src/Unix/video_vosf.h

/*
 *  video_vosf.h - Video/graphics emulation, video on SEGV signals support
 *
 *  Basilisk II (C) 1997-2004 Christian Bauer
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifndef VIDEO_VOSF_H
#define VIDEO_VOSF_H

// Note: this file must be #include'd only in video_x.cpp
#ifdef ENABLE_VOSF

#include "sigsegv.h"
#include "vm_alloc.h"
#ifdef _WIN32
#include "util_windows.h"
#endif

// Glue for SDL and X11 support
#ifdef USE_SDL_VIDEO
#define MONITOR_INIT                    SDL_monitor_desc &monitor
#define VIDEO_DRV_INIT                  driver_window *drv
#define VIDEO_DRV_ROW_BYTES             drv->s->pitch
#define VIDEO_DRV_LOCK_PIXELS   if (SDL_MUSTLOCK(drv->s)) SDL_LockSurface(drv->s)
#define VIDEO_DRV_UNLOCK_PIXELS if (SDL_MUSTLOCK(drv->s)) SDL_UnlockSurface(drv->s)
#else
#ifdef SHEEPSHAVER
#define MONITOR_INIT                    /* nothing */
#define VIDEO_DRV_INIT                  /* nothing */
#define VIDEO_DRV_WINDOW                the_win
#define VIDEO_DRV_GC                    the_gc
#define VIDEO_DRV_IMAGE                 img
#define VIDEO_DRV_HAVE_SHM              have_shm
#else
#define MONITOR_INIT                    X11_monitor_desc &monitor
#define VIDEO_DRV_INIT                  driver_window *drv
#define VIDEO_DRV_WINDOW                drv->w
#define VIDEO_DRV_GC                    drv->gc
#define VIDEO_DRV_IMAGE                 drv->img
#define VIDEO_DRV_HAVE_SHM              drv->have_shm
#endif
#define VIDEO_DRV_LOCK_PIXELS   /* nothing */
#define VIDEO_DRV_UNLOCK_PIXELS /* nothing */
#define VIDEO_DRV_ROW_BYTES             VIDEO_DRV_IMAGE->bytes_per_line
#endif

// Variables for Video on SEGV support
static uint8 *the_host_buffer;  // Host frame buffer in VOSF mode

struct ScreenPageInfo {
    int top, bottom;                    // Mapping between this virtual page and Mac scanlines
};

struct ScreenInfo {
    uintptr memStart;                   // Start address aligned to page boundary
    uint32 memLength;                   // Length of the memory addressed by the screen pages
    
    uintptr pageSize;                   // Size of a page
    int pageBits;                               // Shift count to get the page number
    uint32 pageCount;                   // Number of pages allocated to the screen
    
        bool dirty;                                     // Flag: set if the frame buffer was touched
    char * dirtyPages;                  // Table of flags set if page was altered
    ScreenPageInfo * pageInfo;  // Table of mappings page -> Mac scanlines
};

static ScreenInfo mainBuffer;

#define PFLAG_SET_VALUE                 0x00
#define PFLAG_CLEAR_VALUE               0x01
#define PFLAG_SET_VALUE_4               0x00000000
#define PFLAG_CLEAR_VALUE_4             0x01010101
#define PFLAG_SET(page)                 mainBuffer.dirtyPages[page] = PFLAG_SET_VALUE
#define PFLAG_CLEAR(page)               mainBuffer.dirtyPages[page] = PFLAG_CLEAR_VALUE
#define PFLAG_ISSET(page)               (mainBuffer.dirtyPages[page] == PFLAG_SET_VALUE)
#define PFLAG_ISCLEAR(page)             (mainBuffer.dirtyPages[page] != PFLAG_SET_VALUE)

#ifdef UNALIGNED_PROFITABLE
# define PFLAG_ISSET_4(page)    (*((uint32 *)(mainBuffer.dirtyPages + (page))) == PFLAG_SET_VALUE_4)
# define PFLAG_ISCLEAR_4(page)  (*((uint32 *)(mainBuffer.dirtyPages + (page))) == PFLAG_CLEAR_VALUE_4)
#else
# define PFLAG_ISSET_4(page) \
                PFLAG_ISSET(page  ) && PFLAG_ISSET(page+1) \
        &&      PFLAG_ISSET(page+2) && PFLAG_ISSET(page+3)
# define PFLAG_ISCLEAR_4(page) \
                PFLAG_ISCLEAR(page  ) && PFLAG_ISCLEAR(page+1) \
        &&      PFLAG_ISCLEAR(page+2) && PFLAG_ISCLEAR(page+3)
#endif

// Set the selected page range [ first_page, last_page [ into the SET state
#define PFLAG_SET_RANGE(first_page, last_page) \
        memset(mainBuffer.dirtyPages + (first_page), PFLAG_SET_VALUE, \
                (last_page) - (first_page))

// Set the selected page range [ first_page, last_page [ into the CLEAR state
#define PFLAG_CLEAR_RANGE(first_page, last_page) \
        memset(mainBuffer.dirtyPages + (first_page), PFLAG_CLEAR_VALUE, \
                (last_page) - (first_page))

#define PFLAG_SET_ALL do { \
        PFLAG_SET_RANGE(0, mainBuffer.pageCount); \
        mainBuffer.dirty = true; \
} while (0)

#define PFLAG_CLEAR_ALL do { \
        PFLAG_CLEAR_RANGE(0, mainBuffer.pageCount); \
        mainBuffer.dirty = false; \
} while (0)

