/*

 * AltiVec optimizations for libjpeg-turbo

 *

 * Copyright (C) 2015, 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.

 */

/* This file is included by jdcolor-altivec.c */

void jsimd_ycc_rgb_convert_altivec(JDIMENSION out_width, JSAMPIMAGE input_buf,

                                   JDIMENSION input_row, JSAMPARRAY output_buf,

                                   int num_rows)

{

  JSAMPROW outptr, inptr0, inptr1, inptr2;

  int pitch = out_width * RGB_PIXELSIZE, num_cols;

#if __BIG_ENDIAN__

  int offset;

#endif

  unsigned char __attribute__((aligned(16))) tmpbuf[RGB_PIXELSIZE * 16];

  __vector unsigned char rgb0, rgb1, rgb2, rgbx0, rgbx1, rgbx2, rgbx3,

    y, cb, cr;

#if __BIG_ENDIAN__

  __vector unsigned char edgel, edgeh, edges, out0, out1, out2, out3;

#if RGB_PIXELSIZE == 4

  __vector unsigned char out4;

#endif

#endif

#if RGB_PIXELSIZE == 4

  __vector unsigned char rgb3;

#endif

  __vector short rg0, rg1, rg2, rg3, bx0, bx1, bx2, bx3, yl, yh, cbl, cbh,

    crl, crh, rl, rh, gl, gh, bl, bh, g0w, g1w, g2w, g3w;

  __vector int g0, g1, g2, g3;

  /* Constants

   * NOTE: The >> 1 is to compensate for the fact that vec_madds() returns 17

   * high-order bits, not 16.

   */

  __vector short pw_f0402 = { __8X(F_0_402 >> 1) },

    pw_mf0228 = { __8X(-F_0_228 >> 1) },

    pw_mf0344_f0285 = { __4X2(-F_0_344, F_0_285) },

    pw_one = { __8X(1) }, pw_255 = { __8X(255) },

    pw_cj = { __8X(CENTERJSAMPLE) };

  __vector int pd_onehalf = { __4X(ONE_HALF) };

  __vector unsigned char pb_zero = { __16X(0) },

#if __BIG_ENDIAN__

    shift_pack_index =

      {  0,  1,  4,  5,  8,  9, 12, 13, 16, 17, 20, 21, 24, 25, 28, 29 };

#else

    shift_pack_index =

      {  2,  3,  6,  7, 10, 11, 14, 15, 18, 19, 22, 23, 26, 27, 30, 31 };

#endif

  while (--num_rows >= 0) {

    inptr0 = input_buf[0][input_row];

    inptr1 = input_buf[1][input_row];

    inptr2 = input_buf[2][input_row];

    input_row++;

    outptr = *output_buf++;

    for (num_cols = pitch; num_cols > 0;

         num_cols -= RGB_PIXELSIZE * 16, outptr += RGB_PIXELSIZE * 16,

         inptr0 += 16, inptr1 += 16, inptr2 += 16) {

      y = vec_ld(0, inptr0);

      /* NOTE: We have to use vec_merge*() here because vec_unpack*() doesn't

       * support unsigned vectors.

       */

      yl = (__vector signed short)VEC_UNPACKHU(y);

      yh = (__vector signed short)VEC_UNPACKLU(y);

      cb = vec_ld(0, inptr1);

      cbl = (__vector signed short)VEC_UNPACKHU(cb);

      cbh = (__vector signed short)VEC_UNPACKLU(cb);

      cbl = vec_sub(cbl, pw_cj);

      cbh = vec_sub(cbh, pw_cj);

      cr = vec_ld(0, inptr2);

      crl = (__vector signed short)VEC_UNPACKHU(cr);

      crh = (__vector signed short)VEC_UNPACKLU(cr);

      crl = vec_sub(crl, pw_cj);

      crh = vec_sub(crh, pw_cj);

      /* (Original)

       * R = Y                + 1.40200 * Cr

       * G = Y - 0.34414 * Cb - 0.71414 * Cr

       * B = Y + 1.77200 * Cb

       *

       * (This implementation)

