patch-2.4.20 linux-2.4.20/arch/parisc/math-emu/decode_exc.c

• Lines: 369
• Date: Thu Nov 28 15:53:10 2002
• Orig file: linux-2.4.19/arch/parisc/math-emu/decode_exc.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -urN linux-2.4.19/arch/parisc/math-emu/decode_exc.c linux-2.4.20/arch/parisc/math-emu/decode_exc.c
@@ -0,0 +1,368 @@
+/*
+ * 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., 675 Mass Ave, Cambridge, MA 02139, 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(__FILE__ "(%d) Unknown FPU exception 0x%x\n",
+			__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);
+}