// Set the following macro definition to 1 if your system
// provides a really fast strchr() implementation
//#define HAVE_FAST_STRCHR 0

static inline int find_next_page_set(int page)
{
#if HAVE_FAST_STRCHR
        char *match = strchr(mainBuffer.dirtyPages + page, PFLAG_SET_VALUE);
        return match ? match - mainBuffer.dirtyPages : mainBuffer.pageCount;
#else
        while (PFLAG_ISCLEAR_4(page))
                page += 4;
        while (PFLAG_ISCLEAR(page))
                page++;
        return page;
#endif
}

static inline int find_next_page_clear(int page)
{
#if HAVE_FAST_STRCHR
        char *match = strchr(mainBuffer.dirtyPages + page, PFLAG_CLEAR_VALUE);
        return match ? match - mainBuffer.dirtyPages : mainBuffer.pageCount;
#else
        while (PFLAG_ISSET_4(page))
                page += 4;
        while (PFLAG_ISSET(page))
                page++;
        return page;
#endif
}

#ifdef HAVE_SPINLOCKS
static spinlock_t vosf_lock = SPIN_LOCK_UNLOCKED;                               // Mutex to protect frame buffer (dirtyPages in fact)
#define LOCK_VOSF spin_lock(&vosf_lock)
#define UNLOCK_VOSF spin_unlock(&vosf_lock)
#elif defined(_WIN32)
static mutex_t vosf_lock;                                                                               // Mutex to protect frame buffer (dirtyPages in fact)
#define LOCK_VOSF vosf_lock.lock();
#define UNLOCK_VOSF vosf_lock.unlock();
#elif defined(HAVE_PTHREADS)
static pthread_mutex_t vosf_lock = PTHREAD_MUTEX_INITIALIZER;   // Mutex to protect frame buffer (dirtyPages in fact)
#define LOCK_VOSF pthread_mutex_lock(&vosf_lock);
#define UNLOCK_VOSF pthread_mutex_unlock(&vosf_lock);
#else
#define LOCK_VOSF
#define UNLOCK_VOSF
#endif

static int log_base_2(uint32 x)
{
        uint32 mask = 0x80000000;
        int l = 31;
        while (l >= 0 && (x & mask) == 0) {
                mask >>= 1;
                l--;
        }
        return l;
}

// Extend size to page boundary
static uint32 page_extend(uint32 size)
{
        const uint32 page_size = vm_get_page_size();
        const uint32 page_mask = page_size - 1;
        return (size + page_mask) & ~page_mask;
}


/*
 *  Check if VOSF acceleration is profitable on this platform
 */

const int VOSF_PROFITABLE_TRIES = 3;                    // Make 3 attempts for full screen update
const int VOSF_PROFITABLE_THRESHOLD = 16667;    // 60 Hz

static bool video_vosf_profitable(void)
{
        int64 durations[VOSF_PROFITABLE_TRIES];
        int mean_duration = 0;

        for (int i = 0; i < VOSF_PROFITABLE_TRIES; i++) {
                uint64 start = GetTicks_usec();
                for (int p = 0; p < mainBuffer.pageCount; p++) {
                        uint8 *addr = (uint8 *)(mainBuffer.memStart + (p * mainBuffer.pageSize));
                        addr[0] = 0; // Trigger Screen_fault_handler()
                }
                int64 duration = GetTicks_usec() - start;
                mean_duration += duration;
                durations[i] = duration;

                PFLAG_CLEAR_ALL;
                mainBuffer.dirty = false;
                if (vm_protect((char *)mainBuffer.memStart, mainBuffer.memLength, VM_PAGE_READ) != 0)
                        return false;
        }

        mean_duration /= VOSF_PROFITABLE_TRIES;
        D(bug("Triggered %d screen faults in %ld usec on average\n", mainBuffer.pageCount, mean_duration));
        return (mean_duration < (VOSF_PROFITABLE_THRESHOLD * (frame_skip ? frame_skip : 1)));
}


/*
 *  Initialize the VOSF system (mainBuffer structure, SIGSEGV handler)
 */

static bool video_vosf_init(MONITOR_INIT)
{
        VIDEO_MODE_INIT_MONITOR;

        const uintptr page_size = vm_get_page_size();
        const uintptr page_mask = page_size - 1;
        
        // Round up frame buffer base to page boundary
        mainBuffer.memStart = (((uintptr) the_buffer) + page_mask) & ~page_mask;
        
        // The frame buffer size shall already be aligned to page boundary (use page_extend)
        mainBuffer.memLength = the_buffer_size;
        
        mainBuffer.pageSize = page_size;
        mainBuffer.pageBits = log_base_2(mainBuffer.pageSize);
        mainBuffer.pageCount =  (mainBuffer.memLength + page_mask)/mainBuffer.pageSize;
        
        // The "2" more bytes requested are a safety net to insure the
        // loops in the update routines will terminate.
        // See "How can we deal with array overrun conditions ?" hereunder for further details.
        mainBuffer.dirtyPages = (char *) malloc(mainBuffer.pageCount + 2);
        if (mainBuffer.dirtyPages == NULL)
                return false;
                
        PFLAG_CLEAR_ALL;
        PFLAG_CLEAR(mainBuffer.pageCount);
        PFLAG_SET(mainBuffer.pageCount+1);
        
