src/Unix/video_vosf.h

/*
 *  video_vosf.h - Video/graphics emulation, video on SEGV signals support
 *
 *  Basilisk II (C) 1997-2002 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 is #include'd in video_x.cpp
#ifdef ENABLE_VOSF

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

// 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_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;
}


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

static bool screen_fault_handler(sigsegv_address_t fault_address, sigsegv_address_t fault_instruction);

static bool video_vosf_init(X11_monitor_desc &monitor)
{
        const video_mode &mode = monitor.get_current_mode();

        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 / mode.bytes_per_row;
                if (y1 >= mode.y)
                        y1 = mode.y - 1;

                unsigned y2 = (a + mainBuffer.pageSize) / mode.bytes_per_row;
                if (y2 >= mode.y)
                        y2 = 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;
        
        // Initialize the handler for SIGSEGV
        if (!sigsegv_install_handler(screen_fault_handler))
                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
 */

static bool screen_fault_handler(sigsegv_address_t fault_address, sigsegv_address_t fault_instruction)
{
//      D(bug("screen_fault_handler: ADDR=%p from IP=%p\n", fault_address, 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
 */

// From video_blit.cpp
extern void (*Screen_blit)(uint8 * dest, const uint8 * source, uint32 length);
extern bool Screen_blitter_init(XVisualInfo * visual_info, bool native_byte_order, video_depth mac_depth);
extern uint32 ExpandMap[256];

/*      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(driver_window *drv)
{
        const video_mode &mode = drv->monitor.get_current_mode();

        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;
                
                if (mode.depth < VDEPTH_8BIT) {

                        // Update the_host_buffer and copy of the_buffer
                        const int src_bytes_per_row = mode.bytes_per_row;
                        const int dst_bytes_per_row = drv->img->bytes_per_line;
                        const int pixels_per_byte = 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, 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 = mode.bytes_per_row;
                        const int dst_bytes_per_row = drv->img->bytes_per_line;
                        const int bytes_per_pixel = src_bytes_per_row / 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 * mode.x);
                                i1 += src_bytes_per_row;
                                i2 += dst_bytes_per_row;
                        }
                }

                if (drv->have_shm)
                        XShmPutImage(x_display, drv->w, drv->gc, drv->img, 0, y1, 0, y1, mode.x, height, 0);
                else
                        XPutImage(x_display, drv->w, drv->gc, drv->img, 0, y1, 0, y1, mode.x, height);
        }
        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)
{
        const video_mode &mode = drv->monitor.get_current_mode();

        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 = mode.bytes_per_row;
                const int bytes_per_pixel = mode.bytes_per_row / mode.x;
                int i, j;
                
                // Check for first column from left and first column
                // from right that have changed
                int x1 = 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 = 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
                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;
                }
        }
        mainBuffer.dirty = false;
}
#endif

