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 <fcntl.h>
#include <sys/mman.h>
#include "sigsegv.h"
#include "vm_alloc.h"

// 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(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 = getpagesize();
        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 = getpagesize();
        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:	1.45
Committed:	2004-11-15T23:40:23Z (20 years ago) by gbeauche
Content type:	text/plain
Branch:	MAIN
Changes since 1.44:	+0 -3 lines
Log Message:	lock X11 display better around update_display_window_vosf()
#	User	Rev	Content
1	gbeauche	1.1	/*
2			* video_vosf.h - Video/graphics emulation, video on SEGV signals support
3			*
4	cebix	1.37	* Basilisk II (C) 1997-2004 Christian Bauer
5	gbeauche	1.1	*
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	gbeauche	1.34	// Note: this file must be #include'd only in video_x.cpp
25	gbeauche	1.1	#ifdef ENABLE_VOSF
26
27	cebix	1.19	#include <fcntl.h>
28			#include <sys/mman.h>
29			#include "sigsegv.h"
30			#include "vm_alloc.h"
31
32	gbeauche	1.39	// Glue for SDL and X11 support
33	gbeauche	1.38	#ifdef USE_SDL_VIDEO
34			#define MONITOR_INIT SDL_monitor_desc &monitor
35			#define VIDEO_DRV_INIT driver_window *drv
36			#define VIDEO_DRV_ROW_BYTES drv->s->pitch
37			#define VIDEO_DRV_LOCK_PIXELS if (SDL_MUSTLOCK(drv->s)) SDL_LockSurface(drv->s)
38			#define VIDEO_DRV_UNLOCK_PIXELS if (SDL_MUSTLOCK(drv->s)) SDL_UnlockSurface(drv->s)
39			#else
40	gbeauche	1.39	#ifdef SHEEPSHAVER
41	gbeauche	1.38	#define MONITOR_INIT /* nothing */
42	gbeauche	1.33	#define VIDEO_DRV_INIT /* nothing */
43			#define VIDEO_DRV_WINDOW the_win
44			#define VIDEO_DRV_GC the_gc
45			#define VIDEO_DRV_IMAGE img
46			#define VIDEO_DRV_HAVE_SHM have_shm
47			#else
48	gbeauche	1.38	#define MONITOR_INIT X11_monitor_desc &monitor
49	gbeauche	1.33	#define VIDEO_DRV_INIT driver_window *drv
50			#define VIDEO_DRV_WINDOW drv->w
51			#define VIDEO_DRV_GC drv->gc
52			#define VIDEO_DRV_IMAGE drv->img
53			#define VIDEO_DRV_HAVE_SHM drv->have_shm
54	gbeauche	1.38	#endif
55			#define VIDEO_DRV_LOCK_PIXELS /* nothing */
56			#define VIDEO_DRV_UNLOCK_PIXELS /* nothing */
57			#define VIDEO_DRV_ROW_BYTES VIDEO_DRV_IMAGE->bytes_per_line
58	gbeauche	1.33	#endif
59
60	cebix	1.19	// Variables for Video on SEGV support
61	gbeauche	1.20	static uint8 *the_host_buffer; // Host frame buffer in VOSF mode
62	cebix	1.19
63			struct ScreenPageInfo {
64			int top, bottom; // Mapping between this virtual page and Mac scanlines
65			};
66
67			struct ScreenInfo {
68			uintptr memStart; // Start address aligned to page boundary
69			uint32 memLength; // Length of the memory addressed by the screen pages
70
71	gbeauche	1.27	uintptr pageSize; // Size of a page
72	cebix	1.19	int pageBits; // Shift count to get the page number
73			uint32 pageCount; // Number of pages allocated to the screen
74
75			bool dirty; // Flag: set if the frame buffer was touched
76			char * dirtyPages; // Table of flags set if page was altered
77			ScreenPageInfo * pageInfo; // Table of mappings page -> Mac scanlines
78			};
