Update the flea sprite as it drops. Add random routines. Thanks to John Brooks for those. Use the random routines to pick a column for the flea to drop from. Also, randomly leave behind a mushroom as it falls.

BuGS.xcodeproj/project.pbxproj

@@ -64,6 +64,7 @@
 		9D1716A42491C49300C83148 /* system601.2mg */ = {isa = PBXFileReference; lastKnownFileType = file; path = system601.2mg; sourceTree = "<group>"; };
 		9D1716A62491C49300C83148 /* tail.mk */ = {isa = PBXFileReference; lastKnownFileType = text; path = tail.mk; sourceTree = "<group>"; };
 		9D1716A92491C49300C83148 /* BuGS.xcscheme */ = {isa = PBXFileReference; lastKnownFileType = text.xml; name = BuGS.xcscheme; path = ../../BuGS.xcodeproj/xcshareddata/xcschemes/BuGS.xcscheme; sourceTree = "<group>"; };
+		9D2FF6DA24C4C79A000181E5 /* random.s */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.asm; path = random.s; sourceTree = "<group>"; };
 		9D3396F424AECB1D003222B3 /* explosions.s */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.asm; path = explosions.s; sourceTree = "<group>"; };
 		9D3396F524AECBB1003222B3 /* spiders.s */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.asm; path = spiders.s; sourceTree = "<group>"; };
 		9D3396F624AECC40003222B3 /* scorpions.s */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.asm; path = scorpions.s; sourceTree = "<group>"; };
@@ -131,6 +132,7 @@
 				9D8FFC612491CAF0005C9327 /* game.h */,
 				9DB1505024C3801100558B87 /* gameFlea.s */,
 				9D62AF3B249871A300348F45 /* colour.s */,
+				9D2FF6DA24C4C79A000181E5 /* random.s */,
 				9D3396F324AECACC003222B3 /* sprites */,
 				9D1716912491C49300C83148 /* main.rez */,
 				9D1716932491C49300C83148 /* Makefile */,

BuGS/gameFlea.s

@@ -21,7 +21,8 @@ drawFlea entry
         beq drawFlea_done
         
         ldy fleaScreenOffset
-        jsl flea1
+        ldx fleaSprite
+        jsl fleaJump
         
         ldy numDirtyGameTiles
         
@@ -78,10 +79,23 @@ drawFlea_done anop
         rtl
         
         
+fleaJump entry
+        lda fleaJumpTable,x
+        sta jumpInst+1
+        
+        lda fleaJumpTable+2,x
+        sta jumpInst+3
+        
+jumpInst jmp >flea1
+        nop
+        
+        
 updateFlea entry
         lda fleaState
-        beq updateFlea_done
-        
+        bne updateFlea_cont
+        rtl
+
+updateFlea_cont anop
         lda fleaHeightInTile
         beq updateFlea_nextTile
         dec a
@@ -94,6 +108,22 @@ updateFlea_bottomOfTile anop
         sta fleaTileOffsets+4
         lda fleaTileOffsets+2
         sta fleaTileOffsets+6
+        
+        lda fleaSpriteCounter
+        eor #$1
+        sta fleaSpriteCounter
+        bne updateFlea_nextAction
+        
+        lda fleaSprite
+        cmp #$c
+        beq updateFlea_resetSprite
+        clc
+        adc #$4
+        sta fleaSprite
+        bra updateFlea_nextAction
+        
+updateFlea_resetSprite anop
+        stz fleaSprite
         bra updateFlea_nextAction
         
 updateFlea_nextTile anop
@@ -110,6 +140,16 @@ updateFlea_nextTile anop
         lda tiles+8,x
         sta fleaTileOffsets+2
         
+        ldx fleaTileOffsets+4
+        lda tiles+4,x
+        bne updateFlea_nextAction
+        
+        jsl rand65535
+        and #$7
+        bne updateFlea_nextAction
+        lda #$10
+        sta tiles+4,x
+        
         bra updateFlea_nextAction
         
 updateFlea_bottom anop
@@ -136,7 +176,13 @@ addFlea entry
         lda #$3
         sta fleaHeightInTile
         
-        lda #$40
+        stz fleaSpriteCounter
+        
+        jsl rand25
+        asl a
+        asl a
+        asl a
+        asl a
         sta fleaTileOffsets
         sta fleaTileOffsets+4
         
@@ -161,5 +207,12 @@ fleaTileOffsets  dc i2'0'
                  dc i2'0'
                  dc i2'0'
 fleaHeightInTile dc i2'0'
+fleaSpriteCounter dc i2'0'
+fleaSprite       dc i2'0'
+
+fleaJumpTable    dc i4'flea1'
+                 dc i4'flea2'
+                 dc i4'flea3'
+                 dc i4'flea4'
 
         end

BuGS/main.c

@@ -28,6 +28,7 @@
 /* Globals */
 
 unsigned int userid;
+unsigned int randomSeed;
 
 
 /* Implementation */
@@ -53,7 +54,11 @@ int main(void)
     NewHandle(0x9000, userid, attrLocked | attrFixed | attrAddr | attrBank, (Pointer)0x011000);
     TOOLFAIL("Unable to allocate SHR screen");
     
-    srand((int)(time(NULL)));
+    randomSeed = (int)time(NULL);
+    if (randomSeed == 0)
+        randomSeed = 1;
+    srand(randomSeed);
+    randInit();
     
     initTiles();
     initNonGameTiles();

BuGS/random.s

@@ -0,0 +1,58 @@
+;
+;  random.s
+;  BuGS
+;
+;  Created by Jeremy Rand on 2020-07-19.
+;Copyright © 2020 Jeremy Rand. All rights reserved.
+;
+
+        case on
+        mcopy random.macros
+        keep random
+
+random start
+
+randInit entry
+        lda randomSeed
+        sta seed65535
+        and #$1f
+        bne randInit_store32
+        lda #$1f
+randInit_store32 anop
+        sta seed32
+        rtl
+
+
+; Returns a number from 1 to 31
+rand32  entry
+        lda seed32
+        lsr a
+        bcc skipEor32
+        eor #$0014
+skipEor32 anop
+        sta seed32
+        rtl
+        
+; returns a number from 0 to 24
+rand25  entry
+        jsl rand32
+        dec a
+        cmp #25
+        bge rand25
+        rtl
+
+
+; Returns a number from 1 to 65535
+rand65535 entry
+        lda seed65535
+        lsr a
+        bcc skipEor65535
+        eor #$b400
+skipEor65535 anop
+        sta seed65535
+        rtl
+        
+        
+seed65535 dc i2'0'
+seed32    dc i2'0'
+        end