add directional characters display

src/sections/timer_ghost.asm

@@ -0,0 +1,99 @@
+/*  Timer comparison / update
+    r1, r2: tick duration high, low [IN]
+    r3, r4: next tick high, low
+    r5, r6: tick after this one high, low
+    r7, r8: now high, low [IN]
+    r9: pointer
+*/
+add r9, zr, ptr.timer_ghost_next_tick_high
+load_32 r3, [r9]
+add r9, zr, ptr.timer_ghost_next_tick_low
+load_32 r4, [r9]
+
+cmp r7, r3
+jb timer_ghost.end
+ja timer_ghost.trigger
+cmp r8, r4
+jb timer_ghost.end
+
+pub timer_ghost.trigger:
+; udate next_tick
+call u64.add
+add r9, zr, ptr.timer_ghost_next_tick_high
+store_32 [r9], r5
+add r9, zr, ptr.timer_ghost_next_tick_low
+store_32 [r9], r6
+
+
+/*  Movement
+    r1, r2: x, y
+    r3: rotation
+    r4: direction / sprite id
+    r5, r6: increments x, y
+    r7, r8: [RESERVED]
+    r9: pointer
+    r10: tile content
+    r13: tile address
+*/
+add r9, zr, ptr.state_ghost
+load_8 r1, [r9]
+add r9, r9, 1
+load_8 r2, [r9]
+add r9, r9, 1
+load_8 r4, [r9]
+
+call drawing.clear_tile
+
+mov r5, 0
+mov r6, 0
+
+lsl r9, r4, 3 ; 2 * instruction size = 8
+add r9, r9, timer_ghost.direction_jump_table
+jmp r9
+
+pub timer_ghost.direction_jump_table:
+; direction_up
+sub r6, r6, 1
+jmp timer_ghost.move
+; direction_right
+add r5, r5, 1
+jmp timer_ghost.move
+; direction_down
+add r6, r6, 1
+jmp timer_ghost.move
+; direction_left
+sub r5, r5, 1
+;jmp timer_ghost.move
+
+pub timer_ghost.move:
+add r1, r1, r5
+add r2, r2, r6
+add r9, zr, ptr.state_ghost
+store_8 [r9], r1
+add r9, r9, 1
+store_8 [r9], r2
+
+; draw ghost on new position
+mov r3, sprites.rotation_0
+add r4, r4, sprites.ghost
+call drawing.draw_sprite_at_map_coord
+
+/*
+    Check ahead for direction change
+*/
+add r1, r1, r5
+add r2, r2, r6
+call game.get_tile_address_from_map_coord
+
+load_8 r10, [r13]
+cmp r10, map.tiles.wall
+jne timer_ghost.end
+; increment direction
+add r9, zr, ptr.state_ghost
+add r9, r9, 2
+load_8 r4, [r9]
+add r4, r4, 1
+and r4, r4, 0b11 ; modulo 3
+store_8 [r9], r4
+
+pub timer_ghost.end: