kc3-lang/libjpeg-turbo/simd/arm/jcsample-neon.c

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• Hash : e69dd40c
  Author :
  Date : 2024-01-23T13:26:41
  

  Reorganize source to make things easier to find
  
  - Move all libjpeg documentation, except for README.ijg, into the doc/
    subdirectory.
  
  - Move the TurboJPEG C API documentation from doc/html/ into
    doc/turbojpeg/.
  
  - Move all C source code and headers into a src/ subdirectory.
  
  - Move turbojpeg-jni.c into the java/ subdirectory.
  
  Referring to #226, there is no ideal solution to this problem.  A
  semantically ideal solution would have involved placing all source code,
  including the SIMD and Java source code, under src/ (or perhaps placing
  C library source code under lib/ and C test program source code under
  test/), all header files under include/, and all documentation under
  doc/.  However:
  
  - To me it makes more sense to have separate top-level directories for
    each language, since the SIMD extensions and the Java API are
    technically optional features.  src/ now contains only the code that
    is relevant to the core C API libraries and associated programs.
  - I didn't want to bury the java/ and simd/ directories or add a level
    of depth to them, since both directories already contain source code
    that is 3-4 levels deep.
  - I would prefer not to separate the header files from the C source
    code, because:
    1. It would be disruptive.  libjpeg and libjpeg-turbo have
       historically placed C source code and headers in the same
       directory, and people who are familiar with both projects (self
       included) are used to looking for the headers in the same directory
       as the C source code.
    2. In terms of how the headers are used internally in libjpeg-turbo,
       the distinction between public and private headers is a bit fuzzy.
  - It didn't make sense to separate the test source code from the library
    source code, since there is not a clear distinction in some cases.
    (For instance, the IJG image I/O functions are used by cjpeg and djpeg
    as well as by the TurboJPEG API.)
  
  This solution is minimally disruptive, since it keeps all C source code
  and headers together and keeps java/ and simd/ as top-level directories.
  It is a bit awkward, because java/ and simd/ technically contain source
  code, even though they are not under src/.  However, other solutions
  would have been more awkward for different reasons.
  
  Closes #226
  

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• simd/arm/jcsample-neon.c

• /*
   * jcsample-neon.c - downsampling (Arm Neon)
   *
   * Copyright (C) 2020, Arm Limited.  All Rights Reserved.
   * Copyright (C) 2024, D. R. Commander.  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 "../../src/jinclude.h"
  #include "../../src/jpeglib.h"
  #include "../../src/jsimd.h"
  #include "../../src/jdct.h"
  #include "../../src/jsimddct.h"
  #include "../jsimd.h"
  #include "align.h"
  
  #include <arm_neon.h>
  
  
  ALIGN(16) static const uint8_t jsimd_h2_downsample_consts[] = {
    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,   /* Pad 0 */
    0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,   /* Pad 1 */
    0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0E,
    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,   /* Pad 2 */
    0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0D, 0x0D,
    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,   /* Pad 3 */
    0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0C, 0x0C, 0x0C,
    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,   /* Pad 4 */
    0x08, 0x09, 0x0A, 0x0B, 0x0B, 0x0B, 0x0B, 0x0B,
    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,   /* Pad 5 */
    0x08, 0x09, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A,
    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,   /* Pad 6 */
    0x08, 0x09, 0x09, 0x09, 0x09, 0x09, 0x09, 0x09,
    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,   /* Pad 7 */
    0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08,
    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,   /* Pad 8 */
    0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07,
    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x06,   /* Pad 9 */
    0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06,
    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x05, 0x05,   /* Pad 10 */
    0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05,
    0x00, 0x01, 0x02, 0x03, 0x04, 0x04, 0x04, 0x04,   /* Pad 11 */
    0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04,
    0x00, 0x01, 0x02, 0x03, 0x03, 0x03, 0x03, 0x03,   /* Pad 12 */
    0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03,
    0x00, 0x01, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,   /* Pad 13 */
    0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
    0x00, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,   /* Pad 14 */
    0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,   /* Pad 15 */
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
  };
  
  
  /* Downsample pixel values of a single component.
   * This version handles the common case of 2:1 horizontal and 1:1 vertical,
   * without smoothing.
   */
  
  void jsimd_h2v1_downsample_neon(JDIMENSION image_width, int max_v_samp_factor,
                                  JDIMENSION v_samp_factor,
                                  JDIMENSION width_in_blocks,
                                  JSAMPARRAY input_data, JSAMPARRAY output_data)
  {
    JSAMPROW inptr, outptr;
    /* Load expansion mask to pad remaining elements of last DCT block. */
    const int mask_offset = 16 * ((width_in_blocks * 2 * DCTSIZE) - image_width);
    const uint8x16_t expand_mask =
      vld1q_u8(&jsimd_h2_downsample_consts[mask_offset]);
    /* Load bias pattern (alternating every pixel.) */
    /* { 0, 1, 0, 1, 0, 1, 0, 1 } */
    const uint16x8_t bias = vreinterpretq_u16_u32(vdupq_n_u32(0x00010000));
    unsigned i, outrow;
  
    for (outrow = 0; outrow < v_samp_factor; outrow++) {
      outptr = output_data[outrow];
      inptr = input_data[outrow];
  
      /* Downsample all but the last DCT block of pixels. */
      for (i = 0; i < width_in_blocks - 1; i++) {
        uint8x16_t pixels = vld1q_u8(inptr + i * 2 * DCTSIZE);
        /* Add adjacent pixel values, widen to 16-bit, and add bias. */
        uint16x8_t samples_u16 = vpadalq_u8(bias, pixels);
        /* Divide total by 2 and narrow to 8-bit. */
        uint8x8_t samples_u8 = vshrn_n_u16(samples_u16, 1);
        /* Store samples to memory. */
        vst1_u8(outptr + i * DCTSIZE, samples_u8);
      }
  
