/* IBM_PROLOG_BEGIN_TAG */
/* This is an automatically generated prolog. */
/* */
/* bos720 src/bos/usr/samples/fp/sigfpe_samp2.c 1.1 */
/* */
/* Licensed Materials - Property of IBM */
/* */
/* COPYRIGHT International Business Machines Corp. 1993 */
/* All Rights Reserved */
/* */
/* US Government Users Restricted Rights - Use, duplication or */
/* disclosure restricted by GSA ADP Schedule Contract with IBM Corp. */
/* */
/* IBM_PROLOG_END_TAG */
static char sccsid[] = "@(#)78 1.1 src/bos/usr/samples/fp/sigfpe_samp2.c, fpsamp, bos720 9/8/93 10:22:22";
/*
* COMPONENT_NAME: BOSSAMP
*
* FUNCTIONS: f_trap_sigfpe
* sigfpe_handler
*
* ORIGINS: 27
*
*
* (C) COPYRIGHT International Business Machines Corp. 1993
* All Rights Reserved
* Licensed Materials - Property of IBM
* US Government Users Restricted Rights - Use, duplication or
* disclosure restricted by GSA ADP Schedule Contract with IBM Corp.
*/
/*
* This demonstates a floating point exception handler,
* and some glue code to set up floating point exception
* traping. The glue code can be called from Fortran.
*/
#include <signal.h>
#include <fpxcp.h>
#include <fptrap.h>
#include <stdlib.h>
#include <stdio.h>
/*
* the fp_list structure will allow text descriptions
* of each possible trap type to be tied to the mask
* which identifies it.
*/
typedef struct
{
fpflag_t mask;
char *text;
} fp_list_t;
/* IEEE required trap types */
fp_list_t
trap_list[] =
{
{ FP_INVALID, "FP_INVALID"},
{ FP_OVERFLOW, "FP_OVERFLOW"},
{ FP_UNDERFLOW, "FP_UNDERFLOW"},
{ FP_DIV_BY_ZERO, "FP_DIV_BY_ZERO"},
{ FP_INEXACT, "FP_INEXACT"}
};
/* INEXACT detail list -- this is an IBM RISC System/6000 extension */
fp_list_t
detail_list[] =
{
{ FP_INV_SNAN, "FP_INV_SNAN" } ,
{ FP_INV_ISI, "FP_INV_ISI" } ,
{ FP_INV_IDI, "FP_INV_IDI" } ,
{ FP_INV_ZDZ, "FP_INV_ZDZ" } ,
{ FP_INV_IMZ, "FP_INV_IMZ" } ,
{ FP_INV_CMP, "FP_INV_CMP" } ,
{ FP_INV_SQRT, "FP_INV_SQRT" } ,
{ FP_INV_CVI, "FP_INV_CVI" } ,
{ FP_INV_VXSOFT, "FP_INV_VXSOFT" }
};
/*
* NAME: sigfpe_handler
*
* FUNCTION: a trap handler which is entered when
* a floating point exception occurs. The
* functions determines what exception(s) caused
* the trap, prints this to stdout, and returns
* to the process which caused the trap.
*
* NOTES:
* When entered, all floating point traps are
* disabled.
*
* This sample uses printf(). This should be used
* with caution since since printf() of a floating
* point number can cause a trap, and then a
* another printf() of a floating point number
* in the signal handler will corrupt the static
* buffer used for the conversion.
*
* OUTPUTS: The type of exception(s) which caused
* the trap.
*/
static void
sigfpe_handler(int sig,
int code,
struct sigcontext *SCP)
{
struct mstsave * state = &SCP->sc_jmpbuf.jmp_context;
fp_sh_info_t flt_context; /* structure for fp_sh_info() call */
int i; /* loop counter */
/*
* Determine which floating point exception(s) caused
* the trap. fp_sh_info() is used to build the floating signal
* handler info structure, and then the member flt_context.trap
* can be examined. First the trap type is compared for the IEEE
* required traps, and if the trap type is an invalid operation,
* the detail bits are examined.
*/
fp_sh_info(SCP, &flt_context, FP_SH_INFO_SIZE);
for (i = 0; i < (sizeof(trap_list) / sizeof(fp_list_t)); i++)
{
if (flt_context.trap & trap_list[i].mask)
(void) printf("Trap caused by %s error\n", trap_list[i].text);
}
if (flt_context.trap & FP_INVALID)
{
for (i = 0; i < (sizeof(detail_list) / sizeof(fp_list_t)); i++)
{
if (flt_context.trap & detail_list[i].mask)
(void) printf("Type of invalid op is %s\n", detail_list[i].text);
}
}
/* report which trap mode was in effect */
switch (flt_context.trap_mode)
{
case FP_TRAP_OFF:
puts("Trapping Mode is OFF");
break;
case FP_TRAP_SYNC:
puts("Trapping Mode is SYNC");
break;
case FP_TRAP_IMP:
puts("Trapping Mode is IMP");
break;
case FP_TRAP_IMP_REC:
puts("Trapping Mode is IMP_REC");
break;
default:
puts("ERROR: Invalid trap mode");
}
(void) fflush(stdout);
/* clear exception bits to prevent recurrence of trap */
fp_sh_set_stat(SCP, (flt_context.fpscr & ((fpstat_t) ~flt_context.trap)));
/*
* increment the iar of the process that caused the trap, to prevent
* re-execution of the instruction.
*
* The FP_IAR_STAT bit in flt_context.flags indicates if state->iar points
* to an instruction which has logically been started. If this bit is true,
* state->iar points to an operation which has been started, and if re-executed
* will cause another exception. In this case we want to continue execution and
* ignore the results of that operation, so the iar is advanced to point to the
* next instruction. If the bit is false, the iar already points to the next
* instruction which must be executed.
*/
if ( flt_context.flags & FP_IAR_STAT )
{
puts("Increment IAR");
state->iar += 4;
}
return;
}
#define TRAP_OFF 0
#define TRAP_ON 1
/*
* NAME: f_trap_sigfpe
*
* FUNCTION: provide a sample interface for Fortran to
* enable/disable traping.
*
* DESCRIPTION: The first argument is an action
* code. If non-zero, the call will establish
* sigfpe_handler() as the trap handler for
* for sigfpe, put the process in synchronous
* execution mode, and enable the trap(s)
* specified by the second argument.
*
* If the second argument is zero, the call
* will remove the sigfpe_handler (if installed),
* put the process in synchonous execution mode,
* and disable all traps.
*/
void
f_trap_sigfpe(int *action, fptrap_t *trap_type)
{
struct sigaction response;
static struct sigaction old_response;
static int trap_status = TRAP_OFF;
/* if action is zero, then turn off trapping, and
* also restore previous signal handler(s) if any.
*/
if (! *action)
{
(void) fp_trap(FP_TRAP_OFF);
fp_disable_all();
if (trap_status)
{
trap_status = TRAP_OFF;
(void) sigaction(SIGFPE, &old_response, NULL);
}
}
else
{
if (! trap_status)
{
(void) sigaction(SIGFPE, NULL, &old_response);
(void) sigemptyset(&response.sa_mask);
response.sa_flags = FALSE;
response.sa_handler = (void (*)(int)) sigfpe_handler;
(void) sigaction(SIGFPE, &response, NULL);
(void) fp_trap(FP_TRAP_SYNC);
fp_enable(*trap_type);
trap_status = TRAP_ON;
}
}
}