screen.asm

NES game Emulator in Linux.c and asm codes.

%macro Check_Present_OBJ 1
 test byte %1,0x10
%endmacro

%macro Jump_Present_OBJ 2
 Check_Present_OBJ %1
 jnz (%2)
%endmacro

%macro Jump_Not_Present_OBJ 2
 Check_Present_OBJ %1
 jz (%2)
%endmacro

%macro Jump_BG3_Highest 1
 cmp byte [C_LABEL(Base_BGMODE)],1
 jne %%not_highest
 test byte [C_LABEL(BGMODE)],8
 jnz (%1)
%%not_highest:
%endmacro

%macro Jump_Not_BG3_Highest 1
 cmp byte [C_LABEL(Base_BGMODE)],1
 jne (%1)
 test byte [C_LABEL(BGMODE)],8
 jz (%1)
%endmacro

;requires current line in ebx, uses cl
%macro Check_Present_OBJ_Priority 1
 mov cl,[OAM_Count_Priority+ebx*4-4+(%1)]
 test cl,cl
%endmacro

%macro Jump_Present_OBJ_Priority 2
 Check_Present_OBJ_Priority (%1)
 jnz (%2)
%endmacro

%macro Jump_Not_Present_OBJ_Priority 2
 Check_Present_OBJ_Priority (%1)
 jz (%2)
%endmacro

%macro Get_Clip_Window 1
 mov esi,[Window_Offset_First+(%1)*4]
%endmacro

%macro Render_SM01 2
 Jump_Not_Present_Layer 4,[SM01_Layers+%1],%%bg4_lo_done
 mov ebx,[SM01_Current_Line]
 mov edi,[SM01_BaseDestPtr]
 mov ebp,%2

 Get_Clip_Window %1

%ifndef NO_EARLY_PRIORITY_ELIMINATION
 Jump_Present_Layer 3,[SM01_Layers+%1],%%bg4_lo_priority
 Jump_Not_Present_OBJ [SM01_Layers+%1],%%bg4_no_priority
 Jump_Present_OBJ_Priority 0,%%bg4_lo_priority

%%bg4_no_priority:
 
 RENDER_LINE_NP 4
 and byte [SM01_Layers+%1],~8
 jmp %%bg3_done

%%bg4_lo_priority:
%endif
 RENDER_LINE 4,0

%%bg4_lo_done:

 Jump_Not_Present_Layer 3,[SM01_Layers+%1],%%bg3_lo_done
 mov ebx,[SM01_Current_Line]
 mov edi,[SM01_BaseDestPtr]
 mov ebp,%2

 Get_Clip_Window %1

%ifndef NO_EARLY_PRIORITY_ELIMINATION
 Jump_BG3_Highest %%bg3_lo_priority
 Jump_Present_Layer 4,[SM01_Layers+%1],%%bg3_lo_priority
 Jump_Not_Present_OBJ [SM01_Layers+%1],%%bg3_no_priority
 Jump_Present_OBJ_Priority 0,%%bg3_lo_priority

%%bg3_no_priority:
 RENDER_LINE_NP 3
 and byte [SM01_Layers+%1],~4
 jmp %%bg3_done

%%bg3_lo_priority:
%endif
 RENDER_LINE 3,0

%%bg3_lo_done:

 Jump_Not_Present_OBJ [SM01_Layers+%1],%%no_sprites_0

 mov ebx,[SM01_Current_Line]
 mov edi,[SM01_BaseDestPtr]
 mov ebp,%2
;inc ebx
 mov dl,0x00
 call Plot_Sprites
%%no_sprites_0:

 Jump_Not_Present_Layer 4,[SM01_Layers+%1],%%bg4_hi_done
 mov ebx,[SM01_Current_Line]
 mov edi,[SM01_BaseDestPtr]
 mov ebp,%2

 Get_Clip_Window %1

 RENDER_LINE 4,1
%%bg4_hi_done:

