mirror of https://github.com/rkujawa/rk65c02.git
33 lines
769 B
ArmAsm
33 lines
769 B
ArmAsm
.org 0xC000
|
|
start: jsr min3
|
|
stp
|
|
|
|
; min3
|
|
; Takes 3 numbers (A, B, C), passed on stack, finds the minimum.
|
|
; Result is also passed on stack. Assumes it is being called via jsr.
|
|
.set retl,0x10
|
|
.set reth,0x11
|
|
.set res,0x12
|
|
min3: pla ; pull low byte of return address
|
|
sta retl
|
|
pla
|
|
sta reth
|
|
pla ; pull C from stack
|
|
sta res ; save C into res
|
|
pla ; pull B from stack
|
|
cmp res ; compare B and C
|
|
bpl bltc ; branch if B > C
|
|
sta res ; if C is smaller, save it to res
|
|
bltc: pla ; pull A from stack
|
|
cmp res ; compare A and whatever is in res
|
|
bpl ret ; branch if A > res
|
|
sta res ; otherwise save A to res
|
|
ret: lda res ; load res into accumulator
|
|
pha ; save to the stack
|
|
lda reth ; restore return address
|
|
pha
|
|
lda retl
|
|
pha
|
|
rts ; return from function
|
|
|