      /* Load pixels in last DCT block into a table. */
      uint8x16_t pixels = vld1q_u8(inptr + (width_in_blocks - 1) * 2 * DCTSIZE);
  #if defined(__aarch64__) || defined(_M_ARM64)
      /* Pad the empty elements with the value of the last pixel. */
      pixels = vqtbl1q_u8(pixels, expand_mask);
  #else
      uint8x8x2_t table = { { vget_low_u8(pixels), vget_high_u8(pixels) } };
      pixels = vcombine_u8(vtbl2_u8(table, vget_low_u8(expand_mask)),
                           vtbl2_u8(table, vget_high_u8(expand_mask)));
  #endif
      /* Add adjacent pixel values, widen to 16-bit, and add bias. */
      uint16x8_t samples_u16 = vpadalq_u8(bias, pixels);
      /* Divide total by 2, narrow to 8-bit, and store. */
      uint8x8_t samples_u8 = vshrn_n_u16(samples_u16, 1);
      vst1_u8(outptr + (width_in_blocks - 1) * DCTSIZE, samples_u8);
    }
  }
  
  
  /* Downsample pixel values of a single component.
   * This version handles the standard case of 2:1 horizontal and 2:1 vertical,
   * without smoothing.
   */
  
  void jsimd_h2v2_downsample_neon(JDIMENSION image_width, int max_v_samp_factor,
                                  JDIMENSION v_samp_factor,
                                  JDIMENSION width_in_blocks,
                                  JSAMPARRAY input_data, JSAMPARRAY output_data)
  {
    JSAMPROW inptr0, inptr1, outptr;
    /* Load expansion mask to pad remaining elements of last DCT block. */
    const int mask_offset = 16 * ((width_in_blocks * 2 * DCTSIZE) - image_width);
    const uint8x16_t expand_mask =
      vld1q_u8(&jsimd_h2_downsample_consts[mask_offset]);
    /* Load bias pattern (alternating every pixel.) */
    /* { 1, 2, 1, 2, 1, 2, 1, 2 } */
    const uint16x8_t bias = vreinterpretq_u16_u32(vdupq_n_u32(0x00020001));
    unsigned i, outrow;
  
    for (outrow = 0; outrow < v_samp_factor; outrow++) {
      outptr = output_data[outrow];
      inptr0 = input_data[outrow];
      inptr1 = input_data[outrow + 1];
  
      /* Downsample all but the last DCT block of pixels. */
      for (i = 0; i < width_in_blocks - 1; i++) {
        uint8x16_t pixels_r0 = vld1q_u8(inptr0 + i * 2 * DCTSIZE);
        uint8x16_t pixels_r1 = vld1q_u8(inptr1 + i * 2 * DCTSIZE);
        /* Add adjacent pixel values in row 0, widen to 16-bit, and add bias. */
        uint16x8_t samples_u16 = vpadalq_u8(bias, pixels_r0);
        /* Add adjacent pixel values in row 1, widen to 16-bit, and accumulate.
         */
        samples_u16 = vpadalq_u8(samples_u16, pixels_r1);
        /* Divide total by 4 and narrow to 8-bit. */
        uint8x8_t samples_u8 = vshrn_n_u16(samples_u16, 2);
        /* Store samples to memory and increment pointers. */
        vst1_u8(outptr + i * DCTSIZE, samples_u8);
      }
  
      /* Load pixels in last DCT block into a table. */
      uint8x16_t pixels_r0 =
        vld1q_u8(inptr0 + (width_in_blocks - 1) * 2 * DCTSIZE);
      uint8x16_t pixels_r1 =
        vld1q_u8(inptr1 + (width_in_blocks - 1) * 2 * DCTSIZE);
  #if defined(__aarch64__) || defined(_M_ARM64)
      /* Pad the empty elements with the value of the last pixel. */
      pixels_r0 = vqtbl1q_u8(pixels_r0, expand_mask);
      pixels_r1 = vqtbl1q_u8(pixels_r1, expand_mask);
  #else
      uint8x8x2_t table_r0 =
        { { vget_low_u8(pixels_r0), vget_high_u8(pixels_r0) } };
      uint8x8x2_t table_r1 =
        { { vget_low_u8(pixels_r1), vget_high_u8(pixels_r1) } };
      pixels_r0 = vcombine_u8(vtbl2_u8(table_r0, vget_low_u8(expand_mask)),
                              vtbl2_u8(table_r0, vget_high_u8(expand_mask)));
      pixels_r1 = vcombine_u8(vtbl2_u8(table_r1, vget_low_u8(expand_mask)),
                              vtbl2_u8(table_r1, vget_high_u8(expand_mask)));
  #endif
      /* Add adjacent pixel values in row 0, widen to 16-bit, and add bias. */
      uint16x8_t samples_u16 = vpadalq_u8(bias, pixels_r0);
      /* Add adjacent pixel values in row 1, widen to 16-bit, and accumulate. */
      samples_u16 = vpadalq_u8(samples_u16, pixels_r1);
      /* Divide total by 4, narrow to 8-bit, and store. */
      uint8x8_t samples_u8 = vshrn_n_u16(samples_u16, 2);
      vst1_u8(outptr + (width_in_blocks - 1) * DCTSIZE, samples_u8);
    }
  }
  

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