bg16ome.asm

NES game Emulator in Linux.c and asm codes.

 xor ecx,ecx
 mov cl,[edx+1]
 mov edx,[RO16ME_BG_Table]
 sub cl,bl
 setz ch

 mov [RO16MER_Next_Pixel],ebx
 mov [RO16MER_Pixel_Count],ecx

 dec al
 je .last_run

.not_last_run:
 mov [RO16ME_Runs_Left],al
 call Render_Offset_16M_Even_Run

 mov edx,[RO16ME_RunListPtr]
 mov edi,[RO16ME_Output]
 xor ebx,ebx
 xor ecx,ecx
 mov bl,[edx+2]

 mov cl,[edx+3]
 add edx,byte 2
 sub cl,bl
 mov [RO16ME_RunListPtr],edx
 mov edx,[RO16ME_BG_Table]

 mov [RO16MER_Next_Pixel],ebx
 mov [RO16MER_Pixel_Count],ecx

 mov al,[RO16ME_Runs_Left]
 dec al
 jne .not_last_run
.last_run:
 call Render_Offset_16M_Even_Run

.done:

 mov ebp,[RO16MER_LineCount]

 mov eax,[RO16ME_Current_Line]
 mov ecx,[RO16ME_Lines]
 mov edx,[RO16ME_Countdown]
 add eax,ebp
 sub edx,ebp
 jne .no_update_linecounter
 mov [RO16ME_Current_Line_Mosaic],eax
.no_update_linecounter:
 mov edi,[RO16ME_BaseDestPtr]
 mov [RO16ME_Current_Line],eax
 mov eax,ebp
 mov [RO16ME_Countdown],edx
 shl eax,8
 lea edx,[edi+ebp*GfxBufferLineSlack]
 add eax,edx
 sub ecx,ebp
 mov [RO16ME_BaseDestPtr],eax
 mov [RO16ME_Lines],ecx

%ifndef LAYERS_PER_LINE
;cmp dword [RO16ME_Lines],0
 jnz .next_line
%endif

 mov edx,[RO16ME_BG_Table]
 mov al,[Tile_Priority_Used]
 mov [Priority_Used+edx],al
 mov ah,[Tile_Priority_Unused]
 mov [Priority_Unused+edx],ah

 add esp,byte RO16ME_Local_Bytes
 ret
%endmacro

Render_Offset_16M_Even 4,8
Render_Offset_16M_Even 4,16

;%1 = label, %2 = priority - 0 = none, 1 = low, 2 = high, %3 = lines,
;%4 = tile height
%macro Plot_Lines_Offset_16M_Even_C4 4
ALIGNC
%if %2 > 0
%%wrong_priority_last:
%if %2 == 1 || %2 == 3
 mov [Tile_Priority_Unused],cl
%endif
 add edi,ecx
 add ebp,ecx
%%return:
 ret

ALIGNC
%1_check:
 pop ebp
 pop ebx
 pop esi

 mov eax,[Mosaic_Size]
%%wrong_priority_same_tile:
 cmp ecx,eax
 jbe %%wrong_priority_last
%if %2 == 1 || %2 == 3
 mov [Tile_Priority_Unused],al
%endif
 add edi,eax
 add ebp,eax
 sub ecx,eax

 cmp ebp,byte 8
 jb %%wrong_priority_same_tile
%endif

%%next_tile:
 mov eax,ebp
 and ebp,byte 7
 shr eax,3
 add eax,eax
 add ebx,eax        ; Update screen pointer
 lea esi,[esi+eax-2]

EXPORT_C %1     ; Define label, entry point
 lea eax,[esi+2]
 mov dh,[1+esi]     ; Offset change map
 push eax
 push ebx
 push ebp

 mov ebp,[RO16ME_FirstTile+RO16ME_Inner+12]
 mov eax,[OffsetChangeVMap_VOffset]
 test dh,[RO16ME_OC_Flag+RO16ME_Inner+12]   ; H-offset enabled?
 jz .have_h_offset
 mov dl,[esi]
 mov ebp,edx
 shr ebp,3
 add ebp,ebp
.have_h_offset:

 mov dh,[1+esi+eax] ; Vertical offset change map
 test dh,[RO16ME_OC_Flag+RO16ME_Inner+12]   ; V-offset enabled?
 jz .No_VChange
 mov dl,[esi+eax]
 mov eax,[RO16ME_Current_Line_Offset+RO16ME_Inner+12]
 add eax,edx

