| 0,0 → 1,63 |
|---|
| /* |
| * 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); |
| } |