diff --git a/.gitignore b/.gitignore
index 80f93b0..6ba2d96 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 *.o
-out
\ No newline at end of file
+out
+__pycache__
diff --git a/Makefile b/Makefile
index da996ac..d017fd5 100644
--- a/Makefile
+++ b/Makefile
@@ -1,3 +1,5 @@
+MAKE := make
+
 CC := powerpc-eabi-gcc
 CFLAGS := -O3 -I. -Wa,-mregnames,-mgekko -Wall -fno-asynchronous-unwind-tables -fno-unwind-tables -fverbose-asm -gdwarf
 
@@ -12,20 +14,28 @@ LD := powerpc-eabi-ld
 LDFLAGS := --unresolved-symbols=ignore-in-object-files --enable-non-contiguous-regions -EB --nmagic
 
 OBJCOPY := powerpc-eabi-objcopy
-OBJCOPYFLAGS := -O binary --add-gnu-debuglink=sms.ld --gap-fill 0x00 --pad-to 0x81800000
+#OBJCOPYFLAGS = -O binary $(foreach e,$(LD_FILES),--add-gnu-debuglink=$e) --gap-fill 0x00 --pad-to 0x81800000
+OBJCOPYFLAGS = -O binary $(foreach e,$(LD_FILES),--add-gnu-debuglink=$e)
+
+PY := python3
+BIN2GCT := $(PY) gecko/bin2gct.py
 
 SRC_DIR := source
 INC_DIR := include
+LD_DIR := ldscript
 OUT_DIR := out
 OBJ_DIR := obj
 
-LD_FILE := sms.ld
-OUT_MAP := main.map
+GECKO_DIR := gecko
+GECKO_OUT_DIR := out
 
+OUT_MAP := main.map
 OUT_MAIN := main.out
 OUT_BIN := main.bin
 OUT_LST := main.lst
 OUT_ASM := main.asm
+OUT_LOADER_TXT = loader.txt
+OUT_LOADER_GCT = loader.gct
 
 GMSE01 := 1
 GMSJ01 := 2
@@ -36,11 +46,13 @@ TARGET_VERSION = $($(GAME_VERSION))
 
 SRC_FILES := $(wildcard source/*.c)
 OBJ_FILES := $(SRC_FILES:.c=.o)
+LD_FILES := $(LD_DIR)/sms.ld $(LD_DIR)/$(GAME_VERSION).ld
+GECKO_FILE_LOADER := $(GECKO_DIR)/$(GECKO_OUT_DIR)/gecko-gosub.bin
+GECKO_FILES := $(GECKO_FILE_LOADER) $(GECKO_DIR)/$(GECKO_OUT_DIR)/gecko-return.bin
 
 OBJS := main.o card.o
-blockCount := 7
 
-all: $(OUT_DIR)/$(OUT_BIN) $(OUT_DIR)/$(OUT_LST) $(OUT_DIR)/$(OUT_ASM)
+all: $(OUT_DIR)/$(OUT_BIN) $(OUT_DIR)/$(OUT_LST) $(OUT_DIR)/$(OUT_ASM) $(OUT_DIR)/$(OUT_LOADER_TXT)
 
 $(OUT_DIR)/$(OUT_ASM): $(OUT_DIR)/$(OUT_BIN)
 	$(OD) $(ODASMFLAGS) $(OUT_DIR)/$(OUT_BIN) | grep -Pe "^\t(?!Address)" | sed 's/^\t//'  > $(OUT_DIR)/$(OUT_ASM)
@@ -51,12 +63,17 @@ $(OUT_DIR)/$(OUT_LST): $(OUT_DIR)/$(OUT_BIN)
 $(OUT_DIR)/$(OUT_BIN): $(OUT_DIR)/$(OUT_MAIN)
 	$(OBJCOPY) $(OBJCOPYFLAGS) $< $@
 
-$(OUT_DIR)/$(OUT_MAIN): $(OBJ_FILES) $(LD_FILE) $(OUT_DIR)
-	$(LD) $(LDFLAGS) -o $@ -T $(LD_FILE) -Map $(OUT_DIR)/$(OUT_MAP) $(OBJ_FILES)
+$(OUT_DIR)/$(OUT_MAIN): check-set-GAME_VERSION $(OBJ_FILES) $(LD_FILES) $(OUT_DIR)
+	$(LD) $(LDFLAGS) -o $@ -T $(LD_FILES) -Map $(OUT_DIR)/$(OUT_MAP) $(OBJ_FILES)
 
