Re: [U-Boot] [PATCH 1/2] efi_loader: cursor positioning

On 05.09.19 10:06, Heinrich Schuchardt wrote:

When backspacing in column 0 do no set the column index to ULONG_MAX. Ensure that the row number is not set to ULONG_MAX even if the row count is advertised as 0. Ignore control characters other the 0x08, 0x0a, 0x0d when updating the column.

Signed-off-by: Heinrich Schuchardt xypron.glpk@gmx.de

lib/efi_loader/efi_console.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/lib/efi_loader/efi_console.c b/lib/efi_loader/efi_console.c index d4765afb98..d5222c46b4 100644 --- a/lib/efi_loader/efi_console.c +++ b/lib/efi_loader/efi_console.c @@ -156,13 +156,14 @@ static efi_status_t EFIAPI efi_cout_output_string( * Update the cursor position. * * The UEFI spec provides advance rules for U+0000, U+0008, U+000A,

• * and U000D. All other characters, including control characters
  

• * U+0007 (BEL) and U+0009 (TAB), have to increase the column by one.
  

• * and U000D. All other control characters are ignored. Any non-control
  

• * character increase the column by one.
  

  */ for (p = string; *p; ++p) { switch (*p) { case '\b': /* U+0008, backspace */

• 	con->cursor_column = max(0, con->cursor_column - 1);
  

• 	if (con->cursor_column)
  

• 		con->cursor_column--;
  break;
  

  case '\n': /* U+000A, newline */ con->cursor_column = 0;

@@ -178,13 +179,16 @@ static efi_status_t EFIAPI efi_cout_output_string( */ break; default:

• 	con->cursor_column++;
  

• 	if (*p > 0x1f)
  

What is the 0x1f here? I know, control character, but it's not obvious. Probably wants either a comment or a define.

• 		con->cursor_column++;
  break;
  

  } if (con->cursor_column >= mode->columns) { con->cursor_column = 0; con->cursor_row++; }

• if (con->cursor_row >= mode->rows && con->cursor_row)
  

• 	con->cursor_row--;
  

I don't understand this statement. When is the cursor_row >= mode->rows? Is this just to offset an incorrect cursor_row from the line above? Can't we just fold it in there?

Alex