48 lines
750 B
ArmAsm
48 lines
750 B
ArmAsm
.define .sri2
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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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! Shift 16 bits signed or unsigned integer right
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! Expects in a-reg.: 1 if signed integer
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! 0 if unsigned integer
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! Expects on stack: number of shifts
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! number to be shifted
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! Yields in de-reg.: result
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.sri2: pop h
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shld .retadr
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pop h !hl = number of shifts
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pop d !de = number to be shifted
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mvi h,0
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ora a
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jz 1f !jump if unsigned integer
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mov a,d
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ral
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jnc 1f !jump if positive signed integer
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mvi h,255 !now h=1 if negative signed number, h=0 otherwise.
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1: mov a,l !return 0 or -1 if hl>=16
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cpi 16
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jnc 3f
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2: dcr l
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jm 4f
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mov a,h
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rar !set carry bit correct
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mov a,d
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rar
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mov d,a
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mov a,e
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rar
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mov e,a
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jmp 2b
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3: mov d,h
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mov e,h
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4: lhld .retadr
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pchl
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