#endif /* ENABLE_VOSF */

#endif /* VIDEO_VOSF_H */
Revision:	1.32
Committed:	2002-05-16T15:48:06Z (22 years, 6 months ago) by gbeauche
Content type:	text/plain
Branch:	MAIN
CVS Tags:	nigel-build-12, nigel-build-13
Changes since 1.31:	+0 -19 lines
Log Message:	- video_vosh.h (Screen_fault_handler): Move unrecoverable fault case to... - main_unix.cpp (sigsegv_dump_state): ... Here. - sigsegv.h (sigsegv_fault_handler_t): Rename from sigsegv_handler_t. - sigsegv.h (sigsegv_state_dumper_t): New.
#	Content
1	/*
2	* video_vosf.h - Video/graphics emulation, video on SEGV signals support
3	*
4	* Basilisk II (C) 1997-2002 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 is #include'd in video_x.cpp
25	#ifdef ENABLE_VOSF
26
27	#include <fcntl.h>
28	#include <sys/mman.h>
29	#include "sigsegv.h"
30	#include "vm_alloc.h"
31
32	// Variables for Video on SEGV support
33	static uint8 *the_host_buffer; // Host frame buffer in VOSF mode
34
35	struct ScreenPageInfo {
36	int top, bottom; // Mapping between this virtual page and Mac scanlines
37	};
38
39	struct ScreenInfo {
40	uintptr memStart; // Start address aligned to page boundary
41	uint32 memLength; // Length of the memory addressed by the screen pages
42
43	uintptr pageSize; // Size of a page
44	int pageBits; // Shift count to get the page number
45	uint32 pageCount; // Number of pages allocated to the screen
46
47	bool dirty; // Flag: set if the frame buffer was touched
48	char * dirtyPages; // Table of flags set if page was altered
49	ScreenPageInfo * pageInfo; // Table of mappings page -> Mac scanlines
50	};
51
52	static ScreenInfo mainBuffer;
53
54	#define PFLAG_SET_VALUE 0x00
55	#define PFLAG_CLEAR_VALUE 0x01
56	#define PFLAG_SET_VALUE_4 0x00000000
57	#define PFLAG_CLEAR_VALUE_4 0x01010101
58	#define PFLAG_SET(page) mainBuffer.dirtyPages[page] = PFLAG_SET_VALUE
59	#define PFLAG_CLEAR(page) mainBuffer.dirtyPages[page] = PFLAG_CLEAR_VALUE
60	#define PFLAG_ISSET(page) (mainBuffer.dirtyPages[page] == PFLAG_SET_VALUE)
61	#define PFLAG_ISCLEAR(page) (mainBuffer.dirtyPages[page] != PFLAG_SET_VALUE)
62
63	#ifdef UNALIGNED_PROFITABLE
64	# define PFLAG_ISSET_4(page) (((uint32 )(mainBuffer.dirtyPages + (page))) == PFLAG_SET_VALUE_4)
65	# define PFLAG_ISCLEAR_4(page) (((uint32 )(mainBuffer.dirtyPages + (page))) == PFLAG_CLEAR_VALUE_4)
66	#else
67	# define PFLAG_ISSET_4(page) \
68	PFLAG_ISSET(page ) && PFLAG_ISSET(page+1) \
69	&& PFLAG_ISSET(page+2) && PFLAG_ISSET(page+3)
70	# define PFLAG_ISCLEAR_4(page) \
71	PFLAG_ISCLEAR(page ) && PFLAG_ISCLEAR(page+1) \
72	&& PFLAG_ISCLEAR(page+2) && PFLAG_ISCLEAR(page+3)
73	#endif
74
75	// Set the selected page range [ first_page, last_page [ into the SET state
76	#define PFLAG_SET_RANGE(first_page, last_page) \
77	memset(mainBuffer.dirtyPages + (first_page), PFLAG_SET_VALUE, \
78	(last_page) - (first_page))
79
80	// Set the selected page range [ first_page, last_page [ into the CLEAR state
81	#define PFLAG_CLEAR_RANGE(first_page, last_page) \
82	memset(mainBuffer.dirtyPages + (first_page), PFLAG_CLEAR_VALUE, \
83	(last_page) - (first_page))
84
85	#define PFLAG_SET_ALL do { \
86	PFLAG_SET_RANGE(0, mainBuffer.pageCount); \
87	mainBuffer.dirty = true; \
88	} while (0)
89
90	#define PFLAG_CLEAR_ALL do { \
91	PFLAG_CLEAR_RANGE(0, mainBuffer.pageCount); \
92	mainBuffer.dirty = false; \
93	} while (0)
94
95	// Set the following macro definition to 1 if your system
96	// provides a really fast strchr() implementation
97	//#define HAVE_FAST_STRCHR 0
98
99	static inline int find_next_page_set(int page)
100	{
101	#if HAVE_FAST_STRCHR
102	char *match = strchr(mainBuffer.dirtyPages + page, PFLAG_SET_VALUE);
103	return match ? match - mainBuffer.dirtyPages : mainBuffer.pageCount;
104	#else
105	while (PFLAG_ISCLEAR_4(page))
