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SRB2/src/tmap.nas
James R 7060083db5 Update copyright year to 2020
2020-02-19 14:08:45 -08:00

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;; SONIC ROBO BLAST 2
;;-----------------------------------------------------------------------------
;; Copyright (C) 1998-2000 by DooM Legacy Team.
;; Copyright (C) 1999-2020 by Sonic Team Junior.
;;
;; This program is free software distributed under the
;; terms of the GNU General Public License, version 2.
;; See the 'LICENSE' file for more details.
;;-----------------------------------------------------------------------------
;; FILE:
;; tmap.nas
;; DESCRIPTION:
;; Assembler optimised rendering code for software mode.
;; Draw wall columns.
[BITS 32]
%define FRACBITS 16
%define TRANSPARENTPIXEL 255
%ifdef LINUX
%macro cextern 1
[extern %1]
%endmacro
%macro cglobal 1
[global %1]
%endmacro
%else
%macro cextern 1
%define %1 _%1
[extern %1]
%endmacro
%macro cglobal 1
%define %1 _%1
[global %1]
%endmacro
%endif
; The viddef_s structure. We only need the width field.
struc viddef_s
resb 12
.width: resb 4
resb 44
endstruc
;; externs
;; columns
cextern dc_x
cextern dc_yl
cextern dc_yh
cextern ylookup
cextern columnofs
cextern dc_source
cextern dc_texturemid
cextern dc_texheight
cextern dc_iscale
cextern dc_hires
cextern centery
cextern centeryfrac
cextern dc_colormap
cextern dc_transmap
cextern colormaps
cextern vid
cextern topleft
; DELME
cextern R_DrawColumn_8
; polygon edge rasterizer
cextern prastertab
[SECTION .data]
;;.align 4
loopcount dd 0
pixelcount dd 0
tystep dd 0
[SECTION .text]
;;----------------------------------------------------------------------
;;
;; R_DrawColumn : 8bpp column drawer
;;
;; New optimised version 10-01-1998 by D.Fabrice and P.Boris
;; Revised by G. Dick July 2010 to support the intervening twelve years'
;; worth of changes to the renderer. Since I only vaguely know what I'm
;; doing, this is probably rather suboptimal. Help appreciated!
;;
;;----------------------------------------------------------------------
;; fracstep, vid.width in memory
;; eax = accumulator
;; ebx = colormap
;; ecx = count
;; edx = heightmask
;; esi = source
;; edi = dest
;; ebp = frac
;;----------------------------------------------------------------------
cglobal R_DrawColumn_8_ASM
; align 16
R_DrawColumn_8_ASM:
push ebp ;; preserve caller's stack frame pointer
push esi ;; preserve register variables
push edi
push ebx
;;
;; dest = ylookup[dc_yl] + columnofs[dc_x];
;;
mov ebp,[dc_yl]
mov edi,[ylookup+ebp*4]
mov ebx,[dc_x]
add edi,[columnofs+ebx*4] ;; edi = dest
;;
;; pixelcount = yh - yl + 1
;;
mov ecx,[dc_yh]
add ecx,1
sub ecx,ebp ;; pixel count
jle near .done ;; nothing to scale
;;
;; fracstep = dc_iscale; // But we just use [dc_iscale]
;; frac = (dc_texturemid + FixedMul((dc_yl << FRACBITS) - centeryfrac, fracstep));
;;
mov eax,ebp ;; dc_yl
shl eax,FRACBITS
sub eax,[centeryfrac]
imul dword [dc_iscale]
shrd eax,edx,FRACBITS
add eax,[dc_texturemid]
mov ebp,eax ;; ebp = frac
mov ebx,[dc_colormap]
mov esi,[dc_source]
;;
;; if (dc_hires) frac = 0;
;;
test byte [dc_hires],0x01
jz .texheightcheck
xor ebp,ebp
;;
;; Check for power of two
;;
.texheightcheck:
mov edx,[dc_texheight]
sub edx,1 ;; edx = heightmask
test edx,[dc_texheight]
jnz .notpowertwo
test ecx,0x01 ;; Test for odd no. pixels
jnz .odd
;;
;; Texture height is a power of two, so we get modular arithmetic by
;; masking
;;
.powertwo:
