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Scene Storm - Volume 1.iso
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ylrfill.asm
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Assembly Source File
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1980-01-03
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7KB
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365 lines
; $$TABS=8
include 'demo.i'
xref yadrtable,rightmasktable,leftmasktable
xref vtable
YLRFill::
; fill a list of horizontal spans
; handles reversal cases (left > right)! However, this is an unlikely case
; so it is more optimal for the other case.
; This routine is optimized for SMALL polygons (the only interesting ones)
; input:
; (a0)=ylr array, terminated with y<0.
; trashes: a0/a1/d1-d7
; register usage:
; d0=color
; d7=$fffc ( x adr mask)
; a0=array
; lwordofs[x]=(x>>2)*4
; right mask table=00ffffff, 0000ffff, 000000ff, 00000000
; left masktable= 00000000 ff000000 ffff0000 ffffff00
ONTIMER 10
moveq #$fffffffc,d7
move.l current_color(a6),d0
move.w (a0)+,d1 ; ycoord
bmi.s done_fill ; handle empty case? why?
nextylr:
move.l (yadrtable.w,a6,d1.w*4),a1 ; a1=screen array ptr
move.w (a0)+,d1 ; d1=leftx
move.w (a0)+,d2 ; d2=rightx
cmp.w d1,d2
blt.s ylr_reverse1
re_enter:
move.w d1,d3 ; save leftx
move.w d2,d4 ; save rightx
and.w d7,d3 ; convert coordinate to lword offset
and.w d7,d4 ; convert to lword offset
add d3,a1 ; offset address register
sub.w d3,d4 ; determine # of bytes
beq.s one_lword_case
lsr.w #2,d4
; now do left side
move.l (leftmasktable.w,a6,d1.w*4),d1
move.l (a1),d6
and.l d1,d6
not.l d1
and.l d0,d1
or.l d1,d6
move.l d6,(a1)+
; now, determine # of full words to do
subq #2,d4 ; adjust for ends and dbra
bmi.s no_middle
1$: move.l d0,(a1)+
dbra d4,1$
no_middle:
move.l (rightmasktable.w,a6,d2.w*4),d2
move.l (a1),d1
and.l d2,d1
not.l d2
and.l d0,d2
or.l d2,d1
move.l d1,(a1)
move.w (a0)+,d1 ; fetch next y
bpl.s nextylr
done_fill:
OFFTIMER 10
rts
one_lword_case:
; start and end are in one lword, so:
; mask=lmask | rmask
; if (mask=-1), right and left are reversed!
move.l (leftmasktable.w,a6,d1.w*4),d6
or.l (rightmasktable.w,a6,d2.w*4),d6
move.l (a1),d1
and.l d6,d1
not.l d6
and.l d0,d6
or.l d6,d1
move.l d1,(a1)
move.w (a0)+,d1
bpl.s nextylr
OFFTIMER 10
rts
ylr_reverse1:
; oh no! a backwards one has occurred due to precision problems!
; let's handle it as inefficiently as possible!
exg d1,d2
bra.s re_enter
YLRCCFill::
; fill gradient shaded polygons
ONTIMER 10
move.w (a0)+,d1 ; ycoord
bmi.s done_ylrcc
nextylrcc:
move.l (yadrtable.w,a6,d1.w*4),a1
movem.w (a0)+,d1/d2/d3/d4 ; lx,rx, lc, rc
cmp.w d1,d2
bge.s no_ccrev
exg d3,d4
exg d1,d2
no_ccrev:
; now, determine delta color = (rc-lc)+1/(rc-lx+1)
add d1,a1 ; adjust pointer
sub d1,d2 ; d2=rx-lx
addq #1,d2 ; rx-lc+1
sub d3,d4 ; dc
addq #1,d4 ; dc+1
ext.l d4 ; for divide
divs d2,d4 ; d4=dc*256
; now,
; d2=dbra count for output pixels
; d4=dc (8.8)
; d3=c (8.8)
; a1=output ptr
ror.w #8,d3 ; d3=f.i
move.b d3,d0 ; d0=c.i
clr.b d3 ; d3=c.f
ror.w #8,d4
move.b d4,d1
ext.w d1
clr.b d4
subq #1,d2
lsr.w #1,d2
bcc.s ccfill_even
move.b d0,(a1)+
add.w d4,d3
addx.w d1,d0
ccfill_even:
subq #1,d2
bmi.s ccfill_done
ccfill_bytes:
move.b d0,(a1)+
add.w d4,d3
addx.w d1,d0
move.b d0,(a1)+
add.w d4,d3
addx.w d1,d0
dbra d2,ccfill_bytes
ccfill_done:
move.w (a0)+,d1
bpl.s nextylrcc
done_ylrcc:
OFFTIMER 10
rts
YLRUUFill::
; fill texture mapped polygons
; vbuffer contains v(x)
; out=*(tmapadr+v(x)+u(x)<<8)
; bra YLRUUFillT
move.l current_ltab(a6),d0
bne.s YLRUULFill
move.w (a0)+,d1 ; ycoord