        // Allocate and fill in pageInfo with start and end (inclusive) row in number of bytes
        mainBuffer.pageInfo = (ScreenPageInfo *) malloc(mainBuffer.pageCount * sizeof(ScreenPageInfo));
        if (mainBuffer.pageInfo == NULL)
                return false;
        
        uint32 a = 0;
        for (unsigned i = 0; i < mainBuffer.pageCount; i++) {
                unsigned y1 = a / VIDEO_MODE_ROW_BYTES;
                if (y1 >= VIDEO_MODE_Y)
                        y1 = VIDEO_MODE_Y - 1;

                unsigned y2 = (a + mainBuffer.pageSize) / VIDEO_MODE_ROW_BYTES;
                if (y2 >= VIDEO_MODE_Y)
                        y2 = VIDEO_MODE_Y - 1;

                mainBuffer.pageInfo[i].top = y1;
                mainBuffer.pageInfo[i].bottom = y2;

                a += mainBuffer.pageSize;
                if (a > mainBuffer.memLength)
                        a = mainBuffer.memLength;
        }
        
        // We can now write-protect the frame buffer
        if (vm_protect((char *)mainBuffer.memStart, mainBuffer.memLength, VM_PAGE_READ) != 0)
                return false;
        
        // The frame buffer is sane, i.e. there is no write to it yet
        mainBuffer.dirty = false;
        return true;
}


/*
 * Deinitialize VOSF system
 */

static void video_vosf_exit(void)
{
        if (mainBuffer.pageInfo) {
                free(mainBuffer.pageInfo);
                mainBuffer.pageInfo = NULL;
        }
        if (mainBuffer.dirtyPages) {
                free(mainBuffer.dirtyPages);
                mainBuffer.dirtyPages = NULL;
        }
}


/*
 * Screen fault handler
 */

bool Screen_fault_handler(sigsegv_address_t fault_address, sigsegv_address_t fault_instruction)
{
        const uintptr addr = (uintptr)fault_address;
        
        /* Someone attempted to write to the frame buffer. Make it writeable
         * now so that the data could actually be written to. It will be made
         * read-only back in one of the screen update_*() functions.
         */
        if (((uintptr)addr - mainBuffer.memStart) < mainBuffer.memLength) {
                const int page  = ((uintptr)addr - mainBuffer.memStart) >> mainBuffer.pageBits;
                LOCK_VOSF;
                PFLAG_SET(page);
                vm_protect((char *)(addr & -mainBuffer.pageSize), mainBuffer.pageSize, VM_PAGE_READ | VM_PAGE_WRITE);
                mainBuffer.dirty = true;
                UNLOCK_VOSF;
                return true;
        }
        
        /* Otherwise, we don't know how to handle the fault, let it crash */
        return false;
}


/*
 *      Update display for Windowed mode and VOSF
 */

/*      How can we deal with array overrun conditions ?
        
        The state of the framebuffer pages that have been touched are maintained
        in the dirtyPages[] table. That table is (pageCount + 2) bytes long.

Terminology
        
        "Last Page" denotes the pageCount-nth page, i.e. dirtyPages[pageCount - 1].
        "CLEAR Page Guard" refers to the page following the Last Page but is always
        in the CLEAR state. "SET Page Guard" refers to the page following the CLEAR
        Page Guard but is always in the SET state.

Rough process
        
        The update routines must determine which pages have to be blitted to the
        screen. This job consists in finding the first_page that was touched.
        i.e. find the next page that is SET. Then, finding how many pages were
        touched starting from first_page. i.e. find the next page that is CLEAR.

There are two cases to check:

        - Last Page is CLEAR: find_next_page_set() will reach the SET Page Guard
        but it is beyond the valid pageCount value. Therefore, we exit from the
        update routine.
        
        - Last Page is SET: first_page equals (pageCount - 1) and
        find_next_page_clear() will reach the CLEAR Page Guard. We blit the last
        page to the screen. On the next iteration, page equals pageCount and
        find_next_page_set() will reach the SET Page Guard. We still safely exit
        from the update routine because the SET Page Guard position is greater
        than pageCount.
*/

static inline void update_display_window_vosf(VIDEO_DRV_INIT)
{
        VIDEO_MODE_INIT;

        int page = 0;
        for (;;) {
                const unsigned first_page = find_next_page_set(page);
                if (first_page >= mainBuffer.pageCount)
                        break;

                page = find_next_page_clear(first_page);
                PFLAG_CLEAR_RANGE(first_page, page);

                // Make the dirty pages read-only again
                const int32 offset  = first_page << mainBuffer.pageBits;
                const uint32 length = (page - first_page) << mainBuffer.pageBits;
                vm_protect((char *)mainBuffer.memStart + offset, length, VM_PAGE_READ);
                
                // There is at least one line to update
                const int y1 = mainBuffer.pageInfo[first_page].top;
                const int y2 = mainBuffer.pageInfo[page - 1].bottom;
                const int height = y2 - y1 + 1;

                VIDEO_DRV_LOCK_PIXELS;

                if ((int)VIDEO_MODE_DEPTH < VIDEO_DEPTH_8BIT) {

                        // Update the_host_buffer and copy of the_buffer
                        const int src_bytes_per_row = VIDEO_MODE_ROW_BYTES;
                        const int dst_bytes_per_row = VIDEO_DRV_ROW_BYTES;
                        const int pixels_per_byte = VIDEO_MODE_X / src_bytes_per_row;
                        int i1 = y1 * src_bytes_per_row, i2 = y1 * dst_bytes_per_row, j;
                        for (j = y1; j <= y2; j++) {
                                Screen_blit(the_host_buffer + i2, the_buffer + i1, VIDEO_MODE_X / pixels_per_byte);
                                i1 += src_bytes_per_row;
                                i2 += dst_bytes_per_row;
                        }

