Y2R: Rework conversion process, enabling support for all formats

2 files changed, 384 insertions, 0 deletions

diff --git a/src/core/hw/y2r.cpp b/src/core/hw/y2r.cpp
new file mode 100644
index 00000000..5b7fb39e
--- /dev/null
+++ b/src/core/hw/y2r.cpp
@@ -0,0 +1,369 @@
+// Copyright 2015 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <array>
+#include <numeric>
+
+#include "common/assert.h"
+#include "common/color.h"
+#include "common/common_types.h"
+#include "common/math_util.h"
+#include "common/vector_math.h"
+
+#include "core/hle/service/y2r_u.h"
+#include "core/memory.h"
+
+namespace HW {
+namespace Y2R {
+
+using namespace Y2R_U;
+
+static const size_t MAX_TILES = 1024 / 8;
+static const size_t TILE_SIZE = 8 * 8;
+using ImageTile = std::array<u32, TILE_SIZE>;
+
+/// Converts a image strip from the source YUV format into individual 8x8 RGB32 tiles.
+static void ConvertYUVToRGB(InputFormat input_format,
+        const u8* input_Y, const u8* input_U, const u8* input_V, ImageTile output[],
+        unsigned int width, unsigned int height, const CoefficientSet& coefficients) {
+
+    for (unsigned int y = 0; y < height; ++y) {
+        for (unsigned int x = 0; x < width; ++x) {
+            s32 Y, U, V;
+            switch (input_format) {
+            case InputFormat::YUV422_Indiv8:
+            case InputFormat::YUV422_Indiv16:
+                Y = input_Y[y * width + x];
+                U = input_U[(y * width + x) / 2];
+                V = input_V[(y * width + x) / 2];
+                break;
+            case InputFormat::YUV420_Indiv8:
+            case InputFormat::YUV420_Indiv16:
+                Y = input_Y[y * width + x];
+                U = input_U[((y / 2) * width + x) / 2];
+                V = input_V[((y / 2) * width + x) / 2];
+                break;
+            case InputFormat::YUYV422_Interleaved:
+                Y = input_Y[(y * width + x) * 2];
+                U = input_Y[(y * width + (x / 2) * 2) * 2 + 1];
+                V = input_Y[(y * width + (x / 2) * 2) * 2 + 3];
+                break;
+            }
+
+            // This conversion process is bit-exact with hardware, as far as could be tested.
+            auto& c = coefficients;
+            s32 cY = c[0]*Y;
+
+            s32 r = cY          + c[1]*V;
+            s32 g = cY - c[3]*U - c[2]*V;
+            s32 b = cY + c[4]*U;
+
+            const s32 rounding_offset = 0x18;
+            r = (r >> 3) + c[5] + rounding_offset;
+            g = (g >> 3) + c[6] + rounding_offset;
+            b = (b >> 3) + c[7] + rounding_offset;
+
+            unsigned int tile = x / 8;
+            unsigned int tile_x = x % 8;
+            u32* out = &output[tile][y * 8 + tile_x];
+
+            using MathUtil::Clamp;
+            *out = ((u32)Clamp(r >> 5, 0, 0xFF) << 24) |
+                   ((u32)Clamp(g >> 5, 0, 0xFF) << 16) |
+                   ((u32)Clamp(b >> 5, 0, 0xFF) << 8);
+        }
+    }
+}
+
+/// Simulates an incoming CDMA transfer. The N parameter is used to automatically convert 16-bit formats to 8-bit.
+template <size_t N>
+static void ReceiveData(u8* output, ConversionBuffer& buf, size_t amount_of_data) {
+    const u8* input = Memory::GetPointer(buf.address);
+
+    size_t output_unit = buf.transfer_unit / N;
+    ASSERT(amount_of_data % output_unit == 0);
+
+    while (amount_of_data > 0) {
+        for (size_t i = 0; i < output_unit; ++i) {
+            output[i] = input[i * N];
+        }
+
+        output += output_unit;
+        input += buf.transfer_unit + buf.gap;
+
+        buf.address += buf.transfer_unit + buf.gap;
+        buf.image_size -= buf.transfer_unit;
+        amount_of_data -= output_unit;
+    }
+}
+
+/// Convert intermediate RGB32 format to the final output format while simulating an outgoing CDMA transfer.