bmi.s done_ylrcc
nextylruu: move.l (yadrtable.w,a6,d1.w*4),a1 ; dest coord
movem.w (a0)+,d1/d2/d3/d4 ; lx,rx, lu, ru
cmp.w d1,d2
bge.s no_uurev
exg d3,d4
exg d1,d2
no_uurev:
; now, determine delta color = (rc-lc)+1/(rc-lx+1)
lea (vtable.w,a6,d1.w*4),a2 ; vtable
add d1,a1 ; adjust pointer
sub d1,d2 ; d2=rx-lx
addq #1,d2 ; rx-lc+1
sub d3,d4 ; dc
addq #1,d4 ; dc+1
ext.l d4 ; for divide
divs d2,d4 ; d4=dc*256
; now,
; d2=dbra count
; d4=du (8.8)
; d3=u (8.8)
; a1=output ptr
; a2=vtable
ror.w #8,d3 ; d3=f.i
moveq #0,d0
move.b d3,d0 ; d0=c.i
clr.b d3 ; d3=c.f
ror.w #8,d4
move.b d4,d1
ext.w d1
clr.b d4
ONTIMER 10
lsr.w #1,d2
bcc.s uufill_even
move.l (a2)+,a3
move.b (a3,d0.w),(a1)+
add.w d4,d3
addx.w d1,d0
uufill_even:
subq #1,d2
bmi.s fetchnextuu
uufill_bytes:
move.l (a2)+,a3
move.b (a3,d0.w),(a1)+
add.w d4,d3
addx.w d1,d0
move.l (a2)+,a3
move.b (a3,d0.w),(a1)+
add.w d4,d3
addx.w d1,d0
dbra d2,uufill_bytes
fetchnextuu:
OFFTIMER 10
move.w (a0)+,d1
bpl.s nextylruu
done_ylruu:
rts
YLRUULFill::
; fill texture mapped polygons, lighting with current_ltab
; vbuffer contains v(x)
; out=*(tmapadr+v(x)+u(x)<<8)
move.l d0,a4
move.w (a0)+,d1 ; ycoord
bmi.s done_ylruu
nextylruul:
move.l (yadrtable.w,a6,d1.w*4),a1 ; dest coord
movem.w (a0)+,d1/d2/d3/d4 ; lx,rx, lu, ru
cmp.w d1,d2
bge.s no_uurevl
exg d3,d4
exg d1,d2
no_uurevl:
; now, determine delta color = (rc-lc)+1/(rc-lx+1)
lea (vtable.w,a6,d1.w*4),a2 ; vtable
add d1,a1 ; adjust pointer
sub d1,d2 ; d2=rx-lx
addq #1,d2 ; rx-lc+1
sub d3,d4 ; dc
addq #1,d4 ; dc+1
ext.l d4 ; for divide
divs d2,d4 ; d4=dc*256
; now,
; d2=dbra count
; d4=du (8.8)
; d3=u (8.8)
; a1=output ptr
; a2=vtable
ror.w #8,d3 ; d3=f.i
moveq #0,d0
move.b d3,d0 ; d0=c.i
clr.b d3 ; d3=c.f
ror.w #8,d4
move.b d4,d1
ext.w d1
clr.b d4
moveq #0,d7
ONTIMER 10
lsr.w #1,d2
bcc.s uufill_evenl
move.l (a2)+,a3
move.b (a3,d0.w),d7
move.b (a4,d7.w),(a1)+
add.w d4,d3
addx.w d1,d0
uufill_evenl:
subq #1,d2
bmi.s fetchnextuul
uufill_bytesl:
move.l (a2)+,a3
move.b (a3,d0.w),d7
move.b (a4,d7.w),(a1)+
add.w d4,d3
addx.w d1,d0
move.l (a2)+,a3
move.b (a3,d0.w),d7
move.b (a4,d7.w),(a1)+
add.w d4,d3
addx.w d1,d0
dbra d2,uufill_bytesl
fetchnextuul:
OFFTIMER 10
move.w (a0)+,d1
bpl nextylruul
rts1 rts
xref blend_table
YLRUUFillT::
; fill texture mapped transparent polygons
; vbuffer contains v(x)
; out=*(tmapadr+v(x)+u(x)<<8)
move.l #blend_table,a4
move.w (a0)+,d1 ; ycoord
bmi.s rts1
nextylruut:
move.l (yadrtable.w,a6,d1.w*4),a1 ; dest coord
movem.w (a0)+,d1/d2/d3/d4 ; lx,rx, lu, ru
cmp.w d1,d2
bge.s no_uurevt
exg d3,d4
exg d1,d2
no_uurevt:
; now, determine delta color = (rc-lc)+1/(rc-lx+1)
lea (vtable.w,a6,d1.w*4),a2 ; vtable
add d1,a1 ; adjust pointer
sub d1,d2 ; d2=rx-lx
addq #1,d2 ; rx-lc+1
sub d3,d4 ; dc
addq #1,d4 ; dc+1
ext.l d4 ; for divide
divs d2,d4 ; d4=dc*256
; now,
; d2=dbra count
; d4=du (8.8)
; d3=u (8.8)
; a1=output ptr
; a2=vtable
; a4=ltable
ror.w #8,d3 ; d3=f.i
moveq #0,d0
move.b d3,d0 ; d0=c.i
clr.b d3 ; d3=c.f
ror.w #8,d4
move.b d4,d1
ext.w d1
clr.b d4
ONTIMER 10
lsr.w #1,d2
bcc.s uufill_event
move.l (a2)+,a3
move.w -1(a3,d0.w),d7
move.b (a1),d7
move.b (a4,d7.w),(a1)+
add.w d4,d3
addx.w d1,d0
uufill_event:
subq #1,d2
bmi.s fetchnextuut
uufill_bytest:
move.l (a2)+,a3
move.w -1(a3,d0.w),d7
move.b (a1),d7
move.b (a4,d7.w),(a1)+
add.w d4,d3
addx.w d1,d0
move.l (a2)+,a3
move.w -1(a3,d0.w),d7
move.b (a1),d7
move.b (a4,d7.w),(a1)+
add.w d4,d3
addx.w d1,d0
dbra d2,uufill_bytest
fetchnextuut:
OFFTIMER 10
move.w (a0)+,d1
bpl nextylruut
rts
section __MERGED,data
current_color::
dc.l $ffffffff
current_ltab::
dc.l 0