// Dolphin OS context RE by org
// OSContext.c

// OSLoMem.h
OSContext *__OSPhysicalContext AT_ADDRESS(OS_BASE_CACHED | 0x00C0);
OSContext *__OSCurrentContext  AT_ADDRESS(OS_BASE_CACHED | 0x00D4);

[800000D8] - default thread (OSThread *)

void __OSLoadFPUContext(???, OSContext *context)
{
    if(context->state & OS_CONTEXT_STATE_FPSAVED)
    {
        FPSCR = context.fpscr;

        if(HID2[PSE])
        {
            PS[0] = context->psf[0];
            .
            .
            .
            PS[31] = context->psf[31];
        }
        else
        {
            FPR[0] = context->fpr[0];
            .
            .
            .
            FPR[31] = context->fpr[31];
        }
    }
}

void __OSSaveFPUContext(???, ???, OSContext *context)
{
    context->state |= OS_CONTEXT_STATE_FPSAVED;

    // save FPRs
    context->fpr[0] = FPR[0];
    .
    .
    .
    context->fpr[31] = FPR[31];

    // save FP state/control
    context.fpscr = FPSCR;

    // save paireds
    if(HID2[PSE])
    {
        context->fpr[0] = FPR[0];
        .
        .
        .
        context->fpr[31] = FPR[31];
    }
}

void OSLoadFPUContext(OSContext *context)
{
    __OSLoadFPUContext(???, context);
}

void OSSaveFPUContext(OSContext *context)
{
    __OSSaveFPUContext(???, ???, context);
}

void OSSetCurrentContext(OSContext *context)
{
    __OSCurrentContext = context;
    __OSPhysicalContext= OSCachedToPhysical(context);

    if(context == __OSDefaultThread->context)
    {
        context.srr1 |= MSR_FP;     // floating-point available
        MSR[RI] = 1;                // recoverable interrupt
    }
    else
    {   
        context.srr1 &= ~MSR_FP;
        MSR[FP] = 0;
        MSR[RI] = 1;
        __asm   isync
    }
}

OSContext *OSGetCurrentContext()
{
    return __OSCurrentContext;
}

u32 OSSaveContext(OSContext *context)
{
    // save GPRs
    context.gpr[13...31] = GPR[13...31];

    // save quantization regs (GQR0 is always zero)
    context.gqr[1...7] = GQR[1...7];

    // others
    context.cr   = CR;
    context.srr0 = context.lr = LR;
    context.srr1 = MSR;
    context.ctr  = CTR;
    context.xer  = XER;

    // compiler pointers
    context.gpr[1]  = SP;
    context.gpr[2]  = SDA1;

    context.gpr[12] = 1;
    return 0;
}

void OSLoadContext(OSContext *context)
{
    if(
        context.srr0 >= __RAS_OSDisableInterrupts_begin &&
        context.srr0 <= __RAS_OSDisableInterrupts_end      )
    {
        context.srr0 = __RAS_OSDisableInterrupts_begin;
    }

    // restore GPRs
    GPR[0...2] = context.gpr[0...2];

    if(context.state & OS_CONTEXT_STATE_EXC)
    {
        context.state &= ~OS_CONTEXT_STATE_EXC;
        GPR[5...31] = context.gpr[5...31];
    }
    else GPR[13...31] = context.gpr[13...31];

    // restore GQRs (GQR0 is always 0)
    GQR[1...7] = context.gqr[1...7];

    // others
    CR  = context.cr;
    LR  = context.lr;
    CTR = context.ctr;
    XER = context.xer;

    MSR[IE] = MSR[RI] = 0;
    SRR0 = context.srr0;
    SRR1 = context.srr1;

    GPR[4] = context.gpr[4];
    GPR[3] = context.gpr[3];

    // return from interrupt (update PC and MSR)
    __asm   rfi
}

u32 OSGetStackPointer()
{
    return GPR[1];  // SP
}

u32 OSSwitchStack(u32 newsp)
{
    u32 oldsp = GPR[1];
    GPR[1] = newsp;
    return oldsp;
}

int OSSwitchFiber(u32 pc, u32 newsp)
{
    u32 oldsp = GPR[1];
    int rval;
    GPR[1] = newsp;
    rval = (void *)pc();
    GPR[1] = oldsp;
    return rval;
}

void OSClearContext(OSContext *context)
{
    context.mode  =
    context.state = 0;

    if(context == __OSDefaultThread->context)
    {
        __OSDefaultThread = NULL;
    }
}

void OSInitContext(OSContext *context, u32 pc, u32 sp)
{
    context.srr0 = pc;
    context.gpr[1] = sp;
    context.srr1 = 0x9032;

    context.cr  =
    context.xer = 0;

    context.gpr[2] = GPR[2];
    context.gpr[3...31] = 0;
    context.gpr[13] = GPR[13];

    context.gqr[0...7] = 0;

    OSClearContext(context);
}

void OSDumpContext(OSContext *context)
{
    ...
}

void OSSwitchFPUContext(__OSException exception, OSContext *context)
{
    ...
}

void __OSContextInit()
{
    __OSSetExceptionHandler(
        __OS_EXCEPTION_FLOATING_POINT,
        OSSwitchFPUContext
    );

    DBPrintf("FPU-unavailable handler installed\n");
}

void OSFillFPUContext(OSContext *context)
{
    ...
}