+    return 31 - BUILTIN_CLZ(bitmap0);
+  }
+#endif
+}