More rfu documentation

1 files changed, 66 insertions, 56 deletions

diff --git a/src/librfu_sio32id.c b/src/librfu_sio32id.c
index fc5701986..025d6085b 100644
--- a/src/librfu_sio32id.c
+++ b/src/librfu_sio32id.c
@@ -4,44 +4,56 @@ static void Sio32IDIntr(void);
 static void Sio32IDInit(void);
 static s32 Sio32IDMain(void);
 
+struct RfuSIO32Id
+{
+    u8 unk0;
+    u8 state;
+    u16 unk2;
+    u16 unk4;
+    u16 unk6;
+    u16 unk8; // unused
+    u16 lastId;
+};
+
 struct RfuSIO32Id gRfuSIO32Id;
 
 static const u16 Sio32ConnectionData[] = { 0x494e, 0x544e, 0x4e45, 0x4f44 }; // NINTENDO
 static const char Sio32IDLib_Var[] = "Sio32ID_030820";
 
-s32 AgbRFU_checkID(u8 r5)
+s32 AgbRFU_checkID(u8 maxTries)
 {
-    u16 r8;
-    vu16 *r4;
-    s32 r6;
+    u16 ieBak;
+    vu16 *regTMCNTL;
+    s32 id;
 
+    // Interrupts must be enabled
     if (REG_IME == 0)
         return -1;
-    r8 = REG_IE;
+    ieBak = REG_IE;
     gSTWIStatus->state = 10;
     STWI_set_Callback_ID(Sio32IDIntr);
     Sio32IDInit();
-    r4 = &REG_TMCNT_L(gSTWIStatus->timerSelect);
-    r5 *= 8;
-    while (--r5 != 0xFF)
+    regTMCNTL = &REG_TMCNT_L(gSTWIStatus->timerSelect);
+    maxTries *= 8;
+    while (--maxTries != 0xFF)
     {
-        r6 = Sio32IDMain();
-        if (r6 != 0)
+        id = Sio32IDMain();
+        if (id != 0)
             break;
-        r4[1] = 0;
-        r4[0] = 0;
-        r4[1] = TIMER_1024CLK | TIMER_ENABLE;
-        while (r4[0] < 32)
+        regTMCNTL[1] = 0;
+        regTMCNTL[0] = 0;
+        regTMCNTL[1] = TIMER_1024CLK | TIMER_ENABLE;
+        while (regTMCNTL[0] < 32)
             ;
-        r4[1] = 0;
-        r4[0] = 0;
+        regTMCNTL[1] = 0;
+        regTMCNTL[0] = 0;
     }
     REG_IME = 0;
-    REG_IE = r8;
+    REG_IE = ieBak;
     REG_IME = 1;
     gSTWIStatus->state = 0;
     STWI_set_Callback_ID(NULL);
-    return r6;
+    return id;
 }
 
 static void Sio32IDInit(void)
@@ -58,107 +70,105 @@ static void Sio32IDInit(void)
 
 static s32 Sio32IDMain(void)
 {
-    u8 r12;
-
-    switch (r12 = gRfuSIO32Id.unk1)
+    switch (gRfuSIO32Id.state)
     {
     case 0:
         gRfuSIO32Id.unk0 = 1;
         REG_SIOCNT |= SIO_38400_BPS;
-        REG_IME = r12;
+        REG_IME = 0;
         REG_IE |= INTR_FLAG_SERIAL;
         REG_IME = 1;
-        gRfuSIO32Id.unk1 = 1;
+        gRfuSIO32Id.state = 1;
         *(vu8 *)&REG_SIOCNT |= SIO_ENABLE;
         break;
     case 1:
-        if (gRfuSIO32Id.unkA == 0)
+        if (gRfuSIO32Id.lastId == 0)
         {
             if (gRfuSIO32Id.unk0 == 1)
             {
                 if (gRfuSIO32Id.unk2 == 0)
                 {
-                    REG_IME = gRfuSIO32Id.unk2;
+                    REG_IME = 0;
                     REG_SIOCNT |= SIO_ENABLE;
-                    REG_IME = r12;
+                    REG_IME = 1;
                 }
             }
-            else if (gRfuSIO32Id.unk4 != 0x8001 && !gRfuSIO32Id.unk2)
+            else if (gRfuSIO32Id.unk4 != RFU_ID && !gRfuSIO32Id.unk2)
             {
-                REG_IME = gRfuSIO32Id.unk2;
+                REG_IME = 0;
                 REG_IE &= ~INTR_FLAG_SERIAL;
-                REG_IME = r12;
-                REG_SIOCNT = gRfuSIO32Id.unk2;
+                REG_IME = 1;
+                REG_SIOCNT = 0;
                 REG_SIOCNT = SIO_32BIT_MODE;
                 REG_IF = INTR_FLAG_SERIAL;
                 REG_SIOCNT |= SIO_INTR_ENABLE | SIO_ENABLE;
-                REG_IME = gRfuSIO32Id.unk2;
+                REG_IME = 0;
                 REG_IE |= INTR_FLAG_SERIAL;
-                REG_IME = r12;
+                REG_IME = 1;
             }
             break;
         }
         else
         {
-            gRfuSIO32Id.unk1 = 2;
+            gRfuSIO32Id.state = 2;
             // fallthrough
         }
     default:
-        return gRfuSIO32Id.unkA;
+        return gRfuSIO32Id.lastId;
     }
     return 0;
 }
 