-$(OBJ_FILES): $(SRC_FILES) check-set-TARGET_VERSION
+$(OBJ_FILES): $(SRC_FILES) check-set-GAME_VERSION #check-set-TARGET_VERSION
 	$(CC) $(CFLAGS) -D VERSION=$(TARGET_VERSION) -I $(INC_DIR) -o $@ -c $(@:.o=.c)
 
+$(OUT_DIR)/$(OUT_LOADER_TXT): $(OUT_DIR)/$(OUT_BIN) $(OUT_DIR)/$(OUT_MAP) $(GECKO_FILE_LOADER) | $(OUT_DIR)
+	$(BIN2GCT) hook:$(OUT_DIR)/$(OUT_MAP):$(OUT_DIR)/$(OUT_BIN):onReadOptionBlock C0:$(GECKO_FILE_LOADER) > $@
+$(GECKO_FILES):
+	$(MAKE) -C$(GECKO_DIR) OUT_DIR=$(GECKO_OUT_DIR) $(patsubst $(GECKO_DIR)/%,%,$@)
+
 $(OUT_DIR):
 	mkdir -p $@
 
@@ -68,4 +85,5 @@ check-set-%:
 
 .PHONY: clean
 clean:
-	$(RM) -rv $(OUT_DIR) $(OBJ_FILES)
\ No newline at end of file
+	$(RM) -rv $(OUT_DIR) $(OBJ_FILES)
+	$(MAKE) -C$(GECKO_DIR) $@
diff --git a/build-all.sh b/build-all.sh
index ab7f4b2..0c6ab66 100755
--- a/build-all.sh
+++ b/build-all.sh
@@ -1,6 +1,6 @@
 #!/bin/bash
 
