Everhart, Glenn
From: wayne@tachyon.xxx362482killspam-0dd3
Sent: Wednesday, July 22, 1998 7:51 PM
To: Info-VAX@Mvb.Saic.Com
Subject: Re: help with disk driver acp functions
In article <35B5D3F7.5018C187@epamail.epa.gov>, Charles Hamm <hamm.charles@epamail.epa.gov> writes:
> This is a multi-part message in MIME format.
>
> --------------1AEBB8B457DCACDD758F2052
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> i need some help with the disk driver acp to write to a file.
>
> this is for a real-time application. the reason i am using qios directly
> (from c) is mainly to get access to asynch io's, so i can do something
> else while the data is writing. obviously the lower overhead of the acp
> interface is also attractive.
>
> actually i have gotten the qio part working correctly. the only problem
> i have is that i can't seem to get the file size in the header to be
> updated. no matter how i seem to call the modify function, the actual
> file size stays at 0 after closing. the allocated size is correct. i can
> do a "set file/end" to make the file readable and prove to myself that
> the data was actually written.
>
> does anybody know what i'm doing wrong? the example program is attached.
>
> --
> Charles Hamm US EPA (HERL/NTD) RTP, NC, USA
> (v)919-541-3017 hamm.charles@epamail.epa.gov (f)919-541-4849
>
> --------------1AEBB8B457DCACDD758F2052
> Content-Type: text/plain; charset=us-ascii; name="wtqio.c"
> Content-Transfer-Encoding: 7bit
> Content-Disposition: inline; filename="wtqio.c"
>
> #include <stdlib.h>
> #include <stdio.h>
> #include <string.h>
>
> #include <starlet.h>
> #include <ssdef.h>
> #include <iodef.h>
> #include <fibdef.h>
> #include <psldef.h>
> #include <rms.h>
>
> #include <site_lib/site.h>
>
> #pragma message disable dollarid
>
> typedef struct {
> longword len;
> struct fibdef *fib;
> } FIBD;
>
> typedef struct {
> unsigned status: 16;
> unsigned count: 16;
> unsigned fill: 32;
> } IOSB;
>
> longword qioopen(longword*, FIBD*, char*, longword, longword);
> longword qiowrite(longword, FIBD*, short*, longword);
> longword qioclose(longword, FIBD*);
> void out(char*, longword);
> void done(longword);
>
> boolean Donev = FALSE;
> IOSB Iosb[2];
>
> int main(int argc, char **argv) {
>
> int i, j, k;
> char *name = "wt.dat";
> short a[256];
> longword chan;
> FIBD fibd;
> struct fibdef fib;
>
> /* init the fib and descriptor */
> memclr(&fib, sizeof(struct fibdef));
> fibd.len = sizeof(struct fibdef);
> fibd.fib = &fib;
>
> /* init the data block */
> for (i=0; i<256; i++) a[i] = i;
>
> /* do the io */
> (void)qioopen(&chan, &fibd, name, 1, sizeof(a));
> (void)qiowrite(chan, &fibd, a, sizeof(a));
> for (i=0; i<1000000; i++) j=i+1;
> (void)qioclose(chan, &fibd);
>
> } /* end main */
>
>
> longword qioopen(longword *chan, FIBD *fibd, char *name, longword recs,
> longword recsiz) {
>
> static char spec[256];
> longword status, reslen;
> descrip(namedesc, "SYS$DISK");
> struct FAB fab;
> struct NAM nam;
>
> /* init the fab and nam for rms */
> (void)strcpy(spec, "sys$disk:");
> (void)strcat(spec, name);
> fab = cc$rms_fab;
> fab.fab$l_fna = spec;
> fab.fab$b_fns = (byte)strlen(spec);
> fab.fab$b_rfm = (byte)FAB$C_FIX;
> fab.fab$w_mrs = (word)recsiz;
> nam = cc$rms_nam;
> fab.fab$l_nam = &nam;
>
> /* create and close the file, retaining the fid in the nam block */
> status = sys$create(&fab);
