Refactor of SkColorSpaceXformOpts

src/opts/SkColorXform_opts.h

-/*
- * Copyright 2016 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-#ifndef SkColorXform_opts_DEFINED
-#define SkColorXform_opts_DEFINED
-
-#include "SkNx.h"
-#include "SkColorPriv.h"
-#include "SkHalf.h"
-#include "SkSRGB.h"
-#include "SkTemplates.h"
-
-namespace SK_OPTS_NS {
-
-// Strange that we need a wrapper on SkNx_cast to use as a function ptr.
-static Sk4i Sk4f_trunc(const Sk4f& x) {
-    return SkNx_cast<int>(x);
-}
-
-static Sk4f linear_to_2dot2(const Sk4f& x) {
-    // x^(29/64) is a very good approximation of the true value, x^(1/2.2).
-    auto x2  = x.rsqrt(),                            // x^(-1/2)
-         x32 = x2.rsqrt().rsqrt().rsqrt().rsqrt(),   // x^(-1/32)
-         x64 = x32.rsqrt();                          // x^(+1/64)
-
-    // 29 = 32 - 2 - 1
-    return 255.0f * x2.invert() * x32 * x64.invert();
-}
-
-enum DstGamma {
-    // 8888
-    kSRGB_DstGamma,
-    k2Dot2_DstGamma,
-    kTable_DstGamma,
-
-    // F16
-    kLinear_DstGamma,
-};
-
-template <DstGamma kDstGamma, bool kSwapRB>
-static void color_xform_RGB1(void* dst, const uint32_t* src, int len,
-                             const float* const srcTables[3], const float matrix[16],
-                             const uint8_t* const dstTables[3]) {
-    int kRShift = 0;
-    int kGShift = 8;
-    int kBShift = 16;
-    int kAShift = 24;
-    if (kSwapRB) {
-        kBShift = 0;
-        kRShift = 16;
-    }
-
-    Sk4f rXgXbX = Sk4f::Load(matrix +  0),
-         rYgYbY = Sk4f::Load(matrix +  4),
-         rZgZbZ = Sk4f::Load(matrix +  8),
-         rTgTbT = Sk4f::Load(matrix + 12);
-
-    if (len >= 4) {
-        Sk4f reds, greens, blues;
-        auto load_next_4 = [&reds, &greens, &blues, &src, &len, &srcTables] {
-            reds   = Sk4f{srcTables[0][(src[0] >>  0) & 0xFF],
-                          srcTables[0][(src[1] >>  0) & 0xFF],
-                          srcTables[0][(src[2] >>  0) & 0xFF],
-                          srcTables[0][(src[3] >>  0) & 0xFF]};
-            greens = Sk4f{srcTables[1][(src[0] >>  8) & 0xFF],
-                          srcTables[1][(src[1] >>  8) & 0xFF],
-                          srcTables[1][(src[2] >>  8) & 0xFF],
-                          srcTables[1][(src[3] >>  8) & 0xFF]};
-            blues  = Sk4f{srcTables[2][(src[0] >> 16) & 0xFF],
-                          srcTables[2][(src[1] >> 16) & 0xFF],
-                          srcTables[2][(src[2] >> 16) & 0xFF],
-                          srcTables[2][(src[3] >> 16) & 0xFF]};
-            src += 4;
-            len -= 4;
-        };
-
-        Sk4f dstReds, dstGreens, dstBlues;
-        auto transform_4 = [&reds, &greens, &blues, &dstReds, &dstGreens, &dstBlues, &rXgXbX,
-                            &rYgYbY, &rZgZbZ, &rTgTbT] {
-            dstReds   = rXgXbX[0]*reds + rYgYbY[0]*greens + rZgZbZ[0]*blues + rTgTbT[0];
-            dstGreens = rXgXbX[1]*reds + rYgYbY[1]*greens + rZgZbZ[1]*blues + rTgTbT[1];
-            dstBlues  = rXgXbX[2]*reds + rYgYbY[2]*greens + rZgZbZ[2]*blues + rTgTbT[2];
-        };
-
-        auto store_4 = [&dstReds, &dstGreens, &dstBlues, &dst, &dstTables, kRShift, kGShift,
-                        kBShift, kAShift] {
-            if (kSRGB_DstGamma == kDstGamma || k2Dot2_DstGamma == kDstGamma) {
-                Sk4f (*linear_to_curve)(const Sk4f&) = (kSRGB_DstGamma == kDstGamma) ?