                } else {

                        // Update the_host_buffer and copy of the_buffer
                        const int src_bytes_per_row = VIDEO_MODE_ROW_BYTES;
                        const int dst_bytes_per_row = VIDEO_DRV_ROW_BYTES;
                        const int bytes_per_pixel = src_bytes_per_row / VIDEO_MODE_X;
                        int i1 = y1 * src_bytes_per_row, i2 = y1 * dst_bytes_per_row, j;
                        for (j = y1; j <= y2; j++) {
                                Screen_blit(the_host_buffer + i2, the_buffer + i1, bytes_per_pixel * VIDEO_MODE_X);
                                i1 += src_bytes_per_row;
                                i2 += dst_bytes_per_row;
                        }
                }

                VIDEO_DRV_UNLOCK_PIXELS;

#ifdef USE_SDL_VIDEO
                SDL_UpdateRect(drv->s, 0, y1, VIDEO_MODE_X, height);
#else
                if (VIDEO_DRV_HAVE_SHM)
                        XShmPutImage(x_display, VIDEO_DRV_WINDOW, VIDEO_DRV_GC, VIDEO_DRV_IMAGE, 0, y1, 0, y1, VIDEO_MODE_X, height, 0);
                else
                        XPutImage(x_display, VIDEO_DRV_WINDOW, VIDEO_DRV_GC, VIDEO_DRV_IMAGE, 0, y1, 0, y1, VIDEO_MODE_X, height);
#endif
        }
        mainBuffer.dirty = false;
}


/*
 *      Update display for DGA mode and VOSF
 *      (only in Real or Direct Addressing mode)
 */

#if REAL_ADDRESSING || DIRECT_ADDRESSING
static inline void update_display_dga_vosf(void)
{
        VIDEO_MODE_INIT;

        int page = 0;
        for (;;) {
                const unsigned first_page = find_next_page_set(page);
                if (first_page >= mainBuffer.pageCount)
                        break;

                page = find_next_page_clear(first_page);
                PFLAG_CLEAR_RANGE(first_page, page);

                // Make the dirty pages read-only again
                const int32 offset  = first_page << mainBuffer.pageBits;
                const uint32 length = (page - first_page) << mainBuffer.pageBits;
                vm_protect((char *)mainBuffer.memStart + offset, length, VM_PAGE_READ);
                
                // I am sure that y2 >= y1 and depth != 1
                const int y1 = mainBuffer.pageInfo[first_page].top;
                const int y2 = mainBuffer.pageInfo[page - 1].bottom;
                
                const int bytes_per_row = VIDEO_MODE_ROW_BYTES;
                const int bytes_per_pixel = VIDEO_MODE_ROW_BYTES / VIDEO_MODE_X;
                int i, j;
                
                // Check for first column from left and first column
                // from right that have changed
                int x1 = VIDEO_MODE_X * bytes_per_pixel - 1;
                for (j = y1; j <= y2; j++) {
                        uint8 * const p1 = &the_buffer[j * bytes_per_row];
                        uint8 * const p2 = &the_buffer_copy[j * bytes_per_row];
                        for (i = 0; i < x1; i++) {
                                if (p1[i] != p2[i]) {
                                        x1 = i;
                                        break;
                                }
                        }
                }
                x1 /= bytes_per_pixel;
                
                int x2 = x1 * bytes_per_pixel;
                for (j = y2; j >= y1; j--) {
                        uint8 * const p1 = &the_buffer[j * bytes_per_row];
                        uint8 * const p2 = &the_buffer_copy[j * bytes_per_row];
                        for (i = VIDEO_MODE_X * bytes_per_pixel - 1; i > x2; i--) {
                                if (p1[i] != p2[i]) {
                                        x2 = i;
                                        break;
                                }
                        }
                }
                x2 /= bytes_per_pixel;
                
                // Update the_host_buffer and copy of the_buffer
                // There should be at least one pixel to copy
                VIDEO_DRV_LOCK_PIXELS;
                const int width = x2 - x1 + 1;
                i = y1 * bytes_per_row + x1 * bytes_per_pixel;
                for (j = y1; j <= y2; j++) {
                        Screen_blit(the_host_buffer + i, the_buffer + i, bytes_per_pixel * width);
                        memcpy(the_buffer_copy + i, the_buffer + i, bytes_per_pixel * width);
                        i += bytes_per_row;
                }
                VIDEO_DRV_UNLOCK_PIXELS;
        }
        mainBuffer.dirty = false;
}
#endif

