ragb/io/joypad.c

#include <stdio.h>
#include <gb.h>
#include <r_io.h>
#include <r_util.h>
#include <SDL2/SDL.h>

static bool __check(RIO *io, const char *pathname, bool many) {
	return r_str_startswith (pathname, "gb_joypad://");
}

static RIODesc *__open(RIO *io, const char *pathname, int rw, int mode) {
	if (!r_str_startswith (pathname, "gb_joypad://")) {
		return NULL;
	}
	GBJoypad *joypad = NULL;
	sscanf (pathname, "gb_joybad://%p", &joypad);
	RIODesc *desc = r_io_desc_new (io, &r_io_plugin_gb_joypad, pathname,
		R_PERM_RWX, mode, joypad);
	return desc;
}

static ut64 __lseek(RIO* io, RIODesc *desc, ut64 offset, int whence) {
	GBJoypad *joypad = (GBJoypad *)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) | (seek << 6);
	return seek;
}

static int __read(RIO *io, RIODesc *desc, ut8 *buf, int len) {
	GBJoypad *joypad = (GBJoypad *)desc->data;
	if (!len || (joypad->odata & 0x40)) {
		return 0;
	}
	joypad->data = buf[0] & 0xf;
	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 & 0x40)) {
		return 0;
	}
	joypad->odata |= 0x40;
	joypad->data = (buf[0] & 0x30) | (joypad->data & 0xf);
	return 1;
}

static bool __close(RIODesc *desc) {
	return true;
}

RIOPlugin r_io_plugin_gb_joypad = {
	.meta = {
		.name = "gb_joypad",
		.desc = "gb_joypad",
		.license = "LGPL",
	},
	.uris = "gb_joypad://",
	.open = __open,
	.close = __close,
	.read = __read,
	.check = __check,
	.seek = __lseek,
	.write = __write,
};

GBJoypad *gb_joypad_open (RIO *io) {
	GBJoypad *joypad = R_NEW0 (GBJoypad);
	if (!joypad) {
		return NULL;
	}
	char uri[64];
	memset (uri, 0x00, sizeof (char) * 64);
	sprintf (uri, "gb_joypad://%p", joypad);
	RIODesc *desc = r_io_desc_open_plugin (io, &r_io_plugin_gb_joypad,
		uri, R_PERM_RWX, 0);
	if (!desc) {
		free (joypad);
		return NULL;
	}
	joypad->fd = desc->fd;
	const ut8 *keys = SDL_GetKeyboardState (NULL);
	memcpy (&joypad->keys, &keys, sizeof (ut8 *));
	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)) {	//buttons
		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);
}