371 lines
11 KiB
C
371 lines
11 KiB
C
/*
|
|
* Linux/PA-RISC Project (http://www.parisc-linux.org/)
|
|
*
|
|
* Floating-point emulation code
|
|
* Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2, or (at your option)
|
|
* any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
|
*/
|
|
/*
|
|
* BEGIN_DESC
|
|
*
|
|
* File:
|
|
* @(#) pa/fp/decode_exc.c $ Revision: $
|
|
*
|
|
* Purpose:
|
|
* <<please update with a synopsis of the functionality provided by this file>>
|
|
*
|
|
* External Interfaces:
|
|
* <<the following list was autogenerated, please review>>
|
|
* decode_fpu(Fpu_register, trap_counts)
|
|
*
|
|
* Internal Interfaces:
|
|
* <<please update>>
|
|
*
|
|
* Theory:
|
|
* <<please update with a overview of the operation of this file>>
|
|
*
|
|
* END_DESC
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include "float.h"
|
|
#include "sgl_float.h"
|
|
#include "dbl_float.h"
|
|
#include "cnv_float.h"
|
|
/* #include "types.h" */
|
|
#include <asm/signal.h>
|
|
#include <asm/siginfo.h>
|
|
/* #include <machine/sys/mdep_private.h> */
|
|
|
|
#undef Fpustatus_register
|
|
#define Fpustatus_register Fpu_register[0]
|
|
|
|
/* General definitions */
|
|
#define DOESTRAP 1
|
|
#define NOTRAP 0
|
|
#define SIGNALCODE(signal, code) ((signal) << 24 | (code))
|
|
#define copropbit 1<<31-2 /* bit position 2 */
|
|
#define opclass 9 /* bits 21 & 22 */
|
|
#define fmt 11 /* bits 19 & 20 */
|
|
#define df 13 /* bits 17 & 18 */
|
|
#define twobits 3 /* mask low-order 2 bits */
|
|
#define fivebits 31 /* mask low-order 5 bits */
|
|
#define MAX_EXCP_REG 7 /* number of excpeption registers to check */
|
|
|
|
/* Exception register definitions */
|
|
#define Excp_type(index) Exceptiontype(Fpu_register[index])
|
|
#define Excp_instr(index) Instructionfield(Fpu_register[index])
|
|
#define Clear_excp_register(index) Allexception(Fpu_register[index]) = 0
|
|
#define Excp_format() \
|
|
(current_ir >> ((current_ir>>opclass & twobits)==1 ? df : fmt) & twobits)
|
|
|
|
/* Miscellaneous definitions */
|
|
#define Fpu_sgl(index) Fpu_register[index*2]
|
|
|
|
#define Fpu_dblp1(index) Fpu_register[index*2]
|
|
#define Fpu_dblp2(index) Fpu_register[(index*2)+1]
|
|
|
|
#define Fpu_quadp1(index) Fpu_register[index*2]
|
|
#define Fpu_quadp2(index) Fpu_register[(index*2)+1]
|
|
#define Fpu_quadp3(index) Fpu_register[(index*2)+2]
|
|
#define Fpu_quadp4(index) Fpu_register[(index*2)+3]
|
|
|
|
/* Single precision floating-point definitions */
|
|
#ifndef Sgl_decrement
|
|
# define Sgl_decrement(sgl_value) Sall(sgl_value)--
|
|
#endif
|
|
|
|
/* Double precision floating-point definitions */
|
|
#ifndef Dbl_decrement
|
|
# define Dbl_decrement(dbl_valuep1,dbl_valuep2) \
|
|
if ((Dallp2(dbl_valuep2)--) == 0) Dallp1(dbl_valuep1)--
|
|
#endif
|
|
|
|
|
|
#define update_trap_counts(Fpu_register, aflags, bflags, trap_counts) { \
|
|
aflags=(Fpu_register[0])>>27; /* assumes zero fill. 32 bit */ \
|
|
Fpu_register[0] |= bflags; \
|
|
}
|
|
|
|
u_int
|
|
decode_fpu(unsigned int Fpu_register[], unsigned int trap_counts[])
|
|
{
|
|
unsigned int current_ir, excp;
|
|
int target, exception_index = 1;
|
|
boolean inexact;
|
|
unsigned int aflags;
|
|
unsigned int bflags;
|
|
unsigned int excptype;
|
|
|
|
|
|
/* Keep stats on how many floating point exceptions (based on type)
|
|
* that happen. Want to keep this overhead low, but still provide
|
|
* some information to the customer. All exits from this routine
|
|
* need to restore Fpu_register[0]
|
|
*/
|
|
|
|
bflags=(Fpu_register[0] & 0xf8000000);
|
|
Fpu_register[0] &= 0x07ffffff;
|
|
|
|
/* exception_index is used to index the exception register queue. It
|
|
* always points at the last register that contains a valid exception. A
|
|
* zero value implies no exceptions (also the initialized value). Setting
|
|
* the T-bit resets the exception_index to zero.