+static void SendData(const u32* input, ConversionBuffer& buf, int amount_of_data,
+        OutputFormat output_format, u8 alpha) {
+
+    u8* output = Memory::GetPointer(buf.address);
+
+    while (amount_of_data > 0) {
+        u8* unit_end = output + buf.transfer_unit;
+        while (output < unit_end) {
+            u32 color = *input++;
+            Math::Vec4<u8> col_vec{
+                (color >> 24) & 0xFF, (color >> 16) & 0xFF, (color >>  8) & 0xFF, alpha,
+            };
+
+            switch (output_format) {
+            case OutputFormat::RGBA8:
+                Color::EncodeRGBA8(col_vec, output);
+                output += 4;
+                break;
+            case OutputFormat::RGB8:
+                Color::EncodeRGB8(col_vec, output);
+                output += 3;
+                break;
+            case OutputFormat::RGB5A1:
+                Color::EncodeRGB5A1(col_vec, output);
+                output += 2;
+                break;
+            case OutputFormat::RGB565:
+                Color::EncodeRGB565(col_vec, output);
+                output += 2;
+                break;
+            }
+
+            amount_of_data -= 1;
+        }
+
+        output += buf.gap;
+        buf.address += buf.transfer_unit + buf.gap;
+        buf.image_size -= buf.transfer_unit;
+    }
+}
+
+static const u8 linear_lut[64] = {
+     0,  1,  2,  3,  4,  5,  6,  7,
+     8,  9, 10, 11, 12, 13, 14, 15,
+    16, 17, 18, 19, 20, 21, 22, 23,
+    24, 25, 26, 27, 28, 29, 30, 31,
+    32, 33, 34, 35, 36, 37, 38, 39,
+    40, 41, 42, 43, 44, 45, 46, 47,
+    48, 49, 50, 51, 52, 53, 54, 55,
+    56, 57, 58, 59, 60, 61, 62, 63,
+};
+
+static const u8 morton_lut[64] = {
+     0,  1,  4,  5, 16, 17, 20, 21,
+     2,  3,  6,  7, 18, 19, 22, 23,
+     8,  9, 12, 13, 24, 25, 28, 29,
+    10, 11, 14, 15, 26, 27, 30, 31,
+    32, 33, 36, 37, 48, 49, 52, 53,
+    34, 35, 38, 39, 50, 51, 54, 55,
+    40, 41, 44, 45, 56, 57, 60, 61,
+    42, 43, 46, 47, 58, 59, 62, 63,
+};
+
+static void RotateTile0(const ImageTile& input, ImageTile& output, int height, const u8 out_map[64]) {
+    for (int i = 0; i < height * 8; ++i) {
+        output[out_map[i]] = input[i];
+    }
+}
+
+static void RotateTile90(const ImageTile& input, ImageTile& output, int height, const u8 out_map[64]) {
+    int out_i = 0;
+    for (int x = 0; x < 8; ++x) {
+        for (int y = height - 1; y >= 0; --y) {
+            output[out_map[out_i++]] = input[y * 8 + x];
+        }
+    }
+}
+
+static void RotateTile180(const ImageTile& input, ImageTile& output, int height, const u8 out_map[64]) {
+    int out_i = 0;
+    for (int i = height * 8 - 1; i >= 0; --i) {
+        output[out_map[out_i++]] = input[i];
+    }
+}
+
+static void RotateTile270(const ImageTile& input, ImageTile& output, int height, const u8 out_map[64]) {
+    int out_i = 0;
+    for (int x = 8-1; x >= 0; --x) {
+        for (int y = 0; y < height; ++y) {
+            output[out_map[out_i++]] = input[y * 8 + x];
+        }
+    }
+}
+
+static void WriteTileToOutput(u32* output, const ImageTile& tile, int height, int line_stride) {
+    for (int y = 0; y < height; ++y) {
+        for (int x = 0; x < 8; ++x) {
+            output[y * line_stride + x] = tile[y * 8 + x];
+        }
+    }
+}
+
+/**
+ * Performs a Y2R colorspace conversion.
+ *
+ * The Y2R hardware implements hardware-accelerated YUV to RGB colorspace conversions. It is most
+ * commonly used for video playback or to display camera input to the screen.
+ *
+ * The conversion process is quite configurable, and can be divided in distinct steps. From
+ * observation, it appears that the hardware buffers a single 8-pixel tall strip of image data
+ * internally and converts it in one go before writing to the output and loading the next strip.
