Re: Using the High Halfs of registers

On 27 October 2017 at 21:26, Robin Vowels wrote: > From: "Tony Harminc" > Sent: Saturday, October 28, 2017 11:13 AM > > Add Immediate High (AIH). But when was it introduced...? There are no >> change bars in the -10 edition of the PofO, so before then. >>

Re: Using the High Halfs of registers

Oh, and don't forget 1. IIRC some z/OS services may use (destroy, corrupt, whatever you want to call it) those high halves. Not certain of that -- perhaps Peter or someone will correct me. 2. OTOH it would be polite of you to save and restore your caller's high halves if relevant. IIRC the

Re: Using the High Halfs of registers

I believe those are all z Architecture instructions and should work on any z Architecture machine. NIHF might be your best bet for clearing the high half of a register: no storage access. Requires the extended-immediate facility, available on a z9. You could avoid the storage references on the

Re: Using the High Halfs of registers

According to the 2004 POO (SA22-7832-03), which I believe predates z9, you can: Simulate an LA to clear the high half contents of a register with ICMH Rx,15,=XL4(00) or NG Rx,=XL8() Simulate an LA to increment the count in the high half with AG Rx,=XL8(1) Simulate