src/dev/pixelpump.hh

   1 /*
   2  * Copyright (c) 2015, 2017 ARM Limited
   3  * All rights reserved
   4  *
   5  * The license below extends only to copyright in the software and shall
   6  * not be construed as granting a license to any other intellectual
   7  * property including but not limited to intellectual property relating
   8  * to a hardware implementation of the functionality of the software
   9  * licensed hereunder.  You may use the software subject to the license
  10  * terms below provided that you ensure that this notice is replicated
  11  * unmodified and in its entirety in all distributions of the software,
  12  * modified or unmodified, in source code or in binary form.
  13  *
  14  * Redistribution and use in source and binary forms, with or without
  15  * modification, are permitted provided that the following conditions are
  16  * met: redistributions of source code must retain the above copyright
  17  * notice, this list of conditions and the following disclaimer;
  18  * redistributions in binary form must reproduce the above copyright
  19  * notice, this list of conditions and the following disclaimer in the
  20  * documentation and/or other materials provided with the distribution;
  21  * neither the name of the copyright holders nor the names of its
  22  * contributors may be used to endorse or promote products derived from
  23  * this software without specific prior written permission.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  26  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  27  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  28  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  29  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  30  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  31  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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  34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  35  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  36  */
  37
  38 #ifndef __DEV_PIXELPUMP_HH__
  39 #define __DEV_PIXELPUMP_HH__
  40
  41 #include <vector>
  42
  43 #include "base/framebuffer.hh"
  44 #include "sim/clocked_object.hh"
  45
  46 struct BasePixelPumpParams;
  47
  48 struct DisplayTimings : public Serializable
  49 {
  50     /**
  51      * Create a display timing configuration struct
  52      *
  53      * @param width Width of the visible area of the screen.
  54      * @param height Height of the visible area of the screen.
  55      * @param hfp Horizontal front porch in pixel clocks.
  56      * @param h_sync Horizontal sync in pixel clocks.
  57      * @param hbp Horizontal back porch in pixel clocks.
  58      * @param vfp Vertical front porch in scan lines.
  59      * @param v_sync Vertical sync in scan lines.
  60      * @param vbp Vertical back porch in scan lines.
  61      */
  62     DisplayTimings(unsigned width, unsigned height,
  63                    unsigned hbp, unsigned h_sync, unsigned hfp,
  64                    unsigned vbp, unsigned v_sync, unsigned vfp);
  65
  66     void serialize(CheckpointOut &cp) const override;
  67     void unserialize(CheckpointIn &cp) override;
  68
  69     /** How many pixel clocks are required for one line? */
  70     Cycles
  71     cyclesPerLine() const
  72     {
  73         return Cycles(hSync + hBackPorch +  width + hBackPorch);
  74     }
  75
  76     /** How many pixel clocks are required for one frame? */
  77     Cycles
  78     cyclesPerFrame() const
  79     {
  80         return Cycles(cyclesPerLine() * linesPerFrame());
  81     }
  82
  83     /** Calculate the first line of the vsync signal */
  84     unsigned
  85     lineVSyncStart() const
  86     {
  87         return 0;
  88     }
  89
  90     /** Calculate the first line of the vertical back porch */
  91     unsigned
  92     lineVBackPorchStart() const
  93     {
  94         return lineVSyncStart() + vSync;
  95     }
  96
  97     /** Calculate the first line of the visible region */
  98     unsigned
  99     lineFirstVisible() const
 100     {
 101         return lineVBackPorchStart() + vBackPorch;
 102     }
 103
 104     /** Calculate the first line of the back porch */
 105     unsigned
 106     lineFrontPorchStart() const
 107     {
 108         return lineFirstVisible() + height;
 109     }
 110
 111     /** Calculate the total number of lines in a frame */
 112     unsigned
 113     linesPerFrame() const
 114     {
 115         return lineFrontPorchStart() + vFrontPorch;
 116     }
 117
 118     /** Display width in pixels */
 119     unsigned width;
 120     /** Display height in pixels */
 121     unsigned height;
 122
 123     /** Horizontal back porch in pixels */
 124     unsigned hBackPorch;
 125     /** Horizontal front porch in pixels */
 126     unsigned hFrontPorch;
 127     /** Horizontal sync signal length in pixels */
 128     unsigned hSync;
 129
 130     /** Vertical back porch in lines */
 131     unsigned vBackPorch;
 132     /** Vertical front porch in lines */
 133     unsigned vFrontPorch;
 134     /** Vertical sync signal in lines */
 135     unsigned vSync;
 136
 137     static const DisplayTimings vga;
 138 };
 139
 140 /**
 141  * Timing generator for a pixel-based display.
