usr/src/games/compat/Original/dosig.c

#
/*      Handle signal trapping from version 6 or version 7 compatability
 *      mode programs.
 *      Art Wetzel      November 1979
 */
#ifdef TRACE
#include <stdio.h>
#endif
#include <signal.h>
#include "defs.h"
unsigned int  sigvals[NSIG+1];
/* actual catch point for all signals */
sigcatch(signum) int signum; {
        unsigned short *pcptr;
        extern getregs();
        if(incompat) {
                /* hurry up and get the registers before they are destroyed */
                getregs();
        } else {
                /* we were in native mode simulating a sys call */
                /* set it up with the old values */
                dosig(signum, pc);
                /* go back where we were doing the sys call */
                return(0);
        }
        /* figure out the pc */
        pcptr = (unsigned short *)((char *)&pcptr + 20);
        pc = (unsigned short *) *pcptr;
        /* get the psl with condition codes */
        /* requires UNIX-32V patch to not clear out condition codes */
        psl = 0x83c00000 | (*(pcptr - 6) & 017);
        /* actually do the thing */
        if(sigvals[signum] != (unsigned int)SIG_DFL && (sigvals[signum] & (unsigned int)SIG_IGN) == 0)
                dosig(signum, pc);
        /* go back to compatability mode and the signal routine there */
        incompat++;
        compat();
}
/* routine to set up pdp11 space for return from a signal */
dosig(signum, from) {
        unsigned short *sp;
#ifdef TRACE
        fprintf(stderr,"Caught sig %d from 0%o -> 0%o\n",signum,(pc-1),*(pc-1));
#endif
        /* where is the stack */
        sp = (unsigned short *)regs[6];
        /* stack up psw condition codes so rti works */
        *(--sp) = psl & 017;
        /* stack pc */
        *(--sp) = (unsigned short)(int)pc;
        /* reset stack pointer */
        regs[6] = (unsigned short)(int)sp;
        /* reset pc to signal catching routine */
        pc = (unsigned short *)sigvals[signum];
}