 Jump_Not_Present_Layer 3,[SM01_Layers+%1],%%bg3_hi_done
 Jump_BG3_Highest %%bg3_hi_done
 mov ebx,[SM01_Current_Line]
 mov edi,[SM01_BaseDestPtr]
 mov ebp,%2

 Get_Clip_Window %1

 RENDER_LINE 3,1
%%bg3_hi_done:
%%bg3_done:

 Jump_Not_Present_OBJ [SM01_Layers+%1],%%no_sprites_1

 mov ebx,[SM01_Current_Line]
 mov edi,[SM01_BaseDestPtr]
 mov ebp,%2
;inc ebx
 mov dl,0x10
 call Plot_Sprites
%%no_sprites_1:

 Jump_Not_Present_Layer 2,[SM01_Layers+%1],%%bg2_lo_done
 mov ebx,[SM01_Current_Line]
 mov edi,[SM01_BaseDestPtr]
 mov ebp,%2

 Get_Clip_Window %1

%ifndef NO_EARLY_PRIORITY_ELIMINATION
 Jump_Present_Layer 1,[SM01_Layers+%1],%%bg2_lo_priority
 Jump_Not_Present_OBJ [SM01_Layers+%1],%%bg2_no_priority
 Jump_Present_OBJ_Priority 2,%%bg2_lo_priority

%%bg2_no_priority:
 RENDER_LINE_NP 2
 and byte [SM01_Layers+%1],~2
 jmp %%bg1_done

%%bg2_lo_priority:
%endif
 RENDER_LINE 2,0

%%bg2_lo_done:

 Jump_Not_Present_Layer 1,[SM01_Layers+%1],%%bg1_lo_done
 mov ebx,[SM01_Current_Line]
 mov edi,[SM01_BaseDestPtr]
 mov ebp,%2

 Get_Clip_Window %1

%ifndef NO_EARLY_PRIORITY_ELIMINATION
 Jump_Present_Layer 2,[SM01_Layers+%1],%%bg1_lo_priority
 Jump_Not_Present_OBJ [SM01_Layers+%1],%%bg1_no_priority
 Jump_Present_OBJ_Priority 2,%%bg1_lo_priority

%%bg1_no_priority:
 RENDER_LINE_NP 1
 and byte [SM01_Layers+%1],~1
 jmp %%bg1_done

%%bg1_lo_priority:
%endif
 RENDER_LINE 1,0

%%bg1_lo_done:

 Jump_Not_Present_OBJ [SM01_Layers+%1],%%no_sprites_2

 mov ebx,[SM01_Current_Line]
 mov edi,[SM01_BaseDestPtr]
 mov ebp,%2
;inc ebx
 mov dl,0x20
 call Plot_Sprites
%%no_sprites_2:

 Jump_Not_Present_Layer 2,[SM01_Layers+%1],%%bg2_hi_done
 mov ebx,[SM01_Current_Line]
 mov edi,[SM01_BaseDestPtr]
 mov ebp,%2

 Get_Clip_Window %1

 RENDER_LINE 2,1
%%bg2_hi_done:

 Jump_Not_Present_Layer 1,[SM01_Layers+%1],%%bg1_hi_done
 mov ebx,[SM01_Current_Line]
 mov edi,[SM01_BaseDestPtr]
 mov ebp,%2

 Get_Clip_Window %1

 RENDER_LINE 1,1
%%bg1_hi_done:
%%bg1_done:

 Jump_Not_Present_OBJ [SM01_Layers+%1],%%no_sprites_3

 mov ebx,[SM01_Current_Line]
 mov edi,[SM01_BaseDestPtr]
 mov ebp,%2
;inc ebx
 mov dl,0x30
 call Plot_Sprites
%%no_sprites_3:

 Jump_Not_BG3_Highest %%bg3_max_done
 Jump_Not_Present_Layer 3,[SM01_Layers+%1],%%bg3_max_done
 mov ebx,[SM01_Current_Line]
 mov edi,[SM01_BaseDestPtr]
 mov ebp,%2

