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multiply by 40 routine

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git-svn-id: svn://svn.cc65.org/cc65/trunk@118 b7a2c559-68d2-44c3-8de9-860c34a00d81
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cpg 2000-06-23 22:06:37 +00:00
parent 7b944cae11
commit e51b5c8b59
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libsrc/atari/mul40.s Normal file
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;
; Christian Groessler, June 2000
;
; mul40
; multiplies A by 40 and returns result in AX
; uses tmp4
.importzp tmp4
.export mul40
.proc mul40
ldx #0
stx tmp4
sta loc_tmp
asl a
rol tmp4
asl a
rol tmp4 ; val * 4
adc loc_tmp
bcc L1
inc tmp4 ; val * 5
L1: asl a
rol tmp4 ; val * 10
asl a
rol tmp4
asl a
rol tmp4 ; val * 40
ldx tmp4
rts
.endproc
.bss
loc_tmp:.res 1