ampersand_usr: add code here

hopefully these examples will be useful in the future

basic/ampersand_usr/Makefile

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+include ../../Makefile.inc
+
+DOS33 = ../../utils/dos33fs-utils/dos33
+TOKENIZE = ../../utils/asoft_basic-utils/tokenize_asoft
+LINKERSCRIPTS = ../../linker_scripts
+EMPTYDISK = ../../empty_disk
+
+all:	starpath.dsk ANDOR
+
+$(DOS33):	
+	cd ../../utils/dos33fs-utils && make
+
+starpath.dsk:	$(DOS33) HELLO STARPATH.BAS
+	cp $(EMPTYDISK)/empty.dsk starpath.dsk
+	$(DOS33) -y starpath.dsk SAVE A HELLO
+	$(DOS33) -y starpath.dsk SAVE A STARPATH.BAS
+
+
+
+###
+
+HELLO:	hello.bas
+	$(TOKENIZE) < hello.bas > HELLO
+
+###
+
+STARPATH.BAS:	starpath.bas
+	$(TOKENIZE) < starpath.bas > STARPATH.BAS
+
+
+####
+
+ANDOR:	andor.o
+	ld65 -o ANDOR andor.o -C $(LINKERSCRIPTS)/apple2_300.inc
+
+andor.o:	andor.s
+	ca65 -o andor.o andor.s -l andor.lst
+
+###
+
+
+clean:	
+	rm -f *~ *.o HELLO STARPATH.BAS ANDOR *.lst

basic/ampersand_usr/README

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+Some experiments with using & and USR() to call into assembly
+language from BASIC.
+
+Neither is very convenient when sizecoding.
+
+; When &/ampersand call
+;	jumps to address $3F5 (applesoft already has a placeholder jmp there)
+;       when called next char/token in A (so can easily do things like &PLOT)
+;       can't return anything unless you look up a variable by name and
+;		write to the pointer
+
+; USR() can take one argument, returns value
+;	jumps to $0A in zero page, which is usually a jump
+;		to a USER handler.  BASIC is set up to illegal quant error
+;		by default
+;	need to manipulate the FAC accumulator to handle input/return
+
+
+
+https://mirrors.apple2.org.za/ftp.apple.asimov.net/documentation/magazines/misc/theappleorchard_v1n1_applesoftinternalentrypoints_ocr.pdf
+https://6502disassembly.com/a2-rom/Applesoft.html
+https://wiki.reactivemicro.com/images/f/f7/Applesoft_II_2019.pdf

basic/ampersand_usr/andor.s

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+; calculates &X,Y,Z,C
+;  C = (X|Y)&Z
+
+
+; Routine for calling from &
+;	when called next char/token in A
+;	can't return anything unless you look up a variable by name
+;	and write to it
+
+; USER() can take one argument, returns value
+
+; dump with od -t u1 ./ANDOR
+
+VARPNTL = $83
+VARPNTH = $84
+
+
+FRMEVL = $DD7B
+GETADDR= $E752
+CHKCOM = $DEBE
+SNGFLT = $E301
+PTRGET = $DFE3	; returns pointer to variable in VARPNT and (Y,A)
+MOVMF  = $EB2B
+
+andor:
+	jsr	FRMEVL		; 20 7B DD  (or FRMNUM) 20 67 DD   value->FAC
+	jsr	GETADDR		; 20 52 E7  FAC-> LINNUM ($50/$51)
+	jsr	CHKCOM		; 20 BE DE  move past comma
+	lda	$50
+	sta	$24
+
+	jsr	FRMEVL		; 20 7B DD  (or FRMNUM) 20 67 DD   value->FAC
+	jsr	GETADDR		; 20 52 E7  FAC-> LINNUM ($50/$51)
+	jsr	CHKCOM		; 20 BE DE  move past comma
+	lda	$50		; A5 50
+	sta	$25		; 85 50
+
+	jsr	FRMEVL		; 20 7B DD  (or FRMNUM) 20 67 DD   value->FAC
+	jsr	GETADDR		; 20 52 E7  FAC-> LINNUM ($50/$51)
+	jsr	CHKCOM		; 20 BE DE  move past comma
+
+	lda	$24		; A5 24
+	ora	$25		; 05 25
+	and	$50		; 25 50
+	sta	$24
+
+	jsr	PTRGET		; 20 E3 DF
+	ldy	$24		; A8
+	jsr	SNGFLT		; 20 01 E3  unsigned Y -> FAC
+
+	ldx	VARPNTL		;VARPNT
+	ldy	VARPNTH		;VARPNT+1
+	jmp	MOVMF
+

basic/ampersand_usr/hello.bas

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+5 HOME
+10 PRINT CHR$(4);"CATALOG"

basic/ampersand_usr/starpath.bas

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+0FOR I=0 TO 57:READ D:POKE 768+I,D:NEXT:POKE 1014,0:POKE 1015,3
+1DIML(16):FORI=0TO14:READL(I):NEXT:GR:POKE49234,0
+2FORY=0TO47:FORX=0TO39:D=I
+3Z=Y*4*D:T=X*6-D:IFT<0THENC=31:A=X*6+Z:&0,A,255,A:GOTO8
+4&T*D/256,Z/256,D+F,C:D=D+1:A=0:IFC<16THEN3
+8IFA>6THENC=Y/4+32
+9COLOR=L(C/2-8):PLOTX,Y:NEXTX,Y:F=F+1:GOTO2
+100 DATA 32,123,221,32,82,231,32,190,222,165,80,133,36,32,123,221
+110 DATA 32,82,231,32,190,222,165,80,133,37,32,123,221,32,82,231
+120 DATA 32,190,222,165,36,5,37,37,80,133,36,32,227,223,164,36
+130 DATA 32,1,227,166,131,164,132,76,43,235
+140 DATA0,5,10,5,10,7,15,15,2,1,3,9,13,12,4,4

graphics/gr/starpath/andor.s

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+.org 300
+
+FRMEVL = $DD7B
+GETADDR= $E752
+CHKCOM = $DEBE
+SNGFLT = $E301
+
+andor:
+	jsr	FRMEVL		; 20 7B DD  (or FRMNUM) 20 67 DD   value->FAC
+	jsr	GETADDR		; 20 52 E7  FAC-> LINNUM ($50/$51)
+	jsr	CHKCOM		; 20 BE DE  move past comma
+	lda	$50
+	sta	$24
+
+	jsr	FRMEVL		; 20 7B DD  (or FRMNUM) 20 67 DD   value->FAC
+	jsr	GETADDR		; 20 52 E7  FAC-> LINNUM ($50/$51)
+	jsr	CHKCOM		; 20 BE DE  move past comma
+	lda	$50		; A5 50
+	sta	$25		; 85 50
+
+	jsr	FRMEVL		; 20 7B DD  (or FRMNUM) 20 67 DD   value->FAC
+	jsr	GETADDR		; 20 52 E7  FAC-> LINNUM ($50/$51)
+	jsr	CHKCOM		; 20 BE DE  move past comma
+
+	lda	$50		; A5 50
+	ora	$24		; 05 24
+	and	$25		; 25 25
+	tay			; A8
+	jmp	SNGFLT		; 20 01 E3  unsigned Y -> FAC
+