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