mov eax,ebp ;; eax = frac
sar eax,FRACBITS ;; Integer part
and eax,edx ;; eax &= heightmask
movzx eax,byte [esi + eax] ;; eax = texel
add ebp,[dc_iscale] ;; frac += fracstep
movzx eax,byte [ebx+eax] ;; Map through colormap
mov [edi],al ;; Write pixel
;; dest += vid.width
add edi,[vid + viddef_s.width]
.odd:
mov eax,ebp ;; eax = frac
sar eax,FRACBITS ;; Integer part
and eax,edx ;; eax &= heightmask
movzx eax,byte [esi + eax] ;; eax = texel
add ebp,[dc_iscale] ;; frac += fracstep
movzx eax,byte [ebx+eax] ;; Map through colormap
mov [edi],al ;; Write pixel
;; dest += vid.width
add edi,[vid + viddef_s.width]
sub ecx,2 ;; count -= 2
jg .powertwo
jmp .done
.notpowertwo:
add edx,1
shl edx,FRACBITS
test ebp,ebp
jns .notpowtwoloop
.makefracpos:
add ebp,edx ;; frac is negative; make it positive
js .makefracpos
.notpowtwoloop:
cmp ebp,edx ;; Reduce mod height
jl .writenonpowtwo
sub ebp,edx
jmp .notpowtwoloop
.writenonpowtwo:
mov eax,ebp ;; eax = frac
sar eax,FRACBITS ;; Integer part.
mov bl,[esi + eax] ;; ebx = colormap + texel
add ebp,[dc_iscale] ;; frac += fracstep
movzx eax,byte [ebx] ;; Map through colormap
mov [edi],al ;; Write pixel
;; dest += vid.width
add edi,[vid + viddef_s.width]
sub ecx,1
jnz .notpowtwoloop
;;
.done:
pop ebx ;; restore register variables
pop edi
pop esi
pop ebp ;; restore caller's stack frame pointer
ret
;;----------------------------------------------------------------------
;;
;; R_Draw2sMultiPatchColumn : Like R_DrawColumn, but omits transparent
;; pixels.
;;
;; New optimised version 10-01-1998 by D.Fabrice and P.Boris
;; Revised by G. Dick July 2010 to support the intervening twelve years'
;; worth of changes to the renderer. Since I only vaguely know what I'm
;; doing, this is probably rather suboptimal. Help appreciated!
;;
;;----------------------------------------------------------------------
;; fracstep, vid.width in memory
;; eax = accumulator
;; ebx = colormap
;; ecx = count
;; edx = heightmask
;; esi = source
;; edi = dest
;; ebp = frac
;;----------------------------------------------------------------------
cglobal R_Draw2sMultiPatchColumn_8_ASM
; align 16
R_Draw2sMultiPatchColumn_8_ASM:
push ebp ;; preserve caller's stack frame pointer
push esi ;; preserve register variables
push edi
push ebx
;;
;; dest = ylookup[dc_yl] + columnofs[dc_x];
;;
mov ebp,[dc_yl]
mov edi,[ylookup+ebp*4]
mov ebx,[dc_x]
add edi,[columnofs+ebx*4] ;; edi = dest
;;
;; pixelcount = yh - yl + 1
;;
mov ecx,[dc_yh]
add ecx,1
sub ecx,ebp ;; pixel count
jle near .done ;; nothing to scale
;;
;; fracstep = dc_iscale; // But we just use [dc_iscale]
;; frac = (dc_texturemid + FixedMul((dc_yl << FRACBITS) - centeryfrac, fracstep));
;;
mov eax,ebp ;; dc_yl
shl eax,FRACBITS
sub eax,[centeryfrac]
imul dword [dc_iscale]
shrd eax,edx,FRACBITS
add eax,[dc_texturemid]
mov ebp,eax ;; ebp = frac
mov ebx,[dc_colormap]
mov esi,[dc_source]
;;
;; if (dc_hires) frac = 0;
;;
test byte [dc_hires],0x01
jz .texheightcheck
xor ebp,ebp
;;
;; Check for power of two
;;
.texheightcheck:
mov edx,[dc_texheight]
sub edx,1 ;; edx = heightmask
test edx,[dc_texheight]
jnz .notpowertwo
test ecx,0x01 ;; Test for odd no. pixels
jnz .odd
;;
;; Texture height is a power of two, so we get modular arithmetic by
;; masking
;;
.powertwo:
mov eax,ebp ;; eax = frac
sar eax,FRACBITS ;; Integer part
and eax,edx ;; eax &= heightmask
movzx eax,byte [esi + eax] ;; eax = texel
add ebp,[dc_iscale] ;; frac += fracstep
cmp al,TRANSPARENTPIXEL ;; Is pixel transparent?
