cpuexec.s

著名SFC模拟器Snes9x的源代码。

/*
 * Snes9x - Portable Super Nintendo Entertainment System (TM) emulator.
 *
 * (c) Copyright 1996 - 2001 Gary Henderson ([e-mail]) and
 *                           Jerremy Koot ([e-mail])
 *
 * Super FX C emulator code 
 * (c) Copyright 1997 - 1999 Ivar ([e-mail]) and
 *                           Gary Henderson.
 * Super FX assembler emulator code (c) Copyright 1998 zsKnight and _Demo_.
 *
 * DSP1 emulator code (c) Copyright 1998 Ivar, _Demo_ and Gary Henderson.
 * C4 asm and some C emulation code (c) Copyright 2000 zsKnight and _Demo_.
 * C4 C code (c) Copyright 2001 Gary Henderson ([e-mail]).
 *
 * DOS port code contains the works of other authors. See headers in
 * individual files.
 *
 * Snes9x homepage: www.snes9x.com
 *
 * Permission to use, copy, modify and distribute Snes9x in both binary and
 * source form, for non-commercial purposes, is hereby granted without fee,
 * providing that this license information and copyright notice appear with
 * all copies and any derived work.
 *
 * This software is provided 'as-is', without any express or implied
 * warranty. In no event shall the authors be held liable for any damages
 * arising from the use of this software.
 *
 * Snes9x is freeware for PERSONAL USE only. Commercial users should
 * seek permission of the copyright holders first. Commercial use includes
 * charging money for Snes9x or software derived from Snes9x.
 *
 * The copyright holders request that bug fixes and improvements to the code
 * should be forwarded to them so everyone can benefit from the modifications
 * in future versions.
 *
 * Super NES and Super Nintendo Entertainment System are trademarks of
 * Nintendo Co., Limited and its subsidiary companies.
 */
#include "asmstruc.h"
#include "asmops.h"
#include "spcops.h"

.globl MainAsmLoop

.text
	.align 4
.globl S9xMainLoop
S9xMainLoop:
	pushl %ebp
	pushl %edi
	pushl %esi
	pushl %ebx
	LOAD_REGISTERS
.L9:
	cmpb $0,APUExecuting
	je .L12
.apuloop:
	cmpl CYCLES, APUCycles
	jg .L12
#ifdef DEBUGGER
	testb $2,APUFlags
	je .L14
	STORE_REGISTERS
	ccall S9xTraceAPU
	LOAD_REGISTERS
.L14:
#endif
	xorl %eax,%eax
#ifdef SPC700_C
	movl APUPC, %edx
	SAVE_CYCLES
	movb (%edx),%al
#else
	movb (APUPC),%al
#endif
	movl S9xAPUCycles(,%eax,4), %edx
	movl S9xApuOpcodes(,%eax,4),%eax
	addl %edx, APUCycles
	call *%eax
#ifdef SPC700_C
	LOAD_CYCLES
#endif
	jmp .apuloop
.L12:
	cmpl $0, Flags
	je .L15
	movl Flags, %eax
	testb %al, %al
	jge .NO_NMI
	decl NMICycleCount
	jnz .NO_NMI
	andb $~NMI_FLAG, %al
	movl %eax, Flags
	cmpb $0, WaitingForInterrupt
	je .L17
	movb $0, WaitingForInterrupt
	incl PC
.L17:
	call S9xOpcode_NMI
.NO_NMI:
#ifdef DEBUGGER
	testb $BREAK_FLAG, Flags
	jz .NO_BREAK_POINTS
	pushl %esi
	pushl %ebx
	movl $S9xBreakpoint, %esi
	movb PB, %bl
	xorl %edx, %edx
	movl PC, %ecx
	subl PCBase, %ecx

