scrolling bug fix

kaleid/kernel/io/vga.c

@@ -43,10 +43,10 @@ error_t bvgaflusher(Buffer_t *buf)
     ushort *fbp = BtVideoInfo.framebufferAddr;
     uchar color = 0xf;
 
-    uchar *currentLine = buf->wp - buf->lineLen - buf->lastLF;
+    uchar *currentLine = buf->wp - buf->lastLF;
     uchar *bufStart = (uchar *)lmax((size_t)buf->buf,
                             (size_t)currentLine
-                            - (buf->nLines - 2 + bscroll) * buf->lineLen);
+                            - (buf->nLines - 1 + bscroll) * buf->lineLen);
 
     uchar *ptr = bufStart;
 
@@ -87,10 +87,21 @@ void IoScrollDown(void)
 
 void IoScrollUp(void)
 {
-    // Keep the 8 below the 10 given to BOpenTermBufEx
-    if (bscroll < BtVideoInfo.framebufferHeight * 8) /* XXX */
+    BLockBuf(BStdOut);
+
+    uchar *currentLine = BStdOut->wp - BStdOut->lastLF;
+    assert(currentLine >= BStdOut->buf);
+    
+    // Scrollable lines
+    uint scrabble = max(0, (currentLine-BStdOut->buf)/BStdOut->lineLen
+                            - BStdOut->nLines + 1);
+
+    if (bscroll < scrabble)
         bscroll++;
+
     bvgaflusher(BStdOut);
+    
+    BUnlockBuf(BStdOut);
 }
 
 

kaleid/kernel/sh/shcmds.c

@@ -65,9 +65,12 @@ error_t CmdHelp(int argc, char **argv, char *cmdline)
 
 error_t CmdClear(int argc, char **argv, char *cmdline)
 {
-    size_t i;
-    for (i = 0; i < BtVideoInfo.framebufferHeight; i++)
-        KernLog("\n");
+    BLockBuf(BStdOut);
+    
+    BStdOut->wp = BStdOut->rp = BStdOut->buf;
+    BStdOut->lastLF = 0;
+    
+    BUnlockBuf(BStdOut);
         
     return EOK;
 }