 static void Sio32IDIntr(void)
 {
-    u32 r5;
-    u16 r0;
+    u32 regSIODATA32;
+    u16 delay;
 #ifndef NONMATCHING
-    register u32 r1 asm("r1");
-    register u16 r0_ asm("r0");
+    register u32 rfuSIO32IdUnk0_times_16 asm("r1");
+    register u16 negRfuSIO32IdUnk6 asm("r0");
 #else
-    u32 r1;
-    u16 r0_;
+    u32 rfuSIO32IdUnk0_times_16;
+    u16 negRfuSIO32IdUnk6;
 #endif
 
-    r5 = REG_SIODATA32;
+    regSIODATA32 = REG_SIODATA32;
     if (gRfuSIO32Id.unk0 != 1)
         REG_SIOCNT |= SIO_ENABLE;
-    r1 = 16 * gRfuSIO32Id.unk0; // to handle side effect of inline asm
-    r1 = (r5 << r1) >> 16;
-    r5 = (r5 << 16 * (1 - gRfuSIO32Id.unk0)) >> 16;
-    if (gRfuSIO32Id.unkA == 0)
+    rfuSIO32IdUnk0_times_16 = 16 * gRfuSIO32Id.unk0; // to handle side effect of inline asm
+    rfuSIO32IdUnk0_times_16 = (regSIODATA32 << rfuSIO32IdUnk0_times_16) >> 16;
+    regSIODATA32 = (regSIODATA32 << 16 * (1 - gRfuSIO32Id.unk0)) >> 16;
+    if (gRfuSIO32Id.lastId == 0)
     {
-        if (r1 == gRfuSIO32Id.unk6)
+        if (rfuSIO32IdUnk0_times_16 == gRfuSIO32Id.unk6)
         {
             if (gRfuSIO32Id.unk2 > 3)
             {
-                gRfuSIO32Id.unkA = r5;
+                gRfuSIO32Id.lastId = regSIODATA32;
             }
-            else if (r1 == (u16)~gRfuSIO32Id.unk4)
+            else if (rfuSIO32IdUnk0_times_16 == (u16)~gRfuSIO32Id.unk4)
             {
-                r0_ = ~gRfuSIO32Id.unk6;
-                if (r5 == r0_)
+                negRfuSIO32IdUnk6 = ~gRfuSIO32Id.unk6;
+                if (regSIODATA32 == negRfuSIO32IdUnk6)
                     ++gRfuSIO32Id.unk2;
             }
         }
         else
         {
-            gRfuSIO32Id.unk2 = gRfuSIO32Id.unkA;
+            gRfuSIO32Id.unk2 = gRfuSIO32Id.lastId;
         }
     }
     if (gRfuSIO32Id.unk2 < 4)
         gRfuSIO32Id.unk4 = *(gRfuSIO32Id.unk2 + Sio32ConnectionData);
     else
-        gRfuSIO32Id.unk4 = 0x8001;
-    gRfuSIO32Id.unk6 = ~r5;
+        gRfuSIO32Id.unk4 = RFU_ID;
+    gRfuSIO32Id.unk6 = ~regSIODATA32;
     REG_SIODATA32 = (gRfuSIO32Id.unk4 << 16 * (1 - gRfuSIO32Id.unk0))
                   + (gRfuSIO32Id.unk6 << 16 * gRfuSIO32Id.unk0);
-    if (gRfuSIO32Id.unk0 == 1 && (gRfuSIO32Id.unk2 || r5 == 0x494E))
+    if (gRfuSIO32Id.unk0 == 1 && (gRfuSIO32Id.unk2 || regSIODATA32 == 0x494e))
     {
-        for (r0 = 0; r0 < 600; ++r0)
+        for (delay = 0; delay < 600; ++delay)
             ;
-        if (gRfuSIO32Id.unkA == 0)
+        if (gRfuSIO32Id.lastId == 0)
             REG_SIOCNT |= SIO_ENABLE;
     }
 }