sdl shared buffer support

This patch implements shared buffer support in sdl.c. It also supports paletted 8 bit colour depths using the palette functions provided by the SDL library.

Obviously this patch depends upon the previous shared buffer patch.

---

index a054d97..7d252b7 100644
@@ -81,6 +81,7 @@ struct DisplayState {
     int width;
     int height;
     void *opaque;
+    uint32_t *palette;
     struct QEMUTimer *gui_timer;
     uint64_t gui_timer_interval;
     int idle; /* there is nothing to update (window invisible), set by

vnc/sdl */

index 6e40d3d..d5265c0 100644
@@ -2026,6 +2026,7 @@ void vga_common_init(VGAState *s, DisplayState

*ds, uint8_t *vga_ram_base,

     s->vram_offset = vga_ram_offset;
     s->vram_size = vga_ram_size;
     s->ds = ds;
+    ds->palette = s->last_palette;
     s->get_bpp = vga_get_bpp;
     s->get_offsets = vga_get_offsets;
     s->get_resolution = vga_get_resolution;

ds->linesize, rmask , gmask, bmask, amask);
+ if (ds->depth == 8 && ds->palette != NULL) {

+        SDL_Color palette[256];
+        int i;
+        for (i = 0; i < 256; i++) {
+            uint8_t rgb = ds->palette[i] >> 16;
+            palette[i].r = ((rgb & 0xe0) >> 5) * 255 / 7;
+            palette[i].g = ((rgb & 0x1c) >> 2) * 255 / 7;
+            palette[i].b = (rgb & 0x3) * 255 / 3;

+ }
+ SDL_SetColors(shared, palette, 0, 256);
+ }
+ ds->data = pixels;
+}
+
+static void sdl_resize_shared(DisplayState *ds, int w, int h, int depth, int linesize, void *pixels)

 {
     int flags;

     //    printf("resizing to %d %d\n", w, h);

-    flags = SDL_HWSURFACE|SDL_ASYNCBLIT|SDL_HWACCEL;
-    if (gui_fullscreen)
+    sdl_colourdepth(ds, depth);

+
+ flags =
SDL_HWSURFACE|SDL_ASYNCBLIT|SDL_HWACCEL|SDL_DOUBLEBUF|SDL_HWPALETTE; +

+    if (gui_fullscreen) {
         flags |= SDL_FULLSCREEN;
+        flags &= ~SDL_RESIZABLE;
+    }
     if (gui_noframe)
         flags |= SDL_NOFRAME;

@@ -74,7 +132,7 @@ static void sdl_resize(DisplayState *ds, int w, int h)
again:

     screen = SDL_SetVideoMode(w, h, 0, flags);
     if (!screen) {
-        fprintf(stderr, "Could not open SDL display\n");
+        fprintf(stderr, "Could not open SDL display: %s\n",
SDL_GetError());
         exit(1);
     }
     if (!screen->pixels && (flags & SDL_HWSURFACE) && (flags &
SDL_FULLSCREEN)) {
@@ -83,30 +141,41 @@ static void sdl_resize(DisplayState *ds, int w, int h)
     }

     if (!screen->pixels) {
-        fprintf(stderr, "Could not open SDL display\n");
+        fprintf(stderr, "Could not open SDL display: %s\n",
SDL_GetError());
         exit(1);
     }
-    ds->data = screen->pixels;
-    ds->linesize = screen->pitch;
-    ds->depth = screen->format->BitsPerPixel;
-    /* SDL BitsPerPixel never indicates any values other than

- multiples of 8, so we need to check for strange depths. */
- if (ds->depth == 16) {
- uint32_t mask;
-

-        mask = screen->format->Rmask;
-        mask |= screen->format->Gmask;
-        mask |= screen->format->Bmask;
-        if ((mask & 0x8000) == 0)

- ds->depth = 15;
- }
- if (ds->depth == 32 && screen->format->Rshift == 0) {
- ds->bgr = 1;
- } else {
- ds->bgr = 0;
- }

     ds->width = w;
     ds->height = h;

