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vga: Implement blinking of text cursor

PATCH Superseded Jan Kiszka 3 participants 7 messages Jul 2, 2012 – Jul 14, 2012

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Jan Kiszka

author
#0 lore raw

PATCH 1/1 vga: Implement blinking of text cursor

Let the text cursor blink at 5 Hz. No timer is used, instead we rely on the fact that the display is updated periodically.

---
 hw/vga.c     |   14 +++++++++++++-
 hw/vga_int.h |    2 ++
 2 files changed, 15 insertions(+), 1 deletions(-)
hw/vga.c +13 -1
index acb3f7d..f22c4d9 100644
@@ -38,6 +38,8 @@
 
 //#define DEBUG_BOCHS_VBE
 
+#define VGA_TEXT_CURSOR_PERIOD  200
+
 /*
  * Video Graphics Array (VGA)
  *
@@ -1300,6 +1302,7 @@ 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 +1373,11 @@ 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;
+        s->cursor_blink_state ^= 1;
+        full_update = 1;
+    }
 
     depth_index = get_depth_index(s->ds);
     if (cw == 16)
@@ -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_blink_state != 0) {
                     int line_start, line_last, h;
                     /* draw the cursor */
                     line_start = s->cr[VGA_CRTC_CURSOR_START] & 0x1f;
@@ -1884,6 +1893,9 @@ 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) + VGA_TEXT_CURSOR_PERIOD;
+            s->cursor_blink_state = 1;
             full_update = 1;
         }
         switch(graphic_mode) {
hw/vga_int.h +2 -0
index 3b38764..c374474 100644
@@ -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;
+    int cursor_blink_state;
+    int64_t cursor_blink_time;
     uint32_t cursor_offset;
     unsigned int (*rgb_to_pixel)(unsigned int r,
                                  unsigned int g, unsigned b);
Signature · 1 line
1.7.3.4
#1 lore raw
Quoted 31 lines · Jan Kiszka

Let the text cursor blink at 5 Hz. No timer is used, instead we rely on the fact that the display is updated periodically.

---
 hw/vga.c     |   14 +++++++++++++-
 hw/vga_int.h |    2 ++
 2 files changed, 15 insertions(+), 1 deletions(-)
hw/vga.c +3 -0
index acb3f7d..f22c4d9 100644
@@ -38,6 +38,8 @@
 
 //#define DEBUG_BOCHS_VBE
 
+#define VGA_TEXT_CURSOR_PERIOD  200
+
 /*
  * Video Graphics Array (VGA)
  *
@@ -1300,6 +1302,7 @@ 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];

hw/vga.c static void vga_draw_text(VGACommonState *s, int full_update) · line 1379

Quoted 7 lines
hw/vga.c +4 -0
@@ -1370,6 +1373,11 @@ 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;
+        s->cursor_blink_state ^= 1;
+        full_update = 1;

This would force a whole screen refresh at 5Hz. How about moving the check, which you modify below, outside of
if (full_update || ch_attr != *ch_attr_ptr) {
...
}
block?

Quoted 29 lines
hw/vga.c +6 -1
+    }
 
     depth_index = get_depth_index(s->ds);
     if (cw == 16)
@@ -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_blink_state != 0) {
                     int line_start, line_last, h;
                     /* draw the cursor */
                     line_start = s->cr[VGA_CRTC_CURSOR_START] & 0x1f;
@@ -1884,6 +1893,9 @@ 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) + VGA_TEXT_CURSOR_PERIOD;
+            s->cursor_blink_state = 1;
             full_update = 1;
         }
         switch(graphic_mode) {
hw/vga_int.h +0 -0
index 3b38764..c374474 100644

hw/vga_int.h typedef struct VGACommonState { · line 159

Quoted 4 lines
hw/vga_int.h +1 -0
@@ -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;
+    int cursor_blink_state;

I'd use bool and a name that tells something about the state, like bool cursor_visible;

Quoted 7 lines
hw/vga_int.h +1 -1
+    int64_t cursor_blink_time;
     uint32_t cursor_offset;
     unsigned int (*rgb_to_pixel)(unsigned int r,
                                  unsigned int g, unsigned b);
--

1.7.3.4

author
#2 lore raw

PATCH v2 1/1 vga: Implement blinking of text cursor

Let the text cursor blink at 5 Hz. No timer is used, instead we rely on the fact that the display is updated periodically.

