Re: [Qemu-devel] [4166] Implement ARM floating point exception emulation

[Fabrice Bellard <fabrice@bellard.org>]

If nwfpe is only implemented as software emulation in Linux, I suggest
to use the subversion "move" feature to move it to linux-user/arm/nwfpe.

Fabrice.

Aurelien Jarno wrote:
> Revision: 4166
>           http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=4166
> Author:   aurel32
> Date:     2008-04-07 20:30:53 +0000 (Mon, 07 Apr 2008)
> 
> Log Message:
> -----------
> Implement ARM floating point exception emulation
> 
> Modified Paths:
> --------------
>     trunk/linux-user/main.c
>     trunk/target-arm/nwfpe/fpa11.c
> 
> Modified: trunk/linux-user/main.c
> ===================================================================
> --- trunk/linux-user/main.c	2008-04-07 19:47:25 UTC (rev 4165)
> +++ trunk/linux-user/main.c	2008-04-07 20:30:53 UTC (rev 4166)
> @@ -378,19 +378,68 @@
>              {
>                  TaskState *ts = env->opaque;
>                  uint32_t opcode;
> +                int rc;
>  
>                  /* we handle the FPU emulation here, as Linux */
>                  /* we get the opcode */
>                  /* FIXME - what to do if get_user() fails? */
>                  get_user_u32(opcode, env->regs[15]);
>  
> -                if (EmulateAll(opcode, &ts->fpa, env) == 0) {
> +                rc = EmulateAll(opcode, &ts->fpa, env);
> +                if (rc == 0) { /* illegal instruction */
>                      info.si_signo = SIGILL;
>                      info.si_errno = 0;
>                      info.si_code = TARGET_ILL_ILLOPN;
>                      info._sifields._sigfault._addr = env->regs[15];
>                      queue_signal(info.si_signo, &info);
> -                } else {
> +                } else if (rc < 0) { /* FP exception */
> +                    int arm_fpe=0;
> +
> +                    /* translate softfloat flags to FPSR flags */
> +                    if (-rc & float_flag_invalid)
> +                      arm_fpe |= BIT_IOC;
> +                    if (-rc & float_flag_divbyzero)
> +                      arm_fpe |= BIT_DZC;
> +                    if (-rc & float_flag_overflow)
> +                      arm_fpe |= BIT_OFC;
> +                    if (-rc & float_flag_underflow)
> +                      arm_fpe |= BIT_UFC;
> +                    if (-rc & float_flag_inexact)
> +                      arm_fpe |= BIT_IXC;
> +
> +                    FPSR fpsr = ts->fpa.fpsr;
> +                    //printf("fpsr 0x%x, arm_fpe 0x%x\n",fpsr,arm_fpe);
> +
> +                    if (fpsr & (arm_fpe << 16)) { /* exception enabled? */
> +                      info.si_signo = SIGFPE;
> +                      info.si_errno = 0;
> +
> +                      /* ordered by priority, least first */
> +                      if (arm_fpe & BIT_IXC) info.si_code = TARGET_FPE_FLTRES;
> +                      if (arm_fpe & BIT_UFC) info.si_code = TARGET_FPE_FLTUND;
> +                      if (arm_fpe & BIT_OFC) info.si_code = TARGET_FPE_FLTOVF;
> +                      if (arm_fpe & BIT_DZC) info.si_code = TARGET_FPE_FLTDIV;
> +                      if (arm_fpe & BIT_IOC) info.si_code = TARGET_FPE_FLTINV;
> +
> +                      info._sifields._sigfault._addr = env->regs[15];
> +                      queue_signal(info.si_signo, &info);
> +                    } else {
> +                      env->regs[15] += 4;
> +                    }
> +
> +                    /* accumulate unenabled exceptions */
> +                    if ((!(fpsr & BIT_IXE)) && (arm_fpe & BIT_IXC))
> +                      fpsr |= BIT_IXC;
> +                    if ((!(fpsr & BIT_UFE)) && (arm_fpe & BIT_UFC))
> +                      fpsr |= BIT_UFC;
> +                    if ((!(fpsr & BIT_OFE)) && (arm_fpe & BIT_OFC))
> +                      fpsr |= BIT_OFC;
> +                    if ((!(fpsr & BIT_DZE)) && (arm_fpe & BIT_DZC))
> +                      fpsr |= BIT_DZC;
> +                    if ((!(fpsr & BIT_IOE)) && (arm_fpe & BIT_IOC))
> +                      fpsr |= BIT_IOC;
> +                    ts->fpa.fpsr=fpsr;
> +                } else { /* everything OK */
>                      /* increment PC */
>                      env->regs[15] += 4;
>                  }
> 
> Modified: trunk/target-arm/nwfpe/fpa11.c
> ===================================================================
> --- trunk/target-arm/nwfpe/fpa11.c	2008-04-07 19:47:25 UTC (rev 4165)
> +++ trunk/target-arm/nwfpe/fpa11.c	2008-04-07 20:30:53 UTC (rev 4166)
> @@ -162,6 +162,8 @@
>      fpa11->initflag = 1;
>    }
>  
> +  set_float_exception_flags(0, &fpa11->fp_status);
> +
>    if (TEST_OPCODE(opcode,MASK_CPRT))
>    {
>      //fprintf(stderr,"emulating CPRT\n");
> @@ -191,6 +193,11 @@
>    }
>  
>  //  restore_flags(flags);
> +  if(nRc == 1 && get_float_exception_flags(&fpa11->fp_status))
> +  {
> +    //printf("fef 0x%x\n",float_exception_flags);
> +    nRc=-get_float_exception_flags(&fpa11->fp_status);
> +  }
>  
>    //printf("returning %d\n",nRc);
>    return(nRc);
> 
> 
> 
> 
>