minivmac4ios/Mini vMac/mnvm_core/MINEM68K.c

/*
	MINEM68K.c

	Copyright (C) 2009 Bernd Schmidt, Paul C. Pratt

	You can redistribute this file and/or modify it under the terms
	of version 2 of the GNU General Public License as published by
	the Free Software Foundation.  You should have received a copy
	of the license along with this file; see the file COPYING.

	This file is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	license for more details.
*/

/*
	MINimum EMulator of 68K cpu

	This code descends from a simple 68000 emulator that I
	(Paul C. Pratt) wrote long ago. That emulator ran on a 680x0,
	and used the cpu it ran on to do some of the work. This
	descendent fills in those holes with code from the
	Un*x Amiga Emulator by Bernd Schmidt, as found being used in vMac.

	This emulator is about 10 times smaller than the UAE,
	at the cost of being 2 to 3 times slower.

	FPU Emulation added 9/12/2009 by Ross Martin
		(this code now located in "FPCPEMDV.h")
*/

#ifndef AllFiles
#include "SYSDEPNS.h"

#include "MYOSGLUE.h"
#include "ENDIANAC.h"
#include "EMCONFIG.h"
#include "GLOBGLUE.h"

#include "M68KITAB.h"

#if WantDisasm
#include "DISAM68K.h"
#endif
#endif

#include "MINEM68K.h"

typedef unsigned char flagtype;


/* Memory Address Translation Cache record */

struct MATCr {
	ui5r cmpmask;
	ui5r cmpvalu;
	ui5r usemask;
	ui3p usebase;
};
typedef struct MATCr MATCr;
typedef MATCr *MATCp;

/*
	This variable was introduced because a program could do a Bcc from
	within chip memory to a location within expansion memory. With a
	pointer variable the program counter would point to the wrong
	location. With this variable unset the program counter is always
	correct, but programs will run slower (about 4%).
	Usually, you'll want to have this defined.

	vMac REQUIRES this. It allows for fun things like Restart.
*/

#ifndef USE_POINTER
#define USE_POINTER 1
#endif

#define AKMemory 0
#define AKRegister 1
#define AKConstant 2

union ArgAddrT {
	ui5r mem;
	ui5r *rga;
};
typedef union ArgAddrT ArgAddrT;

LOCALVAR struct regstruct
{
	ui5r regs[16]; /* Data and Address registers */
	ui5r pc; /* Program Counter */
	CPTR usp; /* User Stack Pointer */
	CPTR isp; /* Interrupt Stack Pointer */
#if Use68020
	CPTR msp; /* Master Stack Pointer */
#endif

	/* Status Register */
	ui5r intmask; /* bits 10-8 : interrupt priority mask */
	flagtype t1; /* bit 15: Trace mode 1 */
#if Use68020
	flagtype t0; /* bit 14: Trace mode 0 */
#endif
	flagtype s; /* bit 13: Supervisor or user privilege level */
#if Use68020
	flagtype m; /* bit 12: Master or interrupt mode */
#endif
	flagtype x; /* bit 4: eXtend */
	flagtype n; /* bit 3: Negative */
	flagtype z; /* bit 2: Zero */
	flagtype v; /* bit 1: oVerflow */
	flagtype c; /* bit 0: Carry */

	flagtype TracePending;
	flagtype ExternalInterruptPending;
#if 0
	flagtype ResetPending;
#endif
	ui3b *fIPL;

#if Use68020
	ui5b sfc; /* Source Function Code register */
	ui5b dfc; /* Destination Function Code register */
	ui5b vbr; /* Vector Base Register */
	ui5b cacr; /* Cache Control Register */
		/*
			bit 0 : Enable Cache
			bit 1 : Freeze Cache
			bit 2 : Clear Entry In Cache (write only)
			bit 3 : Clear Cache (write only)
		*/
	ui5b caar; /* Cache Address Register */
#endif
	MATCr MATCrdB;
	MATCr MATCwrB;
	MATCr MATCrdW;
	MATCr MATCwrW;
	MATCr MATCex;
	ATTep HeadATTel;
	DecOpR CurDecOp;


#if USE_POINTER
	ui3p pc_p;
	ui3p pc_oldp;
#endif
	ui5b opsize;
	ui5b ArgKind;
	ArgAddrT ArgAddr;
	ui5b SrcVal;
	ui5b opcode;
	si5r MaxCyclesToGo;
	si5r MoreCyclesToGo;
	si5r ResidualCycles;
	ui3b fakeword[2];

#define disp_table_sz (256 * 256)
#if SmallGlobals
	DecOpR *disp_table;
#else
	DecOpR disp_table[disp_table_sz];
#endif
} regs;

#define ui5r_MSBisSet(x) (((si5r)(x)) < 0)

#define ZFLG regs.z
#define NFLG regs.n
#define CFLG regs.c
#define VFLG regs.v
#define XFLG regs.x

LOCALFUNC ui4b m68k_getCR(void)
{
	return (XFLG << 4) | (NFLG << 3) | (ZFLG << 2)
		| (VFLG << 1) | CFLG;
}

LOCALFUNC MayInline void m68k_setCR(ui4b newcr)
{
	XFL