 Get_Clip_Window %1

 RENDER_LINE 3,1
%%bg3_max_done:

%endmacro

ALIGNC
EXPORT_C SCREEN_MODE_0
EXPORT_C SCREEN_MODE_1
 push eax
 push ebx
 push edi
 push ebp
 push eax

.next_line:
 mov edi,[C_LABEL(SNES_Screen8)]    ; (256+16)*(239+1) framebuffer
 ; Clear the framebuffer
 mov ebx,[SM01_BaseDestPtr]
%ifdef LAYERS_PER_LINE
 mov ebp,1
%else
 mov ebp,[SM01_Lines]
%endif

 add edi,ebx

 ; Clear the framebuffer
 call C_LABEL(Clear_Scanlines)

%ifndef LAYERS_PER_LINE
 Render_SM01 0,[SM01_Lines]
 Render_SM01 1,[SM01_Lines]
%else
 Render_SM01 0,1
 Render_SM01 1,1

 mov eax,[SM01_Layers_Copy]
 mov [SM01_Layers],eax

 mov edi,[SM01_BaseDestPtr]
 inc dword [SM01_Current_Line]
 add edi,GfxBufferLinePitch
 dec dword [SM01_Lines]
 mov [SM01_BaseDestPtr],edi
 jnz .next_line
%endif

 add esp,byte SM01_Local_Bytes
 ret

%if 0
 Mode 2 - 2 background layers, 8x8 and 16x16 tile sizes
  4bpl tile depth in layers 1 and 2
  special: offset change data (h and v) stored in layer 3

 Mode 3 - 2 background layers, 8x8 and 16x16 tile sizes
  8bpl tile depth in layer 1, 4bpl tile depth in layer 2
  special: direct color mode

 Mode 4 - 2 background layers, 8x8 and 16x16 tile sizes
  8bpl tile depth in layer 1, 2bpl tile depth in layer 2
  special: direct color mode
           offset change data (h or v?) stored in layer 3

 Mode 5 - 2 background layers, 16x8 and 16x16 tile sizes
  4bpl tile depth in layer 1, 2bpl tile depth in layer 2
  special: 512 mode

 Mode 6 - 1 background layer, 16x8 and 16x16 tile sizes
  4bpl tile depth in layer 1
  special: 512 mode
           offset change data (h and v?) stored in layer 3 (?)
%endif

%define SM26_Local_Bytes 20
%define SM26_Layers_Copy esp+16
%define SM26_Current_Line esp+12
%define SM26_BaseDestPtr esp+8
%define SM26_Lines esp+4
%define SM26_Layers esp

%macro Render_SM26 2
 Jump_Not_Present_Layer 2,[SM26_Layers+%1],%%bg2_lo_done
 mov ebx,[SM26_Current_Line]
 mov edi,[SM26_BaseDestPtr]
 mov ebp,%2

 Get_Clip_Window %1

%ifndef NO_EARLY_PRIORITY_ELIMINATION
 Jump_Present_Layer 1,[SM26_Layers+%1],%%bg2_lo_priority
 Jump_Not_Present_OBJ [SM26_Layers+%1],%%bg2_no_priority
 Jump_Present_OBJ_Priority 0,%%bg2_lo_priority
 Jump_Present_OBJ_Priority 1,%%bg2_lo_priority

%%bg2_no_priority:
 RENDER_LINE_NP 2
 and byte [SM26_Layers+%1],~2
 jmp %%bg2_done

%%bg2_lo_priority:
%endif

 RENDER_LINE 2,0

%%bg2_lo_done:

 Jump_Not_Present_OBJ [SM26_Layers+%1],%%no_sprites_0

 mov ebx,[SM26_Current_Line]
 mov edi,[SM26_BaseDestPtr]
 mov ebp,%2
;inc ebx
 mov dl,0x00
 call Plot_Sprites
%%no_sprites_0:

 Jump_Not_Present_Layer 1,[SM26_Layers+%1],%%bg1_lo_done
 mov ebx,[SM26_Current_Line]
 mov edi,[SM26_BaseDestPtr]
 mov ebp,%2

 Get_Clip_Window %1

%ifndef NO_EARLY_PRIORITY_ELIMINATION
 Jump_Present_Layer 2,[SM26_Layers+%1],%%bg1_lo_priority
 Jump_Not_Present_OBJ [SM26_Layers+%1],%%bg1_no_priority
 Jump_Present_OBJ_Priority 1,%%bg1_lo_priority
 Jump_Present_OBJ_Priority 2,%%bg1_lo_priority

%%bg1_no_priority:
 RENDER_LINE_NP 1
 and byte [SM26_Layers+%1],~1
 jmp %%bg1_done

%%bg1_lo_priority:
%endif
 RENDER_LINE 1,0

%%bg1_lo_done:

 Jump_Not_Present_OBJ [SM26_Layers+%1],%%no_sprites_1

 mov ebx,[SM26_Current_Line]
 mov edi,[SM26_BaseDestPtr]
 mov ebp,%2
;inc ebx
 mov dl,0x10
 call Plot_Sprites
%%no_sprites_1:

 Jump_Not_Present_Layer 2,[SM26_Layers+%1],%%bg2_hi_done
 mov ebx,[SM26_Current_Line]
 mov edi,[SM26_BaseDestPtr]
 mov ebp,%2

 Get_Clip_Window %1

 RENDER_LINE 2,1
%%bg2_hi_done:
%%bg2_done:

 Jump_Not_Present_OBJ [SM26_Layers+%1],%%no_sprites_2

 mov ebx,[SM26_Current_Line]
 mov edi,[SM26_BaseDestPtr]
 mov ebp,%2
;inc ebx
 mov dl,0x20
 call Plot_Sprites
%%no_sprites_2:

 Jump_Not_Present_Layer 1,[SM26_Layers+%1],%%bg1_hi_done
 mov ebx,[SM26_Current_Line]
 mov edi,[SM26_BaseDestPtr]
 mov ebp,%2

 Get_Clip_Window %1

 RENDER_LINE 1,1
%%bg1_hi_done:
%%bg1_done:

 Jump_Not_Present_OBJ [SM26_Layers+%1],%%no_sprites_3

 mov ebx,[SM26_Current_Line]
 mov edi,[SM26_BaseDestPtr]
 mov ebp,%2
;inc ebx
 mov dl,0x30
 call Plot_Sprites
%%no_sprites_3:

%endmacro

EXPORT_C SCREEN_MODE_2
EXPORT_C SCREEN_MODE_3
EXPORT_C SCREEN_MODE_4
EXPORT_C SCREEN_MODE_5
EXPORT_C SCREEN_MODE_6

 push eax
 push ebx
 push edi
 push ebp
 push eax

.next_line:
 mov edi,[C_LABEL(SNES_Screen8)]    ; (256+16)*(239+1) framebuffer
 ; Clear the framebuffer
 mov ebx,[SM26_BaseDestPtr]
%ifdef LAYERS_PER_LINE
 mov ebp,1
%else
 mov ebp,[SM26_Lines]
%endif

 add edi,ebx

 ; Clear the framebuffer
 call C_LABEL(Clear_Scanlines)

%ifndef LAYERS_PER_LINE
 Render_SM26 0,[SM26_Lines]
 Render_SM26 1,[SM26_Lines]
%else
 Render_SM26 0,1
 Render_SM26 1,1

 mov eax,[SM26_Layers_Copy]
 mov [SM26_Layers],eax

 mov edi,[SM26_BaseDestPtr]
 inc dword [SM26_Current_Line]
 add edi,GfxBufferLinePitch
 dec dword [SM26_Lines]
 mov [SM26_BaseDestPtr],edi
 jnz .next_line
%endif

 add esp,byte SM26_Local_Bytes
 ret

section .text
ALIGNC
section .data
ALIGND
section .bss
ALIGNB