base: Split out the pixel class in framebuffer.(cc|hh).

These are really two separate things. Also, while it's realitively
straightforward to write a unit test for the pixel conversion code, the
framebuffer object is serializable and brings in more dependencies.

Change-Id: If954caeb0bfedb1002cfb1a7a115a00c90d56d19
Reviewed-on: https://gem5-review.googlesource.com/6341
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

1 files changed, 231 insertions, 0 deletions

diff --git a/src/base/pixel.hh b/src/base/pixel.hh
new file mode 100644
index 000000000..f6faacec6
--- /dev/null
+++ b/src/base/pixel.hh
@@ -0,0 +1,231 @@
+/*
+ * Copyright (c) 2015 ARM Limited
+ * All rights reserved
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder.  You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Andreas Sandberg
+ */
+
+#ifndef __BASE_PIXEL_HH__
+#define __BASE_PIXEL_HH__
+
+#include <cmath>
+#include <cstdint>
+#include <string>
+#include <vector>
+
+#include "base/compiler.hh"
+#include "base/cprintf.hh"
+#include "base/str.hh"
+#include "base/types.hh"
+
+/**
+ * Internal gem5 representation of a Pixel.
+ */
+struct Pixel
+{
+    Pixel()
+        : red(0), green(0), blue(0), padding(0) {}
+
+    Pixel(uint8_t _red, uint8_t _green, uint8_t _blue)
+        : red(_red), green(_green), blue(_blue), padding(0) {}
+
+    uint8_t red;
+    uint8_t green;
+    uint8_t blue;
+    uint8_t padding;
+};
+
+inline bool
+operator==(const Pixel &lhs, const Pixel &rhs)
+{
+    return lhs.red == rhs.red &&
+        lhs.green == rhs.green &&
+        lhs.blue == rhs.blue &&
+        lhs.padding == rhs.padding;
+}
+
+/**
+ * Configurable RGB pixel converter.
+ *
+ * This class converts between external RGB representations and gem5's
+ * internal Pixel representation. The class assumes that pixels are
+ * stored in a word of configurable length (up to 32 bits). Individual
+ * pixels are assumed to be represented by contiguous bit ranges in
+ * the word (i.e., it is possible to shift and mask out a contiguous
+ * bit range for each pixel).
+ */
+class PixelConverter
+{
+  public:
+    /**
+     * Color channel conversion and scaling helper class.
+     */
+    struct Channel {
+        /**
+         * @param offset Offset in bits.
+         * @param width Width in bits.
+         */
+        Channel(unsigned offset, unsigned width);
+
+        /**
+         * Get the value of a single color channel represented as an
+         * 8-bit number.
+         */
+        uint8_t toPixel(uint32_t word) const {
+            return round(((word >> offset) & mask) * factor);
+        }
+
+        /**
+         * Convert an 8-bit representation of a color into an external
+         * format.
+         */
+        uint32_t fromPixel(uint8_t ch) const {
+            return (static_cast<uint8_t>(round(ch / factor)) & mask) << offset;
+        }
+
+        /** Offset in bits */
+        unsigned offset;
+        /** Bit mask (after shifting) */
+        unsigned mask;
+        /**
+         * Scaling factor when converting to the full range of an
+         * 8-bit color channel
+         */
+        float factor;
+    };
+
+    PixelConverter(unsigned length,
+                   unsigned ro, unsigned go, unsigned bo,
+                   unsigned rw, unsigned gw, unsigned bw,
+                   ByteOrder byte_order = LittleEndianByteOrder);
+
+    /** Get the Pixel representation of a color word. */
+    Pixel toPixel(uint32_t word) const {
+        return Pixel(ch_r.toPixel(word),
+                     ch_g.toPixel(word),
+                     ch_b.toPixel(word));
+    }
+
+    /** Get a Pixel representation by reading a word from memory. */
+    Pixel toPixel(const uint8_t *rfb) const {
+        return toPixel(readWord(rfb));
+    }
+
+    /** Convert a Pixel into a color word */
+    uint32_t fromPixel(const Pixel &pixel) const {
+        return ch_r.fromPixel(pixel.red) |
+            ch_g.fromPixel(pixel.green) |
+            ch_b.fromPixel(pixel.blue);
+    }
+
+    /**
+     * Convert a pixel into a color word and store the resulting word
+     * in memory.
+     */
+    void fromPixel(uint8_t *rfb, const Pixel &pixel) const {
+        writeWord(rfb, fromPixel(pixel));
+    }
+
+    /**
+     * Read a word of a given length and endianness from memory.
+     *
+     * The number of bytes read from memory is determined by the
+     * length of a color word. Note that some of the bytes may be
+     * padding.
+     *
+     * @param p Pointer to the first byte in the word.
+     * @return Word in host endianness.
+     */
+    uint32_t readWord(const uint8_t *p) const;
+    /**
+     * Write a word of a given length and endianness to memory.
+     *
+     * @param p Pointer to the first byte in memory.
+     * @param word Word to store (host endianness).
+     */
+    void writeWord(uint8_t *p, uint32_t word) const;
+
+    /** Bytes per pixel when stored in memory (including padding) */
+    unsigned length;
+    /**
+     * Number of bits used to represent one pixel value (excluding
+     * padding). This could be less than length * 8 if the pixel value
+     * is padded.
+     */
+    unsigned depth;
+    /** Byte order when stored to memory. */
+    ByteOrder byte_order;
+
+    /** Red channel conversion helper */
+    Channel ch_r;
+    /** Green channel conversion helper */
+    Channel ch_g;
+    /** Blue channel conversion helper */
+    Channel ch_b;
+
+    /** Predefined 32-bit RGB (red in least significant bits, 8
+     * bits/channel, little endian) conversion helper */
+    static const PixelConverter rgba8888_le;
+    /** Predefined 16-bit RGB565 (red in least significant bits,
+     * little endian) conversion helper */
+    static const PixelConverter rgb565_le;
+
+    /** Predefined 32-bit RGB (red in least significant bits, 8
+     * bits/channel, big endian) conversion helper */
+    static const PixelConverter rgba8888_be;
+    /** Predefined 16-bit RGB565 (red in least significant bits,
+     * big endian) conversion helper */
+    static const PixelConverter rgb565_be;
+};
+
+inline bool
+to_number(const std::string &value, Pixel &retval)
+{
+    uint32_t num;
+    if (!to_number(value, num))
+        return false;
+
+    retval = PixelConverter::rgba8888_le.toPixel(num);
+    return true;
+}
+
+inline std::ostream &
+operator<<(std::ostream &os, const Pixel &pxl)
+{
+    os << csprintf("%#.08x", PixelConverter::rgba8888_le.fromPixel(pxl));
+    return os;
+}
+
+#endif // __BASE_PIXEL_HH__