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ANSI command-sequences

ANSI command-sequences. A look at some terminal emulation features utilized in the “console-redirection” mechanism. Clearing the screen. Here is an ANSI command-sequence that clears the terminal’s display-screen: char cmd[] = “33[2J”; int len = strlen( cmd ); write( 1, cmd, len );.

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ANSI command-sequences

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  1. ANSI command-sequences A look at some terminal emulation features utilized in the “console-redirection” mechanism

  2. Clearing the screen • Here is an ANSI command-sequence that clears the terminal’s display-screen: char cmd[] = “\033[2J”; int len = strlen( cmd ); write( 1, cmd, len );

  3. Reposition the cursor • Here is an ANSI command-sequence that moves the cursor to row 12, column 40: char cmd[] = “\033[12;40H”; int len = strlen( cmd ); write( 1, cmd, len );

  4. ANSI color-codes 0 = black 1 = red 2 = green 3 = brown 4 = blue 5 = magenta 6 = cyan 7 = gray

  5. Setting text attributes • Here is an ANSI command-sequence that sets foreground and background colors: char cmd[] = “\033[32;44m”; int len = strlen( cmd ); write( 1, cmd, len );

  6. Cursor visibility commands • Here are ANSI command-sequences that will ‘hide’ or ‘show’ the terminal’s cursor: char hide[] = “\033[?25l”; // lowercase L char show[] = “\033[?25h”; // lowercase H

  7. Demo-program • We created a boot-time program (called ‘emitinfo.s’) that shows how a protected-mode exception-handler can send some diagnostic information via the serial null-modem cable to a remote machine that is running a ‘terminal emulator’ application

  8. In-class exercise • Modify this simple C++ program so that it will print its “Hello” message in colors and be located in the center of the screen: #include <stdio.h> int main( void ) { printf( “Hello, world! \n” ); }

  9. In-class exercise #2 and #3 • Modify the ‘emitinfo.s’ program so that it will also display the FS and GS registers • Modify the ‘emitinfo.s’ program so that its ‘isrGPF’ exception-handler will execute in 64-bit mode (on your ‘anchor’ machine)

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