diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..80f93b0
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+*.o
+out
\ No newline at end of file
diff --git a/.vscode/c_cpp_properties.json b/.vscode/c_cpp_properties.json
index 3e904f3..7923a40 100644
--- a/.vscode/c_cpp_properties.json
+++ b/.vscode/c_cpp_properties.json
@@ -3,7 +3,6 @@
         {
             "name": "Linux",
             "compilerPath": "${DEVKITPPC}/bin/powerpc-eabi-cpp",
-            "cppStandard": "c++11",
             "includePath": [
                 "${workspaceFolder}/include/**",
                 "${DEVKITPPC}/include/**",
@@ -15,7 +14,12 @@
             "browse": {
                 "limitSymbolsToIncludedHeaders": true,
                 "databaseFilename": ""
-            }
+            },
+            "cStandard": "c99",
+            "configurationProvider": "ms-vscode.makefile-tools",
+            "defines": [
+                "VERSION=2"
+            ]
         }
     ],
     "version": 4
diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..d68a79f
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,9 @@
+{
+    "files.associations": {
+        "*.h": "c",
+        "*.c": "c"
+    },
+    "editor.autoIndent": "full",
+    "editor.tabSize": 2,
+    "editor.formatOnSave": true
+}
\ No newline at end of file
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..111481b
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,52 @@
+CC := powerpc-eabi-gcc
+CFLAGS := -D VERSION=${VERSION} -Os -I. -Wa,-mregnames,-mgekko -Wall -fno-asynchronous-unwind-tables -fno-unwind-tables
+
+AS := powerpc-eabi-as
+ASFLAGS := -mregnames -mgekko
+
+OD := powerpc-eabi-objdump
+ODFLAGS := -EB -D -b binary -m powerpc:750 -M gekko --full-content
+
+LD := powerpc-eabi-ld
+
+OBJCOPY := powerpc-eabi-objcopy
+PYTHON := python3
+
+SRC_DIR := source
+INC_DIR := include
+OUT_DIR := out
+OBJ_DIR := obj
+
+LD_FILE := sms.ld
+OUT_MAP := main.map
+
+OUT_MAIN := main.out
+OUT_BIN := main.bin
+OUT_ASM := main.asm
+
+SRC_FILES := $(wildcard source/*.c)
+OBJ_FILES := $(SRC_FILES:.c=.o)
+
+OBJS := main.o card.o
+blockCount := 7
+
+all: $(OUT_DIR)/$(OUT_BIN) $(OUT_DIR)/$(OUT_ASM)
+
+$(OUT_DIR)/$(OUT_ASM): $(OUT_DIR)/$(OUT_BIN)
+	$(OD) $(ODFLAGS) $(OUT_DIR)/${OUT_BIN} > $(OUT_DIR)/$(OUT_ASM)
+
+$(OUT_DIR)/$(OUT_BIN): $(OUT_DIR)/$(OUT_MAIN)
+	$(OBJCOPY) -O binary $< $@
+
+$(OUT_DIR)/$(OUT_MAIN): $(OBJ_FILES) $(LD_FILE) $(OUT_DIR)
+	$(LD) -o $@ -T $(LD_FILE) -Map $(OUT_DIR)/$(OUT_MAP) -r $(OBJ_FILES)
+
+$(OBJ_FILES): $(SRC_FILES)
+	$(CC) $(CFLAGS) -I $(INC_DIR) -o $@ -c $(@:.o=.c)
+
+$(OUT_DIR):
+	mkdir -p $@
+
+.PHONY: clean
+clean:
+	$(RM) -rv $(OUT_DIR) $(OBJ_FILES)
\ No newline at end of file
diff --git a/ReadFile-C2.s b/ReadFile-C2.s
deleted file mode 100644
index 40764f5..0000000
--- a/ReadFile-C2.s
+++ /dev/null
@@ -1,80 +0,0 @@