 142  *
 143  * Pixels are ordered relative to the top left corner of the
 144  * display. Scan lines appear in the following order:
 145  * <ol>
 146  *   <li>Vertical Sync (starting at line 0)
 147  *   <li>Vertical back porch
 148  *   <li>Visible lines
 149  *   <li>Vertical front porch
 150  * </ol>
 151  *
 152  * Pixel order within a scan line:
 153  * <ol>
 154  *   <li>Horizontal Sync
 155  *   <li>Horizontal Back Porch
 156  *   <li>Visible pixels
 157  *   <li>Horizontal Front Porch
 158  * </ol>
 159  */
 160 class BasePixelPump
 161     : public EventManager, public Clocked,
 162       public Serializable
 163 {
 164   public:
 165     BasePixelPump(EventManager &em, ClockDomain &pxl_clk,
 166                   unsigned pixel_chunk);
 167     virtual ~BasePixelPump();
 168
 169     void serialize(CheckpointOut &cp) const override;
 170     void unserialize(CheckpointIn &cp) override;
 171
 172   public: // Public API
 173     /** Update frame size using display timing */
 174     void updateTimings(const DisplayTimings &timings);
 175
 176     /** Render an entire frame in non-caching mode */
 177     void renderFrame();
 178
 179     /** Starting pushing pixels in timing mode */
 180     void start();
 181
 182     /** Immediately stop pushing pixels */
 183     void stop();
 184
 185     /** Get a constant reference of the current display timings */
 186     const DisplayTimings &timings() const { return _timings; }
 187
 188     /** Is the pixel pump active and refreshing the display? */
 189     bool active() const { return evBeginLine.active(); }
 190
 191     /** Did a buffer underrun occur within this refresh interval? */
 192     bool underrun() const { return _underrun; }
 193
 194     /** Is the current line within the visible range? */
 195     bool
 196     visibleLine() const
 197     {
 198         return line >= _timings.lineFirstVisible() &&
 199             line < _timings.lineFrontPorchStart();
 200     }
 201
 202     /** Current pixel position within the visible area */
 203     unsigned posX() const { return _posX; }
 204
 205     /** Current pixel position within the visible area */
 206     unsigned
 207     posY() const
 208     {
 209         return visibleLine() ? line - _timings.lineFirstVisible() : 0;
 210     }
 211
 212     /** Output frame buffer */
 213     FrameBuffer fb;
 214
 215   protected: // Callbacks
 216     /**
 217      * Get the next pixel from the scan line buffer.
 218      *
 219      * @param p Output pixel value, undefined on underrun
 220      * @return true on success, false on buffer underrun
 221      */
 222     virtual bool nextPixel(Pixel &p) = 0;
 223
 224     /**
 225      * Get the next line of pixels directly from memory. This is for use from
 226      * the renderFrame which is called in non-caching mode.
 227      *
 228      * The default implementation falls back to calling nextPixel over and
 229      * over, but a more efficient implementation could retrieve the entire line
 230      * of pixels all at once using fewer access to memory which bypass any
 231      * intermediate structures like an incoming FIFO.
 232      *
 233      * @param ps          A vector iterator to store retrieved pixels into.
 234      * @param line_length The number of pixels being requested.
 235      * @return The number of pixels actually retrieved.