> if ((status != RMS$_NORMAL) && (status != RMS$_CREATED)) out("sys$cre", status);
> status = sys$close(&fab);
> if (status != RMS$_NORMAL) out("sys$clo", status);
>
> /* open a channel to the default disk */
> status = sys$assign(&namedesc, chan, 0, NULL, 0);
> if (status != SS$_NORMAL) out("sys$ass", status);
>
> /* copy the fid from the nam block to the fib and init some fib bits */
> fibd->fib->fib$w_fid_num = nam.nam$w_fid_num;
> fibd->fib->fib$w_fid_seq = nam.nam$w_fid_seq;
> fibd->fib->fib$w_fid_rvn = nam.nam$w_fid_rvn;
> fibd->fib->fib$v_seqonly = TRUE;
> fibd->fib->fib$v_write = TRUE;
> fibd->fib->fib$v_nowrite = TRUE;
> fibd->fib->fib$v_noread = TRUE;
> fibd->fib->fib$v_writethru = TRUE;
> fibd->fib->fib$v_writethru = TRUE;
> fibd->fib->fib$l_exsz = recs * (recsiz / 512);
>
> /* open the file using the fib */
> status = sys$qiow(0, *chan, (IO$_ACCESS | IO$M_ACCESS), &Iosb[0], NULL, 0,
> fibd, NULL, NULL, NULL, NULL, 0);
> if (status != SS$_NORMAL) out("qio acc", status);
> return status;
>
> } /* end qioopen */
>
>
> longword qiowrite(longword chan, FIBD *fibd, short* rec, longword recsiz) {
>
> longword status;
> static block = 0;
> block++;
> IOSB iosb;
>
> /* extend the file */
> fibd->fib->fib$v_extend = TRUE;
> status = sys$qiow(0, chan, IO$_MODIFY,
> &iosb, NULL, 0, fibd, 0, 0, 0, 0, 0);
> (void)printf("ext bl%d st%d iost%d ct%d\n", block, status,
> iosb.status, iosb.count);
> status = sys$qiow(0, chan, IO$_MODIFY,
> &iosb, NULL, 0, fibd, 0, 0, 0, 0, 0);
> (void)printf("ext bl%d st%d iost%d ct%d\n", block, status,
> iosb.status, iosb.count);
> fibd->fib->fib$v_extend = FALSE;
>
> /* write it */
> status = sys$qio(block, chan, IO$_WRITEVBLK, &Iosb[block - 1], done, block,
> rec, recsiz, block, 0, 0, 0);
> (void)printf("wri bl%d st%d do%d\n", block, status, Donev);
> if (status != SS$_NORMAL) out("wri", status);
>
> /* update the filesize */
> status = sys$qiow(0, chan, IO$_MODIFY,
> &iosb, NULL, 0, fibd, 0, 0, 0, 0, 0);
> (void)printf("filsz st%d iost%d ct%d\n", status,
> iosb.status, iosb.count);
>
> return status;
>
> } /* end qiowrite */
>
> void done(longword block) {
>
> if (succ(Iosb[0].status)) Donev = TRUE;
> else (void)printf("ast bl%d io st %d count %d\n", block,
> Iosb[block - 1].status, Iosb[block - 1].count);
> (void)printf("ast bl%d do%d ct%d\n", block, Donev, Iosb[block - 1].count);
>
> } /* end done */
>
>
> longword qioclose(longword chan, FIBD *fibd) {
>
> longword status;
>
> /* close the file */
> status = sys$qiow(0, chan, IO$_DEACCESS, &Iosb[0], NULL, 0, fibd, 0, 0, 0, 0,
> 0);
> (void)printf("deac st%d io err %d count %d\n", status, Iosb[0].status,
> Iosb[0].count);
> if (status != SS$_NORMAL) out("deac", status);
>
> /* close the channel */
> status = sys$dassgn(chan);
> if (status != SS$_NORMAL) out("sys$ass", status);
>
> return status;
>
> } /* end qioclose */
>
>
> void out(char *msg, longword status) {
>
> (void)puts(msg);
> exit(status);
>
> } /* end out */
>
> --------------1AEBB8B457DCACDD758F2052--
Rather than fool with the acp (actually xqp nowadays) interface, why not use
rms? If asynchronous i/o is all you need beyond the language-supplied
routines, rms has this capability. And certainly it will take over a lot of
the housekeeping you are now doing manually.
I don't think the overhead is all that significant, especially since we are
talking about disk i/o.
Wayne
--
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