From 7a97cd577bdcf7d56f45fc6b4a7e680f1d47033b Mon Sep 17 00:00:00 2001
From: Lukas Krickl <lukas@krickl.dev>
Date: Tue, 1 Oct 2024 17:23:52 +0200
Subject: [PATCH] input: added basci controller input subsystem

---
 src/input.s | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 src/main.s  |  1 +
 src/video.s |  7 +++++++
 src/wram.s  |  5 +++++
 4 files changed, 61 insertions(+)
 create mode 100644 src/input.s

diff --git a/src/input.s b/src/input.s
new file mode 100644
index 0000000..b14edfd
--- /dev/null
+++ b/src/input.s
@@ -0,0 +1,48 @@
+  ; poll inputs
+  ; returns:
+  ;   new inputs in [curr_inputs]
+  ;   previous inputs in [prev_inputs]
+poll_inputs:
+  ld a, [curr_inputs]
+  ld [prev_inputs], a
+
+  ld a, P1FDPAD
+  call poll_p1
+  swap a
+  ld b, a
+  
+  ld a, P1FBTN 
+  call poll_p1 
+  or a, b
+   
+  
+  ld [curr_inputs], a
+  ld a, b
+
+  ret 
+
+
+  ; poll p1 
+  ; inputs:
+  ;   a: P1 key matrix flag 
+  ; returns
+  ;   a: A0-3 -> inputs
+poll_p1:
+  ld [RP1], a
+  ; wait for values to become stable 
+  ldh a, [RP1]
+  ldh a, [RP1]
+  ldh a, [RP1]
+  ldh a, [RP1]
+  ldh a, [RP1]
+  ldh a, [RP1] ; last read counts
+  xor a, 0x0F
+  and a, 0x0F
+
+  ld d, a
+  ; reset P1F
+  ld a, P1FNONE 
+  ldh [RP1], a
+  ld a, d
+
+  ret 
diff --git a/src/main.s b/src/main.s
index 5661aed..9d751ff 100644
--- a/src/main.s
+++ b/src/main.s
@@ -30,6 +30,7 @@ main:
 #include "mem.s"
 #include "strings.s"
 #include "sys.s"
+#include "input.s"
 
 ; fill bank
 .fill 0, 0x7FFF - $
diff --git a/src/video.s b/src/video.s
index d7b97dd..b61bac0 100644
--- a/src/video.s
+++ b/src/video.s
@@ -2,19 +2,24 @@
 vblank:
   call OAMDMAFN
   
+  call poll_inputs
+
   ; test puts 
   ld hl, STR_TITLE
   ld de, SCRN0
   call puts
 
+
   ret
 
+  ; wait for next vblank
 vblank_wait:
   ld a, [RLY] 
   cp a, 144
   jp c, vblank_wait
   ret
 
+  ; turns off the lcd
 lcd_off:
   ; *never* turn off LCD without waiting 
   ; for vblank!
@@ -25,12 +30,14 @@ lcd_off:
 
   ret
 
+  ; turns on the lcd 
 lcd_on:
   ld a, LCDCF_ON | LCDCF_BGON | LCDCF_OBJON 
   ld [RLCD], a
 
   ret
 
+  ; init video system
 video_init:
   call copy_tiles
 
diff --git a/src/wram.s b/src/wram.s
index 9bf26c9..c206cc6 100644
--- a/src/wram.s
+++ b/src/wram.s
@@ -8,6 +8,11 @@ shadow_oam: .adv OBJSMAX * oamsize
 
 #define ACTORS_MAX 16
 
+  ; current frame's inputs 
+curr_inputs: .adv 1
+  ; previous frame's inputs
+prev_inputs: .adv 1
+
 ; actor type enum
 .se 1
 .de ACTOR_TYPE_PLAYER, 1
-- 
2.30.2