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.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 hw/vga.c     |   14 +++++++++++++-
 hw/vga_int.h |    2 ++
 2 files changed, 15 insertions(+), 1 deletions(-)

On Mon, Jul 2, 2012 at 8:20 AM, Jan Kiszka <jan.kiszka@siemens.com> wrote:
> Let the text cursor blink at 5 Hz. 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>
> ---
>  hw/vga.c     |   14 +++++++++++++-
>  hw/vga_int.h |    2 ++
>  2 files changed, 15 insertions(+), 1 deletions(-)
>
> diff --git a/hw/vga.c b/hw/vga.c
> index acb3f7d..f22c4d9 100644
> --- a/hw/vga.c
> +++ b/hw/vga.c
> @@ -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;

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?

> +    }
>
>      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) {
> diff --git a/hw/vga_int.h b/hw/vga_int.h
> index 3b38764..c374474 100644
> --- 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;
> +    int cursor_blink_state;

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

> +    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
>