From 933b10c882a7b72a72a184d788d8fc67e829e0d6 Mon Sep 17 00:00:00 2001
From: "Juan J. Martinez" <jjm@usebox.net>
Date: Sat, 6 May 2023 19:21:47 +0100
Subject: Will bounce the walls

---
 example.asm | 108 ++++++++++++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 95 insertions(+), 13 deletions(-)

(limited to 'example.asm')

diff --git a/example.asm b/example.asm
index cffef5e..48ee7db 100644
--- a/example.asm
+++ b/example.asm
@@ -19,30 +19,98 @@
     ; enable interrupts
     cif
 
-    ; loop filling the screen with one
-    ; colour cycling the whole palette
     ld b, 0
 loop:
-    call fill
+    call fill_screen
+    push b
+
+    ; update sprite position
+
+    ld a, >incx
+    ld x, <incx
+    ld y, [a : x]
+    inc x
+    bo
+    inc a
+    ; px
+    ld b, [a : x]
+    ; px + incx
+    add b, y
+    ; 128 - 16
+    cmp b, 112
+    bnc
+    jmp turn_x
+
+    ; new x
+    ld [a : x], b
+    jmp update_y
+
+turn_x:
+    ; update incx
+    ;  1 -> -1
+    ; -1 -> 1
+    ld a, >incx
+    ld x, <incx
+    ld y, [a : x]
+    ld b, 254
+    xor y, b
+    ld [a : x], y
+
+    ; change color
+    pop b
     inc b
     and b, 15
+    push b
+
+update_y:
+    ld a, >incy
+    ld x, <incy
+    ld y, [a : x]
+    inc x
+    bo
+    inc a
+    ; py
+    ld b, [a : x]
+    ; py + incy
+    add b, y
+    ; 128 - 16
+    cmp b, 112
+    bnc
+    jmp turn_y
+
+    ; new y
+    ld [a : x], b
+    jmp update_done
+
+turn_y:
+    ; update incy
+    ;  1 -> -1
+    ; -1 -> 1
+    ld a, >incy
+    ld x, <incy
+    ld y, [a : x]
+    ld b, 254
+    xor y, b
+    ld [a : x], y
 
+    ; change color
+    pop b
+    inc b
+    and b, 15
     push b
+
+update_done:
+
     call draw_sprite
-    pop b
 
-    ; wait 1 second
-    ld x, 60
-wait_loop:
+    ; wait 1 frame
     halt
-    dec x
-    bnz
-    jmp wait_loop
 
+    pop b
     jmp loop
 
     ; fill frame-buffer with a color in reg b
-fill:
+fill_screen:
     ld a, 0xbf
     ld x, 0
     ld y, 0x40
@@ -60,6 +128,7 @@ fill_loop:
 int_handler:
     iret
 
+    ; draw sprite getting coordinates from px, py
 draw_sprite:
     ; blitter in settings mode
     ld x, 128
@@ -73,9 +142,13 @@ draw_sprite:
     port a, x
     ld x, >sprite
     port a, x
-    ; destination (56, 56)
-    ld x, 56
+    ld y, <px
+    ld b, >px
+    ld x, [b : y]
     port a, x
+    ld y, <py
+    ld b, >py
+    ld x, [b : y]
     port a, x
     ; size 16x16
     ld x, 16
@@ -92,3 +165,12 @@ draw_sprite:
 sprite:
     .incpng "assets/icon.png"
 
+incx:
+    .db 1
+px:
+    .db 18
+incy:
+    .db 1
+py:
+    .db 64
+
-- 
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