-	.file	"ReadFile.c"
-	.machine ppc
-	.section	".text"
-	.globl onReadOptionBlock
-	.type	onReadOptionBlock, @function
-onReadOptionBlock:
-.LFB0:
-	stwu 1,-32(1)
-	#mflr 0
-	stmw 27,12(1)
-	lis 29,0x817f
-	ori 29,29,0xe800
-	lis 28,0xabcd
-	lwz 9,0(29)
-	ori 28,28,0x1234
-	#stw 0,36(1)
-	mr 30,3
-	cmpw 0,9,28
-	mr 31,4
-	beq- 0,.L3
-	lis 9,mount_@ha
-	li 4,1
-	la 9,mount_@l(9)
-	mtctr 9
-	bctrl
-	cmpwi 0,3,0
-	bne- 0,.L3
-	lis 9,CARDOpen@ha
-	la 9,CARDOpen@l(9)
-	lwz 3,0(30)
-	mr 5,31
-	bl .LC0
-	.string	"gct"
-	.section	".text"
-	.align 2
-.LC0: mflr 4
-	mtctr 9
-	bctrl
-	cmpwi 0,3,0
-	bne- 0,.L3
-	lis 27,0x817f
-	lis 9,CARDRead@ha
-	la 9,CARDRead@l(9)
-	ori 27,27,0xa800
-	li 6,0
-	li 5,16384
-	mr 4,27
-	mr 3,31
-	mtctr 9
-	bctrl
-	cmpwi 0,3,0
-	bne- 0,.L5
-	lwz 9,0(27)
-	xoris 10,9,0xff2f
-	cmpwi 0,10,-16162
-	bne 0,.L5
-	lis 10,0x817f
-	ori 10,10,0xa804
-	lwz 10,0(10)
-	cmpw 0,10,9
-	bne+ 0,.L5
-	stw 28,0(29)
-.L5:
-	lis 9,CARDClose@ha
-	mr 3,31
-	la 9,CARDClose@l(9)
-	mtctr 9
-	bctrl
-.L3:
-	lis 9,open_@ha
-	mr 4,31
-	la 9,open_@l(9)
-	mr 3,30
-	mtctr 9
-	bctrl
-	lmw 27,12(1)
-	addi 1,1,32
-.LFE0:
-	.size	onReadOptionBlock, .-onReadOptionBlock
-	.ident	"GCC: (devkitPPC release 41) 12.1.0"
diff --git a/ReadFile.c b/ReadFile.c
deleted file mode 100644
index 4910aaa..0000000
--- a/ReadFile.c
+++ /dev/null
@@ -1,68 +0,0 @@
-#include <stdint.h>
-
-typedef struct {
-  char pad[20];
-} CARDFileInfo;
-typedef struct {
-  int slot;
-} TCardManager;
-
-/** For NTSC-J 1.0:
- *
- * mount_    80107b50
- * open_     801072f4
- * CARDOpen  800a3cac
- * CARDRead  800a4640
- * CARDClose 800a3e24
- *
- * onReadOptionBlock 801069f4
- */
-
-typedef int bool;
-int mount_(TCardManager *this, bool);
-int open_(TCardManager *this, CARDFileInfo*);
-int CARDOpen(int slot, const char *fileName, CARDFileInfo*);
-int CARDRead(CARDFileInfo *fileInfo, void *buf, unsigned long size, unsigned long offset);
-int CARDClose(CARDFileInfo *fileInfo);
-
-#define fileName "gct"
-#define dst ((void*)0x817FA800)
-#define size 0x4000 // 2 blocks
-#define magicAddr (dst+size)
-#define magic 0xabcd1234
-int onReadOptionBlock(TCardManager *this, CARDFileInfo *fileInfo) {
-  int rc;
-
-  // if magic is correct -> already loaded -> do not load again
-  if (*(unsigned int*)(magicAddr) == magic) goto orig;
-
-  // mount
-  if ((rc = mount_(this, 1))) goto orig;
-
-  // open file
-  if ((rc = CARDOpen(this->slot, fileName, fileInfo))) {
-    // TODO error handling
-    // if (rc == -4) // file not exists
-    goto orig;
-  }
-
-  // read file to memory
-  if ((rc = CARDRead(fileInfo, dst, size, 0))) {
-    // should not fail if (dst, size) is properly set
-  } else {
-    // everything is good => apply gecko code
-    // TODO entry
-    // ((void(*)())0x817f4000)();
-    if (*(uint32_t*)(dst) == 0x00d0c0de && *(uint32_t*)(dst+4) == 0x00d0c0de) {
