arm7tdmi-opcodes.cpp

一个任天堂掌上游戏机NDS的源代码

/**************************************************************************
* DSemu - The Next Generation                                             *
* Portable ARM7TDMI core: ARM7-specific opcodes [arm7tdmi-opcodes.cpp]    *
* Copyright Imran Nazar, 2005; released under the BSD public licence.     *
**************************************************************************/

// There isn't much in here, because most of the ARM7 is subsumed into the
// ARM9; therefore, those opcodes are common, and defined in arm-dp|ls.

#include "arm7tdmi.h"
#include "plgmmu32.h"
#include "armhelp.h"
#include "armmasks.h"
#include "datadefs.h"
#include "log.h"
#include "err.h"

//---Conditional execution-------------------------------------------------
// Each of these functions returns 1 or 0, dependent on flag state.
// Called by the dispatcher, by lookup in the condition LUT.

int ARM7TDMI::condEQ(){return  reg.flags[FLAG_Z];}
int ARM7TDMI::condNE(){return !reg.flags[FLAG_Z];}
int ARM7TDMI::condCS(){return  reg.flags[FLAG_C];}
int ARM7TDMI::condCC(){return !reg.flags[FLAG_C];}
int ARM7TDMI::condMI(){return  reg.flags[FLAG_N];}
int ARM7TDMI::condPL(){return !reg.flags[FLAG_N];}
int ARM7TDMI::condVS(){return  reg.flags[FLAG_V];}
int ARM7TDMI::condVC(){return !reg.flags[FLAG_V];}

int ARM7TDMI::condHI(){return (!reg.flags[FLAG_Z])&reg.flags[FLAG_C];}
int ARM7TDMI::condLS(){return reg.flags[FLAG_Z]|(!reg.flags[FLAG_C]);}
int ARM7TDMI::condGE(){return !(reg.flags[FLAG_N]^reg.flags[FLAG_V]);}
int ARM7TDMI::condLT(){return  (reg.flags[FLAG_N]^reg.flags[FLAG_V]);}
int ARM7TDMI::condGT(){return (!reg.flags[FLAG_Z])&(!(reg.flags[FLAG_N]^reg.flags[FLAG_V]));}
int ARM7TDMI::condLE(){return reg.flags[FLAG_Z]|(reg.flags[FLAG_N]^reg.flags[FLAG_V]);}
int ARM7TDMI::condAL(){return 1;}
int ARM7TDMI::condNV(){return 0;}

//---Branching-------------------------------------------------------------

OPC opB()
{
    s32 i = (reg.curop & 0x00FFFFFF) << 2;     // Extract address
    i = (i & 0x02000000)?(0xFC000000 | i):i;   // Sign extend
    reg.r[15] += i+4;                          // And branch
    return 3;
}

OPC opBL()
{
    reg.r[14] = reg.r[15];                     // Save link addr
    s32 i = (reg.curop & 0x00FFFFFF) << 2;     // Extract address
    i = (i & 0x02000000)?(0xFC000000 | i):i;   // Sign extend
    reg.r[15] += i+4;                          // And branch
    return 3;
}

OPC opBX()
{
/*  if((_RM&3)==2) opUNP();*/
    reg.r[15]=(_RM&~1)+Rm15hack; reg.flags[FLAG_T]=_RM&1;
    return 1;
}

/*** EOF: arm7tdmi-opcodes.cpp *******************************************/