fxemu2c.asm

著名SFC模拟器Snes9x的源代码。

NEWSYM FxOpd48      ; LDW RN load word from RAM
   LDWRNc 8
NEWSYM FxOpd49      ; LDW RN load word from RAM
   LDWRNc 9
NEWSYM FxOpd4A      ; LDW RN load word from RAM
   LDWRNc 10
NEWSYM FxOpd4B      ; LDW RN load word from RAM
   LDWRNc 11

NEWSYM FxOpd40A1    ; LDB RN load byte from RAM
   LDBRNc 0   
NEWSYM FxOpd41A1    ; LDB RN load byte from RAM
   LDBRNc 1 
NEWSYM FxOpd42A1    ; LDB RN load byte from RAM
   LDBRNc 2   
NEWSYM FxOpd43A1    ; LDB RN load byte from RAM
   LDBRNc 3   
NEWSYM FxOpd44A1    ; LDB RN load byte from RAM
   LDBRNc 4   
NEWSYM FxOpd45A1    ; LDB RN load byte from RAM
   LDBRNc 5
NEWSYM FxOpd46A1    ; LDB RN load byte from RAM
   LDBRNc 6   
NEWSYM FxOpd47A1    ; LDB RN load byte from RAM
   LDBRNc 7   
NEWSYM FxOpd48A1    ; LDB RN load byte from RAM
   LDBRNc 8
NEWSYM FxOpd49A1    ; LDB RN load byte from RAM
   LDBRNc 9
NEWSYM FxOpd4AA1    ; LDB RN load byte from RAM
   LDBRNc 10
NEWSYM FxOpd4BA1    ; LDB RN load byte from RAM
   LDBRNc 11

EXTSYM fxbit01,fxbit23,fxbit45,fxbit67
EXTSYM fxxand

NEWSYM FxOpd4C1284b       ; PLOT 4bit
   plotlines4bb plotb
NEWSYM FxOpd4C1284bz      ; PLOT 4bit, zero check
   plotlines4bb plotbz
NEWSYM FxOpd4C1284bd      ; PLOT 4bit, dither
   plotlines4bb plotbd
NEWSYM FxOpd4C1284bzd     ; PLOT 4bit, zero check + dither
   plotlines4bb plotbzd

NEWSYM FxOpd4C1282b       ; PLOT 2bit
   plotlines2bb plotb
NEWSYM FxOpd4C1282bz      ; PLOT 2bit, zero check
   plotlines2bb plotbz
NEWSYM FxOpd4C1282bd      ; PLOT 2bit, dither
   plotlines2bb plotbd
NEWSYM FxOpd4C1282bzd     ; PLOT 2bit, zero check + dither
   plotlines2bb plotbzd

NEWSYM FxOpd4C1288b       ; PLOT 8bit
   plotlines8bb plotb
NEWSYM FxOpd4C1288bz      ; PLOT 8bit, zero check
   plotlines8bb plotbz
NEWSYM FxOpd4C1288bd      ; PLOT 8bit, dither
   plotlines8bb plotb
NEWSYM FxOpd4C1288bzd     ; PLOT 8bit, zero check + dither
   plotlines8bb plotbz

NEWSYM FxOpd4C1288bl       ; PLOT 8bit
   plotlines8bbl plotb
NEWSYM FxOpd4C1288bzl      ; PLOT 8bit, zero check
   plotlines8bbl plotbz
NEWSYM FxOpd4C1288bdl      ; PLOT 8bit, dither
   plotlines8bbl plotb
NEWSYM FxOpd4C1288bzdl     ; PLOT 8bit, zero check + dither
   plotlines8bbl plotbz

NEWSYM FxOpd4C      ; PLOT   plot pixel with R1,R2 as x,y and the color register as the color
   jmp FxOpd4C1284b

   FETCHPIPE
   inc ebp
   CLRFLAGS
   mov ebx,[SfxR2]
   mov bh,[SfxR1]
   mov eax,[sfxclineloc]
   mov ebx,[eax+ebx*4]
   cmp ebx,0FFFFFFFFh
   je near .nodraw
   xor eax,eax
   ; bits 5/2 : 00 = 128 pixels, 01 = 160 pixels, 10 = 192 pixels, 11 = obj
   ; bits 1/0 : 00 = 4 color, 01 = 16-color, 10 = not used, 11 = 256 color
   ; 192 pixels = 24 tiles, 160 pixels = 20 tiles, 128 pixels = 16 tiles
   ;              16+8(4/3)              16+4(4/2)              16(4/0)
   push ecx
   mov al,[SfxSCMR]
   and al,00000011b     ; 4 + 32
   cmp al,0
   je near .colors4
   cmp al,3
   je near .colors256

