; VARLOAD.Z80
;
; ZCPR3 Shell (Environment) Variable manipulation routines.
; Routines in this module:
;	VARLOAD -- loads the shell variable file into memory.
;	VARDEF	-- finds a variable name in the file.
;	DELVAR	-- deletes a variable.
;	ADDVAR	-- adds a variable.
;	WRTVARS -- writes out the variable file.
; These routines take various parameters passed in the DE and HL registers.
;
; Author: Dreas Nielsen
; Revision history:
;	 Date		 Comments
;	-------		-----------
;	7/11/86		First version.
;	1/15/87		Changed from a single file to separate library modules
;			using shared (semi-PUBLIC) data
;
;	3/19/89		Deleted internal SETDMA and READ code for SYSLIB
;			equivalents (SETDMA and F$READ), deleted F$CLOSE
;			call and external as this is an R/O module.  Note
;			that VARLOAD is non-reentrant unless Z3VARS is
;			explicitly reset to 0000H elsewhere.
;							Bruce Morgen
;
	PUBLIC	VARLOAD,Z3VARS
;
; SYSLIB and Z3LIB routines --
	EXT	RETUD,LOGUD,DNSCAN,ROOT,GETFN1
	EXT	INITFCB,F$OPEN,F$READ,INITFCB,SETDMA
;
EOF	EQU	'Z'-'@'
;
;================  PUBLIC Storage  ================
;
Z3VARS:
	DW	0		;addr of start of list
;
;================  semi-PUBLIC Storage  ================
;
SHVFCB:	DB	0		;SHVFCB: fcb for shell variable file
	DB	'SH      VAR'
	DS	24
RNAME:	DB	'ROOT',0	;name of root directory
;
;================  Private Storage  ================
;
CURRDU:	DW	00
;
;
;===================================================
;
;----  VARLOAD  ----
;
; Enter with:
;	HL = address of beginning of list.
; Return with:
;	if successful,
;		A  = 00 and Z
;		HL = next free addr after var list;
;	if unsuccessful,
;		A=NZ and NZ.
;
; This routine will look for the SH.VAR file (by whatever name) in the ROOT
; directory.  If this directory does not exist, it will look at the bottom
; of the path.  This behavior is different from that of Richard Conn's 
; original utilities.  It is presumed that there is sufficient space for the
; variable list in memory.  No bounds checking is done.
;
VARLOAD:
	LD	A,(Z3VARS+1)
	OR	A
	JR	Z,VARLD1
	XOR	A
	RET
;
VARLD1:	PUSH	BC		;save regs
	PUSH	DE
	LD	(Z3VARS),HL
	CALL	RETUD
	LD	(CURRDU),BC
	CALL	XROOT
	CALL	LOGUD
	LD	HL,(Z3VARS)	;clear varlist in case of error
	LD	(HL),EOF
;
; Get proper name for variable file, or use default
	CALL	SHVNAM
;
; Look for Variable File
V2:
	LD	DE,SHVFCB	;try to open file
	CALL	INITFCB		;init FCB
	CALL	F$OPEN
	JR	NZ,VARL2	;no file, but that's OK
;
; Read in Variable File
	LD	HL,(Z3VARS)	;pt to named variable list
VARL1:
	CALL	SETDMA
	LD	DE,128		;increment DMA addr for next read
	ADD	HL,DE
	LD	DE,SHVFCB	;read a sector
	CALL	F$READ
	JR	Z,VARL1		;if OK, read another
VARL2:	LD	BC,(CURRDU)
	CALL	LOGUD
	LD	A,EOF		;find next free address
	LD	HL,(Z3VARS)
	LD	BC,65535
	CPIR
	POP	DE		;restore regs
	POP	BC
	RET	PO
	XOR	A		;return Z for OK
	RET	
;
XROOT:				;find 'ROOT:' or end of path
	LD	HL,RNAME	;does 'ROOT:' exist?
	CALL	DNSCAN
	RET	NZ		;ret if yes
	JP	ROOT		;otherwise find end of path
;
SHVNAM:	CALL	GETFN1
	LD	A,(HL)
	CP	' '		;is filename undefined?
	RET	Z
	LD	DE,SHVFCB+1	;move filename into fcb
	LD	BC,11
	LDIR
	RET
;
	END