flycast/core/hw/sh4/interpr/sh4_interpreter.cpp

/*
	Highly inefficient and boring interpreter. Nothing special here
*/

#include "types.h"

#include "../sh4_interpreter.h"
#include "../sh4_opcode_list.h"
#include "../sh4_core.h"
#include "../sh4_interrupts.h"
#include "hw/sh4/sh4_mem.h"
#include "../sh4_sched.h"
#include "hw/holly/sb.h"
#include "../sh4_cache.h"

#define CPU_RATIO      (8)

sh4_icache icache;
sh4_ocache ocache;

static s32 l;

static void ExecuteOpcode(u16 op)
{
	if (sr.FD == 1 && OpDesc[op]->IsFloatingPoint())
		RaiseFPUDisableException();
	OpPtr[op](op);
	l -= CPU_RATIO;
}

static u16 ReadNexOp()
{
	u32 addr = next_pc;
	next_pc += 2;

	return IReadMem16(addr);
}

void Sh4_int_Run()
{
	sh4_int_bCpuRun=true;

	l = SH4_TIMESLICE;

	do
	{
#if !defined(NO_MMU)
		try {
#endif
			do
			{
				u32 op = ReadNexOp();

				ExecuteOpcode(op);
			} while (l > 0);
			l += SH4_TIMESLICE;
			UpdateSystem_INTC();
#if !defined(NO_MMU)
		}
		catch (SH4ThrownException& ex) {
			Do_Exception(ex.epc, ex.expEvn, ex.callVect);
			l -= CPU_RATIO * 5;	// an exception requires the instruction pipeline to drain, so approx 5 cycles
		}
#endif
	} while (sh4_int_bCpuRun);

	sh4_int_bCpuRun = false;
}

void Sh4_int_Stop()
{
	if (sh4_int_bCpuRun)
		sh4_int_bCpuRun=false;
}

void Sh4_int_Start()
{
	if (!sh4_int_bCpuRun)
		sh4_int_bCpuRun=true;
}

void Sh4_int_Step()
{
	if (sh4_int_bCpuRun)
	{
		WARN_LOG(INTERPRETER, "Sh4 Is running , can't step");
	}
	else
	{
		u32 op = ReadNexOp();
		ExecuteOpcode(op);
	}
}

void Sh4_int_Skip()
{
	if (sh4_int_bCpuRun)
		WARN_LOG(INTERPRETER, "Sh4 Is running, can't Skip");
	else
		next_pc += 2;
}

void Sh4_int_Reset(bool hard)
{
	if (sh4_int_bCpuRun)
	{
		WARN_LOG(INTERPRETER, "Sh4 Is running, can't Reset");
	}
	else
	{
		if (hard)
			memset(&p_sh4rcb->cntx, 0, sizeof(p_sh4rcb->cntx));
		next_pc = 0xA0000000;

		memset(r,0,sizeof(r));
		memset(r_bank,0,sizeof(r_bank));

		gbr=ssr=spc=sgr=dbr=vbr=0;
		mac.full=pr=fpul=0;

		sh4_sr_SetFull(0x700000F0);
		old_sr.status=sr.status;
		UpdateSR();

		fpscr.full = 0x0004001;
		old_fpscr=fpscr;
		UpdateFPSCR();
		icache.Reset(hard);
		ocache.Reset(hard);

		//Any more registers have default value ?
		INFO_LOG(INTERPRETER, "Sh4 Reset");
	}
}

bool Sh4_int_IsCpuRunning()
{
	return sh4_int_bCpuRun;
}

//TODO : Check for valid delayslot instruction
void ExecuteDelayslot()
{
#if !defined(NO_MMU)
	try {
#endif
		u32 op = ReadNexOp();

		ExecuteOpcode(op);
#if !defined(NO_MMU)
	}
	catch (SH4ThrownException& ex) {
		AdjustDelaySlotException(ex);
		throw ex;
	}
#endif
}

void ExecuteDelayslot_RTE()
{
#if !defined(NO_MMU)
	try {
#endif
		ExecuteDelayslot();
#if !defined(NO_MMU)
	}
	catch (SH4ThrownException& ex) {
		ERROR_LOG(INTERPRETER, "Exception in RTE delay slot");
	}
#endif
}

// every SH4_TIMESLICE cycles
int UpdateSystem()
{
	Sh4cntx.sh4_sched_next -= SH4_TIMESLICE;
	if (Sh4cntx.sh4_sched_next < 0)
		sh4_sched_tick(SH4_TIMESLICE);

	return Sh4cntx.interrupt_pend;
}

int UpdateSystem_INTC()
{
	if (UpdateSystem())
		return UpdateINTC();
	else
		return 0;
}

void sh4_int_resetcache() { }
//Get an interface to sh4 interpreter
void Get_Sh4Interpreter(sh4_if* rv)
{
	rv->Run=Sh4_int_Run;
	rv->Stop=Sh4_int_Stop;
	rv->Start=Sh4_int_Start;
	rv->Step=Sh4_int_Step;
	rv->Skip=Sh4_int_Skip;
	rv->Reset=Sh4_int_Reset;
	rv->Init=Sh4_int_Init;
	rv->Term=Sh4_int_Term;
	rv->IsCpuRunning=Sh4_int_IsCpuRunning;

	rv->ResetCache=sh4_int_resetcache;
}

void Sh4_int_Init()
{
	static_assert(sizeof(Sh4cntx) == 448, "Invalid Sh4Cntx size");

	memset(&p_sh4rcb->cntx, 0, sizeof(p_sh4rcb->cntx));
}

void Sh4_int_Term()
{
	Sh4_int_Stop();
	INFO_LOG(INTERPRETER, "Sh4 Term");
}