i_sub.c

来自「SkyEye是一个可以运行嵌入式操作系统的硬件仿真工具」· C语言 代码 · 共 97 行

/**********************************/
/*                                */
/*  Copyright 2000, David Grant   */
/*                                */
/*  see LICENSE for more details  */
/*                                */
/**********************************/

#include "coldfire.h"

/* Subtract instruction */

/* Format 
   
 15  14  13  12  11  10   9   8   7   6   5   4   3   2   1   0
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| 1 | 0 | 0 | 1 | Register  |  OPmode   |  EA Mode  |EA Register|
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+

*/

int SUBTime[2][8]={{1, 3, 3, 3, 3, 4, 3, 1  },
	          {-1, 3, 3, 3, 3, 4, 3, -1 }};


INSTRUCTION_5ARGS(SUB,
	unsigned Code1,4,
	unsigned Register,3,
	unsigned OPMode,3,
	unsigned EAMode,3,
	unsigned EARegister,3);

static void execute(void)
{
	struct _Address Source,Destination;
	unsigned int Result, SValue, DValue;
	SUB_Instr Instr;
	Memory_RetrWordFromPC(&Instr.Code);

/*	printf("SUB: Register=%d, OPMode=%d, EAMode=%d, EARegister=%d\n", Register, OPMode, EAMode,EARegister);*/
	if(Instr.Bits.OPMode==2) { /* <EA>y + Dx */
		if(!EA_GetFromPC(&Source, 32, Instr.Bits.EAMode, Instr.Bits.EARegister)) return;
		if(!EA_GetFromPC(&Destination, 32, 0, Instr.Bits.Register)) return;
	} else if(Instr.Bits.OPMode==6) { /* Dy + <EA>x -> <EA>x */
		if(Instr.Bits.EAMode==0) {
			SKYEYE_ERR("May not specify Dx for destination when source is Dx");
			return;
		} else if(Instr.Bits.EAMode==1) {
			SKYEYE_ERR("May not specify Ax for destination when source is Dx");
			return;
		}
		if(!EA_GetFromPC(&Source, 32, 0, Instr.Bits.Register)) return;
		if(!EA_GetFromPC(&Destination, 32, Instr.Bits.EAMode, Instr.Bits.EARegister)) return;
	} else {
		SKYEYE_ERR("Unknown opcode %x\n", Instr.Bits.OPMode);
		return;
	}
	EA_GetValue(&SValue, &Source);
	EA_GetValue(&DValue, &Destination);

	Result = DValue - SValue;


	/* Set the status register */
	SR_Set(I_SUB, SValue, DValue, Result);

	EA_PutValue(&Destination, Result);


	if(Instr.Bits.OPMode==2)  /* <EA>y + Dx */
		cycle(SUBTime[0][cycle_EA(Instr.Bits.EARegister,Instr.Bits.EAMode)]);
	else cycle(SUBTime[1][cycle_EA(Instr.Bits.EARegister,Instr.Bits.EAMode)]);

	return;
}

static int disassemble(char *Instruction, char *Arg1, char *Arg2)
{
	SUB_Instr Instr;
	Memory_RetrWordFromPC(&Instr.Code);
	sprintf(Instruction, "SUB.L");
	if(Instr.Bits.OPMode==2) { /* <EA>y & Dx */
		Addressing_Print(32, Instr.Bits.EAMode, Instr.Bits.EARegister, Arg1);
		Addressing_Print(32, 0, Instr.Bits.Register, Arg2);
	} else {
		Addressing_Print(32, 0, Instr.Bits.Register, Arg1);
		Addressing_Print(32, Instr.Bits.EAMode, Instr.Bits.EARegister, Arg2);
	}
 	return 0;
}

int sub_5206_register(void)
{
	instruction_register(0x9000, 0xF000, &execute, &disassemble);
	return 1;
}