78 lines
962 B
ArmAsm
78 lines
962 B
ArmAsm
.define .mli4
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.sect .text
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.sect .rom
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.sect .data
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.sect .bss
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.sect .text
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! 32 bits signed and unsigned integer multiply routine
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! Expects operands on stack
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! Yields product on stack
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.mli4: pop h
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shld .retadr
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mov h,b
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mov l,c
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shld .bcreg
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pop h ! store multiplier
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shld block1
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pop h
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shld block1+2
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pop h ! store multiplicand
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shld block2
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pop h
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shld block2+2
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lxi h,0
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shld block3 ! product = 0
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shld block3+2
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lxi b,0
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lp1: lxi h,block1
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dad b
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mov a,m ! get next byte of multiplier
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mvi b,8
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lp2: rar
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jnc 2f
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lhld block2 ! add multiplicand to product
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xchg
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lhld block3
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dad d
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shld block3
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lhld block2+2
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jnc 1f
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inx h
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1: xchg
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lhld block3+2
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dad d
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shld block3+2
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2: lhld block2 ! shift multiplicand left
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dad h
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shld block2
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lhld block2+2
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jnc 3f
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dad h
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inx h
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jmp 4f
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3: dad h
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4: shld block2+2
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dcr b
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jnz lp2
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inr c
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mov a,c
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cpi 4
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jnz lp1
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lhld block3+2
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push h
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lhld block3
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push h
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lhld .bcreg
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mov b,h
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mov c,l
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lhld .retadr
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pchl
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