79
80			static ScreenInfo mainBuffer;
81
82			#define PFLAG_SET_VALUE 0x00
83			#define PFLAG_CLEAR_VALUE 0x01
84			#define PFLAG_SET_VALUE_4 0x00000000
85			#define PFLAG_CLEAR_VALUE_4 0x01010101
86			#define PFLAG_SET(page) mainBuffer.dirtyPages[page] = PFLAG_SET_VALUE
87			#define PFLAG_CLEAR(page) mainBuffer.dirtyPages[page] = PFLAG_CLEAR_VALUE
88			#define PFLAG_ISSET(page) (mainBuffer.dirtyPages[page] == PFLAG_SET_VALUE)
89			#define PFLAG_ISCLEAR(page) (mainBuffer.dirtyPages[page] != PFLAG_SET_VALUE)
90
91			#ifdef UNALIGNED_PROFITABLE
92			# define PFLAG_ISSET_4(page) (((uint32 )(mainBuffer.dirtyPages + (page))) == PFLAG_SET_VALUE_4)
93			# define PFLAG_ISCLEAR_4(page) (((uint32 )(mainBuffer.dirtyPages + (page))) == PFLAG_CLEAR_VALUE_4)
94			#else
95			# define PFLAG_ISSET_4(page) \
96			PFLAG_ISSET(page ) && PFLAG_ISSET(page+1) \
97			&& PFLAG_ISSET(page+2) && PFLAG_ISSET(page+3)
98			# define PFLAG_ISCLEAR_4(page) \
99			PFLAG_ISCLEAR(page ) && PFLAG_ISCLEAR(page+1) \
100			&& PFLAG_ISCLEAR(page+2) && PFLAG_ISCLEAR(page+3)
101			#endif
102
103			// Set the selected page range [ first_page, last_page [ into the SET state
104			#define PFLAG_SET_RANGE(first_page, last_page) \
105			memset(mainBuffer.dirtyPages + (first_page), PFLAG_SET_VALUE, \
106			(last_page) - (first_page))
107
108			// Set the selected page range [ first_page, last_page [ into the CLEAR state
109			#define PFLAG_CLEAR_RANGE(first_page, last_page) \
110			memset(mainBuffer.dirtyPages + (first_page), PFLAG_CLEAR_VALUE, \
111			(last_page) - (first_page))
112
113			#define PFLAG_SET_ALL do { \
114			PFLAG_SET_RANGE(0, mainBuffer.pageCount); \
115			mainBuffer.dirty = true; \
116			} while (0)
117
118			#define PFLAG_CLEAR_ALL do { \
119			PFLAG_CLEAR_RANGE(0, mainBuffer.pageCount); \
120			mainBuffer.dirty = false; \
121			} while (0)
122
123			// Set the following macro definition to 1 if your system
124			// provides a really fast strchr() implementation
125			//#define HAVE_FAST_STRCHR 0
126
127			static inline int find_next_page_set(int page)
128			{
129			#if HAVE_FAST_STRCHR
130			char *match = strchr(mainBuffer.dirtyPages + page, PFLAG_SET_VALUE);
131			return match ? match - mainBuffer.dirtyPages : mainBuffer.pageCount;
132			#else
133			while (PFLAG_ISCLEAR_4(page))
134			page += 4;
135			while (PFLAG_ISCLEAR(page))
136			page++;
137			return page;
138			#endif
139			}
140
141			static inline int find_next_page_clear(int page)
142			{
143			#if HAVE_FAST_STRCHR
144			char *match = strchr(mainBuffer.dirtyPages + page, PFLAG_CLEAR_VALUE);
145			return match ? match - mainBuffer.dirtyPages : mainBuffer.pageCount;
146			#else
147			while (PFLAG_ISSET_4(page))
148			page += 4;
149			while (PFLAG_ISSET(page))
150			page++;
151			return page;
152			#endif
153			}
154
155	gbeauche	1.36	#ifdef HAVE_SPINLOCKS
156			static spinlock_t vosf_lock = SPIN_LOCK_UNLOCKED; // Mutex to protect frame buffer (dirtyPages in fact)
157			#define LOCK_VOSF spin_lock(&vosf_lock)
158			#define UNLOCK_VOSF spin_unlock(&vosf_lock)
159			#elif defined(HAVE_PTHREADS)
