Re: Does anybody have any experience using SCANWC in MI? Looking to find the first character *not* matching a specific value.

Empiricism has its advantages.

DCL DD FOO CHAR(20) AUTO INIT('00000000001234567890');
DCL SPCPTR BAR AUTO;
DCL SPCPTR BAZ AUTO INIT(FOO);
DCL DD FIRSTNZ BIN(4) AUTO;
DCL DD CONTROL CHAR(8) AUTO INIT(X'010000F000000014');
ENTRY .ENTRY EXT;
SETSPPFP BAR, BAZ;
SCANWC BAR, CONTROL, X'06000000', =+1;
: SUBSPPFO FIRSTNZ, BAR, BAZ;
ADDN(S) FIRSTNZ, 1;
RTX *;
PEND;

FOO is the string to be searched. BAR is the pointer we're going to be feeding to the SCANWC statement. BAZ is a pointer used to initialize BAR, and then subtract from BAR in order to get the character position. FIRSTNZ is where we're going to put the difference.

CONTROL is the 8-byte control word:
01: Base and comparison mode both simple, starting the scan.
00: Reserved
00F0: looking for an EBCDIC '0'
00: Reserved
000014: Base length is 20

First, we SETSPPFP to initialize BAR from BAZ.

Then, we SCANWC our string, with the control, and option word as follows:
06: Option indicators, match if greater or less
000000: Reserved.
The fourth operand is where to go if it finds something that's less than an EBCDIC space; supposedly, it will accept a Null or omitted operand, but I couldn't figure out how. Note that it's essentially a naked branch target; in this case, a naked relative branch target just going to the next instruction.

At the end of the SCANWC, the offset in BAR has been set to the offset of the first character that isn't an EBCDIC zero.

Next, we subtract BAZ from BAR, to get the character position, and add 1, so that we're working with character positions (starting with 1) rather than offsets (starting with 0).


If you then run this in the debugger, with a breakpoint on the RTX, you'll get the expected result.

--
JHHL