pixelpump.hh revision 11168:f98eb2da15a4 
1/*
2 * Copyright (c) 2015 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,
32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * Authors: Andreas Sandberg
38 */
39
40#ifndef __DEV_PIXELPUMP_HH__
41#define __DEV_PIXELPUMP_HH__
42
43#include "base/framebuffer.hh"
44#include "sim/clocked_object.hh"
45
46struct BasePixelPumpParams;
47
48struct 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 cyclesPerLine() const {
71        return Cycles(hSync + hBackPorch +  width + hBackPorch);
72    }
73
74    /** How many pixel clocks are required for one frame? */
75    Cycles cyclesPerFrame() const {
76        return Cycles(cyclesPerLine() * linesPerFrame());
77    }
78
79    /** Calculate the first line of the vsync signal */
80    unsigned lineVSyncStart() const {
81        return 0;
82    }
83
84    /** Calculate the first line of the vertical back porch */
85    unsigned lineVBackPorchStart() const {
86        return lineVSyncStart() + vSync;
87    }
88
89    /** Calculate the first line of the visible region */
90    unsigned lineFirstVisible() const {
91        return lineVBackPorchStart() + vBackPorch;
92    }
93
94    /** Calculate the first line of the back porch */
95    unsigned lineFrontPorchStart() const {
96        return lineFirstVisible() + height;
97    }
98
99    /** Calculate the total number of lines in a frame */
100    unsigned linesPerFrame() const {
101        return lineFrontPorchStart() + vFrontPorch;
102    }
103
104    /** Display width in pixels */
105    unsigned width;
106    /** Display height in pixels */
107    unsigned height;
108
109    /** Horizontal back porch in pixels */
110    unsigned hBackPorch;
111    /** Horizontal front porch in pixels */
112    unsigned hFrontPorch;
113    /** Horizontal sync signal length in pixels */
114    unsigned hSync;
115
116    /** Vertical back porch in lines */
117    unsigned vBackPorch;
118    /** Vertical front porch in lines */
119    unsigned vFrontPorch;
120    /** Vertical sync signal in lines */
121    unsigned vSync;
122
123    static const DisplayTimings vga;
124};
125
126/**
127 * Timing generator for a pixel-based display.
128 *
129 * Pixels are ordered relative to the top left corner of the
130 * display. Scan lines appear in the following order:
131 * <ol>
132 *   <li>Vertical Sync (starting at line 0)
133 *   <li>Vertical back porch
134 *   <li>Visible lines
135 *   <li>Vertical front porch
136 * </ol>
137 *
138 * Pixel order within a scan line:
139 * <ol>
140 *   <li>Horizontal Sync
141 *   <li>Horizontal Back Porch
142 *   <li>Visible pixels
143 *   <li>Horizontal Front Porch
144 * </ol>
145 */
146class BasePixelPump
147    : public EventManager, public Clocked,
148      public Serializable
149{
150  public:
151    BasePixelPump(EventManager &em, ClockDomain &pxl_clk, unsigned pixel_chunk);
152    virtual ~BasePixelPump();
153
154    void serialize(CheckpointOut &cp) const override;
155    void unserialize(CheckpointIn &cp) override;
156
157  public: // Public API
158    /** Starting pushing pixels using the supplied display timings. */
159    void start(const DisplayTimings &timings);
160
161    /** Immediately stop pushing pixels */
162    void stop();
163
164    /** Get a constant reference of the current display timings */
165    const DisplayTimings &timings() const { return _timings; }
166
167    /** Is the pixel pump active and refreshing the display? */
168    bool active() const { return evBeginLine.active(); }
169
170    /** Did a buffer underrun occur within this refresh interval? */
171    bool underrun() const { return _underrun; }
172
173    /** Is the current line within the visible range? */
174    bool visibleLine() const {
175        return line >= _timings.lineFirstVisible() &&
176            line < _timings.lineFrontPorchStart();
177    }
178
179    /** Current pixel position within the visible area */
180    unsigned posX() const { return _posX; }
181
182    /** Current pixel position within the visible area */
183    unsigned posY() const {
184        return visibleLine() ? line - _timings.lineFirstVisible() : 0;
185    }
186
187    /** Output frame buffer */
188    FrameBuffer fb;
189
190  protected: // Callbacks
191    /**
192     * Get the next pixel from the scan line buffer.