#endif /* ENABLE_VOSF */

#endif /* VIDEO_VOSF_H */
Revision:	1.47
Committed:	2004-12-18T22:20:27Z (19 years, 6 months ago) by gbeauche
Content type:	text/plain
Branch:	MAIN
Changes since 1.46:	+2 -2 lines
Log Message:	s/vm_page_size/vm_get_page_size/ to avoid name clash on MacOS X
#	Content
1	/*
2	* video_vosf.h - Video/graphics emulation, video on SEGV signals support
3	*
4	* Basilisk II (C) 1997-2004 Christian Bauer
5	*
6	* This program is free software; you can redistribute it and/or modify
7	* it under the terms of the GNU General Public License as published by
8	* the Free Software Foundation; either version 2 of the License, or
9	* (at your option) any later version.
10	*
11	* This program is distributed in the hope that it will be useful,
12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14	* GNU General Public License for more details.
15	*
16	* You should have received a copy of the GNU General Public License
17	* along with this program; if not, write to the Free Software
18	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19	*/
20
21	#ifndef VIDEO_VOSF_H
22	#define VIDEO_VOSF_H
23
24	// Note: this file must be #include'd only in video_x.cpp
25	#ifdef ENABLE_VOSF
26
27	#include "sigsegv.h"
28	#include "vm_alloc.h"
29	#ifdef _WIN32
30	#include "util_windows.h"
31	#endif
32
33	// Glue for SDL and X11 support
34	#ifdef USE_SDL_VIDEO
35	#define MONITOR_INIT SDL_monitor_desc &monitor
36	#define VIDEO_DRV_INIT driver_window *drv
37	#define VIDEO_DRV_ROW_BYTES drv->s->pitch
38	#define VIDEO_DRV_LOCK_PIXELS if (SDL_MUSTLOCK(drv->s)) SDL_LockSurface(drv->s)
39	#define VIDEO_DRV_UNLOCK_PIXELS if (SDL_MUSTLOCK(drv->s)) SDL_UnlockSurface(drv->s)
40	#else
41	#ifdef SHEEPSHAVER
42	#define MONITOR_INIT /* nothing */
43	#define VIDEO_DRV_INIT /* nothing */
44	#define VIDEO_DRV_WINDOW the_win
45	#define VIDEO_DRV_GC the_gc
46	#define VIDEO_DRV_IMAGE img
47	#define VIDEO_DRV_HAVE_SHM have_shm
48	#else
49	#define MONITOR_INIT X11_monitor_desc &monitor
50	#define VIDEO_DRV_INIT driver_window *drv
51	#define VIDEO_DRV_WINDOW drv->w
52	#define VIDEO_DRV_GC drv->gc
53	#define VIDEO_DRV_IMAGE drv->img
54	#define VIDEO_DRV_HAVE_SHM drv->have_shm
55	#endif
56	#define VIDEO_DRV_LOCK_PIXELS /* nothing */
57	#define VIDEO_DRV_UNLOCK_PIXELS /* nothing */
58	#define VIDEO_DRV_ROW_BYTES VIDEO_DRV_IMAGE->bytes_per_line
59	#endif
60
61	// Variables for Video on SEGV support
62	static uint8 *the_host_buffer; // Host frame buffer in VOSF mode
63
64	struct ScreenPageInfo {
65	int top, bottom; // Mapping between this virtual page and Mac scanlines
66	};
67
68	struct ScreenInfo {
69	uintptr memStart; // Start address aligned to page boundary
70	uint32 memLength; // Length of the memory addressed by the screen pages
71
72	uintptr pageSize; // Size of a page
73	int pageBits; // Shift count to get the page number
74	uint32 pageCount; // Number of pages allocated to the screen
75
76	bool dirty; // Flag: set if the frame buffer was touched
77	char * dirtyPages; // Table of flags set if page was altered
78	ScreenPageInfo * pageInfo; // Table of mappings page -> Mac scanlines
79	};
80
81	static ScreenInfo mainBuffer;
82
83	#define PFLAG_SET_VALUE 0x00
84	#define PFLAG_CLEAR_VALUE 0x01
85	#define PFLAG_SET_VALUE_4 0x00000000
86	#define PFLAG_CLEAR_VALUE_4 0x01010101
87	#define PFLAG_SET(page) mainBuffer.dirtyPages[page] = PFLAG_SET_VALUE
88	#define PFLAG_CLEAR(page) mainBuffer.dirtyPages[page] = PFLAG_CLEAR_VALUE
89	#define PFLAG_ISSET(page) (mainBuffer.dirtyPages[page] == PFLAG_SET_VALUE)
90	#define PFLAG_ISCLEAR(page) (mainBuffer.dirtyPages[page] != PFLAG_SET_VALUE)
91
92	#ifdef UNALIGNED_PROFITABLE
93	# define PFLAG_ISSET_4(page) (((uint32 )(mainBuffer.dirtyPages + (page))) == PFLAG_SET_VALUE_4)
94	# define PFLAG_ISCLEAR_4(page) (((uint32 )(mainBuffer.dirtyPages + (page))) == PFLAG_CLEAR_VALUE_4)
95	#else
96	# define PFLAG_ISSET_4(page) \
97	PFLAG_ISSET(page ) && PFLAG_ISSET(page+1) \
98	&& PFLAG_ISSET(page+2) && PFLAG_ISSET(page+3)
99	# define PFLAG_ISCLEAR_4(page) \
100	PFLAG_ISCLEAR(page ) && PFLAG_ISCLEAR(page+1) \
101	&& PFLAG_ISCLEAR(page+2) && PFLAG_ISCLEAR(page+3)
102	#endif
103
104	// Set the selected page range [ first_page, last_page [ into the SET state
105	#define PFLAG_SET_RANGE(first_page, last_page) \
106	memset(mainBuffer.dirtyPages + (first_page), PFLAG_SET_VALUE, \
107	(last_page) - (first_page))
108
109	// Set the selected page range [ first_page, last_page [ into the CLEAR state