je .nextpowtwoeven ;; If so, advance.
movzx eax,byte [ebx+eax] ;; Map through colormap
mov [edi],al ;; Write pixel
.nextpowtwoeven:
;; dest += vid.width
add edi,[vid + viddef_s.width]
.odd:
mov eax,ebp ;; eax = frac
sar eax,FRACBITS ;; Integer part
and eax,edx ;; eax &= heightmask
movzx eax,byte [esi + eax] ;; eax = texel
add ebp,[dc_iscale] ;; frac += fracstep
cmp al,TRANSPARENTPIXEL ;; Is pixel transparent?
je .nextpowtwoodd ;; If so, advance.
movzx eax,byte [ebx+eax] ;; Map through colormap
mov [edi],al ;; Write pixel
.nextpowtwoodd:
;; dest += vid.width
add edi,[vid + viddef_s.width]
sub ecx,2 ;; count -= 2
jg .powertwo
jmp .done
.notpowertwo:
add edx,1
shl edx,FRACBITS
test ebp,ebp
jns .notpowtwoloop
.makefracpos:
add ebp,edx ;; frac is negative; make it positive
js .makefracpos
.notpowtwoloop:
cmp ebp,edx ;; Reduce mod height
jl .writenonpowtwo
sub ebp,edx
jmp .notpowtwoloop
.writenonpowtwo:
mov eax,ebp ;; eax = frac
sar eax,FRACBITS ;; Integer part.
mov bl,[esi + eax] ;; ebx = colormap + texel
add ebp,[dc_iscale] ;; frac += fracstep
cmp bl,TRANSPARENTPIXEL ;; Is pixel transparent?
je .nextnonpowtwo ;; If so, advance.
movzx eax,byte [ebx] ;; Map through colormap
mov [edi],al ;; Write pixel
.nextnonpowtwo:
;; dest += vid.width
add edi,[vid + viddef_s.width]
sub ecx,1
jnz .notpowtwoloop
;;
.done:
pop ebx ;; restore register variables
pop edi
pop esi
pop ebp ;; restore caller's stack frame pointer
ret
;;----------------------------------------------------------------------
;; R_DrawTranslucentColumnA_8
;;
;; Vertical column texture drawer, with transparency. Replaces Doom2's
;; 'fuzz' effect, which was not so beautiful.
;; Transparency is always impressive in some way, don't know why...
;;----------------------------------------------------------------------
cglobal R_DrawTranslucentColumn_8_ASM
R_DrawTranslucentColumn_8_ASM:
push ebp ;; preserve caller's stack frame pointer
push esi ;; preserve register variables
push edi
push ebx
;;
;; dest = ylookup[dc_yl] + columnofs[dc_x];
;;
mov ebp,[dc_yl]
mov ebx,ebp
mov edi,[ylookup+ebx*4]
mov ebx,[dc_x]
add edi,[columnofs+ebx*4] ;; edi = dest
;;
;; pixelcount = yh - yl + 1
;;
mov eax,[dc_yh]
inc eax
sub eax,ebp ;; pixel count
mov [pixelcount],eax ;; save for final pixel
jle near vtdone ;; nothing to scale
;;
;; frac = dc_texturemid - (centery-dc_yl)*fracstep;
;;
mov ecx,[dc_iscale] ;; fracstep
mov eax,[centery]
sub eax,ebp
imul eax,ecx
mov edx,[dc_texturemid]
sub edx,eax
mov ebx,edx
shr ebx,16 ;; frac int.
