Joystick support

8 files changed, 204 insertions, 15 deletions

diff --git a/README.md b/README.md
index 4ef2ecf..c77c57e 100644
--- a/README.md
+++ b/README.md
@@ -12,15 +12,15 @@ Running the game:
 - At least 4MB of RAM
 - Sound Blaster (or no sound)
 
-The game can be controlled by keyboard.
-
-| Key | Action |
-| --- | --- |
-| Cursor up | Jump |
-| Cursor left | Move left |
-| Cursor right | Move Right |
-| P | Pause / resume game |
-| ESC | Exit the game |
+The game can be controlled by keyboard or joystick.
+
+| Key | Joystick | Action |
+| --- | --- | --- |
+| Cursor left | Joytick left | Move left |
+| Cursor right | Joystick right | Move Right |
+| Z | Button 1 | Jump |
+| P | - | Pause / resume game |
+| ESC | - | Exit the game |
 
 Check `-h` CLI flag for options.
 
diff --git a/TODO.md b/TODO.md
index d639df5..29fee2b 100644
--- a/TODO.md
+++ b/TODO.md
@@ -8,8 +8,6 @@
     - menu?
 - screens
   - end game
-- input
-  - joystick?
 
 # REVIEW
 
diff --git a/src/control.c b/src/control.c
new file mode 100644
index 0000000..ee103f0
--- /dev/null
+++ b/src/control.c
@@ -0,0 +1,36 @@
+#include <stdint.h>
+
+#include "keyb.h"
+#include "joy.h"
+
+#include "control.h"
+
+static uint8_t joy = 0;
+
+void control_init()
+{
+    joy = joy_detect();
+}
+
+uint8_t control_read()
+{
+    uint8_t r = CTL_NONE;
+
+    if (keys[KEY_UP])
+        r |= CTL_UP;
+    if (keys[KEY_DOWN])
+        r |= CTL_DOWN;
+    if (keys[KEY_LEFT])
+        r |= CTL_LEFT;
+    if (keys[KEY_RIGHT])
+        r |= CTL_RIGHT;
+    if (keys[KEY_Z])
+        r |= CTL_FIRE1;
+    if (keys[KEY_X])
+        r |= CTL_FIRE2;
+
+    if (joy)
+        r |= joy_read();
+
+    return r;
+}
diff --git a/src/control.h b/src/control.h
new file mode 100644
index 0000000..f4f02c7
--- /dev/null
+++ b/src/control.h
@@ -0,0 +1,15 @@
+#ifndef _CONTROL_H
+#define _CONTROL_H
+
+#define CTL_NONE    0
+#define CTL_UP      1
+#define CTL_DOWN    2
+#define CTL_RIGHT   4
+#define CTL_LEFT    16
+#define CTL_FIRE1   32
+#define CTL_FIRE2   64
+
+void control_init();
+uint8_t control_read();
+
+#endif /* _CONTROL_H */
diff --git a/src/joy.c b/src/joy.c
new file mode 100644
index 0000000..cda2fcf
--- /dev/null
+++ b/src/joy.c
@@ -0,0 +1,123 @@
+#include <stdint.h>
+#include <stdio.h>
+#include <pc.h>
+#include <dos.h>
+
+#include "vga.h"
+#include "keyb.h"
+#include "control.h"
+
+#include "joy.h"
+
+#define PORT 0x201
+
+#define BUTTON1 0x10
+#define BUTTON2 0x20
+#define AXISX   1
+#define AXISY   2
+
+#define TIMEOUT 16000
+
+static uint16_t j_up, j_down, j_left, j_right;
+
+static uint16_t read_axis(uint8_t axis)
+{
+    uint16_t i;
+
+    disable();
+    outportb(PORT, 0xff);
+    for (i = 0; i < TIMEOUT; i++)
+        if (!(inportb(PORT) & axis))
+            break;
+    enable();
+
+    return i;
+}
+
+static uint8_t calibrate(uint16_t *v, uint16_t *h)
+{
+    while (1)
+    {
+        if (keys[KEY_ESC])
+        {
+            while (keys[KEY_ESC])
+                wait_vsync();
+            return 0;
+        }
+
+        *v = read_axis(AXISY);
+        *h = read_axis(AXISX);
+
+        if (!(inportb(PORT) & BUTTON1))
+        {
+            while (!(inportb(PORT) & BUTTON1))
+                wait_vsync();
+            return 1;
+        }
+
+        wait_vsync();
+    }
+}
+
+uint8_t joy_detect()
+{
+    if (read_axis(AXISX) == TIMEOUT)
+        return 0;
+
+    printf("Joystick detected!\n");
+
+    printf("Please move UP + LEFT and press BUTTON 1 (ESC to abort)\n");
+    if (!calibrate(&j_up, &j_left))
+        return 0;
+    printf("Please move DOWN + RIGHT and press BUTTON 1 (ESC to abort)\n");
+    if (!calibrate(&j_down, &j_right))
+        return 0;
+
+#ifdef DEBUG
+    printf("Joystick reads: up=%04d, down=%04d, left=%04d, right=%04d\n",
+           j_up, j_down, j_left, j_right);
+#endif
+
+    j_up += j_up >> 4;
+    j_down -= j_down >> 4;
+    j_left += j_left >> 4;
+    j_right -= j_right >> 4;
+
+#ifdef DEBUG
+    printf("      Adjusted: up=%04d, down=%04d, left=%04d, right=%04d\n",
+           j_up, j_down, j_left, j_right);
+
+    printf("(press X to continue)\n");
+    while (!keys[KEY_X])
+        wait_vsync();
+#endif
+
+    return 1;
+}
+
+uint8_t joy_read()
+{
+    uint8_t r = CTL_NONE;
+    uint8_t b;
+    uint16_t v;
+
+    b = inportb(PORT);
+    if (!(b & BUTTON1))
+        r |= CTL_FIRE1;
+    if (!(b & BUTTON2))
+        r |= CTL_FIRE2;
+
+    v = read_axis(AXISY);
+    if (v <= j_up)
+        r |= CTL_UP;
+    if (v >= j_down)
+        r |= CTL_DOWN;
+
+    v = read_axis(AXISX);
+    if (v <= j_left)
+        r |= CTL_LEFT;
+    if (v >= j_right)
+        r |= CTL_RIGHT;
+
+    return r;
+}
diff --git a/src/joy.h b/src/joy.h
new file mode 100644
index 0000000..f510c2a
--- /dev/null
+++ b/src/joy.h
@@ -0,0 +1,10 @@
+#ifndef _JOY_H
+#define _JOY_H
+
+/* it also calibrates */
+uint8_t joy_detect();
+
+/* returns the bits specified in control.h */
+uint8_t joy_read();
+
+#endif /* _JOY_H */
diff --git a/src/main.c b/src/main.c
index 5cdcb1b..3a1aca6 100644
--- a/src/main.c
+++ b/src/main.c
@@ -7,6 +7,7 @@
 #include "timer.h"
 #include "keyb.h"
 #include "sound.h"
+#include "control.h"
 #include "vga.h"
 #include "data.h"
 #include "menu.h"
@@ -75,6 +76,9 @@ int main(int argc, char *argv[])
     keyb_init();
     atexit(free_all);
 