110	#define PFLAG_CLEAR_RANGE(first_page, last_page) \
111	memset(mainBuffer.dirtyPages + (first_page), PFLAG_CLEAR_VALUE, \
112	(last_page) - (first_page))
113
114	#define PFLAG_SET_ALL do { \
115	PFLAG_SET_RANGE(0, mainBuffer.pageCount); \
116	mainBuffer.dirty = true; \
117	} while (0)
118
119	#define PFLAG_CLEAR_ALL do { \
120	PFLAG_CLEAR_RANGE(0, mainBuffer.pageCount); \
121	mainBuffer.dirty = false; \
122	} while (0)
123
124	// Set the following macro definition to 1 if your system
125	// provides a really fast strchr() implementation
126	//#define HAVE_FAST_STRCHR 0
127
128	static inline int find_next_page_set(int page)
129	{
130	#if HAVE_FAST_STRCHR
131	char *match = strchr(mainBuffer.dirtyPages + page, PFLAG_SET_VALUE);
132	return match ? match - mainBuffer.dirtyPages : mainBuffer.pageCount;
133	#else
134	while (PFLAG_ISCLEAR_4(page))
135	page += 4;
136	while (PFLAG_ISCLEAR(page))
137	page++;
138	return page;
139	#endif
140	}
141
142	static inline int find_next_page_clear(int page)
143	{
144	#if HAVE_FAST_STRCHR
145	char *match = strchr(mainBuffer.dirtyPages + page, PFLAG_CLEAR_VALUE);
146	return match ? match - mainBuffer.dirtyPages : mainBuffer.pageCount;
147	#else
148	while (PFLAG_ISSET_4(page))
149	page += 4;
150	while (PFLAG_ISSET(page))
151	page++;
152	return page;
153	#endif
154	}
155
156	#ifdef HAVE_SPINLOCKS
157	static spinlock_t vosf_lock = SPIN_LOCK_UNLOCKED; // Mutex to protect frame buffer (dirtyPages in fact)
158	#define LOCK_VOSF spin_lock(&vosf_lock)
159	#define UNLOCK_VOSF spin_unlock(&vosf_lock)
160	#elif defined(_WIN32)
161	static mutex_t vosf_lock; // Mutex to protect frame buffer (dirtyPages in fact)
162	#define LOCK_VOSF vosf_lock.lock();
163	#define UNLOCK_VOSF vosf_lock.unlock();
164	#elif defined(HAVE_PTHREADS)
165	static pthread_mutex_t vosf_lock = PTHREAD_MUTEX_INITIALIZER; // Mutex to protect frame buffer (dirtyPages in fact)
166	#define LOCK_VOSF pthread_mutex_lock(&vosf_lock);
167	#define UNLOCK_VOSF pthread_mutex_unlock(&vosf_lock);
168	#else
169	#define LOCK_VOSF
170	#define UNLOCK_VOSF
171	#endif
172
173	static int log_base_2(uint32 x)
174	{
175	uint32 mask = 0x80000000;
176	int l = 31;
177	while (l >= 0 && (x & mask) == 0) {
178	mask >>= 1;
179	l--;
180	}
181	return l;
182	}
183
184	// Extend size to page boundary
185	static uint32 page_extend(uint32 size)
186	{
187	const uint32 page_size = vm_get_page_size();
188	const uint32 page_mask = page_size - 1;
189	return (size + page_mask) & ~page_mask;
190	}
191
192
193	/*
194	* Check if VOSF acceleration is profitable on this platform
195	*/
196
197	const int VOSF_PROFITABLE_TRIES = 3; // Make 3 attempts for full screen update
198	const int VOSF_PROFITABLE_THRESHOLD = 16667; // 60 Hz
199
200	static bool video_vosf_profitable(void)
201	{
202	int64 durations[VOSF_PROFITABLE_TRIES];
203	int mean_duration = 0;
204
205	for (int i = 0; i < VOSF_PROFITABLE_TRIES; i++) {
206	uint64 start = GetTicks_usec();
207	for (int p = 0; p < mainBuffer.pageCount; p++) {
208	uint8 addr = (uint8 )(mainBuffer.memStart + (p * mainBuffer.pageSize));
209	addr[0] = 0; // Trigger Screen_fault_handler()
210	}
211	int64 duration = GetTicks_usec() - start;
212	mean_duration += duration;
213	durations[i] = duration;
214
215	PFLAG_CLEAR_ALL;
216	mainBuffer.dirty = false;
217	if (vm_protect((char *)mainBuffer.memStart, mainBuffer.memLength, VM_PAGE_READ) != 0)
218	return false;
219	}
220
221	mean_duration /= VOSF_PROFITABLE_TRIES;
222	D(bug("Triggered %d screen faults in %ld usec on average\n", mainBuffer.pageCount, mean_duration));
223	return (mean_duration < (VOSF_PROFITABLE_THRESHOLD * (frame_skip ? frame_skip : 1)));
224	}
225
226
227	/*
228	* Initialize the VOSF system (mainBuffer structure, SIGSEGV handler)
229	*/
230
231	static bool video_vosf_init(MONITOR_INIT)
232	{
233	VIDEO_MODE_INIT_MONITOR;
234
235	const uintptr page_size = vm_get_page_size();
236	const uintptr page_mask = page_size - 1;
237
238	// Round up frame buffer base to page boundary
239	mainBuffer.memStart = (((uintptr) the_buffer) + page_mask) & ~page_mask;
240
241	// The frame buffer size shall already be aligned to page boundary (use page_extend)
242	mainBuffer.memLength = the_buffer_size;
243
244	mainBuffer.pageSize = page_size;
245	mainBuffer.pageBits = log_base_2(mainBuffer.pageSize);
246	mainBuffer.pageCount = (mainBuffer.memLength + page_mask)/mainBuffer.pageSize;
247
248	// The "2" more bytes requested are a safety net to insure the