and ebx,0x7f
shl edx,16 ;; y frac up
mov ebp,ecx
shl ebp,16 ;; fracstep f. up
shr ecx,16 ;; fracstep i. ->cl
and cl,0x7f
push cx
mov ecx,edx
pop cx
mov edx,[dc_colormap]
mov esi,[dc_source]
;;
;; lets rock :) !
;;
mov eax,[pixelcount]
shr eax,0x2
test byte [pixelcount],0x3
mov ch,al ;; quad count
mov eax,[dc_transmap]
je vt4quadloop
;;
;; do un-even pixel
;;
test byte [pixelcount],0x1
je trf2
mov ah,[esi+ebx] ;; fetch texel : colormap number
add ecx,ebp
adc bl,cl
mov al,[edi] ;; fetch dest : index into colormap
and bl,0x7f
mov dl,[eax]
mov dl,[edx]
mov [edi],dl
pf: add edi,0x12345678
;;
;; do two non-quad-aligned pixels
;;
trf2: test byte [pixelcount],0x2
je trf3
mov ah,[esi+ebx] ;; fetch texel : colormap number
add ecx,ebp
adc bl,cl
mov al,[edi] ;; fetch dest : index into colormap
and bl,0x7f
mov dl,[eax]
mov dl,[edx]
mov [edi],dl
pg: add edi,0x12345678
mov ah,[esi+ebx] ;; fetch texel : colormap number
add ecx,ebp
adc bl,cl
mov al,[edi] ;; fetch dest : index into colormap
and bl,0x7f
mov dl,[eax]
mov dl,[edx]
mov [edi],dl
ph: add edi,0x12345678
;;
;; test if there was at least 4 pixels
;;
trf3: test ch,0xff ;; test quad count
je near vtdone
;;
;; ebp : ystep frac. upper 24 bits
;; edx : y frac. upper 24 bits
;; ebx : y i. lower 7 bits, masked for index
;; ecx : ch = counter, cl = y step i.
;; eax : colormap aligned 256
;; esi : source texture column
;; edi : dest screen
;;
vt4quadloop:
mov ah,[esi+ebx] ;; fetch texel : colormap number
mov [tystep],ebp
pi: add edi,0x12345678
mov al,[edi] ;; fetch dest : index into colormap
pj: sub edi,0x12345678
mov ebp,edi
pk: sub edi,0x12345678
jmp short inloop
align 4
vtquadloop:
add ecx,[tystep]
adc bl,cl
q1: add ebp,0x23456789
and bl,0x7f
mov dl,[eax]
mov ah,[esi+ebx] ;; fetch texel : colormap number
mov dl,[edx]
mov [edi],dl
mov al,[ebp] ;; fetch dest : index into colormap
inloop:
add ecx,[tystep]
adc bl,cl
q2: add edi,0x23456789
and bl,0x7f
mov dl,[eax]
mov ah,[esi+ebx] ;; fetch texel : colormap number
mov dl,[edx]
mov [ebp+0x0],dl
mov al,[edi] ;; fetch dest : index into colormap
add ecx,[tystep]
adc bl,cl
q3: add ebp,0x23456789
and bl,0x7f
mov dl,[eax]
mov ah,[esi+ebx] ;; fetch texel : colormap number
mov dl,[edx]
mov [edi],dl
mov al,[ebp] ;; fetch dest : index into colormap
add ecx,[tystep]
adc bl,cl
q4: add edi,0x23456789
and bl,0x7f
mov dl,[eax]
mov ah,[esi+ebx] ;; fetch texel : colormap number
mov dl,[edx]
mov [ebp],dl
mov al,[edi] ;; fetch dest : index into colormap
dec ch
jne vtquadloop
vtdone:
pop ebx
pop edi
pop esi
pop ebp
ret
;;----------------------------------------------------------------------
;; R_DrawShadeColumn
;;
;; for smoke..etc.. test.