160	cebix	1.19	static pthread_mutex_t vosf_lock = PTHREAD_MUTEX_INITIALIZER; // Mutex to protect frame buffer (dirtyPages in fact)
161			#define LOCK_VOSF pthread_mutex_lock(&vosf_lock);
162			#define UNLOCK_VOSF pthread_mutex_unlock(&vosf_lock);
163			#else
164			#define LOCK_VOSF
165			#define UNLOCK_VOSF
166			#endif
167
168			static int log_base_2(uint32 x)
169			{
170			uint32 mask = 0x80000000;
171			int l = 31;
172			while (l >= 0 && (x & mask) == 0) {
173			mask >>= 1;
174			l--;
175			}
176			return l;
177			}
178
179	gbeauche	1.20	// Extend size to page boundary
180			static uint32 page_extend(uint32 size)
181			{
182			const uint32 page_size = getpagesize();
183			const uint32 page_mask = page_size - 1;
184			return (size + page_mask) & ~page_mask;
185			}
186
187	cebix	1.19
188			/*
189	gbeauche	1.40	* Check if VOSF acceleration is profitable on this platform
190			*/
191
192	gbeauche	1.41	const int VOSF_PROFITABLE_TRIES = 3; // Make 3 attempts for full screen update
193			const int VOSF_PROFITABLE_THRESHOLD = 16667; // 60 Hz
194	gbeauche	1.40
195			static bool video_vosf_profitable(void)
196			{
197	gbeauche	1.41	int64 durations[VOSF_PROFITABLE_TRIES];
198			int mean_duration = 0;
199	gbeauche	1.40
200	gbeauche	1.41	for (int i = 0; i < VOSF_PROFITABLE_TRIES; i++) {
201			uint64 start = GetTicks_usec();
202			for (int p = 0; p < mainBuffer.pageCount; p++) {
203			uint8 addr = (uint8 )(mainBuffer.memStart + (p * mainBuffer.pageSize));
204			addr[0] = 0; // Trigger Screen_fault_handler()
205			}
206			int64 duration = GetTicks_usec() - start;
207			mean_duration += duration;
208			durations[i] = duration;
209
210			PFLAG_CLEAR_ALL;
211			mainBuffer.dirty = false;
212			if (vm_protect((char *)mainBuffer.memStart, mainBuffer.memLength, VM_PAGE_READ) != 0)
213			return false;
214	gbeauche	1.40	}
215
216	gbeauche	1.41	mean_duration /= VOSF_PROFITABLE_TRIES;
217			D(bug("Triggered %d screen faults in %ld usec on average\n", mainBuffer.pageCount, mean_duration));
218			return (mean_duration < (VOSF_PROFITABLE_THRESHOLD * (frame_skip ? frame_skip : 1)));
219	gbeauche	1.40	}
220
221
222			/*
223	gbeauche	1.27	* Initialize the VOSF system (mainBuffer structure, SIGSEGV handler)
224	cebix	1.19	*/
225
226	gbeauche	1.38	static bool video_vosf_init(MONITOR_INIT)
227	cebix	1.19	{
228	gbeauche	1.42	VIDEO_MODE_INIT_MONITOR;
229	cebix	1.31
230	gbeauche	1.27	const uintptr page_size = getpagesize();
231			const uintptr page_mask = page_size - 1;
232
233			// Round up frame buffer base to page boundary
234			mainBuffer.memStart = (((uintptr) the_buffer) + page_mask) & ~page_mask;
235
236			// The frame buffer size shall already be aligned to page boundary (use page_extend)
237			mainBuffer.memLength = the_buffer_size;
238
239			mainBuffer.pageSize = page_size;
240			mainBuffer.pageBits = log_base_2(mainBuffer.pageSize);
241			mainBuffer.pageCount = (mainBuffer.memLength + page_mask)/mainBuffer.pageSize;
242
243			// The "2" more bytes requested are a safety net to insure the
244			// loops in the update routines will terminate.
245			// See "How can we deal with array overrun conditions ?" hereunder for further details.