-      // is gct
-      *(uint32_t*)(magicAddr) = magic; // set magic to enable gecko code
-    }
-  }
-
-  // close file
-  CARDClose(fileInfo);
-
-orig:
-  // original function call
-  return open_(this, fileInfo);
-}
diff --git a/ReadFile.ld b/ReadFile.ld
deleted file mode 100644
index 2f109f3..0000000
--- a/ReadFile.ld
+++ /dev/null
@@ -1,4 +0,0 @@
-$$ = 0;
-
-/* TCardManager::cmdLoop() */
-$C2$onReadOptionBlock = 0x801069f4;
diff --git a/example/.gitignore b/example/.gitignore
deleted file mode 100644
index 69976f7..0000000
--- a/example/.gitignore
+++ /dev/null
@@ -1,5 +0,0 @@
-*.o
-*.out
-*.bin
-*.gci
-*.map
diff --git a/example/Makefile b/example/Makefile
deleted file mode 100644
index 3ba7aec..0000000
--- a/example/Makefile
+++ /dev/null
@@ -1,31 +0,0 @@
-CC = powerpc-eabi-gcc
-AS = powerpc-eabi-as
-LD = powerpc-eabi-ld
-OBJCOPY = powerpc-eabi-objcopy
-CFLAGS = -Os -I. -Wa,-mregnames,-mgekko -Wall -fno-asynchronous-unwind-tables -fno-unwind-tables
-ASFLAGS = -mregnames -mgekko
-PYTHON = python3
-
-OBJS = _start.o gameLoop.o qfsync.o
-LDFILE = sms.ld
-MAPOUT = gci.map
-
-GCI = 01-GMSJ-gct.gci
-OBJOUT = a.out
-OBJBIN = a.bin
-blockCount = 7
-
-all: $(GCI)
-
-$(GCI): $(OBJBIN)
-	$(PYTHON) make-gci.py $(blockCount) $< $@
-
-$(OBJOUT): $(OBJS) | $(LDFILE)
-	$(LD) -o $@ -T $(LDFILE) -Map $(MAPOUT) $^
-$(OBJBIN): $(OBJOUT)
-	$(OBJCOPY) -O binary $^ $@
-
-
-.PHONY: clean
-clean:
-	rm -f *.gci*.out *.bin *.o *.map
diff --git a/example/_start.s b/example/_start.s
deleted file mode 100644
index 64a6c5e..0000000
--- a/example/_start.s
+++ /dev/null
@@ -1,38 +0,0 @@
-.include "./macros.s"
-
-.macro .rwbl src dst
-  li32 r3, \src
-  li32 r4, \dst
-  bl replace_with_bl
-.endm
-
-.globl _start
-_start: # right after gci loaded into RAM
-  mflr r11 # need to make sure r11 is not destroyed
-
-## replace original instruction @src with `bl dst`
-## TODO version
-  .rwbl 0x800f9a10, _gameLoop
-  .rwbl 0x800ecde0, _getQFSync
-
-## return
-  mtlr r11
-  blr
-
-/**
- * r3 = address of original code
- * r4 = address of practice code function
- */
-replace_with_bl:
-## bl from r3 to r4
-  sub r4, r4, r3
-  rlwinm r4, r4, 0, 6, 29
-  oris r4, r4, 0x4800
-  ori r4, r4, 0x1
-  stw r4, 0(r3)
-## invalidate cache
-  dcbst 0, r3
-  sync
-  icbi 0, r3
-  isync
-  blr
diff --git a/example/gameLoop.c b/example/gameLoop.c
deleted file mode 100644
index a7b44dd..0000000
--- a/example/gameLoop.c
+++ /dev/null
@@ -1,18 +0,0 @@
-#include <sms.h>
-
-typedef struct {
-  uint8_t qfsync : 2;
-} CodeConfig;
-extern CodeConfig config;
-
-void _gameLoop(void *gamePad) {
-  // original function
-  TMarioGamePad_read(gamePad);
-
-  // check the controller input
-  uint16_t btn = JUTGamePad_mPadStatus.button;
-  config.qfsync =
-    btn == (PRESS_B | PRESS_DL) ? 2 : // 4x