|
|
*/
|
|
|
|
/*
|
|
* Check for reserved-op exception. A reserved-op exception does not
|
|
* set any exception registers nor does it set the T-bit. If the T-bit
|
|
* is not set then a reserved-op exception occurred.
|
|
*
|
|
* At some point, we may want to report reserved op exceptions as
|
|
* illegal instructions.
|
|
*/
|
|
|
|
if (!Is_tbit_set()) {
|
|
update_trap_counts(Fpu_register, aflags, bflags, trap_counts);
|
|
return SIGNALCODE(SIGILL, ILL_COPROC);
|
|
}
|
|
|
|
/*
|
|
* Is a coprocessor op.
|
|
*
|
|
* Now we need to determine what type of exception occurred.
|
|
*/
|
|
for (exception_index=1; exception_index<=MAX_EXCP_REG; exception_index++) {
|
|
current_ir = Excp_instr(exception_index);
|
|
/*
|
|
* On PA89: there are 5 different unimplemented exception
|
|
* codes: 0x1, 0x9, 0xb, 0x3, and 0x23. PA-RISC 2.0 adds
|
|
* another, 0x2b. Only these have the low order bit set.
|
|
*/
|
|
excptype = Excp_type(exception_index);
|
|
if (excptype & UNIMPLEMENTEDEXCEPTION) {
|
|
/*
|
|
* Clear T-bit and exception register so that
|
|
* we can tell if a trap really occurs while
|
|
* emulating the instruction.
|
|
*/
|
|
Clear_tbit();
|
|
Clear_excp_register(exception_index);
|
|
/*
|
|
* Now emulate this instruction. If a trap occurs,
|
|
* fpudispatch will return a non-zero number
|
|
*/
|
|
excp = fpudispatch(current_ir,excptype,0,Fpu_register);
|
|
/* accumulate the status flags, don't lose them as in hpux */
|
|
if (excp) {
|
|
/*
|
|
* We now need to make sure that the T-bit and the
|
|
* exception register contain the correct values
|
|
* before continuing.
|
|
*/
|
|
/*
|
|
* Set t-bit since it might still be needed for a
|
|
* subsequent real trap (I don't understand fully -PB)
|
|
*/
|
|
Set_tbit();
|
|
/* some of the following code uses
|
|
* Excp_type(exception_index) so fix that up */
|
|
Set_exceptiontype_and_instr_field(excp,current_ir,
|
|
Fpu_register[exception_index]);
|
|
if (excp == UNIMPLEMENTEDEXCEPTION) {
|
|
/*
|
|
* it is really unimplemented, so restore the
|
|
* TIMEX extended unimplemented exception code
|
|
*/
|
|
excp = excptype;
|
|
update_trap_counts(Fpu_register, aflags, bflags,
|
|
trap_counts);
|
|
return SIGNALCODE(SIGILL, ILL_COPROC);
|
|
}
|
|
/* some of the following code uses excptype, so
|
|
* fix that up too */
|
|
excptype = excp;
|
|
}
|
|
/* handle exceptions other than the real UNIMPLIMENTED the
|
|
* same way as if the hardware had caused them */
|
|
if (excp == NOEXCEPTION)
|
|
/* For now use 'break', should technically be 'continue' */
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* In PA89, the underflow exception has been extended to encode
|
|
* additional information. The exception looks like pp01x0,
|
|
* where x is 1 if inexact and pp represent the inexact bit (I)
|
|
* and the round away bit (RA)
|
|
*/
|
|
if (excptype & UNDERFLOWEXCEPTION) {
|
|
/* check for underflow trap enabled */
|
|
if (Is_underflowtrap_enabled()) {
|
|
update_trap_counts(Fpu_register, aflags, bflags,
|
|
trap_counts);
|
|
return SIGNALCODE(SIGFPE, FPE_FLTUND);
|
|
} else {
|
|
/*
|
|
* Isn't a real trap; we need to
|
|
* return the default value.
|
|
*/
|
|
target = current_ir & fivebits;
|
|
#ifndef lint
|
|
if (Ibit(Fpu_register[exception_index])) inexact = TRUE;
|
|
else inexact = FALSE;
|
|
#endif
|
|
switch (Excp_format()) {
|
|
case SGL:
|
|
/*
|
|
* If ra (round-away) is set, will
|
|
* want to undo the rounding done
|
|
* by the hardware.
|
|
*/
|
|
if (Rabit(Fpu_register[exception_index]))
|
|
Sgl_decrement(Fpu_sgl(target));
|
|
|
|
/* now denormalize */
|
|
sgl_denormalize(&Fpu_sgl(target),&inexact,Rounding_mode());
|
|
break;
|
|
case DBL:
|
|
/*
|
|
* If ra (round-away) is set, will
|
|
* want to undo the rounding done
|
|
* by the hardware.
