From: "Paul Gilmartin" <[email protected]>
To: <[email protected]>
Sent: Friday, April 22, 2022 8:06 AM
Subject: Re: Unexpected C code
On Apr 21, 2022, at 15:34:21, Seymour J Metz wrote:
All of the logical arithmetic instructions report overflow, but they differ from signed
arithmetic in that
1. PoOps uses the term carry for an overflow on logical arithmetic instructions
Humpty Dumpty. The PoOps, not you, is entitled to define terminology in our
field of discourse.
The (ANSI) C Standard employs the other convention.
A programmer synthesizing multi-precision arithmetic does
not perceive the carry as an overflow, even when I add
Two numbers with pencil and paper I don't call the carry
from any column an "overflow".
Except when the most-signifiat word overflows, when it is overflor.
And, of course, in the more-usual case, when only
one word is required for both operands, a carry out is an overflow.
2. The way the condition code is encoded is different
3. There is no overflow interrupt from a logical instuction
I was thinking Z and should have written BO/BNO for S/370, which did not have branch relative.
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