106	page += 4;
107	while (PFLAG_ISCLEAR(page))
108	page++;
109	return page;
110	#endif
111	}
112
113	static inline int find_next_page_clear(int page)
114	{
115	#if HAVE_FAST_STRCHR
116	char *match = strchr(mainBuffer.dirtyPages + page, PFLAG_CLEAR_VALUE);
117	return match ? match - mainBuffer.dirtyPages : mainBuffer.pageCount;
118	#else
119	while (PFLAG_ISSET_4(page))
120	page += 4;
121	while (PFLAG_ISSET(page))
122	page++;
123	return page;
124	#endif
125	}
126
127	#ifdef HAVE_PTHREADS
128	static pthread_mutex_t vosf_lock = PTHREAD_MUTEX_INITIALIZER; // Mutex to protect frame buffer (dirtyPages in fact)
129	#define LOCK_VOSF pthread_mutex_lock(&vosf_lock);
130	#define UNLOCK_VOSF pthread_mutex_unlock(&vosf_lock);
131	#else
132	#define LOCK_VOSF
133	#define UNLOCK_VOSF
134	#endif
135
136	static int log_base_2(uint32 x)
137	{
138	uint32 mask = 0x80000000;
139	int l = 31;
140	while (l >= 0 && (x & mask) == 0) {
141	mask >>= 1;
142	l--;
143	}
144	return l;
145	}
146
147	// Extend size to page boundary
148	static uint32 page_extend(uint32 size)
149	{
150	const uint32 page_size = getpagesize();
151	const uint32 page_mask = page_size - 1;
152	return (size + page_mask) & ~page_mask;
153	}
154
155
156	/*
157	* Initialize the VOSF system (mainBuffer structure, SIGSEGV handler)
158	*/
159
160	static bool screen_fault_handler(sigsegv_address_t fault_address, sigsegv_address_t fault_instruction);
161
162	static bool video_vosf_init(X11_monitor_desc &monitor)
163	{
164	const video_mode &mode = monitor.get_current_mode();
165
166	const uintptr page_size = getpagesize();
167	const uintptr page_mask = page_size - 1;
168
169	// Round up frame buffer base to page boundary
170	mainBuffer.memStart = (((uintptr) the_buffer) + page_mask) & ~page_mask;
171
172	// The frame buffer size shall already be aligned to page boundary (use page_extend)
173	mainBuffer.memLength = the_buffer_size;
174
175	mainBuffer.pageSize = page_size;
176	mainBuffer.pageBits = log_base_2(mainBuffer.pageSize);
177	mainBuffer.pageCount = (mainBuffer.memLength + page_mask)/mainBuffer.pageSize;
178
179	// The "2" more bytes requested are a safety net to insure the
180	// loops in the update routines will terminate.
181	// See "How can we deal with array overrun conditions ?" hereunder for further details.
182	mainBuffer.dirtyPages = (char *) malloc(mainBuffer.pageCount + 2);
183	if (mainBuffer.dirtyPages == NULL)
184	return false;
185
186	PFLAG_CLEAR_ALL;
187	PFLAG_CLEAR(mainBuffer.pageCount);
188	PFLAG_SET(mainBuffer.pageCount+1);
189
190	// Allocate and fill in pageInfo with start and end (inclusive) row in number of bytes
191	mainBuffer.pageInfo = (ScreenPageInfo ) malloc(mainBuffer.pageCount sizeof(ScreenPageInfo));
192	if (mainBuffer.pageInfo == NULL)
193	return false;
194
195	uint32 a = 0;
196	for (unsigned i = 0; i < mainBuffer.pageCount; i++) {
197	unsigned y1 = a / mode.bytes_per_row;
198	if (y1 >= mode.y)
199	y1 = mode.y - 1;
200
201	unsigned y2 = (a + mainBuffer.pageSize) / mode.bytes_per_row;
202	if (y2 >= mode.y)
203	y2 = mode.y - 1;
204
205	mainBuffer.pageInfo[i].top = y1;
206	mainBuffer.pageInfo[i].bottom = y2;
207
208	a += mainBuffer.pageSize;
209	if (a > mainBuffer.memLength)
210	a = mainBuffer.memLength;
211	}
212
213	// We can now write-protect the frame buffer
214	if (vm_protect((char *)mainBuffer.memStart, mainBuffer.memLength, VM_PAGE_READ) != 0)
215	return false;
216
217	// Initialize the handler for SIGSEGV
218	if (!sigsegv_install_handler(screen_fault_handler))
219	return false;
220
221	// The frame buffer is sane, i.e. there is no write to it yet
222	mainBuffer.dirty = false;
223	return true;
224	}
225
226
227	/*
228	* Deinitialize VOSF system
229	*/
230
231	static void video_vosf_exit(void)