+ if (!ds->shared_buf) {
+ ds->depth = screen->format->BitsPerPixel;
+ if (screen->format->Bshift > screen->format->Rshift) {
+ ds->bgr = 1;
+ } else {
+ ds->bgr = 0;

+        }
+        shared = NULL;
+        ds->data = screen->pixels;
+        ds->linesize = screen->pitch;

+ } else {
+ ds->linesize = linesize;
+ }
+ if (ds->shared_buf) ds->dpy_setdata(ds, pixels);
+}
+
+static void sdl_resize(DisplayState *ds, int w, int h) +{
+ sdl_resize_shared(ds, w, h, 0, w * (ds->depth / 8), NULL);
+}
+
+static void sdl_colourdepth(DisplayState *ds, int depth) +{
+ if (!depth || !ds->depth) {
+ ds->shared_buf = 0;
+ ds->dpy_update = sdl_update;
+ return;

+    }
+    ds->shared_buf = 1;
+    ds->depth = depth;

}

/* generic keyboard conversion */
@@ -339,7 +408,7 @@ static void sdl_send_mouse_event(int dx, int dy, int dz, int x, int y, int state
static void toggle_full_screen(DisplayState *ds)

 {
     gui_fullscreen = !gui_fullscreen;
-    sdl_resize(ds, screen->w, screen->h);
+    sdl_resize_shared(ds, ds->width, ds->height, ds->depth,
ds->linesize, ds->data);
     if (gui_fullscreen) {
         gui_saved_grab = gui_grab;
         sdl_grab_start();

@@ -639,7 +708,9 @@ void sdl_display_init(DisplayState *ds, int full_screen, int no_frame)

     ds->dpy_update = sdl_update;
     ds->dpy_resize = sdl_resize;
+    ds->dpy_resize_shared = sdl_resize_shared;
     ds->dpy_refresh = sdl_refresh;
+    ds->dpy_setdata = sdl_setdata;
     ds->dpy_fill = sdl_fill;
     ds->mouse_set = sdl_mouse_warp;
     ds->cursor_define = sdl_mouse_define;

sorry, thunderbird blew the layout of the previous email.

---

index a054d97..7d252b7 100644
@@ -81,6 +81,7 @@ struct DisplayState {
     int width;
     int height;
     void *opaque;
+    uint32_t *palette;
     struct QEMUTimer *gui_timer;
     uint64_t gui_timer_interval;
     int idle; /* there is nothing to update (window invisible), set by vnc/sdl */

index 6e40d3d..d5265c0 100644
@@ -2026,6 +2026,7 @@ void vga_common_init(VGAState *s, DisplayState *ds, uint8_t *vga_ram_base,
     s->vram_offset = vga_ram_offset;
     s->vram_size = vga_ram_size;
     s->ds = ds;
+    ds->palette = s->last_palette;
     s->get_bpp = vga_get_bpp;
     s->get_offsets = vga_get_offsets;
     s->get_resolution = vga_get_resolution;

Stefano Stabellini writes ("[Qemu-devel] [PATCH] sdl shared buffer support"):

Ian.

This function is broken if BGR-ness of the display is not equal to emulated device BGR-ness.

good catch!
I am going to send an updated version of this and the opengl patch soon to fix the issue.

I replied to this email a little too fast: reading vga.c and vga_template.h again more carefully it occurred to me that the guest is always RGB, only the host can set the sdl display to BGR. Hence we don't need to handle this case in sdl_setdata, because if there is any difference in depth or subpixel ordering between host and guest, is up to SDL_BlitSurface to solve it.

But there is a similar issue that I wasn't handling: guest big endian and host little endian or vice versa.
In fact I need to set different colour masks in sdl setdata according to the guest endianness.

Just to complicate things still further, the endianness of the host running QEMU may not be the same as the endianness of the X server display.

Daniel

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