-    btn == (PRESS_B | PRESS_DR) ? 3 : // 8x
-      0; // 1x
-}
diff --git a/example/macros.s b/example/macros.s
deleted file mode 100644
index 50d0f05..0000000
--- a/example/macros.s
+++ /dev/null
@@ -1,4 +0,0 @@
-.macro li32 reg val
-  lis \reg, \val@h
-  ori \reg, \reg, \val@l
-.endm
diff --git a/example/main.c b/example/main.c
deleted file mode 100644
index 17d985d..0000000
--- a/example/main.c
+++ /dev/null
@@ -1,3 +0,0 @@
-int f(int x) {
-  return x*x;
-}
diff --git a/example/qfsync.s b/example/qfsync.s
deleted file mode 100644
index 99eacfd..0000000
--- a/example/qfsync.s
+++ /dev/null
@@ -1,8 +0,0 @@
-.globl _getQFSync
-_getQFSync:
-  lis r12, 0x8180
-  lwz r12, -0x4000(r12)
-  rlwinm. r12, r12, 2, 0x3
-  li r3, 600
-  slw r3, r3, r12
-  blr
diff --git a/example/sms.h b/example/sms.h
deleted file mode 100644
index 24db64e..0000000
--- a/example/sms.h
+++ /dev/null
@@ -1,34 +0,0 @@
-#ifndef SMS_H
-#define SMS_H
-
-#include <stdint.h>
-
-void TMarioGamePad_read(void*);
-
-typedef struct {
-  uint16_t button;
-  int8_t stickX;
-  int8_t stickY;
-  int8_t substickX;
-  int8_t substickY;
-  uint8_t triggerLeft;
-  uint8_t triggerRight;
-  uint8_t analogA;
-  uint8_t analogB;
-  int8_t err;
-} PADStatus;
-extern PADStatus JUTGamePad_mPadStatus;
-#define PRESS_START 0x1000
-#define PRESS_Y     0x0800
-#define PRESS_X     0x0400
-#define PRESS_B     0x0200
-#define PRESS_A     0x0100
-#define PRESS_L     0x0040
-#define PRESS_R     0x0020
-#define PRESS_Z     0x0010
-#define PRESS_DU    0x0008
-#define PRESS_DD    0x0004
-#define PRESS_DR    0x0002
-#define PRESS_DL    0x0001
-
-#endif
diff --git a/example/sms.ld b/example/sms.ld
deleted file mode 100644
index 73e590d..0000000
--- a/example/sms.ld
+++ /dev/null
@@ -1,14 +0,0 @@
-SECTIONS {
-  . = 0x817F0000;
-  .init : { _start.o }
-  .text : { *(.text) }
-  .rodata : { *(.rodata) }
-  .data : { *(.data) }
-  .bss : { *(.bss) }
-}
-
-/** TODO version */
-TMarioGamePad_read = 0x800fba58;
-JUTGamePad_mPadStatus = 0x80400d50;
-
-config = 0x817fc000;
diff --git a/gecko-gosub.s b/gecko-gosub.s
deleted file mode 100644
index 8dc9fdc..0000000
--- a/gecko-gosub.s
+++ /dev/null
@@ -1,10 +0,0 @@
-.set dst, 0x817fa800
-
-## backup r15 (pointer to current gecko instruction) at dst-4
-  add r0, r15, r4
-  lis r3, dst-4@ha
-  stwu r0, dst-4@l(r3)
-## update r15 = dst + 8(header) - r4(this C0 code size)
-  addi r15, r3, 4+8
-  sub r15, r15, r4
-  blr
diff --git a/gecko-jump.s b/gecko-jump.s
deleted file mode 100644
index 5e049f5..0000000
--- a/gecko-jump.s
+++ /dev/null
@@ -1,29 +0,0 @@
-.set gpApplication, 0x803e6000 # TODO version
-.set dst, 0x817fb000
-
-## TODO prevent softlock: check app state >= 4
-  lis r5, gpApplication+8@ha
-  lbz r5, gpApplication+8@l(r5)
-  cmplwi r5, 4
-  bltlr
-## r5 = 00D0C0DE
-  lis r5, 0x00D0
-  ori r5, r5, 0xC0DE