|
|
*/
|
|
if (Rabit(Fpu_register[exception_index]))
|
|
Dbl_decrement(Fpu_dblp1(target),Fpu_dblp2(target));
|
|
|
|
/* now denormalize */
|
|
dbl_denormalize(&Fpu_dblp1(target),&Fpu_dblp2(target),
|
|
&inexact,Rounding_mode());
|
|
break;
|
|
}
|
|
if (inexact) Set_underflowflag();
|
|
/*
|
|
* Underflow can generate an inexact
|
|
* exception. If inexact trap is enabled,
|
|
* want to do an inexact trap, otherwise
|
|
* set inexact flag.
|
|
*/
|
|
if (inexact && Is_inexacttrap_enabled()) {
|
|
/*
|
|
* Set exception field of exception register
|
|
* to inexact, parm field to zero.
|
|
* Underflow bit should be cleared.
|
|
*/
|
|
Set_exceptiontype(Fpu_register[exception_index],
|
|
INEXACTEXCEPTION);
|
|
Set_parmfield(Fpu_register[exception_index],0);
|
|
update_trap_counts(Fpu_register, aflags, bflags,
|
|
trap_counts);
|
|
return SIGNALCODE(SIGFPE, FPE_FLTRES);
|
|
}
|
|
else {
|
|
/*
|
|
* Exception register needs to be cleared.
|
|
* Inexact flag needs to be set if inexact.
|
|
*/
|
|
Clear_excp_register(exception_index);
|
|
if (inexact) Set_inexactflag();
|
|
}
|
|
}
|
|
continue;
|
|
}
|
|
switch(Excp_type(exception_index)) {
|
|
case OVERFLOWEXCEPTION:
|
|
case OVERFLOWEXCEPTION | INEXACTEXCEPTION:
|
|
/* check for overflow trap enabled */
|
|
update_trap_counts(Fpu_register, aflags, bflags,
|
|
trap_counts);
|
|
if (Is_overflowtrap_enabled()) {
|
|
update_trap_counts(Fpu_register, aflags, bflags,
|
|
trap_counts);
|
|
return SIGNALCODE(SIGFPE, FPE_FLTOVF);
|
|
} else {
|
|
/*
|
|
* Isn't a real trap; we need to
|
|
* return the default value.
|
|
*/
|
|
target = current_ir & fivebits;
|
|
switch (Excp_format()) {
|
|
case SGL:
|
|
Sgl_setoverflow(Fpu_sgl(target));
|
|
break;
|
|
case DBL:
|
|
Dbl_setoverflow(Fpu_dblp1(target),Fpu_dblp2(target));
|
|
break;
|
|
}
|
|
Set_overflowflag();
|
|
/*
|
|
* Overflow always generates an inexact
|
|
* exception. If inexact trap is enabled,
|
|
* want to do an inexact trap, otherwise
|
|
* set inexact flag.
|
|
*/
|
|
if (Is_inexacttrap_enabled()) {
|
|
/*
|
|
* Set exception field of exception
|
|
* register to inexact. Overflow
|
|
* bit should be cleared.
|
|
*/
|
|
Set_exceptiontype(Fpu_register[exception_index],
|
|
INEXACTEXCEPTION);
|
|
update_trap_counts(Fpu_register, aflags, bflags,
|
|
trap_counts);
|
|
return SIGNALCODE(SIGFPE, FPE_FLTRES);
|
|
}
|
|
else {
|
|
/*
|
|
* Exception register needs to be cleared.
|
|
* Inexact flag needs to be set.
|
|
*/
|
|
Clear_excp_register(exception_index);
|
|
Set_inexactflag();
|
|
}
|
|
}
|
|
break;
|
|
case INVALIDEXCEPTION:
|
|
case OPC_2E_INVALIDEXCEPTION:
|
|
update_trap_counts(Fpu_register, aflags, bflags, trap_counts);
|
|
return SIGNALCODE(SIGFPE, FPE_FLTINV);
|
|
case DIVISIONBYZEROEXCEPTION:
|
|
update_trap_counts(Fpu_register, aflags, bflags, trap_counts);
|
|
Clear_excp_register(exception_index);
|
|
return SIGNALCODE(SIGFPE, FPE_FLTDIV);
|
|
case INEXACTEXCEPTION:
|
|
update_trap_counts(Fpu_register, aflags, bflags, trap_counts);
|
|
return SIGNALCODE(SIGFPE, FPE_FLTRES);
|
|
default:
|
|
update_trap_counts(Fpu_register, aflags, bflags, trap_counts);
|
|
printk("%s(%d) Unknown FPU exception 0x%x\n", __FILE__,
|
|
__LINE__, Excp_type(exception_index));
|
|
return SIGNALCODE(SIGILL, ILL_COPROC);
|
|
case NOEXCEPTION: /* no exception */
|
|
/*
|
|
* Clear exception register in case
|
|
* other fields are non-zero.
|
|
*/
|
|
Clear_excp_register(exception_index);
|
|
break;
|
|
}
|
|
}
|
|
/*
|
|
* No real exceptions occurred.
|
|
*/
|
|
Clear_tbit();
|
|
update_trap_counts(Fpu_register, aflags, bflags, trap_counts);
|
|
return(NOTRAP);
|
|
}
|