;;----------------------------------------------------------------------
cglobal R_DrawShadeColumn_8_ASM
R_DrawShadeColumn_8_ASM:
push ebp ;; preserve caller's stack frame pointer
push esi ;; preserve register variables
push edi
push ebx
;;
;; dest = ylookup[dc_yl] + columnofs[dc_x];
;;
mov ebp,[dc_yl]
mov ebx,ebp
mov edi,[ylookup+ebx*4]
mov ebx,[dc_x]
add edi,[columnofs+ebx*4] ;; edi = dest
;;
;; pixelcount = yh - yl + 1
;;
mov eax,[dc_yh]
inc eax
sub eax,ebp ;; pixel count
mov [pixelcount],eax ;; save for final pixel
jle near shdone ;; nothing to scale
;;
;; frac = dc_texturemid - (centery-dc_yl)*fracstep;
;;
mov ecx,[dc_iscale] ;; fracstep
mov eax,[centery]
sub eax,ebp
imul eax,ecx
mov edx,[dc_texturemid]
sub edx,eax
mov ebx,edx
shr ebx,16 ;; frac int.
and ebx,byte +0x7f
shl edx,16 ;; y frac up
mov ebp,ecx
shl ebp,16 ;; fracstep f. up
shr ecx,16 ;; fracstep i. ->cl
and cl,0x7f
mov esi,[dc_source]
;;
;; lets rock :) !
;;
mov eax,[pixelcount]
mov dh,al
shr eax,2
mov ch,al ;; quad count
mov eax,[colormaps]
test dh,3
je sh4quadloop
;;
;; do un-even pixel
;;
test dh,0x1
je shf2
mov ah,[esi+ebx] ;; fetch texel : colormap number
add edx,ebp
adc bl,cl
mov al,[edi] ;; fetch dest : index into colormap
and bl,0x7f
mov dl,[eax]
mov [edi],dl
pl: add edi,0x12345678
;;
;; do two non-quad-aligned pixels
;;
shf2:
test dh,0x2
je shf3
mov ah,[esi+ebx] ;; fetch texel : colormap number
add edx,ebp
adc bl,cl
mov al,[edi] ;; fetch dest : index into colormap
and bl,0x7f
mov dl,[eax]
mov [edi],dl
pm: add edi,0x12345678
mov ah,[esi+ebx] ;; fetch texel : colormap number
add edx,ebp
adc bl,cl
mov al,[edi] ;; fetch dest : index into colormap
and bl,0x7f
mov dl,[eax]
mov [edi],dl
pn: add edi,0x12345678
;;
;; test if there was at least 4 pixels
;;
shf3:
test ch,0xff ;; test quad count
je near shdone
;;
;; ebp : ystep frac. upper 24 bits
;; edx : y frac. upper 24 bits
;; ebx : y i. lower 7 bits, masked for index
;; ecx : ch = counter, cl = y step i.
;; eax : colormap aligned 256
;; esi : source texture column
;; edi : dest screen
;;
sh4quadloop:
mov dh,0x7f ;; prep mask
mov ah,[esi+ebx] ;; fetch texel : colormap number
mov [tystep],ebp
po: add edi,0x12345678
mov al,[edi] ;; fetch dest : index into colormap
pp: sub edi,0x12345678
mov ebp,edi
pq: sub edi,0x12345678
jmp short shinloop
align 4
shquadloop:
add edx,[tystep]
adc bl,cl
and bl,dh
q5: add ebp,0x12345678
mov dl,[eax]
mov ah,[esi+ebx] ;; fetch texel : colormap number
mov [edi],dl
mov al,[ebp] ;; fetch dest : index into colormap
shinloop:
add edx,[tystep]
adc bl,cl
and bl,dh
q6: add edi,0x12345678
mov dl,[eax]
mov ah,[esi+ebx] ;; fetch texel : colormap number
mov [ebp],dl
mov al,[edi] ;; fetch dest : index into colormap
add edx,[tystep]
adc bl,cl
and bl,dh
q7: add ebp,0x12345678
mov dl,[eax]
mov ah,[esi+ebx] ;; fetch texel : colormap number
mov [edi],dl
mov al,[ebp] ;; fetch dest : index into colormap
add edx,[tystep]
adc bl,cl
and bl,dh
q8: add edi,0x12345678
mov dl,[eax]
mov ah,[esi+ebx] ;; fetch texel : colormap number
mov [ebp],dl
mov al,[edi] ;; fetch dest : index into colormap
dec ch
jne shquadloop
shdone:
pop ebx ;; restore register variables
pop edi
pop esi
pop ebp ;; restore caller's stack frame pointer
ret
;; ========================================================================
;; Rasterization of the segments of a LINEAR polygne textur of manire.
