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+/*
+ * 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 "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:
+ 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);
+ 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);
+}