hw/display/artist: Mouse cursor fixes for HP-UX

This patch fix the behaviour and positioning of the X11 mouse cursor in HP-UX.

The current code missed to subtract the offset of the CURSOR_CTRL register from
the current mouse cursor position. The HP-UX graphics driver stores in this
register the offset of the mouse graphics compared to the current cursor
position.  Without this adjustment the mouse behaves strange at the screen
borders.

Additionally, depending on the HP-UX version, the mouse cursor position
in the cursor_pos register reports different values. To accommodate this
track the current min and max reported values and auto-adjust at runtime.

With this fix the mouse now behaves as expected on HP-UX 10 and 11.

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: qemu-stable@nongnu.org
Signed-off-by: Helge Deller <deller@gmx.de>

hw/display/artist.c

@@ -80,6 +80,7 @@ struct ARTISTState {
     uint32_t line_pattern_skip;
 
     uint32_t cursor_pos;
+    uint32_t cursor_cntrl;
 
     uint32_t cursor_height;
     uint32_t cursor_width;
@@ -301,19 +302,42 @@ static void artist_get_cursor_pos(ARTISTState *s, int *x, int *y)
 {
     /*
      * Don't know whether these magic offset values are configurable via
-     * some register. They are the same for all resolutions, so don't
-     * bother about it.
+     * some register. They seem to be the same for all resolutions.
+     * The cursor values provided in the registers are:
+     * X-value: -295 (for HP-UX 11) and 338 (for HP-UX 10.20) up to 2265
+     * Y-value: 1146 down to 0
+     * The emulated Artist graphic is like a CRX graphic, and as such
+     * it's usually fixed at 1280x1024 pixels.
+     * Because of the maximum Y-value of 1146 you can not choose a higher
+     * vertical resolution on HP-UX (unless you disable the mouse).
      */
 
-    *y = 0x47a - artist_get_y(s->cursor_pos);
-    *x = ((artist_get_x(s->cursor_pos) - 338) / 2);
+    static int offset = 338;
+    int lx;
+
+    /* ignore if uninitialized */
+    if (s->cursor_pos == 0) {
+        *x = *y = 0;
+        return;
+    }
+
+    lx = artist_get_x(s->cursor_pos);
+    if (lx < offset)
+        offset = lx;
+    *x = (lx - offset) / 2;
+
+    *y = 1146 - artist_get_y(s->cursor_pos);
+
+    /* subtract cursor offset from cursor control register */
+    *x -= (s->cursor_cntrl & 0xf0) >> 4;
+    *y -= (s->cursor_cntrl & 0x0f);
 
     if (*x > s->width) {
-        *x = 0;
+        *x = s->width;
     }
 
     if (*y > s->height) {
-        *y = 0;
+        *y = s->height;
     }
 }
 
@@ -1027,6 +1051,7 @@ static void artist_reg_write(void *opaque, hwaddr addr, uint64_t val,
         break;
 
     case CURSOR_CTRL:
+        combine_write_reg(addr, val, size, &s->cursor_cntrl);
         break;
 
     case IMAGE_BITMAP_OP:
@@ -1331,8 +1356,8 @@ static int vmstate_artist_post_load(void *opaque, int version_id)
 
 static const VMStateDescription vmstate_artist = {
     .name = "artist",
-    .version_id = 1,
-    .minimum_version_id = 1,
+    .version_id = 2,
+    .minimum_version_id = 2,
     .post_load = vmstate_artist_post_load,
     .fields = (VMStateField[]) {
         VMSTATE_UINT16(height, ARTISTState),
@@ -1352,6 +1377,7 @@ static const VMStateDescription vmstate_artist = {
         VMSTATE_UINT32(line_end, ARTISTState),
         VMSTATE_UINT32(line_xy, ARTISTState),
         VMSTATE_UINT32(cursor_pos, ARTISTState),
+        VMSTATE_UINT32(cursor_cntrl, ARTISTState),
         VMSTATE_UINT32(cursor_height, ARTISTState),
         VMSTATE_UINT32(cursor_width, ARTISTState),
         VMSTATE_UINT32(plane_mask, ARTISTState),