Author: bde
Date: Thu Apr 20 13:46:55 2017
New Revision: 317190
URL: https://svnweb.freebsd.org/changeset/base/317190

Log:
  Attempt to determine the modes in which 8-bit wide characters are actually
  9 wide.
  
  I only need this to improve the mouse cursor, but it has always been
  needed to select and/or adjust fonts.
  
  This is complicated because there are no standard parameter tables
  giving this bit of information directly, and the device register bit
  giving the information can't be trusted even if it is read from the
  hardware.  Use a heuristic to guess if the device register can be
  trusted.  (The device register is normally read from the BIOS mode
  table, but on my system where the device register is wrong, the mode
  table doesn't match the hardware and is not used; the device registers
  are used in this case.)

Modified:
  head/sys/dev/fb/vesa.c
  head/sys/dev/fb/vga.c
  head/sys/sys/fbio.h

Modified: head/sys/dev/fb/vesa.c
==============================================================================
--- head/sys/dev/fb/vesa.c      Thu Apr 20 12:48:01 2017        (r317189)
+++ head/sys/dev/fb/vesa.c      Thu Apr 20 13:46:55 2017        (r317190)
@@ -1359,6 +1359,7 @@ vesa_set_mode(video_adapter_t *adp, int 
        vesa_adp->va_crtc_addr =
                (vesa_adp->va_flags & V_ADP_COLOR) ? COLOR_CRTC : MONO_CRTC;
 
+       vesa_adp->va_flags &= ~V_ADP_CWIDTH9;
        vesa_adp->va_line_width = info.vi_buffer_size / info.vi_height;
        if ((info.vi_flags & V_INFO_GRAPHICS) != 0)
                vesa_adp->va_line_width /= info.vi_planes;

Modified: head/sys/dev/fb/vga.c
==============================================================================
--- head/sys/dev/fb/vga.c       Thu Apr 20 12:48:01 2017        (r317189)
+++ head/sys/dev/fb/vga.c       Thu Apr 20 13:46:55 2017        (r317190)
@@ -862,6 +862,9 @@ update_adapter_info(video_adapter_t *adp
     /* XXX */
     adp->va_buffer = info->vi_buffer;
     adp->va_buffer_size = info->vi_buffer_size;
+    adp->va_flags &= ~V_ADP_CWIDTH9;
+    if (info->vi_flags & V_INFO_CWIDTH9)
+       adp->va_flags |= V_ADP_CWIDTH9;
     if (info->vi_mem_model == V_INFO_MM_VGAX) {
        adp->va_line_width = info->vi_width/2;
     } else if (info->vi_flags & V_INFO_GRAPHICS) {
@@ -1221,6 +1224,29 @@ probe_adapters(void)
        }
     }
 
+#if !defined(VGA_NO_BIOS) && !defined(VGA_NO_MODE_CHANGE)
+    /*
+     * Attempt to determine the real character width for each mode.  9 wide
+     * is supposed to be standard for EGA mono mode and most VGA text modes,
+     * but some hardware doesn't support it, so dynamic configuration is
+     * needed.  Bit 0 in sequencer register 1 is supposed control the width
+     * (set = 8), but this is unreliable too.  Trust that 0 in the sequencer
+     * bit means 9 wide after verifying that 9 is consistent with some CRTC
+     * timing. The ratio (Horizontal Total) / (Horizontal Displayed) is
+     * about 1.2 in all standard 9-wide modes and should be about 9/8 larger
+     * again  in similar 8-wide modes; in practice it is usually about 1.4
+     * times larger.
+     */
+    for (i = 0; i < nitems(bios_vmode); ++i) {
+       if (bios_vmode[i].vi_mem_model == V_INFO_MM_TEXT &&
+           bios_vmode[i].vi_width != 90) {
+           mp = get_mode_param(map_mode_num(bios_vmode[i].vi_mode));
+           if (mp != NULL && !(mp[5] & 1) && mp[10] <= mp[11] * 125 / 100)
+               bios_vmode[i].vi_flags |= V_INFO_CWIDTH9;
+       }
+    }
+#endif
+
     /* buffer address */
     vga_get_info(&biosadapter[V_ADP_PRIMARY],
                 biosadapter[V_ADP_PRIMARY].va_initial_mode, &info);

Modified: head/sys/sys/fbio.h
==============================================================================
--- head/sys/sys/fbio.h Thu Apr 20 12:48:01 2017        (r317189)
+++ head/sys/sys/fbio.h Thu Apr 20 13:46:55 2017        (r317190)
@@ -338,6 +338,7 @@ struct video_info {
 #define V_INFO_LINEAR  (1 << 2)
 #define V_INFO_VESA    (1 << 3)
 #define        V_INFO_NONVGA   (1 << 4)
+#define        V_INFO_CWIDTH9  (1 << 5)
     int                        vi_width;
     int                        vi_height;
     int                        vi_cwidth;
@@ -400,6 +401,7 @@ struct video_adapter {
 #define V_ADP_REGISTERED (1 << 18)
 #define V_ADP_ATTACHED (1 << 19)
 #define        V_ADP_DAC8      (1 << 20)
+#define        V_ADP_CWIDTH9   (1 << 21)
     vm_offset_t                va_io_base;
     int                        va_io_size;
     vm_offset_t                va_crtc_addr;
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