Rev 404 | Go to most recent revision | Blame | Compare with Previous | Last modification | View Log | RSS feed
/* This file is part of the SvarCOM project and is published under the terms
* of the MIT license.
*
* Copyright (C) 2021 Mateusz Viste
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
/*
* cls
*/
static int cmd_cls(struct cmd_funcparam *p) {
unsigned char screenw, screenh;
const char *ansiesc = "\x1B[2J$";
if (cmd_ishlp(p)) {
outputnl("Clears the screen");
outputnl("");
outputnl("CLS");
return(-1);
}
screenw = screen_getwidth();
screenh = screen_getheight();
_asm {
/* output an ANSI ESC code for "clear screen" in case the console is
* some kind of terminal */
mov ah, 0x09 /* write $-terminated string to stdout */
mov dx, ansiesc
int 0x21
/* check what stdout is set to */
mov ax, 0x4400 /* IOCTL query device/flags flags */
mov bx, 1 /* file handle (1 = stdout) */
int 0x21 /* CF set on error, otherwise DX set with flags */
jc DONE /* abort on error */
/* DX = 10000010
| |||
| ||+--- indicates standard output
| |+---- set if NUL device
| +----- set if CLOCK device
+--------- set if handle is a device (ie. not a file)
in other words, DL & 10001110 (8Eh) should result in 10000010 (82h)
*/
and dl, 0x8e
cmp dl, 0x82
jne DONE /* abort on error */
/* scroll vram out of screen */
mov ax, 0x0600 /* scroll up entire rectangle */
mov bh, 0x07 /* fill screen with white-on-black */
xor cx, cx /* upper left location in CH,CL (0,0) */
/* DX is bottom right location of rectangle (DH=row, DL=column) */
mov dh, [screenh]
dec dh
mov dl, [screenw]
dec dl
int 0x10
/* set cursor to top left corner (0,0) of the screen */
mov ah, 0x02 /* set cursor position */
xor bh, bh /* page number */
xor dx, dx /* location in DH,DL */
int 0x10
DONE:
}
return(-1);
}