.calc_v_offset:
 and ah,(%4) / 8
 mov esi,[RO16ME_TMapAddress+RO16ME_Inner+12]
 jz .line_in_screen_map_top
 mov esi,[RO16ME_BMapAddress+RO16ME_Inner+12]
.line_in_screen_map_top:

 ; al contains real Y offset for next tile
 push ecx
%if %4 == 8
 mov ecx,0xF8
 mov edx,7
 and ecx,eax
 and eax,byte 7
 sub edx,eax
 lea esi,[esi+ecx*8]    ; Get screen offset
%else
 shl eax,2          ; Get screen offset
 mov ecx,0x1F0*4    ; Current line + V scroll * 32words
 and ecx,eax
 and eax,byte 0x0F*4    ; Offset into table of line offsets
 mov edx,16*8+7
 mov eax,[Tile_Offset_Table_16_8+eax]
 sub edx,eax
 add esi,ecx
%endif
 pop ecx
 jmp .have_v_offset

.LeftEdge:
 push esi
 push ebx
 push ebp

 mov ebp,[RO16ME_FirstTile+RO16ME_Inner+12]

.No_VChange:
 mov eax,[LineAddress]
 mov esi,[RO16ME_MapAddress_Current+RO16ME_Inner+12]
 mov edx,[LineAddressY]

.have_v_offset:
 add ebp,ebx
 mov [RO16ME_LineAddressOffset+RO16ME_Inner+12],eax
 mov ebx,ebp
 and ebp,byte 31*2  ; X offset wrap
 mov [RO16ME_LineAddressOffsetY+RO16ME_Inner+12],edx
 add esi,ebp        ; Combine X and Y offsets into tile map
 and ebx,byte 32*2
 mov ebx,[RO16ME_RMapDifference+RO16ME_Inner+12]
 jz  .tile_in_screen_map_left
 add esi,ebx
.tile_in_screen_map_left:

 mov al,[esi+1]
 Check_Tile_Priority %2, %1_check

 mov ebp,[RO16ME_LineAddressOffsetY+RO16ME_Inner+12]
 test al,al         ; Check Y flip
 mov si,[esi]       ; Get tile #
 js .flip_y
 mov ebp,[RO16ME_LineAddressOffset+RO16ME_Inner+12]

.flip_y:
 shl esi,3
 mov edx,eax
 add esi,ebp
 and edx,byte 7*4   ; Get palette

 mov edx,[palette_4bpl+edx]
 pop ebp

 add al,al      ; Get X flip (now in MSB)
 mov eax,[Mosaic_Size]
 js %%xflip

%%flip_none_same_tile:
 push esi
 push ebp
 and ebp,byte 4
 add ebp,ebp
 add esi,ebp
 xor ebp,byte -1
 and esi,0x3FF * 8 + 7  ; Clip to tileset
 add esi,[TilesetAddress]
 and esi,0xFFFF * 2 / 8 ; Clip to VRAM
 lea esi,[C_LABEL(TileCache4)+esi*8+ebp+1]
 pop ebp

 cmp ecx,eax
 ja %%flip_none_partial
 mov eax,ecx
%%flip_none_partial:
 mov bl,[esi+ebp*2]
 pop esi
%if %2 == 1 || %2 == 3
 mov [Tile_Priority_Used],al
%endif
 and bl,dl
 jz %%flip_none_empty_run

;eax = count, esi = source base, ebp = offset, edi = dest, ecx = # left
;edx = palette, bl = pixel
 add ebp,eax
 sub ecx,eax

%%flip_none_next_pixel:
%assign PLM16E_Dest_Offset 0
%rep %3
 mov [edi+PLM16E_Dest_Offset],bl
%assign PLM16E_Dest_Offset (PLM16E_Dest_Offset + GfxBufferLinePitch)
%endrep
%undef PLM16E_Dest_Offset
 inc edi
 dec eax
 jnz %%flip_none_next_pixel

 mov eax,[Mosaic_Size]
 test ecx,ecx
 jz %%flip_none_return

 cmp ebp,byte 8
 jb %%flip_none_same_tile

 pop ebx
 pop esi
 jmp %%next_tile

%%flip_none_empty_run:
 add edi,eax
 add ebp,eax
 sub ecx,eax
 jz %%flip_none_return

