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21 lines
316 B
ArmAsm

;
; Ullrich von Bassewitz, 06.08.1998
;
; CC65 runtime: Scale the primary register
;
.export asreax1
.importzp sreg, tmp1
asreax1:
stx tmp1
ldx sreg+1
cpx #$80 ; Get bit 7 into carry
ror sreg+1
ror sreg
ror tmp1
ror a
ldx tmp1
rts