193     *
194     * @param p Output pixel value, undefined on underrun
195     * @return true on success, false on buffer underrun
196     */
197    virtual bool nextPixel(Pixel &p) = 0;
198
199    /** First pixel clock of the first VSync line. */
200    virtual void onVSyncBegin() {};
201
202    /**
203     * Callback on the first pixel of the line after the end VSync
204     * region (typically the first pixel of the vertical back porch).
205     */
206    virtual void onVSyncEnd() {};
207
208    /**
209     * Start of the HSync region.
210     *
211     * @note This is called even for scan lines outside of the visible
212     * region.
213     */
214    virtual void onHSyncBegin() {};
215
216    /**
217     * Start of the first pixel after the HSync region.
218     *
219     * @note This is called even for scan lines outside of the visible
220     * region.
221     */
222    virtual void onHSyncEnd() {};
223
224    /**
225     * Buffer underrun occurred on a frame.
226     *
227     * This method is called once if there is buffer underrun while
228     * refreshing the display. The underrun state is reset on the next
229     * refresh.
230     *
231     * @param x Coordinate within the visible region.
232     * @param y Coordinate within the visible region.
233     */
234    virtual void onUnderrun(unsigned x, unsigned y) {};
235
236    /** Finished displaying the visible region of a frame */
237    virtual void onFrameDone() {};
238
239  private: // Params
240    /** Maximum number of pixels to handle per render callback */
241    const unsigned pixelChunk;
242
243  private:
244    /**
245     * Callback helper class with suspend support.
246     *
247     * Unlike a normal EventWrapper, this class suspends an event on
248     * drain() and restarts it at drainResume(). The suspend operation
249     * stores the tick relative to curTick() and then deschedules the
250     * event. The resume operation schedules the event at curTick()
251     * plus the relative tick stored when the event was suspended.
252     */
253    class PixelEvent : public Event, public Drainable
254    {
255        typedef void (BasePixelPump::* CallbackType)();
256
257      public:
258        PixelEvent(const char *name, BasePixelPump *parent, CallbackType func);
259
260        DrainState drain() override;
261        void drainResume() override;
262
263        void serialize(CheckpointOut &cp) const override;
264        void unserialize(CheckpointIn &cp) override;
265
266        const std::string name() const override { return _name; }
267        void process() override {
268            (parent.*func)();
269        }
270
271        bool active() const { return scheduled() || suspended; }
272
273      private:
274        void suspend();
275        void resume();
276
277        const std::string _name;
278        BasePixelPump &parent;
279        const CallbackType func;
280
281        bool suspended;
282        Tick relativeTick;
283    };
284
285    void beginLine();
286    void renderPixels();
287
288    /** Convenience vector when doing operations on all events */
289    std::vector<PixelEvent *> pixelEvents;
290
291    PixelEvent evVSyncBegin;
292    PixelEvent evVSyncEnd;
293    PixelEvent evHSyncBegin;
294    PixelEvent evHSyncEnd;
295    PixelEvent evBeginLine;
296    PixelEvent evRenderPixels;
297
298    DisplayTimings _timings;
299
300    /**
301     * Current line (including back porch, front porch, and vsync)
302     * within a frame.
303     */
304    unsigned line;
305    /** X-coordinate within the visible region of a frame */
306    unsigned _posX;
307
308    /** Did a buffer underrun occur within this refresh interval? */
309    bool _underrun;
310};
311
312#endif // __DEV_PIXELPUMP_HH__
313