MPE libc sleep() function fix

1. The Problem
2. The program sleep01.c
3. HPUX output
4. The program sleep02.c
5. MPE output
6. sleep() - disassembled
7. New sleep.c
8. New MPE output

The Problem:

The sleep() function attempts to sleep the process for some number of seconds. If an interrupt happens, like a keyboard interrupt SIGINT, the sleep() function stops and returns the unslept number of seconds.
(MPE/iX Developer's Kit Reference Manual Volumme I, page 4-234)
(HP C/iX Library Reference Manual, page 5-274)
(HPUX man 3 sleep)
The program below, sleep01.c, running on HPUX shows this behavior. Under UNIX, the keyboard interrupt is normally generated by typing control-C and generates the signal SIGINT. The default action when receiving this signal is to terminate the progam. Providing a signal trap routine allows the program to continue.
Under MPE (sleep02.c), keyboard interrupt or subsystem-break (control-Y) is normally disabled. Even when enabled, we find that the sleep() function continues to sleep the full number of seconds. Also, signals are only generated via the raise() function.
(HP C/iX Library Reernece Manual, page 5-270)

The program sleep01.c

01 /*----------------------------------------------------------------*/
02 /* sleep01.c   sleep test  Keven Miller   04/25/2011              */
03 /*----------------------------------------------------------------*/
04 #include <stdio.h>
05 #include <unistd.h>
06 #include <signal.h>
07 #include <time.h>
08 
09 #define  proc
10 
11 proc void sleepcy (int sig)
12 {
13    printf ("!! Control-C SIGINT %d !!\n", sig);
14    signal ( sig, &sleepcy );
15 }
16 
17 proc int main ( int ac, char *av[] )
18 {
19    int   uns, secs;
20    time_t t1, t2;
21 
22    signal ( SIGINT, &sleepcy );
23 
24    secs = 10;
25    printf ("Sleep 10\n");
26 
27    t1 = time (0);
28    uns = sleep (secs);
29    t2 = time (0);
30 
31    printf ("Sleep unslept secs %d (Actual secs %d)\n", uns, t2 - t1);
32 }
33/*----------------------------------------------------------------*/

Note worthy lines:
1. 11 signal trap routine with printf so we can see when it happens.
2. 22 Enable SIGINT trap.
3. 27,29 calling time() routine to verify actual time slept.

HPUX output

Run with no interruption




Run again

After 4 seconds, type Control-C

hpux-1:kevenm /home/kevenm/src#
hpux-1:kevenm /home/kevenm/src#
hpux-1:kevenm /home/kevenm/src#sleep01
Sleep 10
Sleep unslept secs 0 (Actual secs 10)
hpux-1:kevenm /home/kevenm/src#
hpux-1:kevenm /home/kevenm/src#
hpux-1:kevenm /home/kevenm/src#sleep01
Sleep 10
!! Control-C SIGINT 2 !!
Sleep unslept secs 6 (Actual secs 4)
hpux-1:kevenm /home/kevenm/src#
hpux-1:kevenm /home/kevenm/src#

It appears to work as documented.

The program sleep02.c

01 /*----------------------------------------------------------------*/
02 /* sleep02.c   sleep test  Keven Miller   04/25/2011              */
03 /*----------------------------------------------------------------*/
04 #pragma list off                       /*MPE*/
05 #include <stdio.h>
06 #include <unistd.h>
07 #include <signal.h>
08 #include <time.h>
09 
10 #pragma intrinsic XCONTRAP             /*MPEcy*/
11 #pragma intrinsic RESETCONTROL         /*MPEcy*/
12 
13 #define  proc
14 
15 /*----------------------------------------------------------------*/
16 proc void cytrap (void)                /*MPEcy*/
17 {                                      /*MPEcy*/
18    raise (SIGINT);                     /*MPEcy*/
19    RESETCONTROL ();                    /*MPEcy*/
20 }                                      /*MPEcy*/
21 /*----------------------------------------------------------------*/
22 
23 proc void sleepcy (int sig)
24 {
25    printf ("!! Control-Y SIGINT %d !!\n", sig);  /*MPEcy*/
26    signal ( sig, &sleepcy );
27 }
28 
29 proc int main ( int ac, char *av[] )
30 {
31    int   uns, secs, old;
32    time_t t1, t2;
33 
34    XCONTRAP ( (int) &cytrap, &old );   /*MPEcy*/
35 
36    signal ( SIGINT, &sleepcy );
37 
38    secs = 10;
39    printf ("Sleep 10\n");
40
41    t1 = time (0);
42    uns = sleep (secs);
43    t2 = time (0);
44 
45    printf ("Sleep unslept secs %d (Actual secs %d)\n", uns, t2 - t1);
46 }
47 /*----------------------------------------------------------------*/

Same program as sleep01.c with added Control-Y support.
1. 16-20 Control-Y trap handler that raises the SIGINT signal.
2. 34 Enable Control-Y interrupt.