;; It is thus a question of interpolating coordinate them at the edges of texture in
;; the time that the X-coordinates minx/maxx for each line.
;; the argument ' dir' indicates which edges of texture are Interpol?:
;; 0: segments associs at edge TOP? and BOTTOM? (constant TY)
;; 1: segments associs at the LEFT and RIGHT edge (constant TX)
;; ========================================================================
;;
;; void rasterize_segment_tex( LONG x1, LONG y1, LONG x2, LONG y2, LONG tv1, LONG tv2, LONG tc, LONG dir );
;; ARG1 ARG2 ARG3 ARG4 ARG5 ARG6 ARG7 ARG8
;;
;; Pour dir = 0, (tv1,tv2) = (tX1,tX2), tc = tY, en effet TY est constant.
;;
;; Pour dir = 1, (tv1,tv2) = (tY1,tY2), tc = tX, en effet TX est constant.
;;
;;
;; Uses: extern struct rastery *_rastertab;
;;
MINX EQU 0
MAXX EQU 4
TX1 EQU 8
TY1 EQU 12
TX2 EQU 16
TY2 EQU 20
RASTERY_SIZEOF EQU 24
cglobal rasterize_segment_tex
rasterize_segment_tex:
push ebp
mov ebp,esp
sub esp,byte +0x8 ;; allocate the local variables
push ebx
push esi
push edi
o16 mov ax,es
push eax
;; #define DX [ebp-4]
;; #define TD [ebp-8]
mov eax,[ebp+0xc] ;; y1
mov ebx,[ebp+0x14] ;; y2
cmp ebx,eax
je near .L_finished ;; special (y1==y2) segment horizontal, exit!
jg near .L_rasterize_right
;;rasterize_left: ;; one rasterize a segment LEFT of the polygne
mov ecx,eax
sub ecx,ebx
inc ecx ;; y1-y2+1
mov eax,RASTERY_SIZEOF
mul ebx ;; * y2
mov esi,[prastertab]
add esi,eax ;; point into rastertab[y2]
mov eax,[ebp+0x8] ;; ARG1
sub eax,[ebp+0x10] ;; ARG3
shl eax,0x10 ;; ((x1-x2)<<PRE) ...
cdq
idiv ecx ;; dx = ... / (y1-y2+1)
mov [ebp-0x4],eax ;; DX
mov eax,[ebp+0x18] ;; ARG5
sub eax,[ebp+0x1c] ;; ARG6
shl eax,0x10
cdq
idiv ecx ;; tdx =((tx1-tx2)<<PRE) / (y1-y2+1)
mov [ebp-0x8],eax ;; idem tdy =((ty1-ty2)<<PRE) / (y1-y2+1)
mov eax,[ebp+0x10] ;; ARG3
shl eax,0x10 ;; x = x2<<PRE
mov ebx,[ebp+0x1c] ;; ARG6
shl ebx,0x10 ;; tx = tx2<<PRE d0
;; ty = ty2<<PRE d1
mov edx,[ebp+0x20] ;; ARG7
shl edx,0x10 ;; ty = ty<<PRE d0
;; tx = tx<<PRE d1
push ebp
mov edi,[ebp-0x4] ;; DX
cmp dword [ebp+0x24],byte +0x0 ;; ARG8 direction ?
