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cc65/libsrc/runtime/asreax2.s

26 lines
529 B
ArmAsm

;
; Ullrich von Bassewitz, 06.08.1998
;
; CC65 runtime: Scale the 32 bit primary register by 4
;
.export asreax2
.importzp sreg, tmp1
asreax2:
stx tmp1
ldx sreg+1
cpx #$80 ; Get bit 7 into carry
ror sreg+1
ror sreg
ror tmp1
ror a
cpx #$80 ; Get bit 7 into carry
ror sreg+1
ror sreg
ror tmp1
ror a
ldx tmp1
rts