-                        sk_linear_to_srgb_needs_trunc : linear_to_2dot2;
-                Sk4i (*float_to_int)(const Sk4f&) = (kSRGB_DstGamma == kDstGamma) ?
-                        Sk4f_trunc : Sk4f_round;
-
-                dstReds   = linear_to_curve(dstReds);
-                dstGreens = linear_to_curve(dstGreens);
-                dstBlues  = linear_to_curve(dstBlues);
-
-                dstReds   = sk_clamp_0_255(dstReds);
-                dstGreens = sk_clamp_0_255(dstGreens);
-                dstBlues  = sk_clamp_0_255(dstBlues);
-
-                auto rgba = (float_to_int(dstReds)   << kRShift)
-                          | (float_to_int(dstGreens) << kGShift)
-                          | (float_to_int(dstBlues)  << kBShift)
-                          | (Sk4i{0xFF}              << kAShift);
-                rgba.store((uint32_t*) dst);
-
-                dst = SkTAddOffset<void>(dst, 4 * sizeof(uint32_t));
-            } else if (kTable_DstGamma == kDstGamma) {
-                Sk4f scaledReds   = Sk4f::Min(Sk4f::Max(1023.0f * dstReds,   0.0f), 1023.0f);
-                Sk4f scaledGreens = Sk4f::Min(Sk4f::Max(1023.0f * dstGreens, 0.0f), 1023.0f);
-                Sk4f scaledBlues  = Sk4f::Min(Sk4f::Max(1023.0f * dstBlues,  0.0f), 1023.0f);
-
-                Sk4i indicesReds   = Sk4f_round(scaledReds);
-                Sk4i indicesGreens = Sk4f_round(scaledGreens);
-                Sk4i indicesBlues  = Sk4f_round(scaledBlues);
-
-                uint32_t* dst32 = (uint32_t*) dst;
-                dst32[0] = dstTables[0][indicesReds  [0]] << kRShift
-                         | dstTables[1][indicesGreens[0]] << kGShift
-                         | dstTables[2][indicesBlues [0]] << kBShift
-                         | 0xFF                           << kAShift;
-                dst32[1] = dstTables[0][indicesReds  [1]] << kRShift
-                         | dstTables[1][indicesGreens[1]] << kGShift
-                         | dstTables[2][indicesBlues [1]] << kBShift
-                         | 0xFF                           << kAShift;
-                dst32[2] = dstTables[0][indicesReds  [2]] << kRShift
-                         | dstTables[1][indicesGreens[2]] << kGShift
-                         | dstTables[2][indicesBlues [2]] << kBShift
-                         | 0xFF                           << kAShift;
-                dst32[3] = dstTables[0][indicesReds  [3]] << kRShift
-                         | dstTables[1][indicesGreens[3]] << kGShift
-                         | dstTables[2][indicesBlues [3]] << kBShift
-                         | 0xFF                           << kAShift;
-
-                dst = SkTAddOffset<void>(dst, 4 * sizeof(uint32_t));
-            } else {
-                Sk4h_store4(dst, SkFloatToHalf_finite(dstReds),
-                                 SkFloatToHalf_finite(dstGreens),
-                                 SkFloatToHalf_finite(dstBlues),
-                                 SK_Half1);
-                dst = SkTAddOffset<void>(dst, 4 * sizeof(uint64_t));
-            }
-        };
-
-        load_next_4();
-
-        while (len >= 4) {
-            transform_4();
-            load_next_4();
-            store_4();
-        }
-
-        transform_4();
-        store_4();
-    }
-
-    while (len > 0) {
-        // Splat r,g,b across a register each.
-        auto r = Sk4f{srcTables[0][(*src >>  0) & 0xFF]},
-             g = Sk4f{srcTables[1][(*src >>  8) & 0xFF]},
-             b = Sk4f{srcTables[2][(*src >> 16) & 0xFF]};
-
-        auto dstPixel = rXgXbX*r + rYgYbY*g + rZgZbZ*b + rTgTbT;
-
-        if (kSRGB_DstGamma == kDstGamma || k2Dot2_DstGamma == kDstGamma) {
-            Sk4f (*linear_to_curve)(const Sk4f&) = (kSRGB_DstGamma == kDstGamma) ?