246	gbeauche	1.29	mainBuffer.dirtyPages = (char *) malloc(mainBuffer.pageCount + 2);
247			if (mainBuffer.dirtyPages == NULL)
248	gbeauche	1.27	return false;
249	cebix	1.19
250	gbeauche	1.27	PFLAG_CLEAR_ALL;
251			PFLAG_CLEAR(mainBuffer.pageCount);
252			PFLAG_SET(mainBuffer.pageCount+1);
253
254			// Allocate and fill in pageInfo with start and end (inclusive) row in number of bytes
255	gbeauche	1.29	mainBuffer.pageInfo = (ScreenPageInfo ) malloc(mainBuffer.pageCount sizeof(ScreenPageInfo));
256			if (mainBuffer.pageInfo == NULL)
257	gbeauche	1.27	return false;
258
259			uint32 a = 0;
260	cebix	1.28	for (unsigned i = 0; i < mainBuffer.pageCount; i++) {
261	gbeauche	1.33	unsigned y1 = a / VIDEO_MODE_ROW_BYTES;
262			if (y1 >= VIDEO_MODE_Y)
263			y1 = VIDEO_MODE_Y - 1;
264
265			unsigned y2 = (a + mainBuffer.pageSize) / VIDEO_MODE_ROW_BYTES;
266			if (y2 >= VIDEO_MODE_Y)
267			y2 = VIDEO_MODE_Y - 1;
268	gbeauche	1.27
269			mainBuffer.pageInfo[i].top = y1;
270			mainBuffer.pageInfo[i].bottom = y2;
271
272			a += mainBuffer.pageSize;
273			if (a > mainBuffer.memLength)
274			a = mainBuffer.memLength;
275			}
276
277			// We can now write-protect the frame buffer
278			if (vm_protect((char *)mainBuffer.memStart, mainBuffer.memLength, VM_PAGE_READ) != 0)
279			return false;
280
281			// The frame buffer is sane, i.e. there is no write to it yet
282			mainBuffer.dirty = false;
283			return true;
284			}
285	cebix	1.19
286
287	gbeauche	1.27	/*
288			* Deinitialize VOSF system
289			*/
290	cebix	1.19
291	gbeauche	1.27	static void video_vosf_exit(void)
292			{
293	gbeauche	1.29	if (mainBuffer.pageInfo) {
294			free(mainBuffer.pageInfo);
295			mainBuffer.pageInfo = NULL;
296	gbeauche	1.27	}
297	gbeauche	1.29	if (mainBuffer.dirtyPages) {
298			free(mainBuffer.dirtyPages);
299			mainBuffer.dirtyPages = NULL;
300	cebix	1.19	}
301			}
302
303
304	gbeauche	1.1	/*
305	gbeauche	1.20	* Screen fault handler
306	gbeauche	1.1	*/
307
308	gbeauche	1.33	bool Screen_fault_handler(sigsegv_address_t fault_address, sigsegv_address_t fault_instruction)
309	gbeauche	1.1	{
310	gbeauche	1.16	const uintptr addr = (uintptr)fault_address;
311
312	gbeauche	1.11	/* Someone attempted to write to the frame buffer. Make it writeable
313	gbeauche	1.20	* now so that the data could actually be written to. It will be made
314	gbeauche	1.11	* read-only back in one of the screen update_*() functions.
315			*/
316	gbeauche	1.27	if (((uintptr)addr - mainBuffer.memStart) < mainBuffer.memLength) {
317			const int page = ((uintptr)addr - mainBuffer.memStart) >> mainBuffer.pageBits;
318	gbeauche	1.11	LOCK_VOSF;
319			PFLAG_SET(page);
320	gbeauche	1.27	vm_protect((char *)(addr & -mainBuffer.pageSize), mainBuffer.pageSize, VM_PAGE_READ \| VM_PAGE_WRITE);
321	gbeauche	1.13	mainBuffer.dirty = true;
322	gbeauche	1.11	UNLOCK_VOSF;
323	gbeauche	1.16	return true;
324	gbeauche	1.1	}
325
326	gbeauche	1.11	/* Otherwise, we don't know how to handle the fault, let it crash */
327	gbeauche	1.16	return false;
328	gbeauche	1.1	}
329
330	gbeauche	1.20
331	gbeauche	1.1	/*
332			* Update display for Windowed mode and VOSF
333			*/
334
335	gbeauche	1.12	/* How can we deal with array overrun conditions ?
336
337			The state of the framebuffer pages that have been touched are maintained
338			in the dirtyPages[] table. That table is (pageCount + 2) bytes long.
339
340			Terminology
341
342			"Last Page" denotes the pageCount-nth page, i.e. dirtyPages[pageCount - 1].
343			"CLEAR Page Guard" refers to the page following the Last Page but is always
344			in the CLEAR state. "SET Page Guard" refers to the page following the CLEAR
345			Page Guard but is always in the SET state.
346
347			Rough process
348
349	gbeauche	1.13	The update routines must determine which pages have to be blitted to the
350	gbeauche	1.12	screen. This job consists in finding the first_page that was touched.
351			i.e. find the next page that is SET. Then, finding how many pages were
352			touched starting from first_page. i.e. find the next page that is CLEAR.