.BREAK_CHECK_LOOP:
	movzwl %dx, %eax
	sall $2, %eax
	cmpb $0, S9xBreakpoint(%eax)
	je .BREAK_MATCH_FAILED
	cmpb %bl, 1(%esi, %eax)
	jne .BREAK_MATCH_FAILED
	movzwl 2(%esi, %eax), %eax
	cmpl %ecx, %eax
	jne .BREAK_MATCH_FAILED
	orb $DEBUG_MODE_FLAG, Flags
.BREAK_MATCH_FAILED:
	incw %dx
	cmpw $6, %dx
	jne .BREAK_CHECK_LOOP
	popl %ebx
	popl %esi
.NO_BREAK_POINTS:
#endif
	testl $IRQ_PENDING_FLAG, Flags
	jz .NO_PENDING_IRQ
	cmpl $0, IRQCycleCount
	jne .DEC_IRQ_CYCLE_COUNT
	testb $0xff, WaitingForInterrupt
	jz .NOT_WAITING
	movb $0, WaitingForInterrupt
	incl PC
.NOT_WAITING:
	testb $0xff, IRQActive
	jz .CLEAR_PENDING_IRQ_FLAG
	testb $0xff, DisableIRQ
	jnz .CLEAR_PENDING_IRQ_FLAG
	testb $IRQ, FLAGS
	jnz .NO_PENDING_IRQ
	call S9xOpcode_IRQ
	jmp .NO_PENDING_IRQ

.CLEAR_PENDING_IRQ_FLAG:
	andl $~IRQ_PENDING_FLAG, Flags
	jmp .NO_PENDING_IRQ

.DEC_IRQ_CYCLE_COUNT:
	decl IRQCycleCount

.NO_PENDING_IRQ:
#ifdef DEBUGGER
	movl Flags, %eax
	testb $DEBUG_MODE_FLAG,%al
	jnz .L31
#else
	movl Flags, %eax
#endif
	testb $SCAN_KEYS_FLAG, %al
	jnz .L31
.L28:
#ifdef DEBUGGER
	testb $TRACE_FLAG, %al
	jz .NO_TRACE
	STORE_REGISTERS
	ccall S9xTrace
	LOAD_REGISTERS
.NO_TRACE:
	movl Flags, %eax
	testb $SINGLE_STEP_FLAG, %al
	jz .L15
	andb $~SINGLE_STEP_FLAG, %al
	orb $DEBUG_MODE_FLAG, %al
	movl %eax, Flags
#endif
.L15:
	xorl %eax,%eax

#ifdef CPU_SHUTDOWN
	movl PC, PCAtOpcodeStart
#endif	
#ifdef VAR_CYCLES
	movb (PC), %al
	addl MemSpeed, CYCLES
#else
	xorl %ecx, %ecx
	movl CPUSpeed, %edx
	movb (PC), %al
	movb (%edx,%eax), %cl
	addl %ecx, CYCLES
#endif
	movl CPUOpcodes, %ecx
	incl PC
	jmp *(%ecx,%eax,4)
MainAsmLoop:
	cmpb $0, SA1Executing
	je .nosa1
	STORE_REGISTERS
	call S9xSA1MainLoop
	LOAD_REGISTERS
.nosa1:
	cmpl NextEvent, CYCLES
	jl .L9
	STORE_REGISTERS
	call S9xDoHBlankProcessing
	LOAD_REGISTERS
	jmp .L9
.L31:
	S9xPackStatus S9xMainLoop
	STORE_REGISTERS
	subl PCBase, PC
	movw %di, PCR
#ifdef SPC700_C
	movl APUPC, %edx
	movl APURAM, %eax
	subl %eax, %edx
	movw %dx, APUPCR
#else
	subl APURAM, APUPC
	movw %bp, APUPCR
#endif
	APUS9xPackStatus S9xMainLoop
	movl Flags, %eax
	testb $SCAN_KEYS_FLAG, %al
	jz .NoScanKeys
	andb $~SCAN_KEYS_FLAG, %al
	movl %eax, Flags
#ifdef DEBUGGER
	testl $FRAME_ADVANCE_FLAG, %eax
	jnz .NoScanKeys
#endif
	ccall S9xSyncSpeed
.NoScanKeys:
	movb BRKTriggered, %al
	andb SuperFXEnabled, %al
	jz .NoSuperFXBrkTest
	andb TriedInterleavedMode2, %al
	jnz .NoSuperFXBrkTest
	movb $1, TriedInterleavedMode2
	movb $0, BRKTriggered
	call S9xDeinterleaveMode2
.NoSuperFXBrkTest:
	popl %ebx
	popl %esi
	popl %edi
	popl %ebp

