From 22fed0fea18af5ce3b58f8c0f448851017293639 Mon Sep 17 00:00:00 2001
From: condret <condr3t@protonmail.com>
Date: Fri, 18 Oct 2024 05:09:58 +0200
Subject: [PATCH] Joypad support

---
 include/gb.h | 14 ++++++++--
 io/joypad.c  | 74 +++++++++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 82 insertions(+), 6 deletions(-)

diff --git a/include/gb.h b/include/gb.h
index 39922d1..0e63cc4 100644
--- a/include/gb.h
+++ b/include/gb.h
@@ -21,17 +21,27 @@ typedef struct gb_timers_t {
 } GBTimers;
 
 GBTimers *gb_timers_open(RIO *io);
-void gb_timers_close(RIO *io, GBTimers *timers);
 void gb_timers_update(GBTimers *timers, ut32 cycles);
+void gb_timers_close(RIO *io, GBTimers *timers);
 
 typedef struct gb_joypad_t {
 	ut8 *keys;
 	int fd;
+	ut16 up;
+	ut16 down;
+	ut16 left;
+	ut16 right;
+	ut16 a;
+	ut16 b;
+	ut16 start;
+	ut16 select;
 	ut8 data;
 	ut8 odata;
 } GBJoypad;
 
-GBJoypad *gb_joypad_open(RIO *io)
+GBJoypad *gb_joypad_open(RIO *io);
+void gb_joypad_update(GBJoypad *joypad);
+void gb_joypad_close(RIO *io, GBJoypad *joypad);
 
 //int gb_mbc1_open(RIO *io, char *path);
 
diff --git a/io/joypad.c b/io/joypad.c
index e4c3c95..477df13 100644
--- a/io/joypad.c
+++ b/io/joypad.c
@@ -19,22 +19,41 @@ static RIODesc *__open(RIO *io, const char *pathname, int rw, int mode) {
 	return desc;
 }
 
+static ut64 __lseek(RIO* io, RIODesc *desc, ut64 offset, int whence) {
+	GBJoypad *joypad = (GBTimers *)desc->data;
+	ut64 seek = (joypad->odata & 0x40) >> 6;
+	switch (whence) {
+	case R_IO_SEEK_SET:
+		seek = R_MIN (1, offset);
+		break;
+	case R_IO_SEEK_CUR:
+		seek = R_MIN (1, seek + offset);
+		break;
+	case R_IO_SEEK_END:
+		seek = 1;
+		break;
+	}
+	joypad->odata = (joypad->odata & 0x3f) | 
+	return seek;
+}
+
 static int __read(RIO *io, RIODesc *desc, ut8 *buf, int len) {
 	GBJoypad *joypad = (GBJoypad *)desc->data;
-	if (!len || (joypad->odata & 0x10)) {
+	if (!len || (joypad->odata & 0x40)) {
 		return 0;
 	}
 	joypad->data = buf[0] & 0xf;
-	joypad->odata |= 0x10;
+	joypad->odata |= 0x40;
 	return 1;
 }
 
 static int __write(RIO *io, RIODesc *desc, const ut8 *buf, int len) {
 	GBJoypad *joypad = (GBJoypad *)desc->data;
-	if (!len || (joypad->odata & 0x10)) {
+	if (!len || (joypad->odata & 0x40)) {
 		return 0;
 	}
-	joypad->odata |= 0x10;
+	joypad->odata |= 0x40;
+	joypad->data = (buf[0] & 0x30) | (joypad->data & 0xf);
 	return 1;
 }
 
@@ -73,5 +92,52 @@ GBJoypad *gb_joypad_open (RIO *io) {
 	}
 	joypad->fd = desc->fd;
 	joypad->keys = SDL_GetKeyboardState (NULL);
+	joypad->up = SDL_SCANCODE_W;
+	joypad->down = SDL_SCANCODE_S;
+	joypad->left = SDL_SCANCODE_A;
+	joypad->right = SDL_SCANCODE_D;
+	joypad->a = SDL_SCANCODE_L;
+	joypad->b = SDL_SCANCODE_K;
+	joypad->start = SDL_SCANCODE_SPACE;
+	joypad->select = SDL_SCANCODE_KP_ENTER;
 	return joypad;
 }
+
+void gb_joypad_update(GBJoypad *joypad) {
+	joypad->odata &= 0xc0;
+	joypad->odata |= joypad->data & 0x3f;
+	SDL_PumpEvents ();
+	ut8 ndata = 0;
+	if (!(joypad->data & 0x8)) {	//d-pad
+		const ut8 data = (~joypad->data) & 0xf;
+		ndata = !!joypad->keys[joypad->right];
+		ndata |= (!!joypad->keys[joypad->left]) << 1;
+		ndata |= (!!joypad->keys[joypad->up]) << 2;
+		ndata |= (!!joypad->keys[joypad->down]) << 3;
+		// on a real gameboy you cannot press up and down, or left and right at the same time
+		if ((ndata & 0x3) == 0x3) {
+			ndata = (ndata & 0xc) | (data & 0x3);
+		}
+		if ((ndata & 0xc) == 0xc) {
+			ndata = (ndata & 0x3) | (data & 0xc);
+		}
+	}
+	if (!(joypad->data & 0x10)) {
+		ndata |= !!joypad->keys[joypad->a];
+		ndata |= (!!joypad->keys[joypad->b]) << 1;
+		ndata |= (!!joypad->keys[joypad->select]) << 2;
+		ndata |= (!!joypad->keys[joypad->start]) << 3;
+	}
+	joypad->data = (joypad->data & 0x30) | (ndata ^ 0xf);
+	if (joypad->odata & ndata) {
+		//TODO: request interrupt
+	}
+}
+
+void gb_joypad_close (RIO *io, GBJoypad *joypad) {
+	if (!io || !joypad) {
+		return;
+	}
+	r_io_fd_close (io, joypad->fd);
+	free (joypad);
+}