I don't want to highjack my own thread. Here is the output (probably edited a
little) from EDCDSECT and the sort of thing you can do with the results:
struct cvt {
void *cvttcbp; /* - Address of PSATNEW.
@PTC */
void *cvt0ef00; /* - ADDRESS OF ROUTINE TO SCHEDULE
*/
void *cvtlink; /* - ADDRESS OF DCB FOR SYS1.LINKLIB DATA
SET. */
void *cvtauscb; /* - ADDRESS OF ASSIGN/UNASSIGN SERVICE
@H1A */
void *cvtbuf; /* - ADDRESS OF THE BUFFER OF THE
RESIDENT */
void *cvtxapg; /* - ADDRESS OF I/O SUPERVISOR APPENDAGE
VECTOR */
void *cvt0vl00; /* - ADDRESS OF ENTRY POINT OF THE TASK
*/
void *cvtpcnvt; /* - ADDRESS OF ENTRY POINT OF THE ROUTINE
*/
void *cvtprltv; /* - ADDRESS OF ENTRY POINT OF THE ROUTINE
*/
void *cvtllcb; /* - ADDRESS OF THE LLCB.
@P1M */
etc.
void GetStepname(char name[9])
{
psa* psaPtr = NULL;
tcb* tcbPtr = (tcb *)psaPtr->psatold;
tiot* tiotPtr = (tiot *)tcbPtr->tcbtio;
memcpy(name, &tiotPtr->tiocstep._tiocjstn, sizeof(name)-1);
name[8] = '\0';
}
BTW, My union example below is wrong. What I mean is it gets the offsets
correct but it "factors" the ORG illogically. Hard to explain. What you
logically think of as two alternate record layouts, one {a,b} and one {c,d}:
union {
struct {int a; int b;};
struct {int c; int d;}; };
it instead renders as
struct {
union {int a; int c;};
union {int b; int d;}; };
If one of those int's is instead itself a struct of a short and two chars it
ends being a hard-to-read mess.
Charles
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf
Of Charles Mills
Sent: Saturday, March 19, 2016 3:47 PM
To: [email protected]
Subject: Re: C struct to DSECT utility?
Well, it's one of those things. EDCDSECT does not do a perfect job but it does
a better job than no job at all. You're not using it "in production" so if it
does a 95% job you are 95% ahead. Well, in my experience it is about 95% pretty
much right and about 1% totally wrong, where it gets an offset wrong. Sometimes
it generates such a flipping mess of unions that it is hopeless to read. It
tends to get unions wrong. How do I say this? Something that logically should
have been rendered
union x {int a; int b;};
union y {int c; int d;};
it instead renders as
union z {int a; int c;};
union w {int b; int d;};
Yes, of course, assembler is weakly typed, and even there, people misuse what
typing there is. EDCDSECT has some options, for example, how do you want to
deal with
FLAG DS X
INPUT EQU X'80'
OPEN EQU X'40'
etc.
Do you want INPUT to be a one-bit integer or a #define mask suitable for use
with logical or? EDCDSECT gives you a choice.
You have a choice whether to lowercase the assembler symbols (because old
assembler is typically all uppercase and C culture is lowercase).
Yes, there would be some challenges going the other direction: Foo and foo are
different C symbols but the same assembler symbol (but do you use both in the
same struct???). C struct symbols typically have local scope; all assembler
symbols have global scope. You could deal with the latter by letting the user
specify a prefix or by rendering
struct Foo { int Bar; };
in assembler as
Foo_Bar DS F
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