MPE output

Build sleep02 without the
  /*MPEcy*/ tagged lines












Run test; wait 2-3 seconds
Then type Control-Y
No interrupt response.




Build with the 
  /*MPEcy*/ tagged lines
  
  
  
  
  
  
  
  
  
  
  
  
  
Run test; wait 2-3 seconds
Then type Control-Y
Interrupt occurrs !!
But sleep not interrupted
It actually increased !!

Fox 11:
Fox 11:
Fox 11:setvar ccopts "-Aa +e +w1"
Fox 11:ccxllk sleep02c,sleep02
MON APR 25 2011 10:50 AM  Copyright Hewlett-Packard Co. 1984. PAGE  1
HP C/iX HP31506 A.05.19                                    "SLEEP02C"

    1  0   # 1 "SLEEP02C.LIBC.KEVENM"
    1  0   #pragma list off
Clean compile
HP Link Editor/iX (HP30315A.06.17) Copyright Hewlett-Packard Co 1986

LinkEd> link from=$oldpass;rl=libc.lib.sys,libcansi.lib.sys;&
>>>>>>> TO=sleep02;SHARE
 
Clean Link
Fox 11:
Fox 11:sleep02
Sleep 10
Sleep unslept secs 0 (Actual secs 10)
Fox 11:
...
Fox 11:
Fox 11:
Fox 11:ccxllk sleep02c,sleep02
CCOPTS=-Aa +e +w1   
MON APR 25 2011 10:53 AM  Copyright Hewlett-Packard Co. 1984. PAGE  1
HP C/iX HP31506 A.05.19                                    "SLEEP02C"

    1  0   # 1 "SLEEP02C.LIBC.KEVENM"
    1  0   #pragma list off
Clean compile
HP Link Editor/iX (HP30315A.06.17) Copyright Hewlett-Packard Co 1986

LinkEd> link from=$oldpass;rl=libc.lib.sys,libcansi.lib.sys;&
>>>>>>> TO=sleep02;SHARE;CAP=
 
Clean Link
Fox 11:
Fox 11:sleep02
Sleep 10
!! Control-Y SIGINT 2 !!
Sleep unslept secs 0 (Actual secs 13)
Fox 11:
Fox 11:

Keyboard interrupt worked. But sleep did not stop and return the unused seconds.
Some problem with the sleep() function.

sleep() - disassembled

Disassemble sleep()



Save seconds into reg3


Save reg 3 into 64 bit field
Load 64 bit fixed into fpreg4
Convert fixed to float fpreg5

Call PAUSE 
Cnvt float to fixed reg26
Call CCODE

Comp CCE(2) to reg28;skip if =
Save secs to reg28;skip
Zero return reg28
 
return 

Fox 11:
Fox 11:run sleep02;debug

DEBUG/iX C.16.01 

DEBUG Intrinsic at: 519.0000a294 ?$START$
$1 ($50) nmdebug > dc sleep,14
USER $1d0.a4c74   
000a4c74  sleep         6bc23fd9  STW      2,-20(0,30)
000a4c78  sleep+$4      6fc30080  STWM     3,64(0,30)
000a4c7c  sleep+$8      081a0243  OR       26,0,3
000a4c80  sleep+$c      0800025f  OR       0,0,31
000a4c84  sleep+$10     0fdf1281  STWS     31,-16(0,30)
000a4c88  sleep+$14     0fc31289  STWS     3,-12(0,30)
000a4c8c  sleep+$18     2fc11004  FLDDS    -16(0,30),4
000a4c90  sleep+$1c     30808a05  FCNVXF,DBL,SGL4,5
000a4c94  sleep+$20     37da3f99  LDO      -52(30),26
000a4c98  sleep+$24     e85f1f6d  BL       ?sleep+$1c,2
000a4c9c  sleep+$28     27401205  FSTWS    5,0(0,26)
000a4ca0  sleep+$2c     e85c11f5  BL       ?access+$9c,2
000a4ca4  sleep+$30     08000240  OR       0,0,0
000a4ca8  sleep+$34     93802004  COMICLR,=2,28,0
000a4cac  sleep+$38     0803125c  OR,TR    3,0,28
000a4cb0  sleep+$3c     0800025c  OR       0,0,28
000a4cb4  sleep+$40     4bc23f59  LDW      -84(0,30),2
000a4cb8  sleep+$44     e840c000  BV       0(2)
000a4cbc  sleep+$48     4fc33f81  LDWM     -64(0,30),3
000a4cc0  ?_system         e84000a0  BL       system,2
$2 ($50) nmdebug >

How do I know those are PAUSE and CCODE calls?
Just single step through the Branch-and-Link (BL) until you enter the next routine.
sleep() calls the PAUSE intrinsic. The PAUSE intrinsic does allow Control-Y interrupts to occur - but on return from the interrupt it apparently starts pausing from the initial value again - making the overall pause time greater than the initial request.
Long ago with MPE-IV or before, I remember seeing documention on another "intrinsic" PAUSEX, which still exists in MPE, but not defined as an intrinsic. It is called just like PAUSE, however on interrupt, the float parameter by reference is updated with the remaining seconds, and on return from the interrupt, PAUSEX continues to pause for number of seconds in the float parameter. This allows you to change the value for the pause.