       * R = Y                + 0.40200 * Cr + Cr

       * G = Y - 0.34414 * Cb + 0.28586 * Cr - Cr

       * B = Y - 0.22800 * Cb + Cb + Cb

       */

      bl = vec_add(cbl, cbl);

      bh = vec_add(cbh, cbh);

      bl = vec_madds(bl, pw_mf0228, pw_one);

      bh = vec_madds(bh, pw_mf0228, pw_one);

      bl = vec_sra(bl, (__vector unsigned short)pw_one);

      bh = vec_sra(bh, (__vector unsigned short)pw_one);

      bl = vec_add(bl, cbl);

      bh = vec_add(bh, cbh);

      bl = vec_add(bl, cbl);

      bh = vec_add(bh, cbh);

      bl = vec_add(bl, yl);

      bh = vec_add(bh, yh);

      rl = vec_add(crl, crl);

      rh = vec_add(crh, crh);

      rl = vec_madds(rl, pw_f0402, pw_one);

      rh = vec_madds(rh, pw_f0402, pw_one);

      rl = vec_sra(rl, (__vector unsigned short)pw_one);

      rh = vec_sra(rh, (__vector unsigned short)pw_one);

      rl = vec_add(rl, crl);

      rh = vec_add(rh, crh);

      rl = vec_add(rl, yl);

      rh = vec_add(rh, yh);

      g0w = vec_mergeh(cbl, crl);

      g1w = vec_mergel(cbl, crl);

      g0 = vec_msums(g0w, pw_mf0344_f0285, pd_onehalf);

      g1 = vec_msums(g1w, pw_mf0344_f0285, pd_onehalf);

      g2w = vec_mergeh(cbh, crh);

      g3w = vec_mergel(cbh, crh);

      g2 = vec_msums(g2w, pw_mf0344_f0285, pd_onehalf);

      g3 = vec_msums(g3w, pw_mf0344_f0285, pd_onehalf);

      /* Clever way to avoid 4 shifts + 2 packs.  This packs the high word from

       * each dword into a new 16-bit vector, which is the equivalent of

       * descaling the 32-bit results (right-shifting by 16 bits) and then

       * packing them.

       */

      gl = vec_perm((__vector short)g0, (__vector short)g1, shift_pack_index);

      gh = vec_perm((__vector short)g2, (__vector short)g3, shift_pack_index);

      gl = vec_sub(gl, crl);

      gh = vec_sub(gh, crh);

      gl = vec_add(gl, yl);

      gh = vec_add(gh, yh);

      rg0 = vec_mergeh(rl, gl);

      bx0 = vec_mergeh(bl, pw_255);

      rg1 = vec_mergel(rl, gl);

      bx1 = vec_mergel(bl, pw_255);

      rg2 = vec_mergeh(rh, gh);

      bx2 = vec_mergeh(bh, pw_255);

      rg3 = vec_mergel(rh, gh);

      bx3 = vec_mergel(bh, pw_255);

      rgbx0 = vec_packsu(rg0, bx0);

      rgbx1 = vec_packsu(rg1, bx1);

      rgbx2 = vec_packsu(rg2, bx2);

      rgbx3 = vec_packsu(rg3, bx3);

#if RGB_PIXELSIZE == 3

      /* rgbx0 = R0 G0 R1 G1 R2 G2 R3 G3 B0 X0 B1 X1 B2 X2 B3 X3

       * rgbx1 = R4 G4 R5 G5 R6 G6 R7 G7 B4 X4 B5 X5 B6 X6 B7 X7

       * rgbx2 = R8 G8 R9 G9 Ra Ga Rb Gb B8 X8 B9 X9 Ba Xa Bb Xb

       * rgbx3 = Rc Gc Rd Gd Re Ge Rf Gf Bc Xc Bd Xd Be Xe Bf Xf

       *

       * rgb0 = R0 G0 B0 R1 G1 B1 R2 G2 B2 R3 G3 B3 R4 G4 B4 R5

       * rgb1 = G5 B5 R6 G6 B6 R7 G7 B7 R8 G8 B8 R9 G9 B9 Ra Ga

       * rgb2 = Ba Rb Gb Bb Rc Gc Bc Rd Gd Bd Re Ge Be Rf Gf Bf

       */

      rgb0 = vec_perm(rgbx0, rgbx1, (__vector unsigned char)RGB_INDEX0);

      rgb1 = vec_perm(rgbx1, rgbx2, (__vector unsigned char)RGB_INDEX1);

      rgb2 = vec_perm(rgbx2, rgbx3, (__vector unsigned char)RGB_INDEX2);