   shl ebx,5    ; x32 (16 colors)
   mov al,[SfxSCBR]
   shl eax,10   ; Get SFX address
   add eax,ebx
   add eax,[sfxramdata]
   mov ebx,[SfxR2]
   and ebx,07h
   shl ebx,1
   add eax,ebx
   mov cl,[SfxR1]
   and cl,07h
   xor cl,07h
   mov bl,1
   shl bl,cl
   mov bh,bl
   xor bh,0FFh
   pop ecx
   test byte[SfxPOR],01h
   jnz .nozerocheck_16
   test byte[SfxCOLR],0Fh
   jz .nodraw
.nozerocheck_16
   mov dl,[SfxCOLR]
   test byte[SfxPOR],02h
   jz .nodither4b
   mov dh,[SfxR1]
   xor dh,[SfxR2]
   test dh,01h
   jz .nodither4b
   shr dh,4
.nodither4b
   and byte[eax],bh
   and byte[eax+1],bh
   and byte[eax+16],bh
   and byte[eax+17],bh
   test dl,01h
   jz .nodraw_16
   or byte[eax],   bl
.nodraw_16
   test dl,02h
   jz .nodraw2_16
   or byte[eax+1], bl
.nodraw2_16
   test dl,04h
   jz .nodraw3_16
   or byte[eax+16],bl
.nodraw3_16
   test dl,08h
   jz .nodraw4_16
   or byte[eax+17],bl
.nodraw4_16
.nodraw
   inc word [SfxR1]
   FXReturn

.colors4
   shl ebx,4    ; x16 (4 colors)
   mov al,[SfxSCBR]
   shl eax,10   ; Get SFX address
   add eax,ebx
   add eax,[sfxramdata]
   mov ebx,[SfxR2]
   and ebx,07h
   shl ebx,1
   add eax,ebx
   mov cl,[SfxR1]
   and cl,07h
   xor cl,07h
   mov bl,1
   shl bl,cl
   mov bh,bl
   xor bh,0FFh
   pop ecx
   test byte[SfxPOR],01h
   jnz .nozerocheck_4
   test byte[SfxCOLR],03h
   jz .noplot_4
.nozerocheck_4
   mov dl,[SfxCOLR]
   test byte[SfxPOR],02h
   jz .nodither2b
   mov dh,[SfxR1]
   xor dh,[SfxR2]
   test dh,01h
   jz .nodither2b
   shr dh,4
.nodither2b
   and byte[eax],bh
   and byte[eax+1],bh
   test dl,01h
   jz .nodraw_4
   or byte[eax],   bl
.nodraw_4
   test dl,02h
   jz .nodraw2_4
   or byte[eax+1], bl
.nodraw2_4
.noplot_4
   inc word [SfxR1]
   FXReturn

.colors256
   shl ebx,6    ; x64 (256 colors)
   mov al,[SfxSCBR]
   shl eax,10   ; Get SFX address
   add eax,ebx
   add eax,[sfxramdata]
   mov ebx,[SfxR2]
   and ebx,07h
   shl ebx,1
   add eax,ebx
   mov cl,[SfxR1]
   and cl,07h
   xor cl,07h
   mov bl,1
   shl bl,cl
   mov bh,bl
   xor bh,0FFh
   pop ecx
   test byte[SfxPOR],01h
   jnz .nozerocheck_256
   mov dl,0FFh
   test byte[SfxPOR],08h
   jz .nozerocheckb_256
   mov dl,0Fh
.nozerocheckb_256
   test byte[SfxCOLR],dl
   jz .noplot_256
.nozerocheck_256
   mov dl,[SfxCOLR]
   and byte[eax],bh
   and byte[eax+1],bh
   and byte[eax+16],bh
   and byte[eax+17],bh
   and byte[eax+32],bh
   and byte[eax+33],bh
   and byte[eax+48],bh
   and byte[eax+49],bh
   test dl,01h
   jz .nodraw_256
   or byte[eax],   bl
.nodraw_256
   test dl,02h
   jz .nodraw2_256
   or byte[eax+1], bl
.nodraw2_256
   test dl,04h
   jz .nodraw3_256
   or byte[eax+16],bl
.nodraw3_256
   test dl,08h
   jz .nodraw4_256
   or byte[eax+17],bl
.nodraw4_256
   test dl,10h
   jz .nodraw5_256
   or byte[eax+32],   bl
.nodraw5_256
   test dl,20h
   jz .nodraw6_256
   or byte[eax+33], bl
.nodraw6_256
   test dl,40h
   jz .nodraw7_256
   or byte[eax+48],bl
.nodraw7_256
   test dl,80h
   jz .nodraw8_256
   or byte[eax+49],bl
.nodraw8_256
.noplot_256
   inc word [SfxR1]
   FXReturn