-## check if code is loaded (check header)
-  lis r3, dst@ha
-### first 00D0C0DE
-### r3 = &dst
-  lwzu r0, dst@l(r3)
-  cmplw r0, r5
-  bnelr
-### second 00D0C0DE
-  lwz r0, 4(r3)
-  cmplw r0, r5
-  bnelr
-## backup r15 (pointer to current gecko instruction) at dst-4
-  add r0, r15, r4
-  stw r0, -4(r3)
-## update r15 = dst + 8(header) - r4(this C0 code size)
-  addi r15, r3, 8
-  sub r15, r15, r4
-  blr
diff --git a/gecko-return.s b/gecko-return.s
deleted file mode 100644
index 94a0114..0000000
--- a/gecko-return.s
+++ /dev/null
@@ -1,8 +0,0 @@
-.set dst, 0x817fa800
-
-## restore r15 (pointer to current gecko instruction) from dst-4
-  lis r3, dst-4@ha
-  lwz r15, dst-4@l(r3)
-## update r15 = restored r15 - r4(this C0 code size)
-  sub r15, r15, r4
-  blr
diff --git a/include/card.h b/include/card.h
new file mode 100644
index 0000000..b34ce1d
--- /dev/null
+++ b/include/card.h
@@ -0,0 +1,11 @@
+
+
+#include "gcn.h"
+#include "sms.h"
+
+#ifndef __CARD_H__
+#define __CARD_H__
+
+bool loadCard(TCardManager *cm, CARDFileInfo *fileInfo, char *fileName, u32 *dst);
+
+#endif
\ No newline at end of file
diff --git a/include/gcn.h b/include/gcn.h
new file mode 100644
index 0000000..cc22ee2
--- /dev/null
+++ b/include/gcn.h
@@ -0,0 +1,33 @@
+#include <stdint.h>
+
+#include "typedefs.h"
+
+#ifndef __GCN_H__
+#define __GCN_H__
+
+#define CARD_SLOT_A 0
+#define CARD_SLOT_B 1
+
+#define MEM1_START 0x8000000
+#define MEM1_END 0x81800000
+
+typedef struct CARDFileInfo
+{
+  s32 chan;
+  s32 fileNo;
+
+  s32 offset;
+  s32 length;
+  u16 iBlock;
+} CARDFileInfo;
+
+// typedef void (*CARDCallback)(s32 chan, s32 result);
+
+s32 CARDOpen(s32 slot, const char *fileName, CARDFileInfo *fileInfo);
+s32 CARDRead(CARDFileInfo *fileInfo, void *addr, s32 length, s32 offset);
+s32 CARDClose(CARDFileInfo *fileInfo);
+// s32 CARDProbeEx(s32 chan, s32 *memSize, s32 *sectorSize);
+// s32 CARDMount(s32 chan, void *workArea, CARDCallback detachCallback);
+s32 CARDUnmount(s32 chan);
+
+#endif
\ No newline at end of file
diff --git a/include/sms.h b/include/sms.h
new file mode 100644
index 0000000..e42aef7
--- /dev/null
+++ b/include/sms.h
@@ -0,0 +1,26 @@
+#ifndef __SMS_H__
+#define __SMS_H__
+
+/** For NTSC-J 1.0:
+ *
+ * mount_    80107b50
+ * open_     801072f4
+ * CARDOpen  800a3cac
+ * CARDRead  800a4640
+ * CARDClose 800a3e24
+ *
+ * onReadOptionBlock 801069f4
+ */
+
+// static void *gpApplication = (void *)0x803e9700;
+// static void *gpCardManager = (void *)0x8040a2b4;
+
+typedef struct
+{
+  int slot;
+} TCardManager;
+
+int mount_(TCardManager *this, bool);
+int open_(TCardManager *this, CARDFileInfo *fileInfo);
+
+#endif
\ No newline at end of file
diff --git a/include/typedefs.h b/include/typedefs.h
new file mode 100644
index 0000000..1df7887
--- /dev/null
+++ b/include/typedefs.h
@@ -0,0 +1,15 @@
+#ifndef __TYPEDEF_H__