249	// loops in the update routines will terminate.
250	// See "How can we deal with array overrun conditions ?" hereunder for further details.
251	mainBuffer.dirtyPages = (char *) malloc(mainBuffer.pageCount + 2);
252	if (mainBuffer.dirtyPages == NULL)
253	return false;
254
255	PFLAG_CLEAR_ALL;
256	PFLAG_CLEAR(mainBuffer.pageCount);
257	PFLAG_SET(mainBuffer.pageCount+1);
258
259	// Allocate and fill in pageInfo with start and end (inclusive) row in number of bytes
260	mainBuffer.pageInfo = (ScreenPageInfo ) malloc(mainBuffer.pageCount sizeof(ScreenPageInfo));
261	if (mainBuffer.pageInfo == NULL)
262	return false;
263
264	uint32 a = 0;
265	for (unsigned i = 0; i < mainBuffer.pageCount; i++) {
266	unsigned y1 = a / VIDEO_MODE_ROW_BYTES;
267	if (y1 >= VIDEO_MODE_Y)
268	y1 = VIDEO_MODE_Y - 1;
269
270	unsigned y2 = (a + mainBuffer.pageSize) / VIDEO_MODE_ROW_BYTES;
271	if (y2 >= VIDEO_MODE_Y)
272	y2 = VIDEO_MODE_Y - 1;
273
274	mainBuffer.pageInfo[i].top = y1;
275	mainBuffer.pageInfo[i].bottom = y2;
276
277	a += mainBuffer.pageSize;
278	if (a > mainBuffer.memLength)
279	a = mainBuffer.memLength;
280	}
281
282	// We can now write-protect the frame buffer
283	if (vm_protect((char *)mainBuffer.memStart, mainBuffer.memLength, VM_PAGE_READ) != 0)
284	return false;
285
286	// The frame buffer is sane, i.e. there is no write to it yet
287	mainBuffer.dirty = false;
288	return true;
289	}
290
291
292	/*
293	* Deinitialize VOSF system
294	*/
295
296	static void video_vosf_exit(void)
297	{
298	if (mainBuffer.pageInfo) {
299	free(mainBuffer.pageInfo);
300	mainBuffer.pageInfo = NULL;
301	}
302	if (mainBuffer.dirtyPages) {
303	free(mainBuffer.dirtyPages);
304	mainBuffer.dirtyPages = NULL;
305	}
306	}
307
308
309	/*
310	* Screen fault handler
311	*/
312
313	bool Screen_fault_handler(sigsegv_address_t fault_address, sigsegv_address_t fault_instruction)
314	{
315	const uintptr addr = (uintptr)fault_address;
316
317	/* Someone attempted to write to the frame buffer. Make it writeable
318	* now so that the data could actually be written to. It will be made
319	* read-only back in one of the screen update_*() functions.
320	*/
321	if (((uintptr)addr - mainBuffer.memStart) < mainBuffer.memLength) {
322	const int page = ((uintptr)addr - mainBuffer.memStart) >> mainBuffer.pageBits;
323	LOCK_VOSF;
324	PFLAG_SET(page);
325	vm_protect((char *)(addr & -mainBuffer.pageSize), mainBuffer.pageSize, VM_PAGE_READ \| VM_PAGE_WRITE);
326	mainBuffer.dirty = true;
327	UNLOCK_VOSF;
328	return true;
329	}
330
331	/* Otherwise, we don't know how to handle the fault, let it crash */
332	return false;
333	}
334
335
336	/*
337	* Update display for Windowed mode and VOSF
338	*/
339
340	/* How can we deal with array overrun conditions ?
341
342	The state of the framebuffer pages that have been touched are maintained
343	in the dirtyPages[] table. That table is (pageCount + 2) bytes long.
344
345	Terminology
346
347	"Last Page" denotes the pageCount-nth page, i.e. dirtyPages[pageCount - 1].
348	"CLEAR Page Guard" refers to the page following the Last Page but is always
349	in the CLEAR state. "SET Page Guard" refers to the page following the CLEAR
350	Page Guard but is always in the SET state.
351
352	Rough process
353
354	The update routines must determine which pages have to be blitted to the
355	screen. This job consists in finding the first_page that was touched.
356	i.e. find the next page that is SET. Then, finding how many pages were
357	touched starting from first_page. i.e. find the next page that is CLEAR.
358
359	There are two cases to check:
360
361	- Last Page is CLEAR: find_next_page_set() will reach the SET Page Guard
362	but it is beyond the valid pageCount value. Therefore, we exit from the
363	update routine.
364
365	- Last Page is SET: first_page equals (pageCount - 1) and
366	find_next_page_clear() will reach the CLEAR Page Guard. We blit the last
367	page to the screen. On the next iteration, page equals pageCount and
368	find_next_page_set() will reach the SET Page Guard. We still safely exit
369	from the update routine because the SET Page Guard position is greater
370	than pageCount.
371	*/
372
373	static inline void update_display_window_vosf(VIDEO_DRV_INIT)
374	{
375	VIDEO_MODE_INIT;
376
377	int page = 0;
378	for (;;) {
379	const unsigned first_page = find_next_page_set(page);
380	if (first_page >= mainBuffer.pageCount)
381	break;
382
