cpu.asm

nes游戏模拟器

; *             STY. Opcodes 84, 94, 8C                              *
; ********************************************************************
CPU_ST? MACRO wAddress:REQ, byData:REQ
	WRITE_MEMORY wAddress, byData
ENDM

; ********************************************************************
; *          TAX. Opcode AA                                          *
; ********************************************************************
CPU_TAX MACRO
	; Transfer the A register to the X register.
	mov al, CPU.A
	mov CPU.X, al
	test al, al
	
	; Set/clear the sign and zero flags.
	MODIFYFLAGS S, , Z,
ENDM

; ********************************************************************
; *          TAY. Opcode A8                                          *
; ********************************************************************
CPU_TAY MACRO
	; Transfer the A register to the Y register.
	mov al, CPU.A
	mov CPU.Y, al
	test al, al
	
	; Set/clear the sign and zero flags.
	MODIFYFLAGS S, , Z,
ENDM

; ********************************************************************
; *          TSX. Opcode BA                                          *
; ********************************************************************
CPU_TSX MACRO
	; Transfer the SP register to the X register.
	mov al, CPU.S
	mov CPU.X, al
	test al, al
	
	; Set/clear the sign and zero flags.
	MODIFYFLAGS S, , Z,
ENDM

; ********************************************************************
; *          TXA. Opcode 8A                                          *
; ********************************************************************
CPU_TXA MACRO
	; Transfer the X register to the A register.
	mov al, CPU.X
	mov CPU.A, al
	test al, al
	
	; Set/clear the sign and zero flags.
	MODIFYFLAGS S, , Z,
ENDM

; ********************************************************************
; *          TXS. Opcode 9A                                          *
; ********************************************************************
CPU_TXS MACRO
	; Transfer the X register to the SP register.
	mov al, CPU.X
	mov CPU.S, al
ENDM

; ********************************************************************
; *          TYA. Opcode 98                                          *
; ********************************************************************
CPU_TYA MACRO
	; Transfer the Y register to the A register.
	mov al, CPU.Y
	mov CPU.A, al
	test al, al
	
	; Set/clear the sign and zero flags.
	MODIFYFLAGS S, , Z,
ENDM





;******************************************************************************
;* Name: _RunCPU
;* Desc: TBA
;******************************************************************************
RunCPU PROC C dwFlags : DWORD
	
	LOCAL dwOpcode : DWORD ; Temporary storage for our opcode.

    ; Save all the registers before entering.
	pushad

RunCPU_RunAgain:

    ; Get the opcode byte.
	GET_MEMORY_BYTE CPU.P

    ; Save the opcode for later use and then jump to the
	; correct opcode using the jump table defined above.
	and eax, 000000FFh
	mov dwOpcode, eax
    jmp [adwOpcodeJumpTable+eax*4]


;********************************** ADC ***************************************
; Add memory to the accumulator with the carry bit as well.

_69::
	GET_ADDR_IMMEDIATE
	CPU_ADC al
	jmp _??

_65::
	GET_ADDR_ZEROPAGE
	GET_MEMORY_BYTE ax
	CPU_ADC al
	jmp _??

_75::
	GET_ADDR_ZEROPAGE_X
	GET_MEMORY_BYTE ax
	CPU_ADC al
	jmp _??

_6D::
	GET_ADDR_ABSOLUTE
	GET_MEMORY_BYTE bx
	CPU_ADC al
    jmp _??

_79::
	GET_ADDR_ABSOLUTE_Y
	GET_MEMORY_BYTE bx
	CPU_ADC al
    jmp _??

_7D::
	GET_ADDR_ABSOLUTE_X
	GET_MEMORY_BYTE bx
	CPU_ADC al
    jmp _??

_61::
	GET_ADDR_PREINDEXED
	GET_MEMORY_BYTE bx
	CPU_ADC al
    jmp _??

_71::
	GET_ADDR_POSTINDEXED
	GET_MEMORY_BYTE bx
	CPU_ADC al
    jmp _??

;********************************** AND ***************************************
; For all the addressing modes except for immediate, get the address 
; of the byte to AND A with, then use that address to get the byte
; and perform the AND operation with it. For the immediate mode,
; just AND the byte with the A register.

_29::
	GET_ADDR_IMMEDIATE
	CPU_AND al
	jmp _??

_25::
	GET_ADDR_ZEROPAGE
	GET_MEMORY_BYTE ax
	CPU_AND al
	jmp _??

_35::
	GET_ADDR_ZEROPAGE_X
	GET_MEMORY_BYTE ax
	CPU_AND al
	jmp _??

_2D::
	GET_ADDR_ABSOLUTE
	GET_MEMORY_BYTE bx
    CPU_AND al
    jmp _??

