Tom Marchant wrote:
On Mon, 2 Aug 2010 13:21:08 -0600, Steve Comstock wrote:
On p. 12, point 3) says:
"... 216-byte save area (if using F5SA) or 288-byte save area
(if using F8SA)..."
but your layout of F5SA (p. 11) is 52 words (208 bytes) and
your layout of F8SA (p. 12) is 70 words (280 bytes)
The DSECT in IHASAVER for SAVF5SA includes 8 bytes at the end
that are reserved. Perhaps the same will be true for the DSECT
that is used to map a F8SA.
Then don't you think they should be documented in the Guide?
If programmers allocate according to the doc (which is more
likely than looking at the IHASAVER DSECT definition, I think),
will they be surprised some time down the road? This is not
good!
On pages 21, 23, and 241 you refer to a F6SA; but you never define
that; how is it different from a F4SA?
There is no such thing as a F6SA or a F1SA.
Then why do we see on p. 21 of the doc:
"Set GPR 13 to indicate that the caller's registers are saved
on the linkage stack:
– If the program creates a save area, obtain a 72-byte
save area on a word boundary (or 144-byte or larger
on a doubleword boundary if routines called by the
program need that extra space) in the primary address
space:
1. Set the second word of the save area to the character
string 'F1SA' if obtaining a 72-byte save area or
'F6SA' if obtaining a 144-byte or larger save area"
I'm afraid this section is full of carelessness like that. Most
uncharacteristic of Peter.
Those values at
offset 4 in the save area that you create for programs that you
call are to document the fact that you stored your registers
using the linkage stack. Perhaps the biggest clarification on
this version of the book is the meaning of the word at offset 4.
As documented in "Using a caller-provided save area" on page 8.
<quote>
In all save areas, the second word (the word at offset 4) of
each save area provides an indication of how the program that
created the save area saved the caller's registers. It does not
describe the contents of this save area.
</quote>
--
Tom Marchant
--
Kind regards,
-Steve Comstock
The Trainer's Friend, Inc.
303-393-8716
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