minix/lib/i86/em/em_dvi4.s
2009-11-09 10:26:00 +00:00

90 lines
1.2 KiB
ArmAsm

.define .dvi4
yl=6
yh=8
xl=10
xh=12
.text
.dvi4:
push si
push di
mov si,sp ! copy of sp
mov bx,yl(si)
mov ax,yh(si)
cwd
mov di,dx
cmp dx,ax
jne 7f
and dx,dx
jge 1f
neg bx
je 7f
1:
xor dx,dx
mov cx,xl(si)
mov ax,xh(si)
and ax,ax
jge 2f
neg ax
neg cx
sbb ax,dx
not di
2:
div bx
xchg ax,cx
div bx ! cx = high abs(result), ax=low abs(result)
9:
and di,di
jge 1f
neg cx
neg ax
sbb cx,#0
1:
! cx is high order result
! ax is low order result
mov dx,cx
pop di
pop si
ret 8 ! result in ax/dx
7:
push dx ! sign of y
mov di,ax
xor bx,bx
and di,di
jge 1f
neg di
neg yl(si)
sbb di,bx
1:
mov ax,xl(si)
mov dx,xh(si)
and dx,dx
jge 1f
neg dx
neg ax
sbb dx,bx
not -2(si)
1:
mov cx,#16
1:
shl ax,#1
rcl dx,#1
rcl bx,#1
cmp di,bx
ja 3f
jb 2f
cmp yl(si),dx
jbe 2f
3:
loop 1b
jmp 1f
2:
sub dx,yl(si)
sbb bx,di
inc ax
loop 1b
1:
pop di ! di=sign of result,ax= result
jmp 9b