add example of toggle code

ReadFile.c

@@ -42,15 +42,15 @@ int onReadOptionBlock(TCardManager *this, CARDFileInfo *fileInfo) {
   if ((rc = CARDRead(fileInfo, dst, size, 0))) {
     // should not fail if (dst, size) is properly set
   } else {
-    // everything is good
-    // TODO apply gecko code
-    *(char*)0x817effff = 1; // ready (temporary solution)
+    // everything is good => apply gecko code
+    // TODO entry
+    ((void(*)())0x817f0000)();
   }
 
   // close file
   CARDClose(fileInfo);
 
 orig:
-  // original function call 
+  // original function call
   return open_(this, fileInfo);
 }

example/.gitignore

@@ -0,0 +1,5 @@
+*.o
+*.out
+*.bin
+*.gci
+*.map

example/Makefile

@@ -0,0 +1,31 @@
+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

example/QFSync.s

@@ -0,0 +1,8 @@
+.globl _getQFSync
+_getQFSync:
+  lis r12, 0x8180
+  lwz r12, -0x4000(r12)
+  rlwinm. r12, r12, 2, 0x3
+  li r3, 600
+  slw r3, r3, r12
+  blr

example/_start.s

@@ -0,0 +1,38 @@
+.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

example/gameLoop.c

@@ -0,0 +1,18 @@
+#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
+}

example/macros.s

@@ -0,0 +1,4 @@
+.macro li32 reg val
+  lis \reg, \val@h
+  ori \reg, \reg, \val@l
+.endm

example/main.c

@@ -0,0 +1,3 @@
+int f(int x) {
+  return x*x;
+}

example/make-gci.py

@@ -0,0 +1,28 @@
+import sys
+
+if len(sys.argv) != 4:
+  print('Usage: %s {block-count} {content.bin} {out.gci}'%sys.argv[0], file=sys.stderr)
+  sys.exit(1)
+
+blockCount = int(sys.argv[1])
+contentPath = sys.argv[2]
+outPath = sys.argv[3]
+
+gameId = b'GMSJ01\xff\x00' # TODO other version
+fileName = b'gct'
+
+pad = lambda buf, size: buf+b'\x00'*(size-len(buf))
+with open(contentPath, 'rb') as fr, open(outPath, 'wb') as fw:
+  content = fr.read()
+  bodySize = 0x2000*blockCount
+  assert len(content)<=bodySize, f'{contentPath} is too big: expect at most {bodySize} bytes, got {len(content)}'
+  fw.write(b''.join((
+    # header
+    gameId,
+    pad(fileName, 0x20),
+    b'\x00'*16,
+    blockCount.to_bytes(2, 'big'),
+    b'\xff'*6,
+    # body
+    pad(content, bodySize),
+  )))

example/sms.h

@@ -0,0 +1,34 @@
+#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

example/sms.ld

@@ -0,0 +1,14 @@
+SECTIONS {
+  . = 0x817F0000;
+  .init : { _start.o }
+  .text : { *(.text) }
+  .rodata : { *(.rodata) }
+  .data : { *(.data) }
+  .bss : { *(.bss) }
+}
+
+/** TODO version */
+TMarioGamePad_read = 0x800fba58;
+JUTGamePad_mPadStatus = 0x80400d50;
+
+config = 0x817fc000;