 236      */
 237     virtual size_t
 238     nextLine(std::vector<Pixel>::iterator ps, size_t line_length)
 239     {
 240         size_t count = 0;
 241         while (count < line_length && nextPixel(*ps++))
 242             count++;
 243         return count;
 244     }
 245
 246     /** First pixel clock of the first VSync line. */
 247     virtual void onVSyncBegin() {};
 248
 249     /**
 250      * Callback on the first pixel of the line after the end VSync
 251      * region (typically the first pixel of the vertical back porch).
 252      */
 253     virtual void onVSyncEnd() {};
 254
 255     /**
 256      * Start of the HSync region.
 257      *
 258      * @note This is called even for scan lines outside of the visible
 259      * region.
 260      */
 261     virtual void onHSyncBegin() {};
 262
 263     /**
 264      * Start of the first pixel after the HSync region.
 265      *
 266      * @note This is called even for scan lines outside of the visible
 267      * region.
 268      */
 269     virtual void onHSyncEnd() {};
 270
 271     /**
 272      * Buffer underrun occurred on a frame.
 273      *
 274      * This method is called once if there is buffer underrun while
 275      * refreshing the display. The underrun state is reset on the next
 276      * refresh.
 277      *
 278      * @param x Coordinate within the visible region.
 279      * @param y Coordinate within the visible region.
 280      */
 281     virtual void onUnderrun(unsigned x, unsigned y) {};
 282
 283     /** Finished displaying the visible region of a frame */
 284     virtual void onFrameDone() {};
 285
 286   private: // Params
 287     /** Maximum number of pixels to handle per render callback */
 288     const unsigned pixelChunk;
 289
 290   private:
 291     /**
 292      * Callback helper class with suspend support.
 293      *
 294      * Unlike a normal EventWrapper, this class suspends an event on
 295      * drain() and restarts it at drainResume(). The suspend operation
 296      * stores the tick relative to curTick() and then deschedules the
 297      * event. The resume operation schedules the event at curTick()
 298      * plus the relative tick stored when the event was suspended.
 299      */
 300     class PixelEvent : public Event, public Drainable
 301     {
 302         typedef void (BasePixelPump::* CallbackType)();
 303
 304       public:
 305         PixelEvent(const char *name, BasePixelPump *parent, CallbackType func);
 306
 307         DrainState drain() override;
 308         void drainResume() override;
 309
 310         void serialize(CheckpointOut &cp) const override;
 311         void unserialize(CheckpointIn &cp) override;
 312
 313         const std::string name() const override { return _name; }
 314
 315         void
 316         process() override
 317         {
 318             (parent.*func)();
 319         }
 320
 321         bool active() const { return scheduled() || suspended; }
 322
 323       private:
 324         void suspend();
 325         void resume();
 326
 327         const std::string _name;
 328         BasePixelPump &parent;
 329         const CallbackType func;
 330
 331         bool suspended;
 332         Tick relativeTick;
 333     };
 334
 335     void beginLine();
 336     void renderPixels();
 337
 338     /** Fast and event-free line rendering function */
 339     void renderLine();
 340
 341     /** Convenience vector when doing operations on all events */
 342     std::vector<PixelEvent *> pixelEvents;
 343
 344     PixelEvent evVSyncBegin;
 345     PixelEvent evVSyncEnd;
 346     PixelEvent evHSyncBegin;
 347     PixelEvent evHSyncEnd;
 348     PixelEvent evBeginLine;
 349     PixelEvent evRenderPixels;
 350
 351     DisplayTimings _timings;
 352
 353     /**
 354      * Current line (including back porch, front porch, and vsync)
 355      * within a frame.
 356      */
 357     unsigned line;
 358     /** X-coordinate within the visible region of a frame */
 359     unsigned _posX;
 360
 361     /** Did a buffer underrun occur within this refresh interval? */
 362     bool _underrun;
 363 };
 364
 365 #endif // __DEV_PIXELPUMP_HH__