[BOOTVID]

- Fix scrolling if ScrollRegion contain whole screen.
- Add backspace support
- Remove unneeded code
- Now screen debugging in BSOD works much better :)

svn path=/trunk/; revision=52239

reactos/drivers/base/bootvid/i386/vga.c

@@ -66,7 +66,6 @@ ULONG lookup[16] =
 ULONG TextColor = 0xF;
 ULONG curr_x = 0;
 ULONG curr_y = 0;
-BOOLEAN NextLine = FALSE;
 ULONG_PTR VgaRegisterBase = 0;
 ULONG_PTR VgaBase = 0;
 
@@ -346,8 +345,7 @@ VgaScroll(ULONG Scroll)
 VOID
 NTAPI
 PreserveRow(IN ULONG CurrentTop,
-            IN ULONG TopDelta,
+            IN ULONG TopDelta)
-            IN BOOLEAN Direction)
 {
     PUCHAR Position1, Position2;
     ULONG Count;
@@ -361,19 +359,9 @@ PreserveRow(IN ULONG CurrentTop,
     /* Set Mode 1 */
     ReadWriteMode(1);
 
-    /* Check which way we're preserving */
-    if (Direction)
-    {
-        /* Calculate the position in memory for the row */
-        Position1 = (PUCHAR)VgaBase + CurrentTop * 80;
-        Position2 = (PUCHAR)VgaBase + 0x9600;
-    }
-    else
-    {
     /* Calculate the position in memory for the row */
     Position1 = (PUCHAR)VgaBase + 0x9600;
     Position2 = (PUCHAR)VgaBase + CurrentTop * 80;
-    }
 
     /* Set the count and make sure it's above 0 */
     Count = TopDelta * 80;
@@ -392,6 +380,33 @@ PreserveRow(IN ULONG CurrentTop,
     }
 }
 
+VOID
+NTAPI
+CleanCharacter(IN ULONG Left,
+               IN ULONG Top,
+               IN ULONG TopDelta)
+{
+    PUCHAR Position1, Position2;
+    ULONG i;
+    
+    /* Clear the 4 planes */
+    __outpw(0x3C4, 0xF02);
+
+    /* Set the bitmask to 0xFF for all 4 planes */
+    __outpw(0x3CE, 0xFF08);
+
+    /* Set Mode 1 */
+    ReadWriteMode(1);
+
+    /* Calculate the position in memory for the character */
+    Position1 = (PUCHAR)VgaBase + 0x9600 + Left / 8;
+    Position2 = (PUCHAR)VgaBase + Top * 80 + Left / 8;
+
+    /* Copy data from preserved row */
+    for(i = 0; i < TopDelta; ++i)
+        WRITE_REGISTER_UCHAR(Position2 + i * 80, READ_REGISTER_UCHAR(Position1));
+}
+
 VOID
 NTAPI
 BitBlt(IN ULONG Left,
@@ -749,57 +764,62 @@ VidDisplayString(PUCHAR String)
         {
             /* Modify Y position */
             curr_y += TopDelta;
-            if (curr_y >= ScrollRegion[3])
+            if (curr_y + TopDelta >= ScrollRegion[3])
             {
                 /* Scroll the view */
                 VgaScroll(TopDelta);
                 curr_y -= TopDelta;
-
+            }
-                /* Preserve row */
+            else
-                PreserveRow(curr_y, TopDelta, TRUE);
+            {
+                /* Preserve the current row */
+                PreserveRow(curr_y, TopDelta);
             }
 
             /* Update current X */
             curr_x = ScrollRegion[0];
-
-            /* Preseve the current row */
-            PreserveRow(curr_y, TopDelta, FALSE);
         }
         else if (*String == '\r')
         {
             /* Update current X */
             curr_x = ScrollRegion[0];
+        }
+        else if (*String == '\b')
+        {
+            /* Update current X */
+            if (curr_x > ScrollRegion[0])
+                curr_x -= 8;
+            else
+            {
+                /* We are at line begin - move to previous row */
+                curr_x = ScrollRegion[0];
+                curr_y -= TopDelta;
+            }
             
-            /* Check if we're being followed by a new line */
+            /* Clean current character */
-            if (String[1] != '\n') NextLine = TRUE;
+            CleanCharacter(curr_x, curr_y, TopDelta);
         }
         else
         {
-            /* Check if we had a \n\r last time */
-            if (NextLine)
-            {
-                /* We did, preserve the current row */
-                PreserveRow(curr_y, TopDelta, TRUE);
-                NextLine = FALSE;
-            }
-
             /* Display this character */
             DisplayCharacter(*String, curr_x, curr_y, TextColor, 16);
             curr_x += 8;
 
             /* Check if we should scroll */
-            if (curr_x > ScrollRegion[2])
+            if (curr_x + 8 > ScrollRegion[2])
             {
                 /* Update Y position and check if we should scroll it */
                 curr_y += TopDelta;
-                if (curr_y > ScrollRegion[3])
+                if (curr_y + TopDelta > ScrollRegion[3])
                 {
                     /* Do the scroll */
                     VgaScroll(TopDelta);
                     curr_y -= TopDelta;
-
+                }
-                    /* Save the row */
+                else
-                    PreserveRow(curr_y, TopDelta, TRUE);
+                {
+                    /* Preserve the current row */
+                    PreserveRow(curr_y, TopDelta);
                 }
 
                 /* Update X */