RetroArch/libretro-common/gfx/scaler/scaler_int.c

/* Copyright  (C) 2010-2020 The RetroArch team
 *
 * ---------------------------------------------------------------------------------------
 * The following license statement only applies to this file (scaler_int.c).
 * ---------------------------------------------------------------------------------------
 *
 * Permission is hereby granted, free of charge,
 * to any person obtaining a copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include <gfx/scaler/scaler_int.h>

#include <retro_inline.h>

#ifdef SCALER_NO_SIMD
#undef __SSE2__
#endif

#if defined(__SSE2__)
#include <emmintrin.h>
#ifdef _WIN32
#include <intrin.h>
#endif
#endif

/* ARGB8888 scaler is split in two:
 *
 * First, horizontal scaler is applied.
 * Here, all 8-bit channels are expanded to 16-bit. Values are then shifted 7
 * to left to occupy 15 bits.
 *
 * The sign bit is kept empty as we have to do signed multiplication for the
 * filter.
 *
 * A mulhi [(a * b) >> 16] is applied which loses some precision, but is
 * very efficient for SIMD.
 * It is accurate enough for 8-bit purposes.
 *
 * The fixed point 1.0 for filter is (1 << 14). After horizontal scale,
 * the output is kept with 16-bit channels, and will now have 13 bits
 * of precision as [(a * (1 << 14)) >> 16] is effectively a right shift by 2.
 *
 * Vertical scaler takes the 13 bit channels, and performs the
 * same mulhi steps.
 * Another 2 bits of precision is lost, which ends up as 11 bits.
 * Scaling is now complete. Channels are shifted right by 3, and saturated
 * into 8-bit values.
 *
 * The C version of scalers perform the exact same operations as the
 * SIMD code for testing purposes.
 */

void scaler_argb8888_vert(const struct scaler_ctx *ctx, void *output_, int stride)
{
   int h, w, y;
   const uint64_t      *input = ctx->scaled.frame;
   uint32_t           *output = (uint32_t*)output_;

   const int16_t *filter_vert = ctx->vert.filter;

   for (h = 0; h < ctx->out_height; h++,
         filter_vert += ctx->vert.filter_stride, output += stride >> 2)
   {
      const uint64_t *input_base = input + ctx->vert.filter_pos[h]
         * (ctx->scaled.stride >> 3);

      for (w = 0; w < ctx->out_width; w++)
      {
         const uint64_t *input_base_y = input_base + w;
#if defined(__SSE2__)
         __m128i final;
         __m128i res = _mm_setzero_si128();

         for (y = 0; (y + 1) < ctx->vert.filter_len; y += 2,
               input_base_y += (ctx->scaled.stride >> 2))
         {
            __m128i coeff = _mm_set_epi64x(filter_vert[y + 1] * 0x0001000100010001ll, filter_vert[y + 0] * 0x0001000100010001ll);
            __m128i col   = _mm_set_epi64x(input_base_y[ctx->scaled.stride >> 3], input_base_y[0]);

            res           = _mm_adds_epi16(_mm_mulhi_epi16(col, coeff), res);
         }

         for (; y < ctx->vert.filter_len; y++, input_base_y += (ctx->scaled.stride >> 3))
         {
            __m128i coeff = _mm_set_epi64x(0, filter_vert[y] * 0x0001000100010001ll);
            __m128i col   = _mm_set_epi64x(0, input_base_y[0]);

            res           = _mm_adds_epi16(_mm_mulhi_epi16(col, coeff), res);
         }

         res       = _mm_adds_epi16(_mm_srli_si128(res, 8), res);
         res       = _mm_srai_epi16(res, (7 - 2 - 2));

         final     = _mm_packus_epi16(res, res);

         output[w] = _mm_cvtsi128_si32(final);
#else
         int16_t res_a = 0;
         int16_t res_r = 0;
         int16_t res_g = 0;
         int16_t res_b = 0;

         for (y = 0; y < ctx->vert.filter_len; y++,
               input_base_y += (ctx->scaled.stride >> 3))
         {
            uint64_t col   = *input_base_y;

            int16_t a      = (col >> 48) & 0xffff;
            int16_t r      = (col >> 32) & 0xffff;
            int16_t g      = (col >> 16) & 0xffff;
            int16_t b      = (col >>  0) & 0xffff;

            int16_t coeff  = filter_vert[y];

            res_a         += (a * coeff) >> 16;
            res_r         += (r * coeff) >> 16;
            res_g         += (g * coeff) >> 16;
            res_b         += (b * coeff) >> 16;
         }

         res_a           >>= (7 - 2 - 2);
         res_r           >>= (7 - 2 - 2);
         res_g           >>= (7 - 2 - 2);
         res_b           >>= (7 - 2 - 2);