+ *
+ * The steps taken to convert one strip of image data are:
+ *
+ * - The hardware receives data via CDMA (http://3dbrew.org/wiki/Corelink_DMA_Engines), which is
+ *   presumably stored in one or more internal buffers. This process can be done in several separate
+ *   transfers, as long as they don't exceed the size of the internal image buffer. This allows
+ *   flexibility in input strides.
+ * - The input data is decoded into a YUV tuple. Several formats are suported, see the `InputFormat`
+ *   enum.
+ * - The YUV tuple is converted, using fixed point calculations, to RGB. This step can be configured
+ *   using a set of coefficients to support different colorspace standards. See `CoefficientSet`.
+ * - The strip can be optionally rotated 90, 180 or 270 degrees. Since each strip is processed
+ *   independently, this notably rotates each *strip*, not the entire image. This means that for 90
+ *   or 270 degree rotations, the output will be in terms of several 8 x height images, and for any
+ *   non-zero rotation the strips will have to be re-arranged so that the parts of the image will
+ *   not be shuffled together. This limitation makes this a feature of somewhat dubious utility. 90
+ *   or 270 degree rotations in images with non-even height don't seem to work properly.
+ * - The data is converted to the output RGB format. See the `OutputFormat` enum.
+ * - The data can be output either linearly line-by-line or in the swizzled 8x8 tile format used by
+ *   the PICA. This is decided by the `BlockAlignment` enum. If 8x8 alignment is used, then the
+ *   image must have a height divisible by 8. The image width must always be divisible by 8.
+ * - The final data is then CDMAed out to main memory and the next image strip is processed. This
+ *   offers the same flexibility as the input stage.
+ *
+ * In this implementation, to avoid the combinatorial explosion of parameter combinations, common
+ * intermediate formats are used and where possible tables or parameters are used instead of
+ * diverging code paths to keep the amount of branches in check. Some steps are also merged to
+ * increase efficiency.
+ *
+ * Output for all valid settings combinations matches hardware, however output in some edge-cases
+ * differs:
+ *
+ * - `Block8x8` alignment with non-mod8 height produces different garbage patterns on the last
+ *   strip, especially when combined with rotation.
+ * - Hardware, when using `Linear` alignment with a non-even height and 90 or 270 degree rotation
+ *   produces misaligned output on the last strip. This implmentation produces output with the
+ *   correct "expected" alignment.
+ *
+ * Hardware behaves strangely (doesn't fire the completion interrupt, for example) in these cases,
+ * so they are believed to be invalid configurations anyway.
+ */
+void PerformConversion(ConversionConfiguration& cvt) {
+    ASSERT(cvt.input_line_width % 8 == 0);
+    ASSERT(cvt.block_alignment != BlockAlignment::Block8x8 || cvt.input_lines % 8 == 0);
+    // Tiles per row
+    size_t num_tiles = cvt.input_line_width / 8;
+    ASSERT(num_tiles < MAX_TILES);
+
+    // Buffer used as a CDMA source/target.
+    std::unique_ptr<u8[]> data_buffer(new u8[cvt.input_line_width * 8 * 4]);
+    // Intermediate storage for decoded 8x8 image tiles. Always stored as RGB32.
+    std::unique_ptr<ImageTile[]> tiles(new ImageTile[num_tiles]);
+    ImageTile tmp_tile;
+
+    // LUT used to remap writes to a tile. Used to allow linear or swizzled output without
+    // requiring two different code paths.
+    const u8* tile_remap;
+    switch (cvt.block_alignment) {
+    case BlockAlignment::Linear:
+        tile_remap = linear_lut; break;
+    case BlockAlignment::Block8x8:
+        tile_remap = morton_lut; break;
+    }
+
+    for (unsigned int y = 0; y < cvt.input_lines; y += 8) {
+        unsigned int row_height = std::min(cvt.input_lines - y, 8u);
+
+        // Total size in pixels of incoming data required for this strip.
