From af5f8e9bff801e32977d6a50c79a1bd7cb60ad92 Mon Sep 17 00:00:00 2001
From: kougyokugentou <41278462+kougyokugentou@users.noreply.github.com>
Date: Sun, 24 Oct 2021 16:14:48 -0700
Subject: [PATCH] Various DOS related functions (2002)

---
 demos/dosfuncs.h | 61 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 demos/dosfuncs.h

diff --git a/demos/dosfuncs.h b/demos/dosfuncs.h
new file mode 100644
index 0000000..1c91f95
--- /dev/null
+++ b/demos/dosfuncs.h
@@ -0,0 +1,61 @@
+#include <dos.h>
+#define VIDEO 0x10      //video interrupt
+#define COLS 80         //screen width
+#define ROWS 25         //screen rows
+#define PRINTER 0x17    //BIOS printer interrupt
+#define LPT1 0x00       //LPT1. your first printer
+#define EJECT 0x0c      //Eject page printer command
+
+void cls(void);
+void locate(int col,int row);
+void eject(void);
+void prnchar(char c);
+void prnstring(char *string);
+
+void cls(void)
+{
+ union REGS regs;
+
+ regs.h.ah=0x06;        //func 6, scroll window
+ regs.h.al=0x00;        //clear screen
+ regs.h.bh=0x07;        //make screen "blank"
+ regs.h.ch=0x00;        //upper left row
+ regs.h.cl=0x00;        //upper left column
+ regs.h.dh=ROWS-1;      //lower right row
+ regs.h.dl=COLS-1;      //lower right column
+ int86(VIDEO,&regs,&regs);
+
+ locate(0,0);           //"Home" the cursor
+}
+
+void locate(int col,int row)
+{
+ union REGS regs;
+
+ regs.h.ah=0x02;        //vid func 2, move cursor
+ regs.h.bh=0x00;        //video screen (always 0)
+ regs.h.dh=row;         //cursor's row pos
+ regs.h.dl=col;         //cursor's col pos
+ int86(VIDEO,&regs,&regs);
+}
+
+void eject(void)
+{
+ prnchar(EJECT);
+}
+
+void prnchar(char c)
+{
+ union REGS regs;
+
+ regs.h.ah=0x00;        //print character function
+ regs.h.al=c;           //character to print
+ regs.x.dx=LPT1;        //printer port to print to
+ int86(PRINTER,&regs,&regs);
+}
+
+void prnstring(char *string)
+{
+ while(*string) //while there's a char to print
+      prnchar(*string++);        //print it and increment
+}