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cc65/libsrc/cx16/get_numbanks.s

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;
; 2020-01-29, Greg King
;
; unsigned short get_numbanks (void);
; /* Return the number of RAM banks that the machine has. */
;
; The Commander X16 version of MEMTOP returns with an extra value:
; The accumulator describes the number of RAM banks that exist on the hardware.
; A zero accumulator means that there are 256 RAM banks.
;
.export _get_numbanks
.import MEMTOP
_get_numbanks:
sec
jsr MEMTOP
ldx #>$0000
cmp #<$0100 ; are there 256 banks?
bne :+
inx ; yes
: rts