From 2cdf5ca5b03757e7ac1974f47ec0544cdf5a6d7e Mon Sep 17 00:00:00 2001
From: Thomas Martitz <thomas.martitz@student.htw-berlin.de>
Date: Fri, 9 Oct 2009 17:40:42 +0200
Subject: [PATCH] Convert chopper to do floating point math, allowing for more
 flexible game speeds in the future.

---
 apps/plugin.h          |  1 +
 apps/plugins/chopper.c | 57 +++++++++++++++++++++++++++++++-------------------
 2 files changed, 37 insertions(+), 21 deletions(-)

diff --git a/apps/plugin.h b/apps/plugin.h
index b06010437..2d8df6add 100644
--- a/apps/plugin.h
+++ b/apps/plugin.h
@@ -94,6 +94,7 @@ void* plugin_get_buffer(size_t *buffer_size);
 #include "ata_idle_notify.h"
 #include "settings_list.h"
 #include "timefuncs.h"
+#include "fixedpoint.h"
 
 #ifdef HAVE_ALBUMART
 #include "albumart.h"
diff --git a/apps/plugins/chopper.c b/apps/plugins/chopper.c
index 5c4af3b11..76e1083a8 100644
--- a/apps/plugins/chopper.c
+++ b/apps/plugins/chopper.c
@@ -186,16 +186,31 @@ static inline int SCALE(int x)
 /* in 10 milisecond (ticks) */
 #define CYCLETIME ((CYCLES*HZ)/1000)
 
+
+ /* some fixed-point math for speed calculation
+  * based on brickmania after r22882 */
+#define FRAC_BITS           8
+#define TO_FIXED(x)         ((x)<<FRAC_BITS)
+#define FIXED_MUL(x, y)     fp_mul(x,y,FRAC_BITS)
+#define FIXED_DIV(x, y)     fp_div(x,y,FRAC_BITS)
+#define TO_INT(x)           ((x)>>FRAC_BITS)
+
+
 /*Chopper's local variables to track the terrain position etc*/
 static int chopCounter;
 static int iRotorOffset;
 static int iScreenX;
 static int iScreenY;
-static int iPlayerPosX;
-static int iPlayerPosY;
-static int iCameraPosX;
-static int iPlayerSpeedX;
-static int iPlayerSpeedY;
+static int fPlayerPosX;
+#define iPlayerPosX (TO_INT(fPlayerPosX))
+static int fPlayerPosY;
+#define iPlayerPosY (TO_INT(fPlayerPosY))
+static int fCameraPosX;
+#define iCameraPosX (TO_INT(fCameraPosX))
+static unsigned fPlayerSpeedX;
+#define iPlayerSpeedX (TO_INT(fPlayerSpeedX))
+static unsigned fPlayerSpeedY;
+#define iPlayerSpeedY (TO_INT(fPlayerSpeedY))
 static int iLastBlockPlacedPosX;
 static int iGravityTimerCountdown;
 static int iPlayerAlive;
@@ -378,7 +393,7 @@ int chopUpdateTerrainRecycling(struct CTerrain *ter)
             iNewNodePos = ter->iLastNodePlacedPosX + 50;
             g = iScreenY - 10;
 
-            v = 3*iPlayerSpeedX;
+            v = TO_INT(fPlayerSpeedX*3);
             if(v>50)
                 v=50;
             if(iLevelMode == LEVEL_MODE_STEEP)
@@ -489,7 +504,7 @@ static void chopAddParticle(int x,int y,int sx,int sy)
 static void chopGenerateBlockIfNeeded(void)
 {
     int i=0;
-    int DistSpeedX = iPlayerSpeedX * 5;
+    int DistSpeedX = TO_INT(fPlayerSpeedX * 5);
     if(DistSpeedX<200) DistSpeedX = 200;
 
     while(i < NUMBER_OF_BLOCKS)
@@ -857,7 +872,7 @@ static int chopGameLoop(void)
                    )
                     bdelay = -2;
                 if (bdelay == 0)
-                    iPlayerSpeedY = -3;
+                    fPlayerSpeedY = TO_FIXED(-3);
                 break;
 
             default:
@@ -868,7 +883,7 @@ static int chopGameLoop(void)
                    )
                     bdelay = 3;
                 if (bdelay == 0)
-                    iPlayerSpeedY = 4;
+                    fPlayerSpeedY = TO_FIXED(4);
 
                 if (rb->default_event_handler(move_button) == SYS_USB_CONNECTED)
                     return PLUGIN_USB_CONNECTED;
@@ -877,21 +892,21 @@ static int chopGameLoop(void)
         last_button = move_button;
 
         if (bdelay < 0) {
-            iPlayerSpeedY = bdelay;
+            fPlayerSpeedY = TO_FIXED(bdelay);
             bdelay++;
         } else if (bdelay > 0) {
-            iPlayerSpeedY = bdelay;
+            fPlayerSpeedY = TO_FIXED(bdelay);
             bdelay--;
         }
 
-        iCameraPosX = iPlayerPosX - 25;
-        iPlayerPosX += iPlayerSpeedX;
-        iPlayerPosY += iPlayerSpeedY;
+        fCameraPosX = fPlayerPosX - TO_FIXED(25);
+        fPlayerPosX += fPlayerSpeedX;
+        fPlayerPosY += fPlayerSpeedY;
 
         chopCounter++;
         /* increase speed as we go along */
         if (chopCounter == 100){
-            iPlayerSpeedX++;
+            fPlayerSpeedX += TO_FIXED(1);
             chopCounter=0;
         }
 
@@ -1003,14 +1018,14 @@ void chopper_load(bool newgame)
         score = 0;
     }
     iRotorOffset = 0;
-    iPlayerPosX = 60;
-    iPlayerPosY = (iScreenY * 4) / 10;
+    fPlayerPosX = TO_FIXED(60);
+    fPlayerPosY = TO_FIXED(iScreenY * 4) / 10;
     iLastBlockPlacedPosX = 0;
     iGravityTimerCountdown = 2;
     chopCounter = 0;
-    iPlayerSpeedX = 3;
-    iPlayerSpeedY = 0;
-    iCameraPosX = 30;
+    fPlayerSpeedX = TO_FIXED(3);
+    fPlayerSpeedY = TO_FIXED(0);
+    fCameraPosX = TO_FIXED(30);
 
     for (i=0; i < NUMBER_OF_PARTICLES; i++)
         mParticles[i].bIsActive = 0;
@@ -1030,7 +1045,7 @@ void chopper_load(bool newgame)
 
     if (iLevelMode == LEVEL_MODE_NORMAL)
         /* make it a bit more exciting, cause it's easy terrain... */
-        iPlayerSpeedX *= 2;
+        fPlayerSpeedX *= 2;
 }
 
 /* this is the plugin entry point */
-- 
2.11.4.GIT