+    /* requires keyboard */
+    control_init();
+
     /* to update mikmod */
     timer_user_fn(sound_update);
 
diff --git a/src/player.c b/src/player.c
index 96fb283..28ad76e 100644
--- a/src/player.c
+++ b/src/player.c
@@ -1,6 +1,6 @@
 #include <stdint.h>
 
-#include "keyb.h"
+#include "control.h"
 #include "vga.h"
 #include "sound.h"
 #include "map.h"
@@ -133,6 +133,7 @@ static void player_dying()
 void player_update()
 {
     uint8_t moved = 0;
+    uint8_t ctl = CTL_NONE;
 
     ox = x;
     oy = y;
@@ -143,6 +144,8 @@ void player_update()
         return;
     }
 
+    ctl = control_read();
+
     if (invuln)
         invuln--;
 
@@ -158,7 +161,7 @@ void player_update()
         moved = 1;
     }
 
-    if (keys[KEY_UP])
+    if (ctl & CTL_FIRE1)
     {
         if ((gravity == GRAVITY_OFF || momentum) && !jump)
         {
@@ -172,7 +175,7 @@ void player_update()
     else
         jump = 0;
 
-    if (keys[KEY_RIGHT] && !keys[KEY_LEFT])
+    if (ctl & CTL_RIGHT && !(ctl & CTL_LEFT))
     {
         moved = 1;
         dir = DIR_RIGHT;
@@ -192,7 +195,7 @@ void player_update()
         }
     }
 
-    if (keys[KEY_LEFT] && !keys[KEY_RIGHT])
+    if (ctl & CTL_LEFT && !(ctl & CTL_RIGHT))
     {
         moved = 1;
         dir = DIR_LEFT;