232	{
233	if (mainBuffer.pageInfo) {
234	free(mainBuffer.pageInfo);
235	mainBuffer.pageInfo = NULL;
236	}
237	if (mainBuffer.dirtyPages) {
238	free(mainBuffer.dirtyPages);
239	mainBuffer.dirtyPages = NULL;
240	}
241	}
242
243
244	/*
245	* Screen fault handler
246	*/
247
248	static bool screen_fault_handler(sigsegv_address_t fault_address, sigsegv_address_t fault_instruction)
249	{
250	// D(bug("screen_fault_handler: ADDR=%p from IP=%p\n", fault_address, fault_instruction));
251	const uintptr addr = (uintptr)fault_address;
252
253	/* Someone attempted to write to the frame buffer. Make it writeable
254	* now so that the data could actually be written to. It will be made
255	* read-only back in one of the screen update_*() functions.
256	*/
257	if (((uintptr)addr - mainBuffer.memStart) < mainBuffer.memLength) {
258	const int page = ((uintptr)addr - mainBuffer.memStart) >> mainBuffer.pageBits;
259	LOCK_VOSF;
260	PFLAG_SET(page);
261	vm_protect((char *)(addr & -mainBuffer.pageSize), mainBuffer.pageSize, VM_PAGE_READ \| VM_PAGE_WRITE);
262	mainBuffer.dirty = true;
263	UNLOCK_VOSF;
264	return true;
265	}
266
267	/* Otherwise, we don't know how to handle the fault, let it crash */
268	return false;
269	}
270
271
272	/*
273	* Update display for Windowed mode and VOSF
274	*/
275
276	// From video_blit.cpp
277	extern void (Screen_blit)(uint8 dest, const uint8 * source, uint32 length);
278	extern bool Screen_blitter_init(XVisualInfo * visual_info, bool native_byte_order, video_depth mac_depth);
279	extern uint32 ExpandMap[256];
280
281	/* How can we deal with array overrun conditions ?
282
283	The state of the framebuffer pages that have been touched are maintained
284	in the dirtyPages[] table. That table is (pageCount + 2) bytes long.
285
286	Terminology
287
288	"Last Page" denotes the pageCount-nth page, i.e. dirtyPages[pageCount - 1].
289	"CLEAR Page Guard" refers to the page following the Last Page but is always
290	in the CLEAR state. "SET Page Guard" refers to the page following the CLEAR
291	Page Guard but is always in the SET state.
292
293	Rough process
294
295	The update routines must determine which pages have to be blitted to the
296	screen. This job consists in finding the first_page that was touched.
297	i.e. find the next page that is SET. Then, finding how many pages were
298	touched starting from first_page. i.e. find the next page that is CLEAR.
299
300	There are two cases to check:
301
302	- Last Page is CLEAR: find_next_page_set() will reach the SET Page Guard
303	but it is beyond the valid pageCount value. Therefore, we exit from the
304	update routine.
305
306	- Last Page is SET: first_page equals (pageCount - 1) and
307	find_next_page_clear() will reach the CLEAR Page Guard. We blit the last
308	page to the screen. On the next iteration, page equals pageCount and
309	find_next_page_set() will reach the SET Page Guard. We still safely exit
310	from the update routine because the SET Page Guard position is greater
311	than pageCount.
312	*/
313
314	static inline void update_display_window_vosf(driver_window *drv)
315	{
316	const video_mode &mode = drv->monitor.get_current_mode();
317
318	int page = 0;
319	for (;;) {
320	const unsigned first_page = find_next_page_set(page);
321	if (first_page >= mainBuffer.pageCount)
322	break;
323
324	page = find_next_page_clear(first_page);
325	PFLAG_CLEAR_RANGE(first_page, page);
326
327	// Make the dirty pages read-only again
328	const int32 offset = first_page << mainBuffer.pageBits;
329	const uint32 length = (page - first_page) << mainBuffer.pageBits;
330	vm_protect((char *)mainBuffer.memStart + offset, length, VM_PAGE_READ);
331
332	// There is at least one line to update
333	const int y1 = mainBuffer.pageInfo[first_page].top;
