mirror of
https://github.com/OpenSourcedGames/Heretic.git
synced 2026-09-22 12:30:16 +02:00
inital import
This commit is contained in:
Alex Bevilacqua
@@ -0,0 +1,258 @@
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.386
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.MODEL small
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INCLUDE defs.inc
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;============================================================================
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;
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; unwound vertical scaling code
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;
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; eax light table pointer, 0 lowbyte overwritten
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; ebx all 0, low byte overwritten
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; ecx fractional step value
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; edx fractional scale value
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; esi start of source pixels
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; edi bottom pixel in screenbuffer to blit into
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;
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; ebx should be set to 0 0 0 dh to feed the pipeline
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;
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; The graphics wrap vertically at 128 pixels
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;============================================================================
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.DATA
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EXTRN _centery:DWORD
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SCALEDEFINE MACRO number
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dd vscale&number
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ENDM
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ALIGN 4
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scalecalls LABEL
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LINE = 0
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REPT SCREENHEIGHT+1
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SCALEDEFINE %LINE
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LINE = LINE+1
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ENDM
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;=================================
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.CODE
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;================
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;
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; R_DrawColumn
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;
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;================
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PROC R_DrawColumn_
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PUBLIC R_DrawColumn_
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PUSHR
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mov ebp,[_dc_yh]
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mov ebx,ebp
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mov edi,[_ylookup+ebx*4]
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mov ebx,[_dc_x]
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add edi,[_columnofs + ebx*4]
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mov eax,[_dc_yl]
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sub ebp,eax ; ebp = pixel count
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or ebp,ebp
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js done
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mov ecx,[_dc_iscale]
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sub eax,[_centery]
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imul ecx
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mov edx,[_dc_texturemid]
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add edx,eax
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shl edx,9 ; 7 significant bits, 25 frac
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shl ecx,9 ; 7 significant bits, 25 frac
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mov esi,[_dc_source]
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mov eax,[_dc_colormap]
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xor ebx,ebx
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shld ebx,edx,7 ; get address of first location
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call [scalecalls+4+ebp*4]
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done:
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POPR
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ret
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;============ HIGH DETAIL ============
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SCALELABEL MACRO number
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vscale&number:
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ENDM
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LINE = SCREENHEIGHT
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REPT SCREENHEIGHT-1
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SCALELABEL %LINE
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mov al,[esi+ebx] ; get source pixel
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add edx,ecx ; calculate next location
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mov al,[eax] ; translate the color
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; xor ebx,ebx
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; shld ebx,edx,7 ; get address of next location
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mov ebx,edx
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shr ebx,25
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mov [edi-(LINE-1)*SCREENWIDTH],al ; draw a pixel to the buffer
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LINE = LINE-1
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ENDM
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vscale1:
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mov al,[esi+ebx]
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mov al,[eax]
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mov [edi],al
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vscale0:
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ret
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ENDP
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;============================================================================
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;
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; unwound horizontal texture mapping code
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;
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; eax lighttable
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; ebx scratch register
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; ecx position 6.10 bits x, 6.10 bits y
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; edx step 6.10 bits x, 6.10 bits y
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; esi start of block
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; edi dest
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; ebp fff to mask bx
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;
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; ebp should by preset from ebx / ecx before calling
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;============================================================================
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OP_SHLD = 0fh
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.DATA
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MAPDEFINE MACRO number
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dd hmap&number
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ENDM
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ALIGN 4
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mapcalls LABEL
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LINE = 0
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REPT SCREENWIDTH+1
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MAPDEFINE %LINE
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LINE = LINE+1
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ENDM
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callpoint dd 0
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returnpoint dd 0
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.CODE
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;================
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;
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; R_DrawSpan
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;
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; Horizontal texture mapping
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;
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;================
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PROC R_DrawSpan_
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PUBLIC R_DrawSpan_
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PUSHR
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IFE SKIPPRIMITIVES
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mov eax,[_ds_x1]
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mov ebx,[_ds_x2]
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mov eax,[mapcalls+eax*4]
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mov [callpoint],eax ; spot to jump into unwound
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mov eax,[mapcalls+4+ebx*4]
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mov [returnpoint],eax ; spot to patch a ret at
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mov BYTE PTR [eax], OP_RET
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;
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; build composite position
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;
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mov ecx,[_ds_xfrac]
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shl ecx,10
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and ecx,0ffff0000h
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mov eax,[_ds_yfrac]
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shr eax,6
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and eax,0ffffh
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or ecx,eax
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;
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; build composite step
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;
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mov edx,[_ds_xstep]
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shl edx,10
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and edx,0ffff0000h
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mov eax,[_ds_ystep]
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shr eax,6
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and eax,0ffffh
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or edx,eax
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mov esi,[_ds_source]
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mov edi,[_ds_y]
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mov edi,[_ylookup+edi*4]
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add edi,[_columnofs]
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mov eax,[_ds_colormap]
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;
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; feed the pipeline and jump in
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;
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mov ebp,0fffh ; used to mask off slop high bits from position
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shld ebx,ecx,22 ; shift y units in
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shld ebx,ecx,6 ; shift x units in
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and ebx,ebp ; mask off slop bits
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call [callpoint]
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mov ebx,[returnpoint]
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mov BYTE PTR [ebx],OP_MOVAL ; remove the ret patched in
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ENDIF
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POPR
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ret
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;============= HIGH DETAIL ============
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.CODE
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MAPLABEL MACRO number
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hmap&number:
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ENDM
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LINE = 0
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PCOL = 0
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REPT SCREENWIDTH/4
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PLANE = 0
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REPT 4
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MAPLABEL %LINE
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LINE = LINE + 1
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mov al,[esi+ebx] ; get source pixel
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shld ebx,ecx,22 ; shift y units in
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shld ebx,ecx,6 ; shift x units in
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mov al,[eax] ; translate color
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and ebx,ebp ; mask off slop bits
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add ecx,edx ; position += step
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mov [edi+PLANE+PCOL*4],al ; write pixel
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PLANE = PLANE + 1
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ENDM
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PCOL = PCOL + 1
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ENDM
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hmap320:
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ret
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ENDP
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END
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