 cmp ebp,byte 8
 jb %%flip_none_same_tile

 pop ebx
 pop esi
 jmp %%next_tile

%%flip_none_return:
 pop ebx
 pop esi
 ret

ALIGNC
%%xflip:
 xor ebp,byte -1
%%flip_x_same_tile:
 push esi
 push ebp
 and ebp,byte 4
 add ebp,ebp
 add esi,ebp
 xor ebp,byte 8
 and esi,0x3FF * 8 + 7  ; Clip to tileset
 add esi,[TilesetAddress]
 and esi,0xFFFF * 2 / 8 ; Clip to VRAM
 lea esi,[C_LABEL(TileCache4)+esi*8+ebp+8]
 pop ebp

 cmp ecx,eax
 ja %%flip_x_partial
 mov eax,ecx
%%flip_x_partial:
 mov bl,[esi+ebp*2]
 pop esi
%if %2 == 1 || %2 == 3
 mov [Tile_Priority_Used],al
%endif
 and bl,dl
 jz %%flip_x_empty_run

;eax = count, esi = source base, ebp = offset, edi = dest, ecx = # left
;edx = palette, bl = pixel
 sub ebp,eax
 sub ecx,eax

%%flip_x_next_pixel:
%assign PLM16E_Dest_Offset 0
%rep %3
 mov [edi+PLM16E_Dest_Offset],bl
%assign PLM16E_Dest_Offset (PLM16E_Dest_Offset + GfxBufferLinePitch)
%endrep
%undef PLM16E_Dest_Offset
 inc edi
 dec eax
 jnz %%flip_x_next_pixel

 mov eax,[Mosaic_Size]
 test ecx,ecx
 jz %%flip_x_return

 cmp ebp,byte ~8
 ja %%flip_x_same_tile

 pop ebx
 pop esi
 xor ebp,byte -1
 jmp %%next_tile

%%flip_x_empty_run:
 add edi,eax
 sub ebp,eax
 sub ecx,eax
 jz %%flip_x_return

 cmp ebp,byte ~8
 ja %%flip_x_same_tile

 pop ebx
 pop esi
 xor ebp,byte -1
 jmp %%next_tile

%%flip_x_return:
 pop ebx
 pop esi
 ret
%endmacro

;%1 = depth, %2 = count, %3 = tile height
%macro Generate_Line_Plotters_Offset_16M_Even 3
%ifndef NO_NP_RENDER
 Plot_Lines_Offset_16M_Even_C%1 Plot_Lines_%2_NP_Offset_16x%3M_Even_C%1,0,%2,%3
%endif
 Plot_Lines_Offset_16M_Even_C%1 Plot_Lines_%2_V_Offset_16x%3M_Even_C%1,3,%2,%3
%endmacro

%macro Generate_Line_Plotters_Offset_16M_Even_Depth 2
%assign GLPO_16ME_Count 1
%rep RO16ME_MAX_LINE_COUNT
Generate_Line_Plotters_Offset_16M_Even %1,GLPO_16ME_Count,%2
%assign GLPO_16ME_Count GLPO_16ME_Count+1
%endrep
%undef GLPO_16ME_Count
%endmacro

Generate_Line_Plotters_Offset_16M_Even_Depth 4,8
Generate_Line_Plotters_Offset_16M_Even_Depth 4,16

section .data
%macro Generate_Line_Plotter_Offsets_16M_Even 4
dd C_LABEL(Plot_Lines_%3_%1_Offset_16x%4M_Even_C%2).LeftEdge
dd C_LABEL(Plot_Lines_%3_%1_Offset_16x%4M_Even_C%2)
%endmacro

;%1 = type, %2 = depth, %3 = tile height
%macro Generate_Line_Plotter_Table_Offset_16M_Even 3
ALIGND
EXPORT_C Plot_Lines_%1_Offset_16x%3M_Even_Table_C%2
%assign GLPTO_16ME_Count 1
%rep RO16ME_MAX_LINE_COUNT
Generate_Line_Plotter_Offsets_16M_Even %1,%2,GLPTO_16ME_Count,%3
%assign GLPTO_16ME_Count GLPTO_16ME_Count+1
%endrep
%undef GLPTO_16ME_Count
%endmacro

%ifndef NO_NP_RENDER
Generate_Line_Plotter_Table_Offset_16M_Even NP,4,8
Generate_Line_Plotter_Table_Offset_16M_Even NP,4,16
%endif

Generate_Line_Plotter_Table_Offset_16M_Even V,4,8
Generate_Line_Plotter_Table_Offset_16M_Even V,4,16

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