	ret

.globl S9xDoHBlankProcessing

S9xDoHBlankProcessing:
	pushl %edi
	pushl %esi
	pushl %ebx
#ifdef CPU_SHUTDOWN
	incl WaitCounter
#endif
	movb WhichEvent,%bl
	cmpb $1,%bl
	je .hblank_end
	jg .L196
	testb %bl,%bl
	jz .hblank_start
	jmp .reschedule
.L196:
	cmpb $3,%bl
	jle .htimer_trigger
	jmp .reschedule
.hblank_start:
	movb HDMA,%dl
	testb %dl,%dl
	je .reschedule
	movl V_Counter, %eax
	cmpw ScreenHeight, %ax
	ja .reschedule 
	xorl %eax,%eax
	movb %dl,%al
	pushl %eax
	ccall S9xDoHDMA
	movb %al,HDMA
	addl $4,%esp
	jmp .reschedule
.hblank_end:
	ccall S9xSuperFXExec
	testb $0xff, SoundSync
	jz .nosoundsync
	ccall S9xGenerateSound
.nosoundsync:
	movl H_Max,%eax
	subl %eax, Cycles
	cmpb $0, APUExecuting
	je .apunotrunning
	subl %eax, APUCycles
	jmp .apucycleskip
.apunotrunning:
	movl $0, APUCycles
.apucycleskip:	
	movl V_Counter,%ecx
	incl %ecx
	incl Scanline
	movl $-1,NextEvent
	movl %ecx,V_Counter
	testb $0xff, PAL
	jz .ntsc_tv
	cmpl $312,%ecx
	jbe .L161
	jmp .endofframe
.ntsc_tv:
	cmpl $262,%ecx
	jbe .L161
.endofframe:
	movw SavedOAMAddr,%ax
	xorl %edx,%edx
	movl Flags,%ecx
	movw %ax,OAMAddr
	movb %dl,OAMFlip
	movb %dl,NMIActive
	orl $16,%ecx
	movl %edx,V_Counter
	movb %dl,HVBeamCounterLatched
	movl %ecx,Flags
	ccall S9xStartHDMA
.L161:
	movb VTimerEnabled,%al
	testb %al,%al
	je .L162
	movb HTimerEnabled,%dl
	testb %dl,%dl
	jne .L162
	xorl %eax,%eax
	movw IRQVBeamPos,%ax
	movl V_Counter,%ecx
	cmpl %eax,%ecx
	jne .L162
	
	pushl $2
	call S9xSetIRQ
	addl $4, %esp

.L162:
	xorl %eax,%eax
	movl V_Counter,%edx
	movw ScreenHeight,%ax
	incl %eax
	cmpl %eax,%edx
	jne .L165
	ccall S9xEndScreenRefresh
	movb Brightness,%al
	xorl %ecx,%ecx
	movb %al,MaxBrightness
	movb %cl,FirstSprite
	movl FillRAM,%eax
	movb %cl,HDMA
	movb 0x2100(%eax),%cl
	movb 0x4200(%eax),%dl
	shrb $7,%cl
	movb %cl,ForcedBlanking
	movb $0x80, 0x4210(%eax)
	testb %dl,%dl
	jge .L165
	orl $NMI_FLAG, Flags
	movb $1, NMIActive
	movl NMITriggerPoint, %eax
	movl %eax, NMICycleCount
.L165:
	xorl %eax, %eax
	movw ScreenHeight,%ax
	addl $3,%eax
	cmpl V_Counter,%eax
	jne .NoJoypadUpdate
	ccall S9xUpdateJoypads
.NoJoypadUpdate:
	movl V_Counter,%eax
	cmpl $1,%eax
	jne .L177
	movl FillRAM,%eax
	andl $~NMI_FLAG,Flags
	movb $0,0x4210(%eax)
	ccall S9xStartScreenRefresh
.L177:
	movl V_Counter,%edx
	testl %edx,%edx
	je .L178
	xorl %eax,%eax
	movw ScreenHeight,%ax
	incl %eax
	cmpl %eax,%edx
	jae .L178
	movb V_Counter,%al
	decb %al
	andl $255,%eax
	pushl %eax
	ccall RenderLine
	addl $4,%esp
.L178:
#if 0
	movl APUTimerErrorCounter,%eax
	incl %eax
	movl %eax,APUTimerErrorCounter
	andl $31,%eax
	jz .reschedule
#endif