334	const int y2 = mainBuffer.pageInfo[page - 1].bottom;
335	const int height = y2 - y1 + 1;
336
337	if (mode.depth < VDEPTH_8BIT) {
338
339	// Update the_host_buffer and copy of the_buffer
340	const int src_bytes_per_row = mode.bytes_per_row;
341	const int dst_bytes_per_row = drv->img->bytes_per_line;
342	const int pixels_per_byte = mode.x / src_bytes_per_row;
343	int i1 = y1 * src_bytes_per_row, i2 = y1 * dst_bytes_per_row, j;
344	for (j = y1; j <= y2; j++) {
345	Screen_blit(the_host_buffer + i2, the_buffer + i1, mode.x / pixels_per_byte);
346	i1 += src_bytes_per_row;
347	i2 += dst_bytes_per_row;
348	}
349
350	} else {
351
352	// Update the_host_buffer and copy of the_buffer
353	const int src_bytes_per_row = mode.bytes_per_row;
354	const int dst_bytes_per_row = drv->img->bytes_per_line;
355	const int bytes_per_pixel = src_bytes_per_row / mode.x;
356	int i1 = y1 * src_bytes_per_row, i2 = y1 * dst_bytes_per_row, j;
357	for (j = y1; j <= y2; j++) {
358	Screen_blit(the_host_buffer + i2, the_buffer + i1, bytes_per_pixel * mode.x);
359	i1 += src_bytes_per_row;
360	i2 += dst_bytes_per_row;
361	}
362	}
363
364	if (drv->have_shm)
365	XShmPutImage(x_display, drv->w, drv->gc, drv->img, 0, y1, 0, y1, mode.x, height, 0);
366	else
367	XPutImage(x_display, drv->w, drv->gc, drv->img, 0, y1, 0, y1, mode.x, height);
368	}
369	mainBuffer.dirty = false;
370	}
371
372
373	/*
374	* Update display for DGA mode and VOSF
375	* (only in Real or Direct Addressing mode)
376	*/
377
378	#if REAL_ADDRESSING \|\| DIRECT_ADDRESSING
379	static inline void update_display_dga_vosf(void)
380	{
381	const video_mode &mode = drv->monitor.get_current_mode();
382
383	int page = 0;
384	for (;;) {
385	const unsigned first_page = find_next_page_set(page);
386	if (first_page >= mainBuffer.pageCount)
387	break;
388
389	page = find_next_page_clear(first_page);
390	PFLAG_CLEAR_RANGE(first_page, page);
391
392	// Make the dirty pages read-only again
393	const int32 offset = first_page << mainBuffer.pageBits;
394	const uint32 length = (page - first_page) << mainBuffer.pageBits;
395	vm_protect((char *)mainBuffer.memStart + offset, length, VM_PAGE_READ);
396
397	// I am sure that y2 >= y1 and depth != 1
398	const int y1 = mainBuffer.pageInfo[first_page].top;
399	const int y2 = mainBuffer.pageInfo[page - 1].bottom;
400
401	const int bytes_per_row = mode.bytes_per_row;
402	const int bytes_per_pixel = mode.bytes_per_row / mode.x;
403	int i, j;
404
405	// Check for first column from left and first column
406	// from right that have changed
407	int x1 = mode.x * bytes_per_pixel - 1;
408	for (j = y1; j <= y2; j++) {
409	uint8 * const p1 = &the_buffer[j * bytes_per_row];
410	uint8 * const p2 = &the_buffer_copy[j * bytes_per_row];
411	for (i = 0; i < x1; i++) {
412	if (p1[i] != p2[i]) {
413	x1 = i;
414	break;
415	}
416	}
417	}
418	x1 /= bytes_per_pixel;
419
420	int x2 = x1 * bytes_per_pixel;
421	for (j = y2; j >= y1; j--) {
422	uint8 * const p1 = &the_buffer[j * bytes_per_row];
423	uint8 * const p2 = &the_buffer_copy[j * bytes_per_row];
424	for (i = mode.x * bytes_per_pixel - 1; i > x2; i--) {
425	if (p1[i] != p2[i]) {
426	x2 = i;
427	break;
428	}
429	}
430	}
431	x2 /= bytes_per_pixel;
432
433	// Update the_host_buffer and copy of the_buffer
434	// There should be at least one pixel to copy
435	const int width = x2 - x1 + 1;
436	i = y1 * bytes_per_row + x1 * bytes_per_pixel;
437	for (j = y1; j <= y2; j++) {
438	Screen_blit(the_host_buffer + i, the_buffer + i, bytes_per_pixel * width);
439	memcpy(the_buffer_copy + i, the_buffer + i, bytes_per_pixel * width);
440	i += bytes_per_row;
441	}
442	}
443	mainBuffer.dirty = false;
444	}
445	#endif
446
447	#endif /* ENABLE_VOSF */
448
449	#endif /* VIDEO_VOSF_H */