Date: Wed, 14 Oct 1998 14:24:17 -0400
From: milendor@chicklet.east.sun.com (Michael Milendorf (Godin))
Subject: Item #449: The definition of ABORT function is unclear


P1275 Open Firmware Working Group Proposal -- Proposal #:449 Ver 1

Title:         Clarification on ABORT function description

Author:        Michael Milendorf

Date:          October 14, 1998

Ed/Tech:       Technical

Synopsis:      The definition of ABORT function is unclear

Doc & Version: IEEE Std. 1275-1994

Problem:       

	IEEE 1275-1994 explains the function of ABORT in the following way: 

	Abort program execution; clear stacks.
	The version of ABORT defined by the ANS Forth EXCEPTION wordset 
	applies.

	While the second sentence is clear and correct, the attempt to 
	provide a "casual" description with the first sentence makes 
	the whole explanation unclear. The casual definition explains 
	the function of the CORE 6.1.0670 ABORT word of ANS Forth, not 
	the function of the EXCEPTION 9.6.2.0670 ABORT word, which
	1275 descriptions actually refers to (in the second sentence). 
	While according to ANS Forth, the function of 6.1.0670 ABORT can be 
	explained with the words "Abort program execution; clear stacks.", 
	the description of 9.6.2.0670 ABORT is "performing the function 
	of -1 THROW". The problem is that the function of 9.6.2.0670 ABORT, 
	which IEEE 1275 refers to, doesn't necessarily clear stacks in all 
	cases. 1275 ABORT clears stacks only if there is no exception frame 
	on the exception stack, otherwise both return and data stacks 
	remain uncleared which contradicts 1275 description.

	Finally, it is understood that for all ANS Forth words of
	IEEE 1275-1994, the 1275 descriptions may be rather casual
	and usually take a second priority after ANS Forth, when
	clarification is needed. However it would be undesirable
	to alter the meaning or functionality of any specific ANS Forth
	function, like ABORT, by providing too casual definition in 
	IEEE 1275-1994 Std. document.


Proposal:

	I would suggest to change the text, describing the function of 
	ABORT functions in IEEE 1275-1994 document (p. 107) by dropping 
	the first misleading sentence of the ABORT description altogether
	and leaving the description to be:

	"The version of ABORT defined by the ANS Forth EXCEPTION 
	wordset applies."

	Another possibility would be to change IEEE 1275 ABORT description 
	to the following text:

	"Abort program execution; clear stacks, if there is no exception 
	frame on the exception stack. The version of ABORT defined by the 
	ANS Forth EXCEPTION wordset applies."

 

[ P1275 Item #449 -- Received: Wed Oct 14 11:24:22 PDT 1998 ]