VGA hardware cursor query

[Elliot Nunn]

Dear all,

I want to give Mac OS 9 clients access to hardware cursor support, to improve
responsiveness in absolute-cursor mode.

Would it be acceptable to add a hardware cursor interface to the VGA device?
And if so, can anyone advise on an appropriate register layout?

This is an example of such a patch. Because it alters the Bochs VBE interface
it is ONLY an example, NOT fit for acceptance. I have omitted the changes to
the binary driver qemu_vga.ndrv.

Kind regards,

Elliot Nunn

---
 hw/display/vga.c               |  35 +++++++++++++++++++++++++++++++++
 include/hw/display/bochs-vbe.h |   7 +++++--
 pc-bios/qemu_vga.ndrv          | Bin 18752 -> 20944 bytes
 3 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/hw/display/vga.c b/hw/display/vga.c
index 5dca2d1528..9b562e24e2 100644
--- a/hw/display/vga.c
+++ b/hw/display/vga.c
@@ -744,6 +744,10 @@ void vbe_ioport_write_data(void *opaque, uint32_t addr, 
uint32_t val)
 {
     VGACommonState *s = opaque;
 
+    static size_t cursorCounter;
+    static uint8_t cursorData[16 * 16 * 4];
+    QEMUCursor *cursor;
+
     if (s->vbe_index <= VBE_DISPI_INDEX_NB) {
         trace_vga_vbe_write(s->vbe_index, val);
         switch(s->vbe_index) {
@@ -796,6 +800,37 @@ void vbe_ioport_write_data(void *opaque, uint32_t addr, 
uint32_t val)
             s->vbe_regs[s->vbe_index] = val;
             vga_update_memory_access(s);
             break;
+
+        case VBE_DISPI_INDEX_CURSOR_IMG:
+            cursorData[cursorCounter++] = val >> 8;
+            cursorData[cursorCounter++] = val;
+            cursorCounter &= sizeof(cursorData) - 1;
+            break;
+
+        case VBE_DISPI_INDEX_CURSOR_HOTSPOT:
+            cursor = cursor_alloc(16, 16);
+            
+            if (val == 0x8080) { // blank cursor
+                for (int i = 0; i < 16*16; i++) {
+                    cursor->data[i] = 0;
+                }
+            } else {
+                for (int i = 0; i < 16*16; i++) {
+                    cursor->data[i] = 
+                        ((uint32_t)cursorData[i*4] << 24) |
+                        ((uint32_t)cursorData[i*4+1] << 16) |
+                        ((uint32_t)cursorData[i*4+2] << 8) |
+                        (uint32_t)cursorData[i*4+3];
+                }
+
+                cursor->hot_x = (int8_t)(val >> 8);
+                cursor->hot_y = (int8_t)val;
+            }
+
+            dpy_cursor_define(s->con, cursor);
+            cursor_put(cursor); // dealloc
+            break;
+
         default:
             break;
         }
diff --git a/include/hw/display/bochs-vbe.h b/include/hw/display/bochs-vbe.h
index bc2f046eee..7de409bae7 100644
--- a/include/hw/display/bochs-vbe.h
+++ b/include/hw/display/bochs-vbe.h
@@ -19,7 +19,10 @@
 #define VBE_DISPI_INDEX_VIRT_HEIGHT     0x7
 #define VBE_DISPI_INDEX_X_OFFSET        0x8
 #define VBE_DISPI_INDEX_Y_OFFSET        0x9
-#define VBE_DISPI_INDEX_NB              0xa /* size of vbe_regs[] */
+#define VBE_DISPI_INDEX_CURSOR_IMG      0xb
+#define VBE_DISPI_INDEX_CURSOR_HOTSPOT  0xc
+#define VBE_DISPI_INDEX_CURSOR_ABS      0xd
+#define VBE_DISPI_INDEX_NB              0xe /* size of vbe_regs[] */
 #define VBE_DISPI_INDEX_VIDEO_MEMORY_64K 0xa /* read-only, not in vbe_regs */
 
 /* VBE_DISPI_INDEX_ID */
@@ -54,7 +57,7 @@
 
 /* bochs vbe register region */
 #define PCI_VGA_BOCHS_OFFSET  0x500
-#define PCI_VGA_BOCHS_SIZE    (0x0b * 2)
+#define PCI_VGA_BOCHS_SIZE    (VBE_DISPI_INDEX_NB * 2)
 
 /* qemu extension register region */
 #define PCI_VGA_QEXT_OFFSET   0x600

-- 
2.30.1 (Apple Git-130)