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Language Assembler (PIC/14bit)
| Date: | 04/20/05 |
| Author: | Thilo Manske |
| URL: | n/a |
| Comments: | 6 |
| Info: | n/a |
| Score: |  (3.49 in 41 votes) |
; $Id: 99bottlesofbeer.asm,v 1.3 2003/10/23 10:17:21 thilo Exp thilo $
;
; 99 bottles of beer on the wall for any recent midrange Microchip MCU with 14bit
; programm word (PIC16CXXX/PIC16FXXX family) and USART module, e.g. all PIC16F87x
;
; written by Thilo Manske
;
; needs 3 GP registers and 158 words (~277 bytes) of program memory
; use gpasm to assemble (see http://gputils.sourceforge.net/)
; adjust the following lines for your CPU
list p=16f873
include "p16f873.inc"
__config _WDT_OFF & _XT_OSC
; GP registers, since they are in [0x70..0x7f] they are available in all banks
; and we don't have to care about bank switching when we access them
cblock 0x70
pointer
bottles10
bottles1
endc
;; macro to select the correct bank for <address>
;; The default BANKSEL macro always sets/clears both bank bits, but we only
;; use bank 0 and 1 and don't have to take care of RP1
SELBANK macro address
if address < 0x80
bcf STATUS,RP0
else
bsf STATUS,RP0
endif
endm
; start
org 0
SELBANK SPBRG
movlw d'38' ; adjust this for your clock freq/baud rate
movwf SPBRG
movlw (1<<TXEN) ; enable the transmitter
movwf TXSTA ; TXSTA is in the same bank as SPBRG
SELBANK RCSTA
movlw (1<<SPEN) ; enable the serial port
movwf RCSTA
restart:
movlw 9
movwf bottles10
movwf bottles1
bigloop:
call nbottlesofbeer
call onthewall
call commacrlf
call nbottlesofbeer
call stopcrlf
movlw takeonedowntxt
call stringout
call commacrlf
decf bottles1,f
bnz goon ; second digit==0?
tstf bottles10,f ; and first digit==0 as well?
bz outofbeer ; no more bottles of beer :(
goon:
btfss bottles1,7 ; underflow in second digit?
goto ok
decf bottles10,f ; yes
movlw 9
movwf bottles1
ok:
call nbottlesofbeer
call onthewall
call stopcrlf
call crlf
goto bigloop
outofbeer:
movlw nomoretxt
call stringout
call bottlesofbeer
call stopcrlf
SELBANK TXSTA
btfss TXSTA,TRMT ; wait for the transmit buffer to drain
goto $-1
sleep ; Good night!
goto restart ; since we haven't enabled any interrupts, there isn't
; any chance the PIC will ever wake up and get here
; subroutines
;; writes ".\r\n"
stopcrlf
movlw '.'
goto $+2 ; skip next instruction
;; writes ",\r\n"
commacrlf:
movlw ','
call charout
;; writes carriage return + linefeed
crlf:
movlw '\r'
call charout
movlw '\n'
;; puts char in w out on the serial bus
charout:
SELBANK TXSTA
btfss TXSTA,TRMT ; send buffer empty?
goto $-1
SELBANK TXREG
movwf TXREG
return
;; writes "n bottles of beer"
nbottlesofbeer:
movf bottles10,w
bnz firstdigit ; first digit zero?
decf bottles1,w ; second digit one?
bz onebottleofbeer ; one last bottle :-/
goto seconddigit
firstdigit
addlw '0'
call charout
seconddigit
movf bottles1,w
addlw '0'
call charout
;; writes "bottles of beer"
bottlesofbeer
movlw bottletxt
call stringout
movlw 's'
call charout
;; writes "of beer"
ofbeer
movlw ofbeertxt
;; writes string w is pointing to
stringout
movwf pointer
call getchar
addlw 0 ; test for zero (flag is not set by retlw)
skpnz
return ; yes -> end of string
call charout
incf pointer,w
goto stringout
getchar ; this will look weird to people who don't know how
movwf PCL ; you read data out of a PICs program memory ;)
;; writes "1 bottle of beer"
onebottleofbeer
movlw '1'
call charout
movlw bottletxt
call stringout
goto ofbeer
;; writes "on the wall"
onthewall
movlw onthewalltxt
goto stringout
; "data subroutines"
bottletxt
dt " bottle{CODE}"
ofbeertxt
dt " of beer{CODE}"
onthewalltxt
dt " on the wall{CODE}"
takeonedowntxt
dt "Take one down, pass it around{CODE}"
nomoretxt
dt "No more{CODE}"
end
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Comments
i worked with pics some time ago,
so can say this is GREAT!
i'd love to see this code running
bnz MACRO _Address
btfss STATUS, Z
goto _Address
ENDM
bz MACRO _Address
btfsc STATUS, Z
goto _Address
ENDM
tstf MACRO _reg
movf _reg, F
ENDM
skpnz MACRO
btfsc STATUS, Z
ENDM