         output[w]         =
            (clamp_8bit(res_a) << 24) |
            (clamp_8bit(res_r) << 16) |
            (clamp_8bit(res_g) << 8)  |
            (clamp_8bit(res_b) << 0);
#endif
      }
   }
}

void scaler_argb8888_horiz(const struct scaler_ctx *ctx, const void *input_, int stride)
{
   int h, w, x;
   const uint32_t *input = (uint32_t*)input_;
   uint64_t *output      = ctx->scaled.frame;

   for (h = 0; h < ctx->scaled.height; h++, input += stride >> 2,
         output += ctx->scaled.stride >> 3)
   {
      const int16_t *filter_horiz = ctx->horiz.filter;

      for (w = 0; w < ctx->scaled.width; w++,
            filter_horiz += ctx->horiz.filter_stride)
      {
         const uint32_t *input_base_x = input + ctx->horiz.filter_pos[w];
#if defined(__SSE2__)
         __m128i res = _mm_setzero_si128();
#ifndef __x86_64__
         union
         {
            uint32_t *u32;
            uint64_t *u64;
         } u;
#endif
         for (x = 0; (x + 1) < ctx->horiz.filter_len; x += 2)
         {
            __m128i coeff = _mm_set_epi64x(filter_horiz[x + 1] * 0x0001000100010001ll, filter_horiz[x + 0] * 0x0001000100010001ll);

            __m128i col   = _mm_unpacklo_epi8(_mm_set_epi64x(0,
                     ((uint64_t)input_base_x[x + 1] << 32) | input_base_x[x + 0]), _mm_setzero_si128());

            col           = _mm_slli_epi16(col, 7);
            res           = _mm_adds_epi16(_mm_mulhi_epi16(col, coeff), res);
         }

         for (; x < ctx->horiz.filter_len; x++)
         {
            __m128i coeff = _mm_set_epi64x(0, filter_horiz[x] * 0x0001000100010001ll);
            __m128i col   = _mm_unpacklo_epi8(_mm_set_epi32(0, 0, 0, input_base_x[x]), _mm_setzero_si128());

            col           = _mm_slli_epi16(col, 7);
            res           = _mm_adds_epi16(_mm_mulhi_epi16(col, coeff), res);
         }

         res              = _mm_adds_epi16(_mm_srli_si128(res, 8), res);

#ifdef __x86_64__
         output[w]        = _mm_cvtsi128_si64(res);
#else /* 32-bit doesn't have si64. Do it in two steps. */
         u.u64    = output + w;
         u.u32[0] = _mm_cvtsi128_si32(res);
         u.u32[1] = _mm_cvtsi128_si32(_mm_srli_si128(res, 4));
#endif
#else
         int16_t res_a = 0;
         int16_t res_r = 0;
         int16_t res_g = 0;
         int16_t res_b = 0;

         for (x = 0; x < ctx->horiz.filter_len; x++)
         {
            uint32_t col   = input_base_x[x];

            int16_t a      = (col >> (24 - 7)) & (0xff << 7);
            int16_t r      = (col >> (16 - 7)) & (0xff << 7);
            int16_t g      = (col >> ( 8 - 7)) & (0xff << 7);
            int16_t b      = (col << ( 0 + 7)) & (0xff << 7);

            int16_t coeff  = filter_horiz[x];

            res_a         += (a * coeff) >> 16;
            res_r         += (r * coeff) >> 16;
            res_g         += (g * coeff) >> 16;
            res_b         += (b * coeff) >> 16;
         }

         output[w]         = (
               (uint64_t)res_a  << 48)  |
               ((uint64_t)res_r << 32)  |
               ((uint64_t)res_g << 16)  |
               ((uint64_t)res_b << 0);
#endif
      }
   }
}

void scaler_argb8888_point_special(const struct scaler_ctx *ctx,
      void *output_, const void *input_,
      int out_width, int out_height,
      int in_width, int in_height,
      int out_stride, int in_stride)
{
   int h, w;
   int x_pos             = (1 << 15) * in_width / out_width - (1 << 15);
   int x_step            = (1 << 16) * in_width / out_width;
   int y_pos             = (1 << 15) * in_height / out_height - (1 << 15);
   int y_step            = (1 << 16) * in_height / out_height;
   const uint32_t *input = (const uint32_t*)input_;
   uint32_t *output      = (uint32_t*)output_;

   if (x_pos < 0)
      x_pos = 0;
   if (y_pos < 0)
      y_pos = 0;

   for (h = 0; h < out_height; h++, y_pos += y_step, output += out_stride >> 2)
   {
      int               x = x_pos;
      const uint32_t *inp = input + (y_pos >> 16) * (in_stride >> 2);

      for (w = 0; w < out_width; w++, x += x_step)
         output[w] = inp[x >> 16];
   }
}