_39::
	GET_ADDR_ABSOLUTE_Y
	GET_MEMORY_BYTE bx
    CPU_AND al
    jmp _??

_3D::
	GET_ADDR_ABSOLUTE_X
	GET_MEMORY_BYTE bx
    CPU_AND al
    jmp _??

_21::
	GET_ADDR_PREINDEXED
	GET_MEMORY_BYTE bx
    CPU_AND al
    jmp _??

_31::
	GET_ADDR_POSTINDEXED
	GET_MEMORY_BYTE bx
    CPU_AND al
    jmp _??

;********************************** ASL ***************************************
; Perform a logical shift left with least significant bit being filled
; with a zero and the most significant bit going into the carry.
_0A::
	mov ebx, OFFSET (CPU.A)
	CPU_ASL ebx
	jmp _??
	
_06::
	GET_ADDR_ZEROPAGE
	GET_MEMORY_POINTER ax
	mov ebx, eax
	CPU_ASL ebx
	jmp _??
	
_16::
	GET_ADDR_ZEROPAGE_X
	GET_MEMORY_POINTER ax
	mov ebx, eax
	CPU_ASL ebx
	jmp _??

_0E::
	GET_ADDR_ABSOLUTE
	GET_MEMORY_POINTER bx
	mov ebx, eax
	CPU_ASL ebx
	jmp _??

_1E::
	GET_ADDR_ABSOLUTE_X
	GET_MEMORY_POINTER bx
	mov ebx, eax
	CPU_ASL ebx
	jmp _??

;********************************** BCC ***************************************
; Branches to a memory location if the carry flag is clear.
_90::
	GET_ADDR_RELATIVE
	CPU_BCC ax
	jmp _??

;********************************** BCS ***************************************
; Branches to a memory location if the carry flag is set.
_B0::
	GET_ADDR_RELATIVE
	CPU_BCS ax
	jmp _??

;********************************** BEQ ***************************************
; Branches to a memory location if the zero flag is set.
_F0::
	GET_ADDR_RELATIVE
	CPU_BEQ ax
	jmp _??

;********************************** BIT ***************************************
; Ands the operand with the A register and transfers bit 7 and 6 to 
; the flags register.

_24::
	GET_ADDR_ZEROPAGE
	GET_MEMORY_BYTE ax
	CPU_BIT al
	jmp _??
	
_2C::
	GET_ADDR_ABSOLUTE
	GET_MEMORY_BYTE bx
	CPU_BIT al
	jmp _??

;********************************** BMI ***************************************
; Branches to a memory location if the sign flag is set.
_30::
	GET_ADDR_RELATIVE
	CPU_BMI ax
	jmp _??

;********************************** BNE ***************************************
; Branches to a memory location if the zero flag is clear.
_D0::
	GET_ADDR_RELATIVE
	CPU_BNE ax
	jmp _??

;********************************** BPL ***************************************
; Branches to a memory location if the sign flag is clear.
_10::
	GET_ADDR_RELATIVE
	CPU_BPL ax
	jmp _??

;********************************** BRK ***************************************
; Push the PC and flags onto the stack and then jump to the word 
; address specified in the PRG-ROM at $FFFE
_00::
	CPU_BRK
	jmp _??
	
;********************************** BVC ***************************************
; Branches to a memory location if the overflow flag is clear.
_50::
	GET_ADDR_RELATIVE
	CPU_BVC ax
	jmp _??

;********************************** BVS ***************************************
; Branches to a memory location if the overflow flag is set.
_70::
	GET_ADDR_RELATIVE
	CPU_BVS ax
	jmp _??

;********************************** CLC ***************************************
; Clears the carry flag.
_18::
	CPU_CLC
	jmp _??

;********************************** CLD ***************************************
; Clears the decimal flag.
_D8::
	CPU_CLD
	jmp _??

;********************************** CLI ***************************************
; Clears the interrupt flag.
_58::
	CPU_CLI
	jmp _??

;********************************** CLV ***************************************
; Clears the overflow flag.
_B8::
	CPU_CLV
	jmp _??

;********************************** CMP ***************************************
; Compares memory with the A register by using subtraction.

_C9::
	GET_ADDR_IMMEDIATE
	CPU_CP? CPU.A, al
	jmp _??

_C5::
	GET_ADDR_ZEROPAGE
	GET_MEMORY_BYTE ax
	CPU_CP? CPU.A, al
	jmp _??

_D5::
	GET_ADDR_ZEROPAGE_X
	GET_MEMORY_BYTE ax
	CPU_CP? CPU.A, al
	jmp _??

_CD::
	GET_ADDR_ABSOLUTE
	GET_MEMORY_BYTE bx
	CPU_CP? CPU.A, al
    jmp _??

