Ref: Your note of 14 March 2018, 08:51:22 -0700
Charles Mills wrote:
> 1. Is there a machine instruction that will find one string within
> another? That given "Now is the time" and "is" would find the "is" and
> return a pointer to it? A machine instruction analog of Rexx POS?
I'm not aware of any such instruction. You can use SRST to find a
single character, and that can be used as part of a search algorithm.
> 2. Searching the PoOp for such an instruction led me to CUSE. It does
> not seem that CUSE could be used for this - is that correct? If I am reading
> CUSE correctly, then given "Now is the time", "All is well" and 2 or 3 would
> return the position of "is". Is my reading correct? What would that be good
> for? What would be a reasonable real-world use?
CUSE is very useful for creating an efficient representation of the
differences between two versions of a record, for example to create a
log record showing which bytes changed. It finds the end of a block of
changed data, ignoring unchanged sequences which are too small to be
worth representing as a separate section. To skip to the end of the
unchanged data, CLCL or CLCLE can be used.
Jonathan Scott
HLASM, IBM Hursley, UK