#else

      /* rgbx0 = R0 G0 R1 G1 R2 G2 R3 G3 B0 X0 B1 X1 B2 X2 B3 X3

       * rgbx1 = R4 G4 R5 G5 R6 G6 R7 G7 B4 X4 B5 X5 B6 X6 B7 X7

       * rgbx2 = R8 G8 R9 G9 Ra Ga Rb Gb B8 X8 B9 X9 Ba Xa Bb Xb

       * rgbx3 = Rc Gc Rd Gd Re Ge Rf Gf Bc Xc Bd Xd Be Xe Bf Xf

       *

       * rgb0 = R0 G0 B0 X0 R1 G1 B1 X1 R2 G2 B2 X2 R3 G3 B3 X3

       * rgb1 = R4 G4 B4 X4 R5 G5 B5 X5 R6 G6 B6 X6 R7 G7 B7 X7

       * rgb2 = R8 G8 B8 X8 R9 G9 B9 X9 Ra Ga Ba Xa Rb Gb Bb Xb

       * rgb3 = Rc Gc Bc Xc Rd Gd Bd Xd Re Ge Be Xe Rf Gf Bf Xf

       */

      rgb0 = vec_perm(rgbx0, rgbx0, (__vector unsigned char)RGB_INDEX);

      rgb1 = vec_perm(rgbx1, rgbx1, (__vector unsigned char)RGB_INDEX);

      rgb2 = vec_perm(rgbx2, rgbx2, (__vector unsigned char)RGB_INDEX);

      rgb3 = vec_perm(rgbx3, rgbx3, (__vector unsigned char)RGB_INDEX);

#endif

#if __BIG_ENDIAN__

      offset = (size_t)outptr & 15;

      if (offset) {

        __vector unsigned char unaligned_shift_index;

        int bytes = num_cols + offset;

        if (bytes < (RGB_PIXELSIZE + 1) * 16 && (bytes & 15)) {

          /* Slow path to prevent buffer overwrite.  Since there is no way to

           * write a partial AltiVec register, overwrite would occur on the

           * last chunk of the last image row if the right edge is not on a

           * 16-byte boundary.  It could also occur on other rows if the bytes

           * per row is low enough.  Since we can't determine whether we're on

           * the last image row, we have to assume every row is the last.

           */

          vec_st(rgb0, 0, tmpbuf);

          vec_st(rgb1, 16, tmpbuf);

          vec_st(rgb2, 32, tmpbuf);

#if RGB_PIXELSIZE == 4

          vec_st(rgb3, 48, tmpbuf);

#endif

          memcpy(outptr, tmpbuf, min(num_cols, RGB_PIXELSIZE * 16));

        } else {

          /* Fast path */

          unaligned_shift_index = vec_lvsl(0, outptr);

          edgel = vec_ld(0, outptr);

          edgeh = vec_ld(min(num_cols - 1, RGB_PIXELSIZE * 16), outptr);

          edges = vec_perm(edgeh, edgel, unaligned_shift_index);

          unaligned_shift_index = vec_lvsr(0, outptr);

          out0 = vec_perm(edges, rgb0, unaligned_shift_index);

          out1 = vec_perm(rgb0, rgb1, unaligned_shift_index);

          out2 = vec_perm(rgb1, rgb2, unaligned_shift_index);

#if RGB_PIXELSIZE == 4

          out3 = vec_perm(rgb2, rgb3, unaligned_shift_index);

          out4 = vec_perm(rgb3, edges, unaligned_shift_index);

#else

          out3 = vec_perm(rgb2, edges, unaligned_shift_index);

#endif

          vec_st(out0, 0, outptr);

          if (bytes > 16)

            vec_st(out1, 16, outptr);

          if (bytes > 32)

            vec_st(out2, 32, outptr);

          if (bytes > 48)

            vec_st(out3, 48, outptr);

#if RGB_PIXELSIZE == 4

          if (bytes > 64)

            vec_st(out4, 64, outptr);

#endif

        }

      } else {

#endif /* __BIG_ENDIAN__ */

        if (num_cols < RGB_PIXELSIZE * 16 && (num_cols & 15)) {

          /* Slow path */

          VEC_ST(rgb0, 0, tmpbuf);

          VEC_ST(rgb1, 16, tmpbuf);

          VEC_ST(rgb2, 32, tmpbuf);

#if RGB_PIXELSIZE == 4

          VEC_ST(rgb3, 48, tmpbuf);

#endif

          memcpy(outptr, tmpbuf, min(num_cols, RGB_PIXELSIZE * 16));

        } else {

          /* Fast path */

          VEC_ST(rgb0, 0, outptr);

          if (num_cols > 16)

            VEC_ST(rgb1, 16, outptr);

          if (num_cols > 32)

            VEC_ST(rgb2, 32, outptr);

#if RGB_PIXELSIZE == 4

          if (num_cols > 48)

            VEC_ST(rgb3, 48, outptr);

#endif

        }

#if __BIG_ENDIAN__

      }

#endif

    }

  }

}