353
354	gbeauche	1.13	There are two cases to check:
355	gbeauche	1.12
356			- Last Page is CLEAR: find_next_page_set() will reach the SET Page Guard
357			but it is beyond the valid pageCount value. Therefore, we exit from the
358			update routine.
359
360			- Last Page is SET: first_page equals (pageCount - 1) and
361			find_next_page_clear() will reach the CLEAR Page Guard. We blit the last
362			page to the screen. On the next iteration, page equals pageCount and
363			find_next_page_set() will reach the SET Page Guard. We still safely exit
364			from the update routine because the SET Page Guard position is greater
365			than pageCount.
366			*/
367
368	gbeauche	1.33	static inline void update_display_window_vosf(VIDEO_DRV_INIT)
369	gbeauche	1.1	{
370	gbeauche	1.33	VIDEO_MODE_INIT;
371	cebix	1.31
372	gbeauche	1.1	int page = 0;
373			for (;;) {
374	cebix	1.28	const unsigned first_page = find_next_page_set(page);
375	gbeauche	1.11	if (first_page >= mainBuffer.pageCount)
376	gbeauche	1.1	break;
377	gbeauche	1.11
378			page = find_next_page_clear(first_page);
379			PFLAG_CLEAR_RANGE(first_page, page);
380	cebix	1.7
381	gbeauche	1.1	// Make the dirty pages read-only again
382			const int32 offset = first_page << mainBuffer.pageBits;
383			const uint32 length = (page - first_page) << mainBuffer.pageBits;
384	gbeauche	1.17	vm_protect((char *)mainBuffer.memStart + offset, length, VM_PAGE_READ);
385	gbeauche	1.1
386			// There is at least one line to update
387			const int y1 = mainBuffer.pageInfo[first_page].top;
388			const int y2 = mainBuffer.pageInfo[page - 1].bottom;
389			const int height = y2 - y1 + 1;
390	gbeauche	1.38
391			VIDEO_DRV_LOCK_PIXELS;
392
393	gbeauche	1.43	if ((int)VIDEO_MODE_DEPTH < VIDEO_DEPTH_8BIT) {
394	cebix	1.6
395			// Update the_host_buffer and copy of the_buffer
396	gbeauche	1.33	const int src_bytes_per_row = VIDEO_MODE_ROW_BYTES;
397	gbeauche	1.38	const int dst_bytes_per_row = VIDEO_DRV_ROW_BYTES;
398	gbeauche	1.33	const int pixels_per_byte = VIDEO_MODE_X / src_bytes_per_row;
399	cebix	1.24	int i1 = y1 * src_bytes_per_row, i2 = y1 * dst_bytes_per_row, j;
400	cebix	1.6	for (j = y1; j <= y2; j++) {
401	gbeauche	1.33	Screen_blit(the_host_buffer + i2, the_buffer + i1, VIDEO_MODE_X / pixels_per_byte);
402	cebix	1.24	i1 += src_bytes_per_row;
403			i2 += dst_bytes_per_row;
404	cebix	1.6	}
405
406			} else {
407
408			// Update the_host_buffer and copy of the_buffer
409	gbeauche	1.33	const int src_bytes_per_row = VIDEO_MODE_ROW_BYTES;
410	gbeauche	1.38	const int dst_bytes_per_row = VIDEO_DRV_ROW_BYTES;
411	gbeauche	1.33	const int bytes_per_pixel = src_bytes_per_row / VIDEO_MODE_X;
412	cebix	1.23	int i1 = y1 * src_bytes_per_row, i2 = y1 * dst_bytes_per_row, j;
413	cebix	1.6	for (j = y1; j <= y2; j++) {
414	gbeauche	1.33	Screen_blit(the_host_buffer + i2, the_buffer + i1, bytes_per_pixel * VIDEO_MODE_X);
415	cebix	1.23	i1 += src_bytes_per_row;
416			i2 += dst_bytes_per_row;
417	cebix	1.6	}
418	gbeauche	1.1	}
419	cebix	1.15
420	gbeauche	1.38	VIDEO_DRV_UNLOCK_PIXELS;
421
422			#ifdef USE_SDL_VIDEO
423			SDL_UpdateRect(drv->s, 0, y1, VIDEO_MODE_X, height);
424			#else
425	gbeauche	1.33	if (VIDEO_DRV_HAVE_SHM)
