Start implementing mbc1

include/gb.h

@@ -24,6 +24,9 @@ GBTimers *gb_timers_open(RIO *io);
 void gb_timers_close(RIO *io, GBTimers *timers);
 void gb_timers_update(GBTimers *timers, ut32 cycles);
 
+int gb_mbc1_open(RIO *io, char *path);
+
 extern RIOPlugin r_io_plugin_gb_timers;
+extern RIOPlugin r_io_plugin_gb_mbc1;
 
 #endif

io/mbc1.c

@@ -0,0 +1,137 @@
+#include <stdio.h>
+#include <gb.h>
+#include <r_io.h>
+#include <r_util.h>
+
+typedef struct gb_mbc1_data {
+	RIO *io;
+	ut32 *rombank_to_io_map;
+	ut32 *rambank_to_io_map;
+	ut64 seek;
+	ut32 size;
+	int file_fd;
+	int mem_fd;
+	ut8 n_rombanks;
+	ut8 n_rambanks;
+	ut8 rombank_mask;
+	ut8 rombank;
+	union {
+		ut8 high_rombank;
+		ut8 rambank;
+	};
+	bool ram_enable;
+	bool small_ram;
+} MBC1;
+
+ut8 mbc1_mask[] = { 0x1, 0x3, 0x7, 0xf, 0x1f, 0x1f, 0x1f };
+
+static RIODesc *__open(RIO *io, const char *pathname, int rw, int mode) {
+	if (!r_str_startswith (pathname, "gb_mbc1://")) {
+		return NULL;
+	}
+	if (!r_file_exists (&pathname[10]) || !r_file_is_regular (&pathname[10])) {
+		return NULL;
+	}
+	RIODesc *desc = r_io_desc_open (io, &pathname[10], R_PERM_R, 0);
+	if (!desc) {
+		return NULL;
+	}
+	ut8 mbc_info[3] = {0xfb, 0xff, 0xff};
+	r_io_desc_read_at (desc, 0x147, mbc_info, 3);
+	r_io_desc_close (desc);
+	if (R_UNLIKELY (!mbc_info[0] || (mbc_info[0] > 3) ||
+		(mbc_info[1] > 6) || (mbc_info[2] > 2))) {
+		//not a mbc1 game
+		return NULL;
+	}
+	MBC1 *mbc = R_NEW0 (MBC1);
+	if (!mbc) {
+		return NULL;
+	}
+	mbc->n_rombanks = 0x1 << (mbc_info[1] + 1);
+	mbc->rombank_to_io_map = R_NEWS0 (ut32, mbc->n_rombanks);
+	if (!mbc->rombank_to_io_map) {
+		free (mbc);
+		return NULL;
+	}
+	mbc->rombank_mask = mbc1_mask[mbc_info[1]];
+	if (mbc_info[0] != 1) {
+		switch (mbc_info[2]) {
+		case 0x1:
+			mbc->small_ram = true;
+		case 0x3:
+			mbc->n_rambanks = 4;
+			break;
+		case 0x2:
+			mbc->n_rambanks = 1;
+			break;
+		}
+		mbc->rambank_to_io_map = R_NEWS0 (ut32, mbc->n_rambanks);
+		if (!mbc->rambank_to_io_map) {
+			free (mbc->rombank_to_io_map);
+			free (mbc);
+			return NULL;
+		}
+	}
+	mbc->io = r_io_new ();
+	if (!mbc->io) {
+		free (mbc->rombank_to_io_map);
+		free (mbc->rambank_to_io_map);
+		free (mbc);
+		return NULL;
+	}
+	mbc->file_fd = r_io_fd_open (mbc->io, &pathname[10], R_PERM_R, 0);
+	{
+		char *malloc_uri = r_str_newf ("malloc://0x%"PFMT64x, 
+			mbc->small_ram? 0x800: (0x2000 * mbc->n_rambanks));
+		mbc->mem_fd = r_io_fd_open (mbc->io, malloc_uri, R_PERM_RW, 0);
+		free (malloc_uri);
+	}
+	if ((mbc->file_fd < 0) || (mbc->mem_fd < 0)) {
+		goto fail;
+	}
+	RIOMap *map = r_io_map_add (mbc->io, mbc->file_fd, R_PERM_R, 0ULL, 0ULL, 0x4000);
+	if (!map) {
+		goto fail;
+	}
+	mbc->rombank_to_io_map[0] = map->id;
+	ut32 i;
+	for (i = 1; i < mbc->n_rombanks; i++) {
+		map = r_io_map_add_bottom (mbc->io, mbc->file_fd, R_PERM_R,
+			0x4000 * i, 0x4000, 0x4000);
+		if (!map) {
+			goto fail;
+		}
+		mbc->rombank_to_io_map[i] = map->id;
+	}
+	if (mbc->small_ram) {
+		for (i = 0; i < 4; i++) {
+			map = r_io_map_add (mbc->io, mbc->mem_fd, R_PERM_RW,
+				0ULL, 0xa000 + 0x800 * i, 0x800);
+			if (!map) {
+				goto fail;
+			}
+			mbc->rambank_to_io_map[i] = map->id;
+		}
+	} else {
+		for (i = 0; i < 4; i++) {
+			map = r_io_map_add_bottom (mbc->io, mbc->mem_fd, R_PERM_RW,
+				0x2000 * i, 0xa000, 0x2000);
+			if (!map) {
+				goto fail;
+			}
+			mbc->rambank_to_io_map[i] = map->id;
+		}
+	}
+	mbc->rombank = 1;
+	mbc->io->cache.mode = 0;
+	desc = r_io_desc_new (io, &r_io_plugin_gb_mbc1, pathname,
+		R_PERM_RWX, mode, mbc);
+	return desc;
+fail:
+	r_io_free (mbc->io);
+	free (mbc->rombank_to_io_map);
+	free (mbc->rambank_to_io_map);
+	free (mbc);
+	return NULL;
+}