New sleep.c

01 /*----------------------------------------------------------------*/          
02 /* csleep.c    Keven Miller   24 Apr 2011    kevenm@3kranger.com  */
03 /* CCOPTS "-Aa +e +w1 +O2"                                        */
04 /*----------------------------------------------------------------*/
05 #pragma list off
06 #pragma LOCALITY "3kRanger"
07 #include "cstd.h"
08 
09 #pragma intrinsic CCODE
10 #pragma intrinsic PAUSE
11 #pragma intrinsic RESETCONTROL
12 #pragma intrinsic XCONTRAP
13 
14 extern void PAUSEX ( f32* );
15 
16 #ifndef  ORG
17 
18 static f32 sleep_time;
19 static f32 unsleep_time;
20 static s32 prev_cytrap;
21 /*----------------------------------------------------------------*/
22 
23 proc static void sleep_cytrap (void)
24 {
25    unsleep_time = sleep_time;
26    sleep_time = 0.0;
27    if ( prev_cytrap )
28       (*(vfp)prev_cytrap)();
29    RESETCONTROL ();
30 }
31 
32 #endif
33 /*----------------------------------------------------------------*/
34 
35 proc u32 sleep ( u32 isecs )
36 {
37 #ifdef   ORG
38 
39    f32   f;
40 
41    f = isecs;
42    PAUSE ( &f );
43    if ( MPE_CCE != CCODE () )
44       return   isecs;
45    else
46       return   0;
47 
48 #else /* NEW */
49 
50    XCONTRAP ( (int) &sleep_cytrap, &prev_cytrap );
51 
52    sleep_time = isecs;
53    unsleep_time = sleep_time;
54 
55    PAUSEX ( &sleep_time );
56 
57    isecs = ( unsleep_time + 0.499999 );
58 
59    XCONTRAP ( prev_cytrap, &prev_cytrap );
60 
61    return   isecs;
62 
63 #endif
64 }
65 /*----------------------------------------------------------------*/

Note worthy lines:
1. 37 The ifdef ORG block surrounds the original code.
2. 18-20 We need a global variable for the float sleep time so that a Control-Y trap can access the pause value. We need a variable to retain the unused seconds. Also we need to retain any user Control-Y trap.
3. 23-30 the sleep Control-Y trap routine. Save the unused seconds; Set the remaining time to 0; if it exists, call the user Control-Y trap.
4. 50 Set the sleep Control-Y trap routine, saving the user routine.
5. 52 Set the float value from the given seconds.
6. 57 Convert the float unused seconds to fixed integer.
7. 59 Reset the Control-Y trap to the user trap.

New MPE output

   
   
   
Create NMOBJ of our sleep















Build sleep02 linking in 
 our sleep
 
 
 
 










Run test

Hit Control-Y
 We see the user trap output
 
Remove the Control-Y trap 
 from sleep02
Hit Control-Y
No user trap, or SIGINT
 but sleep now stops!

Fox 11:
Fox 11:
Fox 11:setvar ccopts "-Aa +e +w1 +O2"
Fox 11:ccxl csleep,csleepo
CCOPTS=-Aa +e +w1 +O2   
MON APR 25 2011  2:02 PM  Copyright Hewlett-Packard Co. 1984. PAGE  1
HP C/iX HP31506 A.05.19                                      "CSLEEP"

    1  0   # 1 "CSLEEP.LIBC.KEVENM"
    1  0   
    2  0   
    3  0   
    4  0   
    5  0   #pragma list off
Clean compile
Fox 11:
Fox 11:
Fox 11:setvar ccopts "-Aa +e +w1"
Fox 11:setvar linkobj "csleepo"
Fox 11:ccxllk sleep02c,sleep02
CCOPTS=-Aa +e +w1   
MON APR 25 2011  2:02 PM  Copyright Hewlett-Packard Co. 1984. PAGE  1
HP C/iX HP31506 A.05.19                                    "SLEEP02C"

    1  0   # 1 "SLEEP02C.LIBC.KEVENM"
    1  0   #pragma list off
Clean compile
HP Link Editor/iX (HP30315A.06.17) Copyright Hewlett-Packard Co 1986

LinkEd> link from=$oldpass,csleepo;rl=libc.lib.sys,libcansi.lib.sys;&
>>>>>>> TO=sleep02;SHARE;CAP=
 
Clean Link
Fox 11:
Fox 11:
Fox 11:sleep02
Sleep 10
!! Control-Y SIGINT 2 !!
Sleep unslept secs 7 (Actual secs 3)
Fox 11:
...
Fox 11:sleep02
Sleep 10
Sleep unslept secs 5 (Actual secs 5)
Fox 11:
Fox 11: