Serial port debug output

serial.c

@@ -0,0 +1,32 @@
+#include <dos.h>
+#include "serial.h"
+
+int comport = 0;
+
+#define SER_LATCH_LO 0
+#define SER_LATCH_HI 1
+#define SER_TX 0
+#define SER_LCR 3
+#define SER_LSR 5
+
+void ser_init(int port, int baudrate, int protocol) {
+  int far *comport_addr = MK_FP(0x0040, 0x0000);
+  int lcr;
+  comport = comport_addr[port];
+
+  outp(comport + SER_LCR, 0x80);
+  outp(comport + SER_LATCH_HI, baudrate >> 8);
+  outp(comport + SER_LATCH_LO, baudrate & 0xff);
+  outp(comport + SER_LCR, protocol);
+}
+
+void ser_write_byte(char byte) {
+  while (!(inp(comport + SER_LSR) & 0x20)) {}
+  outp(comport + SER_TX, byte);
+}
+
+void ser_write(char *str) {
+  for (; *str; str ++) {
+    ser_write_byte(*str);
+  }
+}

serial.h

@@ -0,0 +1,24 @@
+#define SER_COM1 0
+#define SER_COM2 1
+#define SER_COM3 2
+#define SER_COM4 3
+
+#define SER_8N1 0x03
+
+#define BAUD_50     0x0900
+#define BAUD_110    0x0417
+#define BAUD_220    0x020c
+#define BAUD_300    0x0180
+#define BAUD_600    0x00c0
+#define BAUD_1200   0x0060
+#define BAUD_2400   0x0030
+#define BAUD_4800   0x0018
+#define BAUD_9600   0x000c
+#define BAUD_19200  0x0006
+#define BAUD_38400  0x0003
+#define BAUD_57600  0x0002
+#define BAUD_115200 0x0001
+
+void ser_init(int port, int baudrate, int protocol);
+void ser_write_byte(char byte);
+void ser_write(char *str);

testbed.c

@@ -7,6 +7,7 @@
 #include "mouse.h"
 #include "tiff.h"
 #include "tiles.h"
+#include "serial.h"
 
 /*** S C R A T C H ***/
 
@@ -117,19 +118,12 @@ void game_init() {
   scroll(0, 0);
 }
 
-int main() {
-  game_init();
-
-  while (!keyIsDown(K_ESC)) {
-    kbd_debounce();
-    if (game.state == STATE_MAP) {
-      if (keyWasPressed(K_SPACE)) {
+void showDialog() {
   game.state = STATE_DIALOG;
   game.footer.dy = 1;
-      }
-      playerThink(&game.player);
-      scroll(game.player.x - 152, game.player.y - 92);
-    } else if (game.state == STATE_DIALOG) {
+}
+
+void dialogThink() {
   if (keyWasPressed(K_SPACE)) {
     game.footer.dy = -1;
   }
@@ -143,6 +137,27 @@ int main() {
     game.state = STATE_MAP;
   }
   setSplitScreen(399 - (game.footer.y << 1));
+}
+
+void overworldThink() {
+  if (keyWasPressed(K_SPACE)) {
+    showDialog();
+  }
+  playerThink(&game.player);
+  scroll(game.player.x - 152, game.player.y - 92);
+}
+
+int main() {
+  game_init();
+  ser_init(SER_COM2, BAUD_19200, SER_8N1);
+  ser_write("JORTS QUEST DEBUG OUTPUT\r\n");
+
+  while (!keyIsDown(K_ESC)) {
+    kbd_debounce();
+    if (game.state == STATE_MAP) {
+      overworldThink();
+    } else if (game.state == STATE_DIALOG) {
+      dialogThink();
     }
     drawEntity(&game.player);
     drawScreen();