mov ebp,[ebp-0x8] ;; TD
je .L_rleft_h_loop
;;
;; TY varies, TX is constant
;;
.L_rleft_v_loop:
mov [esi+MINX],eax ;; rastertab[y].minx = x
add ebx,ebp
mov [esi+TX1],edx ;; .tx1 = tx
add eax,edi
mov [esi+TY1],ebx ;; .ty1 = ty
;;addl DX, %eax // x += dx
;;addl TD, %ebx // ty += tdy
add esi,RASTERY_SIZEOF ;; next raster line into rastertab[]
dec ecx
jne .L_rleft_v_loop
pop ebp
jmp .L_finished
;;
;; TX varies, TY is constant
;;
.L_rleft_h_loop:
mov [esi+MINX],eax ;; rastertab[y].minx = x
add eax,edi
mov [esi+TX1],ebx ;; .tx1 = tx
add ebx,ebp
mov [esi+TY1],edx ;; .ty1 = ty
;;addl DX, %eax // x += dx
;;addl TD, %ebx // tx += tdx
add esi,RASTERY_SIZEOF ;; next raster line into rastertab[]
dec ecx
jne .L_rleft_h_loop
pop ebp
jmp .L_finished
;;
;; one rasterize a segment LINE of the polygne
;;
.L_rasterize_right:
mov ecx,ebx
sub ecx,eax
inc ecx ;; y2-y1+1
mov ebx,RASTERY_SIZEOF
mul ebx ;; * y1
mov esi,[prastertab]
add esi,eax ;; point into rastertab[y1]
mov eax,[ebp+0x10] ;; ARG3
sub eax,[ebp+0x8] ;; ARG1
shl eax,0x10 ;; ((x2-x1)<<PRE) ...
cdq
idiv ecx ;; dx = ... / (y2-y1+1)
mov [ebp-0x4],eax ;; DX
mov eax,[ebp+0x1c] ;; ARG6
sub eax,[ebp+0x18] ;; ARG5
shl eax,0x10
cdq
idiv ecx ;; tdx =((tx2-tx1)<<PRE) / (y2-y1+1)
mov [ebp-0x8],eax ;; idem tdy =((ty2-ty1)<<PRE) / (y2-y1+1)
mov eax,[ebp+0x8] ;; ARG1
shl eax,0x10 ;; x = x1<<PRE
mov ebx,[ebp+0x18] ;; ARG5
shl ebx,0x10 ;; tx = tx1<<PRE d0
;; ty = ty1<<PRE d1
mov edx,[ebp+0x20] ;; ARG7
shl edx,0x10 ;; ty = ty<<PRE d0
;; tx = tx<<PRE d1
push ebp
mov edi,[ebp-0x4] ;; DX
cmp dword [ebp+0x24], 0 ;; direction ?
mov ebp,[ebp-0x8] ;; TD
je .L_rright_h_loop
;;
;; TY varies, TX is constant
;;
.L_rright_v_loop:
mov [esi+MAXX],eax ;; rastertab[y].maxx = x
add ebx,ebp
mov [esi+TX2],edx ;; .tx2 = tx
add eax,edi
mov [esi+TY2],ebx ;; .ty2 = ty
;;addl DX, %eax // x += dx
;;addl TD, %ebx // ty += tdy
add esi,RASTERY_SIZEOF
dec ecx
jne .L_rright_v_loop
pop ebp
jmp short .L_finished
;;
;; TX varies, TY is constant
;;
.L_rright_h_loop:
mov [esi+MAXX],eax ;; rastertab[y].maxx = x
add eax,edi
mov [esi+TX2],ebx ;; .tx2 = tx
add ebx,ebp
mov [esi+TY2],edx ;; .ty2 = ty
;;addl DX, %eax // x += dx
;;addl TD, %ebx // tx += tdx
add esi,RASTERY_SIZEOF
dec ecx
jne .L_rright_h_loop
pop ebp
.L_finished:
pop eax
o16 mov es,ax
pop edi
pop esi
pop ebx
mov esp,ebp
pop ebp
ret
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