+        const size_t row_data_size = row_height * cvt.input_line_width;
+
+        u8* input_Y = data_buffer.get();
+        u8* input_U = input_Y + 8 * cvt.input_line_width;
+        u8* input_V = input_U + 8 * cvt.input_line_width / 2;
+
+        switch (cvt.input_format) {
+        case InputFormat::YUV422_Indiv8:
+            ReceiveData<1>(input_Y, cvt.src_Y, row_data_size);
+            ReceiveData<1>(input_U, cvt.src_U, row_data_size / 2);
+            ReceiveData<1>(input_V, cvt.src_V, row_data_size / 2);
+            break;
+        case InputFormat::YUV420_Indiv8:
+            ReceiveData<1>(input_Y, cvt.src_Y, row_data_size);
+            ReceiveData<1>(input_U, cvt.src_U, row_data_size / 4);
+            ReceiveData<1>(input_V, cvt.src_V, row_data_size / 4);
+            break;
+        case InputFormat::YUV422_Indiv16:
+            ReceiveData<2>(input_Y, cvt.src_Y, row_data_size);
+            ReceiveData<2>(input_U, cvt.src_U, row_data_size / 2);
+            ReceiveData<2>(input_V, cvt.src_V, row_data_size / 2);
+            break;
+        case InputFormat::YUV420_Indiv16:
+            ReceiveData<2>(input_Y, cvt.src_Y, row_data_size);
+            ReceiveData<2>(input_U, cvt.src_U, row_data_size / 4);
+            ReceiveData<2>(input_V, cvt.src_V, row_data_size / 4);
+            break;
+        case InputFormat::YUYV422_Interleaved:
+            input_U = nullptr;
+            input_V = nullptr;
+            ReceiveData<1>(input_Y, cvt.src_YUYV, row_data_size * 2);
+            break;
+        }
+
+        // Note(yuriks): If additional optimization is required, input_format can be moved to a
+        // template parameter, so that its dispatch can be moved to outside the inner loop.
+        ConvertYUVToRGB(cvt.input_format, input_Y, input_U, input_V, tiles.get(),
+                cvt.input_line_width, row_height, cvt.coefficients);
+
+        u32* output_buffer = reinterpret_cast<u32*>(data_buffer.get());
+
+        for (int i = 0; i < num_tiles; ++i) {
+            int image_strip_width, output_stride;
+
+            switch (cvt.rotation) {
+            case Rotation::None:
+                RotateTile0(tiles[i], tmp_tile, row_height, tile_remap);
+                image_strip_width = cvt.input_line_width;
+                output_stride = 8;
+                break;
+            case Rotation::Clockwise_90:
+                RotateTile90(tiles[i], tmp_tile, row_height, tile_remap);
+                image_strip_width = 8;
+                output_stride = 8 * row_height;
+                break;
+            case Rotation::Clockwise_180:
+                // For 180 and 270 degree rotations we also invert the order of tiles in the strip,
+                // since the rotates are done individually on each tile.
+                RotateTile180(tiles[num_tiles - i - 1], tmp_tile, row_height, tile_remap);
+                image_strip_width = cvt.input_line_width;
+                output_stride = 8;
+                break;
+            case Rotation::Clockwise_270:
+                RotateTile270(tiles[num_tiles - i - 1], tmp_tile, row_height, tile_remap);
+                image_strip_width = 8;
+                output_stride = 8 * row_height;
+                break;
+            }
+
+            switch (cvt.block_alignment) {
+            case BlockAlignment::Linear:
+                WriteTileToOutput(output_buffer, tmp_tile, row_height, image_strip_width);
+                output_buffer += output_stride;
+                break;
+            case BlockAlignment::Block8x8:
+                WriteTileToOutput(output_buffer, tmp_tile, 8, 8);
+                output_buffer += TILE_SIZE;
+                break;
+            }
+        }
+
+        // Note(yuriks): If additional optimization is required, output_format can be moved to a
+        // template parameter, so that its dispatch can be moved to outside the inner loop.
+        SendData(reinterpret_cast<u32*>(data_buffer.get()), cvt.dst, (int)row_data_size, cvt.output_format, (u8)cvt.alpha);
+    }
+}
+
+}
+}
diff --git a/src/core/hw/y2r.h b/src/core/hw/y2r.h
new file mode 100644
index 00000000..729e1eee
--- /dev/null
+++ b/src/core/hw/y2r.h
@@ -0,0 +1,15 @@
+// Copyright 2015 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+namespace Y2R_U {
+    struct ConversionConfiguration;
+}
+
+namespace HW {
+namespace Y2R {
+
+void PerformConversion(Y2R_U::ConversionConfiguration& cvt);
+
+}
+}