426			XShmPutImage(x_display, VIDEO_DRV_WINDOW, VIDEO_DRV_GC, VIDEO_DRV_IMAGE, 0, y1, 0, y1, VIDEO_MODE_X, height, 0);
427	gbeauche	1.1	else
428	gbeauche	1.33	XPutImage(x_display, VIDEO_DRV_WINDOW, VIDEO_DRV_GC, VIDEO_DRV_IMAGE, 0, y1, 0, y1, VIDEO_MODE_X, height);
429	gbeauche	1.38	#endif
430	gbeauche	1.1	}
431	gbeauche	1.13	mainBuffer.dirty = false;
432	gbeauche	1.1	}
433
434
435			/*
436			* Update display for DGA mode and VOSF
437	gbeauche	1.20	* (only in Real or Direct Addressing mode)
438	gbeauche	1.1	*/
439
440			#if REAL_ADDRESSING \|\| DIRECT_ADDRESSING
441			static inline void update_display_dga_vosf(void)
442			{
443	gbeauche	1.33	VIDEO_MODE_INIT;
444	cebix	1.31
445	gbeauche	1.1	int page = 0;
446			for (;;) {
447	cebix	1.28	const unsigned first_page = find_next_page_set(page);
448	gbeauche	1.11	if (first_page >= mainBuffer.pageCount)
449	gbeauche	1.1	break;
450	gbeauche	1.11
451			page = find_next_page_clear(first_page);
452			PFLAG_CLEAR_RANGE(first_page, page);
453
454	gbeauche	1.1	// Make the dirty pages read-only again
455			const int32 offset = first_page << mainBuffer.pageBits;
456			const uint32 length = (page - first_page) << mainBuffer.pageBits;
457	gbeauche	1.17	vm_protect((char *)mainBuffer.memStart + offset, length, VM_PAGE_READ);
458	gbeauche	1.1
459			// I am sure that y2 >= y1 and depth != 1
460			const int y1 = mainBuffer.pageInfo[first_page].top;
461			const int y2 = mainBuffer.pageInfo[page - 1].bottom;
462
463	gbeauche	1.33	const int bytes_per_row = VIDEO_MODE_ROW_BYTES;
464			const int bytes_per_pixel = VIDEO_MODE_ROW_BYTES / VIDEO_MODE_X;
465	gbeauche	1.1	int i, j;
466
467			// Check for first column from left and first column
468			// from right that have changed
469	gbeauche	1.33	int x1 = VIDEO_MODE_X * bytes_per_pixel - 1;
470	gbeauche	1.1	for (j = y1; j <= y2; j++) {
471			uint8 * const p1 = &the_buffer[j * bytes_per_row];
472			uint8 * const p2 = &the_buffer_copy[j * bytes_per_row];
473			for (i = 0; i < x1; i++) {
474			if (p1[i] != p2[i]) {
475			x1 = i;
476			break;
477			}
478			}
479			}
480			x1 /= bytes_per_pixel;
481
482			int x2 = x1 * bytes_per_pixel;
483			for (j = y2; j >= y1; j--) {
484			uint8 * const p1 = &the_buffer[j * bytes_per_row];
485			uint8 * const p2 = &the_buffer_copy[j * bytes_per_row];
486	gbeauche	1.33	for (i = VIDEO_MODE_X * bytes_per_pixel - 1; i > x2; i--) {
487	gbeauche	1.1	if (p1[i] != p2[i]) {
488			x2 = i;
489			break;
490			}
491			}
492			}
493			x2 /= bytes_per_pixel;
494
495			// Update the_host_buffer and copy of the_buffer
496			// There should be at least one pixel to copy
497	gbeauche	1.38	VIDEO_DRV_LOCK_PIXELS;
498	gbeauche	1.1	const int width = x2 - x1 + 1;
499			i = y1 * bytes_per_row + x1 * bytes_per_pixel;
500			for (j = y1; j <= y2; j++) {
501	gbeauche	1.13	Screen_blit(the_host_buffer + i, the_buffer + i, bytes_per_pixel * width);
502	gbeauche	1.1	memcpy(the_buffer_copy + i, the_buffer + i, bytes_per_pixel * width);
503			i += bytes_per_row;
504			}
505	gbeauche	1.38	VIDEO_DRV_UNLOCK_PIXELS;
506	gbeauche	1.1	}
507	gbeauche	1.13	mainBuffer.dirty = false;
508	gbeauche	1.1	}
509			#endif
510
511			#endif /* ENABLE_VOSF */
512
513			#endif /* VIDEO_VOSF_H */