vga: Implement blinking of text cursor

Let the text cursor blink at 1.875 Hz, the original VGA cursor
frequency. No timer is used, instead we rely on the fact that the
display is updated periodically.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

diff --git a/hw/vga.c b/hw/vga.c
index acb3f7d924cd9c835f64d6eefdb46ff7951ff998..f82ced8e662cecfb26d2ac223e56fb340c7fd4cd 100644 (file)
--- a/hw/vga.c
+++ b/hw/vga.c
@@ -38,6 +38,9 @@
 
 //#define DEBUG_BOCHS_VBE
 
+/* 16 state changes per vertical frame @60 Hz */
+#define VGA_TEXT_CURSOR_PERIOD_MS       (1000 * 2 * 16 / 60)
+
 /*
  * Video Graphics Array (VGA)
  *
@@ -1300,6 +1303,7 @@ static void vga_draw_text(VGACommonState *s, int full_update)
     uint32_t *ch_attr_ptr;
     vga_draw_glyph8_func *vga_draw_glyph8;
     vga_draw_glyph9_func *vga_draw_glyph9;
+    int64_t now = qemu_get_clock_ms(vm_clock);
 
     /* compute font data address (in plane 2) */
     v = s->sr[VGA_SEQ_CHARACTER_MAP];
@@ -1370,6 +1374,10 @@ static void vga_draw_text(VGACommonState *s, int full_update)
         s->cursor_end = s->cr[VGA_CRTC_CURSOR_END];
     }
     cursor_ptr = s->vram_ptr + (s->start_addr + cursor_offset) * 4;
+    if (now >= s->cursor_blink_time) {
+        s->cursor_blink_time = now + VGA_TEXT_CURSOR_PERIOD_MS / 2;
+        s->cursor_visible_phase = !s->cursor_visible_phase;
+    }
 
     depth_index = get_depth_index(s->ds);
     if (cw == 16)
@@ -1390,7 +1398,7 @@ static void vga_draw_text(VGACommonState *s, int full_update)
         cx_max = -1;
         for(cx = 0; cx < width; cx++) {
             ch_attr = *(uint16_t *)src;
-            if (full_update || ch_attr != *ch_attr_ptr) {
+            if (full_update || ch_attr != *ch_attr_ptr || src == cursor_ptr) {
                 if (cx < cx_min)
                     cx_min = cx;
                 if (cx > cx_max)
@@ -1420,7 +1428,8 @@ static void vga_draw_text(VGACommonState *s, int full_update)
                                     font_ptr, cheight, fgcol, bgcol, dup9);
                 }
                 if (src == cursor_ptr &&
-                    !(s->cr[VGA_CRTC_CURSOR_START] & 0x20)) {
+                    !(s->cr[VGA_CRTC_CURSOR_START] & 0x20) &&
+                    s->cursor_visible_phase) {
                     int line_start, line_last, h;
                     /* draw the cursor */
                     line_start = s->cr[VGA_CRTC_CURSOR_START] & 0x1f;
@@ -1884,6 +1893,7 @@ static void vga_update_display(void *opaque)
         }
         if (graphic_mode != s->graphic_mode) {
             s->graphic_mode = graphic_mode;
+            s->cursor_blink_time = qemu_get_clock_ms(vm_clock);
             full_update = 1;
         }
         switch(graphic_mode) {

diff --git a/hw/vga_int.h b/hw/vga_int.h
index 3b38764a38a8df7c3fdb19458ca72d73673e0b7d..8938093682e764d47a7778a4df6a8e5f6f582dc7 100644 (file)
--- a/hw/vga_int.h
+++ b/hw/vga_int.h
@@ -156,6 +156,8 @@ typedef struct VGACommonState {
     uint32_t last_scr_width, last_scr_height; /* in pixels */
     uint32_t last_depth; /* in bits */
     uint8_t cursor_start, cursor_end;
+    bool cursor_visible_phase;
+    int64_t cursor_blink_time;
     uint32_t cursor_offset;
     unsigned int (*rgb_to_pixel)(unsigned int r,
                                  unsigned int g, unsigned b);