.prevx dw 0
.prevy dw 0

NEWSYM FxOpd4CA1    ; RPIX   read color of the pixel with R1,R2 as x,y
   FETCHPIPE
   mov ebx,[SfxR2]
   mov bh,[SfxR1]
   test byte[SfxPOR],10h
   jnz .objmode
   mov al,[SfxSCMR]
   and al,00100100b     ; 4 + 32
   cmp al,4
   je .lines160
   cmp al,32
   je .lines192
   cmp al,36
   je .objmode
   mov eax,[sfx128lineloc]
   jmp .donelines
.lines160
   mov eax,[sfx160lineloc]
   jmp .donelines
.lines192
   mov eax,[sfx192lineloc]
   jmp .donelines
.objmode
   mov eax,[sfxobjlineloc]
.donelines
   mov ebx,[eax+ebx*4]
   cmp ebx,0FFFFFFFFh
   je near .nodraw
   xor eax,eax
   ; bits 5/2 : 00 = 128 pixels, 01 = 160 pixels, 10 = 192 pixels, 11 = obj
   ; bits 1/0 : 00 = 4 color, 01 = 16-color, 10 = not used, 11 = 256 color
   ; 192 pixels = 24 tiles, 160 pixels = 20 tiles, 128 pixels = 16 tiles
   ;              16+8(4/3)              16+4(4/2)              16(4/0)
   push ecx
   mov al,[SfxSCMR]
   and al,00000011b     ; 4 + 32

   cmp al,0
   je near .colors4
   cmp al,3
   je near .colors256

   shl ebx,5    ; x32 (16 colors)
   mov al,[SfxSCBR]
   shl eax,10   ; Get SFX address
   add eax,ebx
   add eax,[sfxramdata]
   mov ebx,[SfxR2]
   and ebx,07h
   shl ebx,1
   add eax,ebx
   mov cl,[SfxR1]
   and cl,07h
   xor cl,07h
   mov bl,1
   shl bl,cl
   pop ecx
   xor bh,bh
   test byte[eax],bl
   jz .nodraw_16
   or bh,01h
.nodraw_16
   test byte[eax+1],bl
   jz .nodraw2_16
   or bh,02h
.nodraw2_16
   test byte[eax+16],bl
   jz .nodraw3_16
   or bh,04h
.nodraw3_16
   test byte[eax+17],bl
   jz .nodraw4_16
   or bh,08h
.nodraw4_16
.nodraw
   mov bl,bh
   and ebx,0FFh
   inc ebp
;   UpdateR14
   CLRFLAGS
   mov [edi],ebx            ; Write Destination
   mov [flagnz],ebx
   FXReturn

.colors4
   shl ebx,4    ; x16 (4 colors)
   mov al,[SfxSCBR]
   shl eax,10   ; Get SFX address
   add eax,ebx
   add eax,[sfxramdata]
   mov ebx,[SfxR2]
   and ebx,07h
   shl ebx,1
   add eax,ebx
   mov cl,[SfxR1]
   and cl,07h
   xor cl,07h
   mov bl,1
   shl bl,cl
   mov bh,bl
   xor bh,0FFh
   pop ecx
   xor bh,bh
   test byte[eax],bl
   jz .nodraw_4
   or bh,01h
.nodraw_4
   test byte[eax+1],bl
   jz .nodraw2_4
   or bh,02h
.nodraw2_4
   mov bl,bh
   and ebx,0FFh
   inc ebp
;   UpdateR14
   CLRFLAGS
   mov [edi],ebx            ; Write Destination
   mov [flagnz],ebx
   FXReturn

.colors256
   shl ebx,6    ; x64 (256 colors)
   mov al,[SfxSCBR]
   shl eax,10   ; Get SFX address
   add eax,ebx
   add eax,[sfxramdata]
   mov ebx,[SfxR2]
   and ebx,07h
   shl ebx,1
   add eax,ebx
   mov cl,[SfxR1]
   and cl,07h
   xor cl,07h
   mov bl,1
   shl bl,cl
   mov bh,bl
   xor bh,0FFh
   pop ecx
   xor bh,bh
   test byte[eax],bl
   jz .nodraw_256
   or bh,01h
.nodraw_256
   test byte[eax+1],bl
   jz .nodraw2_256
   or bh,02h
.nodraw2_256
   test byte[eax+16],bl
   jz .nodraw3_256
   or bh,04h
.nodraw3_256
   test byte[eax+17],bl
   jz .nodraw4_256
   or bh,08h
.nodraw4_256
   test byte[eax+32],bl
   jz .nodraw5_256
   or bh,10h
.nodraw5_256
   test byte[eax+33],bl
   jz .nodraw6_256
   or bh,20h
.nodraw6_256
   test byte[eax+48],bl
   jz .nodraw7_256
   or bh,40h
.nodraw7_256
   test byte[eax+49],bl
   jz .nodraw8_256
   or bh,80h
.nodraw8_256
   mov bl,bh
   and ebx,0FFh
   inc ebp
;   UpdateR14
   CLRFLAGS
   mov [edi],ebx            ; Write Destination
   mov [flagnz],ebx
   FXReturn

NEWSYM FxOpd4D      ; SWAP   swap upper and lower byte of a register    ; V
   mov eax,[esi]            ; Read Source
   FETCHPIPE
   ror ax,8   
   inc ebp                ; Increase program counter
   mov [SfxSignZero],eax
   mov [edi],eax            ; Write Destination
   CLRFLAGS
   FXReturn

NEWSYM FxOpd4E      ; COLOR  copy source register to color register     ; V
   FETCHPIPE
   mov eax,[esi]            ; Read Source
   ; if bit 3 of SfxPOR is set, then don't modify the upper 4 bits
   test byte[SfxPOR],04h
   jz .nohighnibble
   mov bl,al
   shr bl,4