Added ACTOR_FLAG to set high bit on text page at enemy location

constants.s

@@ -52,6 +52,8 @@ TILE_HORZ = TILE_LEFT|TILE_RIGHT
 TILE_VERT = TILE_UP|TILE_DOWN
 DIR_MASK = $0f
 TILE_DOT = $10
+ACTOR_FLAG = $80
+ACTOR_FLAG_MASK = $7f
 CLEAR_TILE_DOT = $ef ;%11101111
 
 LEFT_TILE = TILE_DOT|TILE_RIGHT

logic.s

@@ -108,6 +108,28 @@ has_dot nop
     and #TILE_DOT
     rts
 
+clear_actor_flag nop
+    lda actor_row,x
+    tay
+    jsr mazerow
+    lda actor_col,x
+    tay
+    lda (mazeaddr),y
+    and #ACTOR_FLAG_MASK
+    sta (mazeaddr),y
+    rts
+
+set_actor_flag nop
+    lda actor_row,x
+    tay
+    jsr mazerow
+    lda actor_col,x
+    tay
+    lda (mazeaddr),y
+    ora #ACTOR_FLAG
+    sta (mazeaddr),y
+    rts
+
 
 ; # Determine the tile location given the direction of the actor's movement
 ; def get_next_tile(r, c, dir):

main.s

@@ -230,7 +230,9 @@ game_loop nop
     lda actor_active,x
     bmi ?player ; negative = end
     beq ?enemy ; zero = skip
+    jsr clear_actor_flag
     jsr move_enemy
+    jsr set_actor_flag
     jmp ?enemy
 
 ?player lda #0

platform-apple2.s

@@ -460,13 +460,14 @@ draw_to_page2 lda #$60
 ; image with tile 15 when necessary
 fastfont nop
     cmp #12
-    bne fastfont_smc
+    bne ?2
     txa
     and #1
     bne ?1
     lda #15
-    bne fastfont_smc
+    bne ?2
 ?1  lda #12
+?2  and #ACTOR_FLAG_MASK
 fastfont_smc jmp $ffff
 
 ; restore a horizontal segment from the text page to the current screen
@@ -481,13 +482,14 @@ fasttiles ldx param_col
     sta fasttiles_row_smc+1
 fasttiles_row_smc lda $ffff,x
     cmp #12
-    bne fasttiles_smc
+    bne ?2
     txa
     and #1
     bne ?1
     lda #15
-    bne fasttiles_smc
+    bne ?2
 ?1  lda #12
+?2  and #ACTOR_FLAG_MASK
 fasttiles_smc jsr $ffff
     inx
     dec param_count