-make GAME_VERSION=GMSE01 OUT_DIR=out/gmse01
-make GAME_VERSION=GMSJ01 OUT_DIR=out/gmsj01
-make GAME_VERSION=GMSP01 OUT_DIR=out/gmsp01
-make GAME_VERSION=GMSJ0A OUT_DIR=out/gmsj0a
\ No newline at end of file
+make GAME_VERSION=GMSE01 OUT_DIR=out/GMSE01
+make GAME_VERSION=GMSJ01 OUT_DIR=out/GMSJ01
+make GAME_VERSION=GMSP01 OUT_DIR=out/GMSP01
+make GAME_VERSION=GMSJ0A OUT_DIR=out/GMSJ0A
diff --git a/gecko/GeckoFactory.py b/gecko/GeckoFactory.py
new file mode 100644
index 0000000..3782a69
--- /dev/null
+++ b/gecko/GeckoFactory.py
@@ -0,0 +1,27 @@
+def int2bytes(x):
+  return x.to_bytes(4, 'big')
+
+def makeC0(arg):
+  ## read bin file
+  with open(arg, 'rb') as f:
+    raw = f.read()
+  ## .align 2
+  if len(raw) % 4:
+    raw += b'\x00'*(4 - len(raw)%4)
+  ## add `blr` to align 3
+  if len(raw) % 8:
+    raw += b'\x4E\x80\x00\x20'
+  ## add C0 header
+  raw = b'\xC0\x00\x00\x00' + int2bytes(len(raw) >> 3) + raw
+  return raw
+
+def make06(dst, fn):
+  ## read bin file
+  with open(fn, 'rb') as f:
+    raw = f.read()
+  size06 = len(raw)
+  ## .align 3
+  if len(raw) % 8:
+    raw += b'\x00'*(8 - len(raw)%8)
+  ## header
+  return int2bytes(0x06<<24 | dst & 0x1ffffff) + int2bytes(size06) + raw
diff --git a/gecko/Makefile b/gecko/Makefile
new file mode 100644
index 0000000..595eca2
--- /dev/null
+++ b/gecko/Makefile
@@ -0,0 +1,40 @@
+AS := powerpc-eabi-as
+ASFLAGS := -mregnames -mgekko
+
+LD := powerpc-eabi-ld
+LDFLAGS := --unresolved-symbols=ignore-in-object-files --enable-non-contiguous-regions -EB --nmagic
+
+OBJCOPY := powerpc-eabi-objcopy
+OBJCOPYFLAGS = -O binary
+
+PY := python3
+BIN2GCT := $(PY) bin2gct.py
+
+LD_DIR := ../ldscript
+LD_FILES := $(LD_DIR)/sms.ld
+
+SRC_DIR := code
+OUT_DIR := out
+
+SRC_FILES := $(wildcard $(SRC_DIR)/*.s)
+OBJ_FILES := $(SRC_FILES:.s=.o)
+LDO_FILES := $(OBJ_FILES:.o=.ld.o)
+OUT_TXT := $(patsubst $(SRC_DIR)/%.s,$(OUT_DIR)/%.txt,$(SRC_FILES))
+
+all: $(OUT_TXT)
+
+%.o: %.s
+	$(AS) $(ASFLAGS) -o $@ -c $^
+%.ld.o: %.o
+	$(LD) $(LDFLAGS) -o $@ -T $(LD_FILES) $^
+$(OUT_DIR)/%.bin: $(SRC_DIR)/%.ld.o | $(OUT_DIR)
+	$(OBJCOPY) $(OBJCOPYFLAGS) $< $@
+$(OUT_DIR)/%.txt: $(OUT_DIR)/%.bin | $(OUT_DIR)
+	$(BIN2GCT) C0:$^ > $@
+
+$(OUT_DIR):
+	mkdir -p $@
+
+.PHONY: clean
+clean:
+	$(RM) -rv $(OUT_DIR) $(OBJ_FILES) $(LDO_FILES)
diff --git a/gecko/bin2gct.py b/gecko/bin2gct.py
new file mode 100644
index 0000000..c3ffd01
--- /dev/null
+++ b/gecko/bin2gct.py
@@ -0,0 +1,101 @@
+import sys
+import os
+from GeckoFactory import int2bytes, make06, makeC0
+
+validArguments = '''
+  C0:{input.bin}
+  hook:{input.map}:{input.bin}:{symbol=fromAddr}...
+'''[1:-1]
+
+def exitInvalidSyntax(arg):
+  print('Invalid argument `%s`\nValid arguments:\n%s'%(arg, validArguments))
+  sys.exit(1)
+def exitMessage(msg):
+  print(msg)
+  sys.exit(1)
+
+def printCode(raw, file=sys.stdout):
+  assert len(raw)%8 == 0, \
+      f'Expect code with length of multiple of 8, got {len(raw)}'
+  for i in range(0, len(raw), 8):
+    print(raw[i:i+4].hex().upper(), raw[i+4:i+8].hex().upper(), file=file)
+
+def loadHookDB(fn):
+  import csv
+  with open(fn) as f:
+    reader = csv.DictReader(f)
+    return {
+      row['symbol']: row
+      for row in reader
+    }
+
+def parseMap(fn):
+  with open(fn) as f:
+    sections = {}
+    symbols = {}
+    for line in f:
+      args = line.split()
+      try:
+        if line.startswith('.') and len(args) == 3:
+          # .text 0x00000000817fe800 0x1dc
+          sections[args[0]] = int(args[1], 16)
+        elif len(args) == 2:
+          # 0x00000000817fe800 loadCard
+          symbols[args[1]] = int(args[0], 16)
+      except: pass
+  return sections, symbols
+
+if __name__ == '__main__':
+  if len(sys.argv) < 2:
+    print('Usage: %s {ARG}...\nARG:\n%s'%(sys.argv[0], validArguments))
+    sys.exit(1)
+
+  __dirname = os.path.dirname(__file__)
+  hookDB = loadHookDB(os.path.join(__dirname, './hook.csv'))
+
+  code = b''
+  for arg0 in sys.argv[1:]:
+    toks = arg0.split(':', 1)
+    if len(toks) != 2: exitInvalidSyntax(arg)
+    ct, arg = toks
+    if ct == 'C0':
+      code += makeC0(arg)
+    elif ct == 'hook':
+      args = arg.split(':')
+      if len(args) < 3: exitInvalidSyntax(arg)
+      fnMap, fnBin, *entries = args
+      ## parse map file
+      sections, symbols = parseMap(fnMap)
+      assert '.text' in sections, f'.text section does not exists in file {fnMap}'
+      dst = sections['.text']
+      ## 06
+      code += make06(dst, fnBin)
+      ## 04 entries
+      for entry in entries:
+        toks = entry.split('=')
+        name = toks[0]
+        if len(toks) == 1:
+          version = os.environ.get('GAME_VERSION')
+          if not version: exitMessage('Environment variable `GAME_VERSION` is not set. Please set the GAME_VERSION environment variable or specify the address manually')
+          if name not in hookDB: exitMessage('The address for symbol `%s` is unknown. Please specify it manually\nSyntax: {name}={addr}'%name)
+          hook = hookDB[name]
+          if version not in hook: exitMessage(f'Invalid GAME_VERSION: {version}')
+          addr0 = int(hook[version], 16)
+        elif len(toks) == 2:
+          try:
+            addr0 = int(toks[1], 16)
+          except ValueError:
+            exitInvalidSyntax(arg)
+        else:
+          exitInvalidSyntax(arg)
+        assert name in symbols, f'symbol `{name}` does not exists in file {fnMap}'
+        addr1 = symbols[name]
+        dis = addr1 - addr0
+        assert -0x200_0000 <= dis < 0x200_0000, 'too far to branch from %s(%08X) to %08X'%(name, addr0, addr1)
+        ## make 04
+        code += int2bytes(0x0400_0000 | addr0 & 0x1ff_ffff)
+        code += int2bytes(0x4800_0001 | dis   & 0x3ff_ffff)
+    else:
+      exitInvalidSyntax(arg)
+
+  printCode(code)
diff --git a/gecko/code/gecko-gosub.s b/gecko/code/gecko-gosub.s
new file mode 100644
index 0000000..e095477
--- /dev/null
+++ b/gecko/code/gecko-gosub.s
@@ -0,0 +1,15 @@
+## check status
+### r3 = GCTDST
+  lis r3, GCTDST@ha
+  lwzu r0, GCTDST@l(r3)
+### return if not DONE(2)
+  cmpwi r0, 2
+  bnelr
+
+## backup r15 (pointer to current gecko instruction)
+  add r0, r15, r4
+  stw r0, 4(r3)
+## update r15 = dst + 8(GCTDST.code-r3) - r4(this C0 code size)
+  addi r15, r3, 8
+  sub r15, r15, r4
+  blr
diff --git a/gecko/code/gecko-return.s b/gecko/code/gecko-return.s
new file mode 100644
index 0000000..ad3f3c1
--- /dev/null
+++ b/gecko/code/gecko-return.s
@@ -0,0 +1,6 @@
+## restore r15 (pointer to current gecko instruction)
+  lis r3, GCTDST+4@ha
+  lwz r15, GCTDST+4@l(r3)
+## update r15 = restored r15 - r4(this C0 code size)
+  sub r15, r15, r4
+  blr
diff --git a/gecko/hook.csv b/gecko/hook.csv
new file mode 100644
index 0000000..ca5c713
--- /dev/null
+++ b/gecko/hook.csv
@@ -0,0 +1,2 @@
+symbol,GMSE01,GMSJ01,GMSP01,GMSJ0A
+onReadOptionBlock,802A96E0,801069F4,802A96E0,80291538
diff --git a/include/card.h b/include/card.h
index b34ce1d..4eccc44 100644
--- a/include/card.h
+++ b/include/card.h
@@ -1,11 +1,14 @@
-
-
 #include "gcn.h"
 #include "sms.h"
 