_D9::
	GET_ADDR_ABSOLUTE_Y
	GET_MEMORY_BYTE bx
	CPU_CP? CPU.A, al
    jmp _??

_DD::
	GET_ADDR_ABSOLUTE_X
	GET_MEMORY_BYTE bx
	CPU_CP? CPU.A, al
    jmp _??

_C1::
	GET_ADDR_PREINDEXED
	GET_MEMORY_BYTE bx
	CPU_CP? CPU.A, al
    jmp _??

_D1::
	GET_ADDR_POSTINDEXED
	GET_MEMORY_BYTE bx
	CPU_CP? CPU.A, al
    jmp _??

;********************************** CPX ***************************************
; Compares memory with the X register by using subtraction.

_E0::
	GET_ADDR_IMMEDIATE
	CPU_CP? CPU.X, al
	jmp _??

_E4:: 
	GET_ADDR_ZEROPAGE
	GET_MEMORY_BYTE ax
    CPU_CP? CPU.X, al
	jmp _??

_EC::
	GET_ADDR_ABSOLUTE
	GET_MEMORY_BYTE bx
    CPU_CP? CPU.X, al
    jmp _??

;********************************** CPY ***************************************
; Compares memory with the Y register by using subtraction.

_C0::
	GET_ADDR_IMMEDIATE
	CPU_CP? CPU.Y, al
	jmp _??

_C4:: 
	GET_ADDR_ZEROPAGE
	GET_MEMORY_BYTE ax
    CPU_CP? CPU.Y, al
	jmp _??

_CC::
	GET_ADDR_ABSOLUTE
	GET_MEMORY_BYTE bx
    CPU_CP? CPU.Y, al
    jmp _??

;********************************** DEC ***************************************
; Decrement the value in memory by 1.

_C6::
	GET_ADDR_ZEROPAGE
	GET_MEMORY_POINTER ax
	mov ebx, eax
	CPU_DEC ebx
	jmp _??
_D6::
	GET_ADDR_ZEROPAGE_X
	GET_MEMORY_POINTER ax
	mov ebx, eax
	CPU_DEC ebx
	jmp _??

_CE::
	GET_ADDR_ABSOLUTE
	GET_MEMORY_POINTER bx
	mov ebx, eax
	CPU_DEC ebx
	jmp _??

_DE::
	GET_ADDR_ABSOLUTE_X
	GET_MEMORY_POINTER bx
	mov ebx, eax
	CPU_DEC ebx
	jmp _??

;********************************** DEX ***************************************
; Decrement the value in the X register by one.
_CA::
	CPU_DEX
	jmp _??
	
;********************************** DEY ***************************************
; Decrement the value in the Y register by one.
_88::
	CPU_DEY
	jmp _??
	
;********************************** EOR ***************************************
; Perform a logical exclusive or operation on the memory and the A register
; storing the result in the A register.
_49::
	GET_ADDR_IMMEDIATE
	CPU_EOR al
	jmp _??

_45::
	GET_ADDR_ZEROPAGE
	GET_MEMORY_BYTE ax
	CPU_EOR al
	jmp _??

_55::
	GET_ADDR_ZEROPAGE_X
	GET_MEMORY_BYTE ax
	CPU_EOR al
	jmp _??

_4D::
	GET_ADDR_ABSOLUTE
	GET_MEMORY_BYTE bx
	CPU_EOR al
    jmp _??

_59::
	GET_ADDR_ABSOLUTE_Y
	GET_MEMORY_BYTE bx
	CPU_EOR al
    jmp _??

_5D::
	GET_ADDR_ABSOLUTE_X
	GET_MEMORY_BYTE bx
	CPU_EOR al
    jmp _??

_41::
	GET_ADDR_PREINDEXED
	GET_MEMORY_BYTE bx
	CPU_EOR al
    jmp _??

_51::
	GET_ADDR_POSTINDEXED
	GET_MEMORY_BYTE bx
	CPU_EOR al
    jmp _??

;********************************** INC ***************************************
; Increment the value in memory by 1.

_E6::
	GET_ADDR_ZEROPAGE
	GET_MEMORY_POINTER ax
	mov ebx, eax
	CPU_INC ebx
	jmp _??
_F6::
	GET_ADDR_ZEROPAGE_X
	GET_MEMORY_POINTER ax
	mov ebx, eax
	CPU_INC ebx
	jmp _??

_EE::
	GET_ADDR_ABSOLUTE
	GET_MEMORY_POINTER bx
	mov ebx, eax
	CPU_INC ebx
	jmp _??

_FE::
	GET_ADDR_ABSOLUTE_X
	GET_MEMORY_POINTER bx
	mov ebx, eax
	CPU_INC ebx
	jmp _??

;********************************** INX ***************************************
; Increment the value in the X register by one.
_E8::