[reactos] 01/06: [BOOTVID] Fix drawing strings on top of the bitmap (#2936)

[Dmitry Borisov]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=4d54b8ce6954afa09b136a...

commit 4d54b8ce6954afa09b136a7cfe3a1cafb2bda7eb
Author:     Dmitry Borisov [e-mail]
AuthorDate: Sat Jun 20 17:21:42 2020 +0600
Commit:     Stanislav Motylkov [e-mail]
CommitDate: Wed Jul 29 19:10:38 2020 +0300

[BOOTVID] Fix drawing strings on top of the bitmap (#2936)

Also fix VGA pixel drawing.

CORE-15896
---
 drivers/base/bootvid/i386/pc/pc.h  | 7 +++++--
 drivers/base/bootvid/i386/pc/vga.c | 2 ++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/base/bootvid/i386/pc/pc.h b/drivers/base/bootvid/i386/pc/pc.h
index c1a96e797a6..c299a1ecd81 100644
--- a/drivers/base/bootvid/i386/pc/pc.h
+++ b/drivers/base/bootvid/i386/pc/pc.h
@@ -43,8 +43,11 @@ SetPixel(
     /* Select the bitmask register and write the mask */
     __outpw(VGA_BASE_IO_PORT + GRAPH_ADDRESS_PORT, (PixelMask[Left & 7] << 8) | IND_BIT_MASK);

-    /* Read the current pixel value and add our color */
-    WRITE_REGISTER_UCHAR(PixelPosition, READ_REGISTER_UCHAR(PixelPosition) & Color);
+    /* Dummy read to load latch registers */
+    (VOID)READ_REGISTER_UCHAR(PixelPosition);
+
+    /* Set the new color */
+    WRITE_REGISTER_UCHAR(PixelPosition, Color);
 }

VOID
diff --git a/drivers/base/bootvid/i386/pc/vga.c b/drivers/base/bootvid/i386/pc/vga.c
index b985bc68eb1..3f6c9bc703c 100644
--- a/drivers/base/bootvid/i386/pc/vga.c
+++ b/drivers/base/bootvid/i386/pc/vga.c
@@ -94,6 +94,8 @@ PrepareForSetPixel(VOID)
 do {                                                        \
     /* Select the bitmask register and write the mask */    \
     __outpw(VGA_BASE_IO_PORT + GRAPH_ADDRESS_PORT, ((_PixelMask) << 8) | IND_BIT_MASK); \
+    /* Dummy read to load latch registers */                \
+    (VOID)READ_REGISTER_UCHAR((_PixelPtr));                 \
     /* Set the new color */                                 \
     WRITE_REGISTER_UCHAR((_PixelPtr), (UCHAR)(_TextColor)); \
 } while (0);