+#define __TYPEDEF_H__
+
+typedef int bool;
+
+typedef unsigned long long u64;
+typedef signed long long s64;
+typedef unsigned int u32;
+typedef signed int s32;
+typedef unsigned short u16;
+typedef signed short s16;
+typedef unsigned char u8;
+typedef signed char s8;
+
+#endif
\ No newline at end of file
diff --git a/example/make-gci.py b/make-gci.py
similarity index 100%
rename from example/make-gci.py
rename to make-gci.py
diff --git a/sms.ld b/sms.ld
new file mode 100644
index 0000000..4046c1f
--- /dev/null
+++ b/sms.ld
@@ -0,0 +1,14 @@
+mount_ = 0x80107b50;
+open_ = 0x801072f4;
+CARDOpen = 0x800a3cac;
+CARDRead = 0x800a4640;
+CARDClose = 0x800a3e24;
+
+SECTIONS {
+  /* . = 0x817fa000; */
+  .text : { *(.text) }
+  .rodata : { *(.rodata) }
+  .data : { *(.data) }
+  .bss : { *(.bss) }
+  .sdata : { *(.sdata) }
+}
diff --git a/source/card.c b/source/card.c
new file mode 100644
index 0000000..ba21269
--- /dev/null
+++ b/source/card.c
@@ -0,0 +1,25 @@
+#include "gcn.h"
+#include "sms.h"
+
+bool loadCard(TCardManager *cm, CARDFileInfo *fileInfo, char *fileName, u32 *dst)
+{
+  // Mount the card
+  if (!mount_(cm, 1))
+    return -1;
+
+  // Open the card
+  if (!CARDOpen(cm->slot, fileName, fileInfo))
+    return -1;
+
+  // Too many codes
+  if (fileInfo->length > (MEM1_END - (u32)dst))
+    return -1;
+
+  // Read codes into destination address
+  if (CARDRead(fileInfo, dst, fileInfo->length, 0))
+    return -1;
+
+  // Done
+  CARDClose(fileInfo);
+  return 0;
+}
diff --git a/source/main.c b/source/main.c
new file mode 100644
index 0000000..c4e2700
--- /dev/null
+++ b/source/main.c
@@ -0,0 +1,39 @@
+#include "gcn.h"
+#include "card.h"
+
+#if VERSION == 1
+#define FILENAME "GCT_GMSE01"
+#elif VERSION == 2
+#define FILENAME "GCT_GMSJ01"
+#elif VERSION == 3
+#define FILENAME "GCT_GMSP01"
+#elif VERSION == 4
+#define FILENAME "GCT_GMSJ0A"
+#endif
+
+// Memory space reserved for Gecko codes to store their state
+// data, based on the current usage
+// See: https://github.com/BitPatty/gctGenerator/blob/375ba5eb73e50894d4e765fdfddbe004e3b4949d/Readme.md#reserved-memory
+// Range: 0x817F0000 - 0x817F1000
+#define ADDR_GECKO_HEAP_START 0x817F0000
+#define ADDR_GECKO_HEAP_SIZE 0x00001000
+#define ADDR_GECKO_HEAP_END (ADDR_GECKO_HEAP_START + ADDR_GECKO_HEAP_SIZE)
+#define PTR_FLG_LOADED (bool *)ADDR_GECKO_HEAP_END
+#define GECKO_CODE_START (ADDR_GECKO_HEAP_END + sizeof(*PTR_FLG_LOADED))
+
+void loadCodes(TCardManager *cm, CARDFileInfo *fileInfo)
+{
+  *PTR_FLG_LOADED = -1;
+
+  if (loadCard(cm, fileInfo, FILENAME, (void *)GECKO_CODE_START))
+    *PTR_FLG_LOADED = 0;
+}
+
+// int onReadOptionBlock(TCardManager *this, CARDFileInfo *fileInfo)
+// {
+//   if (*PTR_FLG_LOADED)
+//     return open_(this, fileInfo);
+
+//   loadCodes(this, fileInfo);
+//   return open_(this, fileInfo);
+// }