 #ifndef __CARD_H__
 #define __CARD_H__
 
-bool loadCard(TCardManager *cm, CARDFileInfo *fileInfo, char *fileName, u32 *dst);
+#define LOAD_ERR_MOUNT -1
+#define LOAD_ERR_OPEN  -2
+#define LOAD_ERR_SIZE  -3
+#define LOAD_ERR_FILE_NOT_EXIST -4
+#define LOAD_ERR_READ  -5
+int loadCard(TCardManager *cm, CARDFileInfo *fileInfo, char *fileName, u32 *dst);
 
-#endif
\ No newline at end of file
+#endif
diff --git a/include/gcn.h b/include/gcn.h
index e7c226b..c85e055 100644
--- a/include/gcn.h
+++ b/include/gcn.h
@@ -8,8 +8,12 @@
 #define CARD_SLOT_A 0
 #define CARD_SLOT_B 1
 
-#define MEM1_START 0x8000000
-#define MEM1_END 0x81800000
+#define MEM1_START 0x80000000
+#define MEM1_END   0x81800000
+// The area beyond ArenaHi is used by system
+// and should not be modified
+// TODO version?
+#define ArenaHi    0x817FEEA0
 
 typedef struct CARDFileInfo
 {
@@ -30,4 +34,4 @@ s32 CARDUnmount(s32 chan);
 // s32 CARDProbeEx(s32 chan, s32 *memSize, s32 *sectorSize);
 // s32 CARDMount(s32 chan, void *workArea, CARDCallback detachCallback);
 
-#endif
\ No newline at end of file
+#endif
diff --git a/include/sms.h b/include/sms.h
index e42aef7..e8f88a9 100644
--- a/include/sms.h
+++ b/include/sms.h
@@ -1,20 +1,6 @@
 #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;
@@ -23,4 +9,4 @@ typedef struct
 int mount_(TCardManager *this, bool);
 int open_(TCardManager *this, CARDFileInfo *fileInfo);
 
-#endif
\ No newline at end of file
+#endif
diff --git a/include/typedefs.h b/include/typedefs.h
index 1df7887..13babcb 100644
--- a/include/typedefs.h
+++ b/include/typedefs.h
@@ -2,6 +2,8 @@
 #define __TYPEDEF_H__
 
 typedef int bool;
+#define true  1
+#define false 0
 
 typedef unsigned long long u64;
 typedef signed long long s64;
@@ -12,4 +14,4 @@ typedef signed short s16;
 typedef unsigned char u8;
 typedef signed char s8;
 
-#endif
\ No newline at end of file
+#endif
diff --git a/ldscript/GMSE01.ld b/ldscript/GMSE01.ld
new file mode 100644
index 0000000..c801869
--- /dev/null
+++ b/ldscript/GMSE01.ld
@@ -0,0 +1,5 @@
+mount_ = 0x802b2914;
+open_ = 0x802b20d0;
+CARDOpen = 0x8035938c;
+CARDRead = 0x80359d20;
+CARDClose = 0x80359504;
diff --git a/ldscript/GMSJ01.ld b/ldscript/GMSJ01.ld
new file mode 100644
index 0000000..b4953a6
--- /dev/null
+++ b/ldscript/GMSJ01.ld
@@ -0,0 +1,5 @@
+mount_ = 0x80107b50;
+open_ = 0x801072f4;
+CARDOpen = 0x800a3cac;
+CARDRead = 0x800a4640;
+CARDClose = 0x800a3e24;
diff --git a/ldscript/GMSJ0A.ld b/ldscript/GMSJ0A.ld
new file mode 100644
index 0000000..8202a66
--- /dev/null
+++ b/ldscript/GMSJ0A.ld
@@ -0,0 +1,5 @@
+mount_ = 0x80292634;
+open_ = 0x80291e38;
+CARDOpen = 0x80338c8c;
+CARDRead = 0x80339620;
+CARDClose = 0x80338e04;
diff --git a/ldscript/GMSP01.ld b/ldscript/GMSP01.ld
new file mode 100644
index 0000000..dfc9cd9
--- /dev/null
+++ b/ldscript/GMSP01.ld
@@ -0,0 +1,5 @@
+mount_ = 0x802aa824;
+open_ = 0x802a9fe0;
+CARDOpen = 0x803515ac;
+CARDRead = 0x80351f40;
+CARDClose = 0x80351724;
diff --git a/ldscript/sms.ld b/ldscript/sms.ld
new file mode 100644
index 0000000..e16880d
--- /dev/null
+++ b/ldscript/sms.ld
@@ -0,0 +1,14 @@
+/**
+ * There seems to be an alignment issue
+ * addr of GCTDST.code may need to be a multiple of 0x200 or something?
+ */
+GCTDST = 0x817F1800 - 8;
+
+SECTIONS {
+  . = 0x817FE800;  /* TODO: Determine Best Address */
+  .text : { *(.text) }
+  .rodata : { *(.rodata) }
+  .data : { *(.data) }
+  .bss : { *(.bss) }
+  .sdata : { *(.sdata) }
+}
diff --git a/sms.ld b/sms.ld
deleted file mode 100644
index 5a75926..0000000
--- a/sms.ld
+++ /dev/null
@@ -1,14 +0,0 @@
-SECTIONS {
-  . = 0x817FF000;  /* TODO: Determine Best Address */
-  .text : { *(.text) }
-  .rodata : { *(.rodata) }
-  .data : { *(.data) }
-  .bss : { *(.bss) }
-  .sdata : { *(.sdata) }
-}
-
-mount_ = 0x80107b50;
-open_ = 0x801072f4;
-CARDOpen = 0x800a3cac;
-CARDRead = 0x800a4640;
-CARDClose = 0x800a3e24;
diff --git a/source/card.c b/source/card.c
index 1234db1..1325f8c 100644
--- a/source/card.c
+++ b/source/card.c
@@ -1,23 +1,32 @@
-#include "gcn.h"
-#include "sms.h"
+#include "card.h"
 
