Anubha Agarwal wrote and asked for a video covering Search String (SRST). I don’t have a video quite yet, but here are my notes on this instruction. It’s an interesting one that can be used to search for the first occurrence of a single character in a given area of storage. It was probably added to the instruction set to help compiler writers who needed to search for C strings which are terminated with X’00’.
The interesting feature of the instruction is that it can be interrupted by the CPU for efficiency reasons when searching large areas of storage. The programmer can then decide whether to continue searching or not.
I stumbled over the examples given in the Principles of Operation, until I realized the code is flawed. A BC 1,LOOP instruction should be BC 3,LOOP, so pay close attention to those two examples.
Now that I’ve written down my thoughts, I’ll put together a video soon and provide some program examples you can experiment with. This instruction is definitely worth a look.
The Marist Enterprise Computing conference (ECC) confernce is one of the best IBM mainframe conferences going: Great speakers, food, location, and no conference fee. This year it’s meeting face-to-face again on the beautiful Marist College campus, Poughkeepsie, NY. There is even an opportunity to give a presention of your own.
I’m in full assembler mode these days, preparing to teach an assembler class for Marist College that starts on Monday. It’s playing havoc with my golf game, but the upside is I’m getting a lot done. I’ve recently updated chapters 1-4 of the assembler book. That includes a complete re-write of Chapter 4, trying to provide explanations of addressing on IBM mainframes. I’m also adding a problem set to the end of each chapter, trying to make the book function better as a textbook.
I will always provide access to the individual chapters online, but my plan is to self-publish an ebook and a printed version that can be ordered. More about that later.
I want to thank everyone who has pointed out errors or suggested improvements in the text. I am listening and making the changes you suggested.
It has been fun to be part of the IBM Champions program this year – an honor! The IBM Champions program is taking currently taking nominations through November 30. Is there someone who helps you or answers your questions? Say thank you by nominating them to be an #IBMChampion. Tell their story to help them earn their star. You can even nominate yourself. https://developer.ibm.com/champions/