mesa/src/compiler/nir/nir_format_convert.h

/*
 * Copyright © 2017 Intel Corporation
 *
 * 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 (including the next
 * paragraph) 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 "nir_builder.h"

static inline nir_ssa_def *
nir_shift(nir_builder *b, nir_ssa_def *value, int left_shift)
{
   if (left_shift > 0)
      return nir_ishl(b, value, nir_imm_int(b, left_shift));
   else if (left_shift < 0)
      return nir_ushr(b, value, nir_imm_int(b, -left_shift));
   else
      return value;
}

static inline nir_ssa_def *
nir_mask_shift(struct nir_builder *b, nir_ssa_def *src,
               uint32_t mask, int left_shift)
{
   return nir_shift(b, nir_iand(b, src, nir_imm_int(b, mask)), left_shift);
}

static inline nir_ssa_def *
nir_mask_shift_or(struct nir_builder *b, nir_ssa_def *dst, nir_ssa_def *src,
                  uint32_t src_mask, int src_left_shift)
{
   return nir_ior(b, nir_mask_shift(b, src, src_mask, src_left_shift), dst);
}

static inline nir_ssa_def *
nir_format_unpack_uint(nir_builder *b, nir_ssa_def *packed,
                       const unsigned *bits, unsigned num_components)
{
   assert(num_components >= 1 && num_components <= 4);
   nir_ssa_def *comps[4];

   if (bits[0] >= packed->bit_size) {
      assert(bits[0] == packed->bit_size);
      assert(num_components == 1);
      return packed;
   }

   unsigned offset = 0;
   for (unsigned i = 0; i < num_components; i++) {
      assert(bits[i] < 32);
      nir_ssa_def *mask = nir_imm_int(b, (1u << bits[i]) - 1);
      comps[i] = nir_iand(b, nir_shift(b, packed, -offset), mask);
      offset += bits[i];
   }
   assert(offset <= packed->bit_size);

   return nir_vec(b, comps, num_components);
}

static inline nir_ssa_def *
nir_format_pack_uint_unmasked(nir_builder *b, nir_ssa_def *color,
                              const unsigned *bits, unsigned num_components)
{
   assert(num_components >= 1 && num_components <= 4);
   nir_ssa_def *packed = nir_imm_int(b, 0);
   unsigned offset = 0;
   for (unsigned i = 0; i < num_components; i++) {
      packed = nir_ior(b, packed, nir_shift(b, nir_channel(b, color, i),
                                               offset));
      offset += bits[i];
   }
   assert(offset <= packed->bit_size);

   return packed;
}

static inline nir_ssa_def *
nir_format_pack_uint(nir_builder *b, nir_ssa_def *color,
                     const unsigned *bits, unsigned num_components)
{
   nir_const_value mask;
   for (unsigned i = 0; i < num_components; i++) {
      assert(bits[i] < 32);
      mask.u32[i] = (1u << bits[i]) - 1;
   }
   nir_ssa_def *mask_imm = nir_build_imm(b, num_components, 32, mask);

   return nir_format_pack_uint_unmasked(b, nir_iand(b, color, mask_imm),
                                        bits, num_components);
}

static inline nir_ssa_def *
nir_format_linear_to_srgb(nir_builder *b, nir_ssa_def *c)
{
   nir_ssa_def *linear = nir_fmul(b, c, nir_imm_float(b, 12.92f));
   nir_ssa_def *curved =
      nir_fsub(b, nir_fmul(b, nir_imm_float(b, 1.055f),
                              nir_fpow(b, c, nir_imm_float(b, 1.0 / 2.4))),
                  nir_imm_float(b, 0.055f));

   return nir_fsat(b, nir_bcsel(b, nir_flt(b, c, nir_imm_float(b, 0.0031308f)),
                                   linear, curved));
}

static inline nir_ssa_def *
nir_format_srgb_to_linear(nir_builder *b, nir_ssa_def *c)
{
   nir_ssa_def *linear = nir_fdiv(b, c, nir_imm_float(b, 12.92f));
   nir_ssa_def *curved =
      nir_fpow(b, nir_fdiv(b, nir_fadd(b, c, nir_imm_float(b, 0.055f)),
                              nir_imm_float(b, 1.055f)),
                  nir_imm_float(b, 2.4f));

   return nir_fsat(b, nir_bcsel(b, nir_fge(b, nir_imm_float(b, 0.04045f), c),
                                   linear, curved));
}

static inline nir_ssa_def *
nir_format_unpack_11f11f10f(nir_builder *b, nir_ssa_def *packed)
{
   nir_ssa_def *chans[3];
   chans[0] = nir_mask_shift(b, packed, 0x000007ff, 4);
   chans[1] = nir_mask_shift(b, packed, 0x003ff100, -7);
   chans[2] = nir_mask_shift(b, packed, 0xffc00000, -17);

   for (unsigned i = 0; i < 3; i++)
      chans[i] = nir_unpack_half_2x16_split_x(b, chans[i]);

   return nir_vec(b, chans, 3);
}

static inline nir_ssa_def *
nir_format_pack_r11g11b10f(nir_builder *b, nir_ssa_def *color)
{
   /* 10 and 11-bit floats are unsigned.  Clamp to non-negative */
   nir_ssa_def *clamped = nir_fmax(b, color, nir_imm_float(b, 0));

   nir_ssa_def *undef = nir_ssa_undef(b, 1, color->bit_size);
   nir_ssa_def *p1 = nir_pack_half_2x16_split(b, nir_channel(b, clamped, 0),
                                                 nir_channel(b, clamped, 1));
   nir_ssa_def *p2 = nir_pack_half_2x16_split(b, nir_channel(b, clamped, 2),
                                                 undef);

   /* A 10 or 11-bit float has the same exponent as a 16-bit float but with
    * fewer mantissa bits and no sign bit.  All we have to do is throw away
    * the sign bit and the bottom mantissa bits and shift it into place.
    */
   nir_ssa_def *packed = nir_imm_int(b, 0);
   packed = nir_mask_shift_or(b, packed, p1, 0x00007ff0, -4);
   packed = nir_mask_shift_or(b, packed, p1, 0x7ff00000, -9);
   packed = nir_mask_shift_or(b, packed, p2, 0x00007fe0, 17);

   return packed;
}