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[SANiK]

I've begun writing an X86 emu for the PSP using code from my other project.

I don't want to use DOSbox because instead of "building DOS into the emulator," it's going to be easier to emulate the DOS binaries.

I've written about 75% of the code so far, but I need a FEW more opcodes (doesn't include the FPU and 0x0F opcodes yet).
I'm writing it in Windows currently.

ANY HELP WILL BE APPRECIATED!

Here's the code so far:
http://jamesseph.phpwebhosting.com/users/sanik/x86emu.rar

Understanding my code (if you wish to help):

flag_ops.inc - contains the flag operations, which are opcodes that change the flags one way or another. So, shl, shr, and add are in there.

vm.h - contains the defines to the registers and misc stuff.

types.h - read these before you start! These are the datatypes which I use.

regs.inc - many of you will think "why did he line the registers like that?" It's simple, it makes mod-r/m byte access faster.

vm.c - contains the switch statement to the individual opcodes. (I'll change it to an array when it's done, this just makes coding easier)

util_ops.inc - MOST IMPORTANT OF ALL I'd say to understanding the emulator. I use defines which are basic but people might overlook them.
If you understand these defines, then you're perfect for the project:

//Reads a dword from RAM
#define vm_ddw() ((dword*)(vm_code + a_rm.address))

//Reads a word from RAM
#define vm_dw() ((word*)(vm_code + a_rm.address))

//Reads a byte from RAM
#define vm_db() ((byte*)(vm_code + a_rm.address))

//Reads a dword from RAM
#define vm_pdw() *((dword*)(vm_code + a_rm.address))

//Reads a word from RAM
#define vm_pw() *((word*)(vm_code + a_rm.address))

//Reads a byte from RAM
#define vm_pb() *((byte*)(vm_code + a_rm.address))

//This is used to check if the mode R/M byte is register to register or not
//Basicly, if a_rm.mode (that's the data from the mod r/m byte) is not 3, do the first statement, if not do the other, check the example below
#define vm_ar(a_a, a_b) if(a_rm.mode != 3) { a_a; } else { a_b; }

//Sample opcode:
case 0x31:
////printf("XOR r/m, reg\n");
vm_rm(); //This fills out the MOD R/M BYTE sttructure
if(vm_prefix[PS]) //Checks if the PREFIX SIZE is there, if not, then use the 16bit version of the opcode, else use the 32bit version
{
vm_ar(vm_xor32(vm_ddw(), vm_reg32[a_rm.reg]), vm_xor32(&vm_reg32[a_rm.rm], vm_reg32[a_rm.reg]));
}
else
{
vm_ar(vm_xor16(vm_dw(), *vm_reg16[a_rm.reg]), vm_xor16(vm_reg16[a_rm.rm], *vm_reg16[a_rm.reg])); //Now, what vm_ar does is interchange between XOR16(MEMORY, REGISTER) and XOR16(REGISTER, REGISTER) depending on the MOD R/M BYTE sttructure
}
break;

[pixel]

Yet one more wheel reinventor...
_________________
pixel: A mischievous magical spirit associated with screen displays. The computer industry has frequently borrowed from mythology. Witness the sprites in computer graphics, the demons in artificial intelligence and the trolls in the marketing department.

[ector]

Just port DOSbox... look at how much time they have needed to get that far.