; skeleton of a module that gets the address of the ZCPR33 
; environmental descriptor from the command processor, and 
; stores it away.  Also a routine to retrieve it later, 
; accessible from Turbo-Modula2.
;
;	Steve Cohen
;	June 8, 1987
;
	PUBLIC  GETENV

	DB	'Z33ENV'		; JUST FOR FINDING THIS CODE WITH
					; PATCHER OR DEBUGGER

; this is the routine to which a program will jump (after 
; we patch it to do so) immediately upon execution which 
; saves the ENV address which Z33 provides us in HL.
					
	LD	(Z33ADR),HL		; PATCH FIRST JUMP INSTRUCTION TO
					; JUMP TO HERE

	JP	0			; PATCH THIS JUMP TO WHERE THE
					; OLD FIRST JUMP INSTRUCTION
					; JUMPED TO
					
Z33ADR:	DW	0			; STORAGE FOR Z33 ENV ADDRESS
;
; this routine can be called by any TM2 module that imports 
; to return the ENV address.  The procedure is in this form:
;
; 	PROCEDURE GETENV():CARDINAL;
;
GETENV: 
	LD	HL,(Z33ADR)		; MUST HAVE BEEN PREVIOUSLY INITIALIZED
	EX	(SP),HL			; RETURN IT VIA STACK
	PUSH	HL			; put return address back
	RET
	
	END