---

Changes in v2:
- avoid full screen updates for cursor blinking
- convert cursor_blink_state to cursor_visible_phase

 hw/vga.c     |   14 ++++++++++++--
 hw/vga_int.h |    2 ++
 2 files changed, 14 insertions(+), 2 deletions(-)
hw/vga.c +12 -2
index acb3f7d..a1644f3 100644
@@ -38,6 +38,8 @@
 
 //#define DEBUG_BOCHS_VBE
 
+#define VGA_TEXT_CURSOR_PERIOD  200
+
 /*
  * Video Graphics Array (VGA)
  *
@@ -1300,6 +1302,7 @@ 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 +1373,10 @@ 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;
+        s->cursor_visible_phase = !s->cursor_visible_phase;
+    }
 
     depth_index = get_depth_index(s->ds);
     if (cw == 16)
@@ -1390,7 +1397,7 @@ 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 +1427,8 @@ 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 +1892,8 @@ 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) + VGA_TEXT_CURSOR_PERIOD;
             full_update = 1;
         }
         switch(graphic_mode) {
hw/vga_int.h +2 -0
index 3b38764..8938093 100644
@@ -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);
Signature · 1 line
1.7.3.4
#3 lore raw

Hi Jan,

please see my comments below.

Am 04.07.2012 15:40, schrieb Jan Kiszka:

Quoted 36 lines

Let the text cursor blink at 5 Hz. No timer is used, instead we rely on the fact that the display is updated periodically.

---

Changes in v2:
- avoid full screen updates for cursor blinking
- convert cursor_blink_state to cursor_visible_phase

  hw/vga.c     |   14 ++++++++++++--
  hw/vga_int.h |    2 ++
  2 files changed, 14 insertions(+), 2 deletions(-)
hw/vga.c +3 -0
index acb3f7d..a1644f3 100644
@@ -38,6 +38,8 @@
 
  //#define DEBUG_BOCHS_VBE
 
+#define VGA_TEXT_CURSOR_PERIOD  200
+
  /*
   * Video Graphics Array (VGA)
   *
@@ -1300,6 +1302,7 @@ 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];

hw/vga.c static void vga_draw_text(VGACommonState *s, int full_update) · line 1380

Quoted 8 lines
hw/vga.c +4 -0
@@ -1370,6 +1373,10 @@ 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;
+        s->cursor_visible_phase = !s->cursor_visible_phase;
+    }
 

It's named VGA_TEXT_CURSOR_PERIOD, but it looks like it is not the period, but the time for each of two states (on/off), so it's 1/2 the period.

With your patch, I'd expect a blink frequency of 2.5 Hz.

According to the VGA documentation (I used
http://www.stanford.edu/class/cs140/projects/pintos/specs/freevga/vga/textcur.htm#blink),
the time for each state should be 16 / (60 Hz) or 266 ms resulting in a blink frequency of 1.875 Hz.

Quoted 37 lines
hw/vga.c +5 -2
      depth_index = get_depth_index(s->ds);
      if (cw == 16)
@@ -1390,7 +1397,7 @@ 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 +1427,8 @@ 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 +1892,8 @@ 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) + VGA_TEXT_CURSOR_PERIOD;
              full_update = 1;
          }
          switch(graphic_mode) {
hw/vga_int.h +0 -0
index 3b38764..8938093 100644

hw/vga_int.h typedef struct VGACommonState { · line 163

Quoted 8 lines
hw/vga_int.h +2 -0
@@ -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);

As far as I can tell, there are more cursor features missing:
do we support an invisible cursor (your patch doesn't) or cursor shape? See also this URL for more information:
http://www.stanford.edu/class/cs140/projects/pintos/specs/freevga/vga/textcur.htm

Blinking is also missing for text with the blink attribute. I don't know whether real hardware synchronizes text and cursor blinking. If it does, we should do that, too.

What about vertical blank interrupt? It is the base of text cursor blinking. We don't support it currently.

Regards,
Stefan

author
#4 lore raw
Quoted 39 lines · Stefan Weil

Hi Jan,

please see my comments below.

Am 04.07.2012 15:40, schrieb Jan Kiszka:

Quoted 33 lines

Let the text cursor blink at 5 Hz. No timer is used, instead we rely on the fact that the display is updated periodically.