-bool loadCard(TCardManager *cm, CARDFileInfo *fileInfo, char *fileName, u32 *dst)
+// TODO: we need to keep some space to store this loader code
+// #define DST_END ArenaHi
+#define DST_END 0x817FE800
+
+int loadCard(TCardManager *cm, CARDFileInfo *fileInfo, char *fileName, u32 *dst)
 {
+  int rc;
+
   // Mount the card
-  if (!mount_(cm, 1))
-    return -1;
+  if (mount_(cm, 1))
+    return LOAD_ERR_MOUNT;
 
   // Open the card
-  if (!CARDOpen(cm->slot, fileName, fileInfo))
-    return -1;
+  if ((rc = CARDOpen(cm->slot, fileName, fileInfo))) {
+    return rc == -4 ? LOAD_ERR_FILE_NOT_EXIST : LOAD_ERR_OPEN;
+  }
 
   // Too many codes
-  if (fileInfo->length > (MEM1_END - (u32)dst))
-    return -1;
+  // TODO fileInfo->length seems to be 0?
+  // int fileSize = fileInfo->length;
+  int fileSize = 0x2000 * 6;
+  if (fileSize > (DST_END - (u32)dst))
+    return LOAD_ERR_SIZE;
 
   // Read codes into destination address
-  if (!CARDRead(fileInfo, dst, fileInfo->length, 0))
-    return -1;
+  if (CARDRead(fileInfo, dst, fileSize, 0))
+     return LOAD_ERR_READ;
 
   // Done
   CARDClose(fileInfo);
diff --git a/source/main.c b/source/main.c
index c4e2700..899b1dc 100644
--- a/source/main.c
+++ b/source/main.c
@@ -16,24 +16,35 @@
 // 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_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))
+// GCTDST = 0x817F1000; // in ldscripts/sms.ld
+
+extern struct GCTBuffer {
+  // =0: initialized
+  // >0: Loading(1), Done(2)
+  // <0: error
+  int status;
+  // return address to the original Gecko handler
+  void *returnAddr;
+  // actual Gecko code
+  u32 code[0];
+} GCTDST;
+
+#define GCT_LOAD_LOADING 1
+#define GCT_LOAD_DONE 2
 
 void loadCodes(TCardManager *cm, CARDFileInfo *fileInfo)
 {
-  *PTR_FLG_LOADED = -1;
-
-  if (loadCard(cm, fileInfo, FILENAME, (void *)GECKO_CODE_START))
-    *PTR_FLG_LOADED = 0;
+  GCTDST.status = GCT_LOAD_LOADING;
+  // load card
+  int rc = loadCard(cm, fileInfo, FILENAME, GCTDST.code);
+  GCTDST.status = rc == 0 ? GCT_LOAD_DONE : rc; // DONE or Error code
 }
 
-// int onReadOptionBlock(TCardManager *this, CARDFileInfo *fileInfo)
-// {
-//   if (*PTR_FLG_LOADED)
-//     return open_(this, fileInfo);
-
-//   loadCodes(this, fileInfo);
-//   return open_(this, fileInfo);
-// }
+int onReadOptionBlock(TCardManager *this, CARDFileInfo *fileInfo)
+{
+  if (GCTDST.status <= 0) // Initialized(=0) or Error(<0)
+    loadCodes(this, fileInfo);
+  return open_(this, fileInfo);
+}