	movb APUTimerEnabled + 2,%cl
	testb %cl,%cl
	je .L179
	movw APUTimer + 4,%ax
	addl $4,%eax
	movw %ax,APUTimer + 4
	cmpw %ax,APUTimerTarget + 4
	ja .L179
.L182:
	movl APURAM,%edx
	movb 255(%edx),%al
	incb %al
	andb $15,%al
	movb %al,255(%edx)
	movw APUTimerTarget + 4,%dx
	movw APUTimer + 4,%ax
	movl APUWaitCounter,%ecx
	subl %edx,%eax
	incl %ecx
	movb $1,APUExecuting
	movw %ax,APUTimer + 4
	movl %ecx,APUWaitCounter
	cmpw %dx,%ax
	jae .L182
.L179:
	testb $1,V_Counter
	je .reschedule
	movb APUTimerEnabled,%al
	testb %al,%al
	je .L185
	incw APUTimer
	movw APUTimerTarget,%ax
	cmpw %ax,APUTimer
	jb .L185
	movl APURAM,%edx
	movb 253(%edx),%al
	incb %al
	andb $15,%al
	movb %al,253(%edx)
	movl APUWaitCounter,%edx
	incl %edx
	movw $0,APUTimer
	movb $1,APUExecuting
	movl %edx,APUWaitCounter
.L185:
	movb APUTimerEnabled + 1,%al
	testb %al,%al
	je .reschedule
	incw APUTimer + 2
	movw APUTimerTarget + 2,%ax
	cmpw %ax,APUTimer + 2
	jb .reschedule
	movl APURAM,%edx
	movb 254(%edx),%al
	incb %al
	andb $15,%al
	movb %al,254(%edx)
	movl APUWaitCounter,%edx
	incl %edx
	movw $0,APUTimer + 2
	movb $1,APUExecuting
	movl %edx,APUWaitCounter
	jmp .reschedule
.htimer_trigger:
	cmpb $0, HTimerEnabled
	je .reschedule
	cmpb $0, VTimerEnabled
	je .L191
	xorl %eax,%eax
	movw IRQVBeamPos,%ax
	movl V_Counter,%edx
	cmpl %eax,%edx
	jne .reschedule
.L191:
	// CHANGED: 20/11/00
	pushl $1
	call S9xSetIRQ
	addl $4, %esp

.reschedule:
	cmpb $0, WhichEvent
	je .next_is_hblank_end
	cmpb $3, WhichEvent
	jne .next_is_hblank_start
.next_is_hblank_end:
	movb $1,%bl
	movl H_Max,%edx
	jmp .skip
.next_is_hblank_start:
	xorl %ebx,%ebx
	movl HBlankStart,%edx
.skip:
	cmpb $0, HTimerEnabled
	je .not_enabled
	movswl HTimerPosition,%esi
	cmpl %edx,%esi
	jge .not_enabled
	movl NextEvent,%eax
	cmpl %eax,%esi
	jle .not_enabled
	cmpb $0, VTimerEnabled
	je .enabled
	xorl %eax,%eax
	movw IRQVBeamPos,%ax
	movl V_Counter,%ecx
	cmpl %eax,%ecx
	jne .not_enabled
.enabled:
	movb $2,%bl
	cmpl %esi, HBlankStart
	jg .before
	movb $3,%bl
.before:
	movl %esi,%edx
.not_enabled:
	movb %bl,WhichEvent
	popl %ebx
	popl %esi
	movl %edx,NextEvent
	popl %edi
	ret

.text
	.align 4
.globl S9xSetIRQ
S9xSetIRQ:
	movl 4(%esp), %eax
	orb %al,IRQActive
	// CHANGED: 20/11/00
	movl $3, IRQCycleCount
	orl $IRQ_PENDING_FLAG, Flags
	cmpb $0, WaitingForInterrupt
	je .NoIncPC
	movb $0, WaitingForInterrupt
	// IRQ must trigger immediately after a WAI instruction - 
	// Final Fantasy Mystic Quest requires this.
	movl $0, IRQCycleCount
	incl PCS
.NoIncPC:
	ret

.globl S9xClearIRQ
S9xClearIRQ:
	movl 4(%esp), %eax
	xorl $~0, %eax
	andb IRQActive, %al
	movb %al, IRQActive
	jnz .irqsstillpending
	andl $~IRQ_PENDING_FLAG, Flags	
.irqsstillpending:
	ret