-                    sk_linear_to_srgb_needs_trunc : linear_to_2dot2;
-            Sk4i (*float_to_int)(const Sk4f&) = (kSRGB_DstGamma == kDstGamma) ?
-                    Sk4f_trunc : Sk4f_round;
-
-            dstPixel = sk_clamp_0_255(linear_to_curve(dstPixel));
-
-            uint32_t rgba;
-            SkNx_cast<uint8_t>(float_to_int(dstPixel)).store(&rgba);
-            rgba |= 0xFF000000;
-            if (kSwapRB) {
-                *((uint32_t*) dst) = SkSwizzle_RB(rgba);
-            } else {
-                *((uint32_t*) dst) = rgba;
-            }
-            dst = SkTAddOffset<void>(dst, sizeof(uint32_t));
-        } else if (kTable_DstGamma == kDstGamma) {
-            Sk4f scaledPixel = Sk4f::Min(Sk4f::Max(1023.0f * dstPixel, 0.0f), 1023.0f);
-
-            Sk4i indices = Sk4f_round(scaledPixel);
-
-            *((uint32_t*) dst) = dstTables[0][indices[0]] << kRShift
-                               | dstTables[1][indices[1]] << kGShift
-                               | dstTables[2][indices[2]] << kBShift
-                               | 0xFF                     << kAShift;
-
-            dst = SkTAddOffset<void>(dst, sizeof(uint32_t));
-        } else {
-            uint64_t rgba;
-            SkFloatToHalf_finite(dstPixel).store(&rgba);
-            rgba |= static_cast<uint64_t>(SK_Half1) << 48;
-            *((uint64_t*) dst) = rgba;
-            dst = SkTAddOffset<void>(dst, sizeof(uint64_t));
-        }
-
-        src += 1;
-        len -= 1;
-    }
-}
-
-static void color_xform_RGB1_to_2dot2(uint32_t* dst, const uint32_t* src, int len,
-                                      const float* const srcTables[3], const float matrix[16]) {
-    color_xform_RGB1<k2Dot2_DstGamma, false>(dst, src, len, srcTables, matrix, nullptr);
-}
-
-static void color_xform_RGB1_to_srgb(uint32_t* dst, const uint32_t* src, int len,
-                                     const float* const srcTables[3], const float matrix[16]) {
-    color_xform_RGB1<kSRGB_DstGamma, false>(dst, src, len, srcTables, matrix, nullptr);
-}
-
-static void color_xform_RGB1_to_table(uint32_t* dst, const uint32_t* src, int len,
-                                      const float* const srcTables[3], const float matrix[16],
-                                      const uint8_t* const dstTables[3]) {
-    color_xform_RGB1<kTable_DstGamma, false>(dst, src, len, srcTables, matrix, dstTables);
-}
-
-static void color_xform_RGB1_to_linear(uint64_t* dst, const uint32_t* src, int len,
-                                       const float* const srcTables[3], const float matrix[16]) {
-    color_xform_RGB1<kLinear_DstGamma, false>(dst, src, len, srcTables, matrix, nullptr);
-}
-
-static void color_xform_RGB1_to_2dot2_swaprb(uint32_t* dst, const uint32_t* src, int len,
-                                             const float* const srcTables[3],
-                                             const float matrix[16]) {
-    color_xform_RGB1<k2Dot2_DstGamma, true>(dst, src, len, srcTables, matrix, nullptr);
-}
-
-static void color_xform_RGB1_to_srgb_swaprb(uint32_t* dst, const uint32_t* src, int len,
-                                            const float* const srcTables[3],
-                                            const float matrix[16]) {
-    color_xform_RGB1<kSRGB_DstGamma, true>(dst, src, len, srcTables, matrix, nullptr);
-}
-
-static void color_xform_RGB1_to_table_swaprb(uint32_t* dst, const uint32_t* src, int len,
-                                             const float* const srcTables[3],
-                                             const float matrix[16],
-                                             const uint8_t* const dstTables[3]) {
-    color_xform_RGB1<kTable_DstGamma, true>(dst, src, len, srcTables, matrix, dstTables);
-}
-
-}  // namespace SK_OPTS_NS
-
-#endif // SkColorXform_opts_DEFINED