383	page = find_next_page_clear(first_page);
384	PFLAG_CLEAR_RANGE(first_page, page);
385
386	// Make the dirty pages read-only again
387	const int32 offset = first_page << mainBuffer.pageBits;
388	const uint32 length = (page - first_page) << mainBuffer.pageBits;
389	vm_protect((char *)mainBuffer.memStart + offset, length, VM_PAGE_READ);
390
391	// There is at least one line to update
392	const int y1 = mainBuffer.pageInfo[first_page].top;
393	const int y2 = mainBuffer.pageInfo[page - 1].bottom;
394	const int height = y2 - y1 + 1;
395
396	VIDEO_DRV_LOCK_PIXELS;
397
398	if ((int)VIDEO_MODE_DEPTH < VIDEO_DEPTH_8BIT) {
399
400	// Update the_host_buffer and copy of the_buffer
401	const int src_bytes_per_row = VIDEO_MODE_ROW_BYTES;
402	const int dst_bytes_per_row = VIDEO_DRV_ROW_BYTES;
403	const int pixels_per_byte = VIDEO_MODE_X / src_bytes_per_row;
404	int i1 = y1 * src_bytes_per_row, i2 = y1 * dst_bytes_per_row, j;
405	for (j = y1; j <= y2; j++) {
406	Screen_blit(the_host_buffer + i2, the_buffer + i1, VIDEO_MODE_X / pixels_per_byte);
407	i1 += src_bytes_per_row;
408	i2 += dst_bytes_per_row;
409	}
410
411	} else {
412
413	// Update the_host_buffer and copy of the_buffer
414	const int src_bytes_per_row = VIDEO_MODE_ROW_BYTES;
415	const int dst_bytes_per_row = VIDEO_DRV_ROW_BYTES;
416	const int bytes_per_pixel = src_bytes_per_row / VIDEO_MODE_X;
417	int i1 = y1 * src_bytes_per_row, i2 = y1 * dst_bytes_per_row, j;
418	for (j = y1; j <= y2; j++) {
419	Screen_blit(the_host_buffer + i2, the_buffer + i1, bytes_per_pixel * VIDEO_MODE_X);
420	i1 += src_bytes_per_row;
421	i2 += dst_bytes_per_row;
422	}
423	}
424
425	VIDEO_DRV_UNLOCK_PIXELS;
426
427	#ifdef USE_SDL_VIDEO
428	SDL_UpdateRect(drv->s, 0, y1, VIDEO_MODE_X, height);
429	#else
430	if (VIDEO_DRV_HAVE_SHM)
431	XShmPutImage(x_display, VIDEO_DRV_WINDOW, VIDEO_DRV_GC, VIDEO_DRV_IMAGE, 0, y1, 0, y1, VIDEO_MODE_X, height, 0);
432	else
433	XPutImage(x_display, VIDEO_DRV_WINDOW, VIDEO_DRV_GC, VIDEO_DRV_IMAGE, 0, y1, 0, y1, VIDEO_MODE_X, height);
434	#endif
435	}
436	mainBuffer.dirty = false;
437	}
438
439
440	/*
441	* Update display for DGA mode and VOSF
442	* (only in Real or Direct Addressing mode)
443	*/
444
445	#if REAL_ADDRESSING \|\| DIRECT_ADDRESSING
446	static inline void update_display_dga_vosf(void)
447	{
448	VIDEO_MODE_INIT;
449
450	int page = 0;
451	for (;;) {
452	const unsigned first_page = find_next_page_set(page);
453	if (first_page >= mainBuffer.pageCount)
454	break;
455
456	page = find_next_page_clear(first_page);
457	PFLAG_CLEAR_RANGE(first_page, page);
458
459	// Make the dirty pages read-only again
460	const int32 offset = first_page << mainBuffer.pageBits;
461	const uint32 length = (page - first_page) << mainBuffer.pageBits;
462	vm_protect((char *)mainBuffer.memStart + offset, length, VM_PAGE_READ);
463
464	// I am sure that y2 >= y1 and depth != 1
465	const int y1 = mainBuffer.pageInfo[first_page].top;
466	const int y2 = mainBuffer.pageInfo[page - 1].bottom;
467
468	const int bytes_per_row = VIDEO_MODE_ROW_BYTES;
469	const int bytes_per_pixel = VIDEO_MODE_ROW_BYTES / VIDEO_MODE_X;
470	int i, j;
471
472	// Check for first column from left and first column
473	// from right that have changed
474	int x1 = VIDEO_MODE_X * bytes_per_pixel - 1;
475	for (j = y1; j <= y2; j++) {
476	uint8 * const p1 = &the_buffer[j * bytes_per_row];
477	uint8 * const p2 = &the_buffer_copy[j * bytes_per_row];
478	for (i = 0; i < x1; i++) {
479	if (p1[i] != p2[i]) {
480	x1 = i;
481	break;
482	}
483	}
484	}
485	x1 /= bytes_per_pixel;
486
487	int x2 = x1 * bytes_per_pixel;
488	for (j = y2; j >= y1; j--) {
489	uint8 * const p1 = &the_buffer[j * bytes_per_row];
490	uint8 * const p2 = &the_buffer_copy[j * bytes_per_row];
491	for (i = VIDEO_MODE_X * bytes_per_pixel - 1; i > x2; i--) {
492	if (p1[i] != p2[i]) {
493	x2 = i;
494	break;
495	}
496	}
497	}
498	x2 /= bytes_per_pixel;
499
500	// Update the_host_buffer and copy of the_buffer
501	// There should be at least one pixel to copy
502	VIDEO_DRV_LOCK_PIXELS;
503	const int width = x2 - x1 + 1;
504	i = y1 * bytes_per_row + x1 * bytes_per_pixel;
505	for (j = y1; j <= y2; j++) {
506	Screen_blit(the_host_buffer + i, the_buffer + i, bytes_per_pixel * width);
507	memcpy(the_buffer_copy + i, the_buffer + i, bytes_per_pixel * width);
508	i += bytes_per_row;
509	}
510	VIDEO_DRV_UNLOCK_PIXELS;
511	}
512	mainBuffer.dirty = false;
513	}
514	#endif
515
516	#endif /* ENABLE_VOSF */
517
518	#endif /* VIDEO_VOSF_H */