89 lines
1.5 KiB
ArmAsm
89 lines
1.5 KiB
ArmAsm
.define .cii
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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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! Convert integer to integer
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! Expects in a-reg: 1 for signed integer to signed integer (cii)
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! 0 for unsigned integer to unsigned integer (cuu)
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! Expects on stack: destination size
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! source size
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! source
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! Yields on stack: result
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.cii: 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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sta .areg ! save a-register
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pop b
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mov e,c
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pop b ! c = source size
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mov b,e ! b = destination size
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mov a,b
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cmp c
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jz 3f ! destination size = source size
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jc shrink ! destination size < source size
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! if destination size > source size only:
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lxi h,0
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dad sp
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mov e,l
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mov d,h ! de = stackpointer
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mov a,b
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sub c ! c = (still) source size
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mov b,a ! b = destination size - source size
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cma
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mov l,a
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mvi h,255
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inx h
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dad d ! hl = stackpointer - (dest. size - source size)
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sphl ! new stackpointer
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1: ldax d ! move source downwards
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mov m,a
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inx d
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inx h
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dcr c
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jnz 1b
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ral ! a-reg still contains most significant byte of source
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jnc 1f ! jump if is a positive integer
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lda .areg
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ora a
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jz 1f ! jump if it is a cuu
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mvi c,255 ! c-reg contains filler byte
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1: mov m,c ! fill
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inx h
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dcr b
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jnz 1b
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jmp 3f ! done
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!if destination size < source size only:
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shrink: mov l,c ! load source size in hl
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mvi h,0
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dad sp
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mov d,h
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mov e,l ! de points just above source
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mov l,b ! load destination size in hl
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mvi h,0
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dad sp ! hl points just above "destination"
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1: dcx d ! move upwards
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dcx h
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mov a,m
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stax d
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dcr b
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jnz 1b
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sphl
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3: 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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