---

Changes in v2:
- avoid full screen updates for cursor blinking
- convert cursor_blink_state to cursor_visible_phase

  hw/vga.c     |   14 ++++++++++++--
  hw/vga_int.h |    2 ++
  2 files changed, 14 insertions(+), 2 deletions(-)
hw/vga.c +3 -0
index acb3f7d..a1644f3 100644
@@ -38,6 +38,8 @@
 
  //#define DEBUG_BOCHS_VBE
 
+#define VGA_TEXT_CURSOR_PERIOD  200
+
  /*
   * Video Graphics Array (VGA)
   *
@@ -1300,6 +1302,7 @@ 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);
 
Quoted 15 lines

hw/vga.c static void vga_draw_text(VGACommonState *s, int full_update) · line 1380

Quoted 11 lines
hw/vga.c +4 -0
      /* compute font data address (in plane 2) */
      v = s->sr[VGA_SEQ_CHARACTER_MAP];
@@ -1370,6 +1373,10 @@ 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;
+        s->cursor_visible_phase = !s->cursor_visible_phase;
+    }
 

It's named VGA_TEXT_CURSOR_PERIOD, but it looks like it is not the period, but the time for each of two states (on/off), so it's 1/2 the period.

Err, of course.

Quoted 7 lines

With your patch, I'd expect a blink frequency of 2.5 Hz.

According to the VGA documentation (I used
http://www.stanford.edu/class/cs140/projects/pintos/specs/freevga/vga/textcur.htm#blink),
the time for each state should be 16 / (60 Hz) or 266 ms resulting in a blink frequency of 1.875 Hz.

Interesting. The real hardware I was looking at is using a rate definitely larger than 2 HZ. But I can change this to the original rate.

Quoted 53 lines
Quoted 39 lines
hw/vga.c +5 -2
      depth_index = get_depth_index(s->ds);
      if (cw == 16)
@@ -1390,7 +1397,7 @@ 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 +1427,8 @@ 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 +1892,8 @@ 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) + VGA_TEXT_CURSOR_PERIOD;
              full_update = 1;
          }
          switch(graphic_mode) {
hw/vga_int.h +0 -0
index 3b38764..8938093 100644

hw/vga_int.h typedef struct VGACommonState { · line 163

Quoted 8 lines
hw/vga_int.h +2 -0
@@ -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);

As far as I can tell, there are more cursor features missing:
do we support an invisible cursor (your patch doesn't) or cursor shape? See also this URL for more information:
http://www.stanford.edu/class/cs140/projects/pintos/specs/freevga/vga/textcur.htm

Quoted 6 lines

Blinking is also missing for text with the blink attribute. I don't know whether real hardware synchronizes text and cursor blinking. If it does, we should do that, too.

What about vertical blank interrupt? It is the base of text cursor blinking. We don't support it currently.

As always: patches are welcome :). This covers at least the most prominent use case.

Thanks,
Jan

Signature · 2 lines
Siemens AG, Corporate Technology, CT RTC ITP SDP-DE
Corporate Competence Center Embedded Linux
author
#5 lore raw

PATCH v3 1/1 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.

---

Changes in v3:
- adjusted frequency to original value
- fixed semantic of VGA_TEXT_CURSOR_PERIOD_MS

 hw/vga.c     |   14 ++++++++++++--
 hw/vga_int.h |    2 ++
 2 files changed, 14 insertions(+), 2 deletions(-)
hw/vga.c +12 -2
index acb3f7d..f82ced8 100644
@@ -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) {
hw/vga_int.h +2 -0
index 3b38764..8938093 100644
@@ -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);
Signature · 1 line
1.7.3.4
Applied
#6 lore raw

Thanks, applied.

Quoted 90 lines · Jan Kiszka

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.

---

Changes in v3:
- adjusted frequency to original value
- fixed semantic of VGA_TEXT_CURSOR_PERIOD_MS

 hw/vga.c     |   14 ++++++++++++--
 hw/vga_int.h |    2 ++
 2 files changed, 14 insertions(+), 2 deletions(-)
hw/vga.c +12 -2
index acb3f7d..f82ced8 100644
@@ -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) {
hw/vga_int.h +2 -1
index 3b38764..8938093 100644
@@ -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);
--

1.7.3.4