From f1e26358e1772e961c60a368f46c04d73386edf8 Mon Sep 17 00:00:00 2001
From: bde <bde@FreeBSD.org>
Date: Sat, 15 Feb 1997 17:09:00 +0000
Subject: Restored my fixes for printing the FP registers.  Their history was
 lost with FreeBSD-1.x and they were blown away by the gdb-4.16 merge.  I
 needed this to debug e_exp.S ...

Restored even older code (from 386BSD-0.0) for converting the
FP registers to doubles.  floatformat_to_double() and/or
valprint() still don't understand NaNs.

Removed unnecessary #include of obsolete <sys/dir.h> again.
---
 contrib/gdb/gdb/i386b-nat.c | 47 +++++++++++++++++++++++++++++++++++++++------
 1 file changed, 41 insertions(+), 6 deletions(-)

(limited to 'contrib/gdb')

diff --git a/contrib/gdb/gdb/i386b-nat.c b/contrib/gdb/gdb/i386b-nat.c
index cefb99f..2645302 100644
--- a/contrib/gdb/gdb/i386b-nat.c
+++ b/contrib/gdb/gdb/i386b-nat.c
@@ -150,7 +150,6 @@ i386_register_u_addr (blockend, regnum)
 #include "floatformat.h"
 
 #include <sys/param.h>
-#include <sys/dir.h>
 #include <signal.h>
 #include <sys/ioctl.h>
 #include <fcntl.h>
@@ -173,6 +172,37 @@ extern void print_387_status_word ();
 #define	fpstate		save87
 #define	U_FPSTATE(u)	u.u_pcb.pcb_savefpu
 
+static void
+i387_to_double (from, to)
+     char *from;
+     char *to;
+{
+  long *lp;
+  /* push extended mode on 387 stack, then pop in double mode
+   *
+   * first, set exception masks so no error is generated -
+   * number will be rounded to inf or 0, if necessary
+   */
+  asm ("pushl %eax"); 		/* grab a stack slot */
+  asm ("fstcw (%esp)");		/* get 387 control word */
+  asm ("movl (%esp),%eax");	/* save old value */
+  asm ("orl $0x3f,%eax");		/* mask all exceptions */
+  asm ("pushl %eax");
+  asm ("fldcw (%esp)");		/* load new value into 387 */
+
+  asm ("movl 8(%ebp),%eax");
+  asm ("fldt (%eax)");		/* push extended number on 387 stack */
+  asm ("fwait");
+  asm ("movl 12(%ebp),%eax");
+  asm ("fstpl (%eax)");		/* pop double */
+  asm ("fwait");
+
+  asm ("popl %eax");		/* flush modified control word */
+  asm ("fnclex");			/* clear exceptions */
+  asm ("fldcw (%esp)");		/* restore original control word */
+  asm ("popl %eax");		/* flush saved copy */
+}
+
 struct env387 
 {
   unsigned short control;
@@ -225,12 +255,18 @@ print_387_status (status, ep)
 
   top = (ep->status >> 11) & 7;
   
-  printf_unfiltered ("regno     tag  msb              lsb  value\n");
+  printf_unfiltered (" regno     tag  msb              lsb  value\n");
   for (fpreg = 7; fpreg >= 0; fpreg--) 
     {
+      int st_regno;
       double val;
       
-      printf_unfiltered ("%s %d: ", fpreg == top ? "=>" : "  ", fpreg); 
+      /* The physical regno `fpreg' is only relevant as an index into the
+       * tag word.  Logical `%st' numbers are required for indexing ep->regs.
+       */
+      st_regno = (fpreg + 8 - top) & 7;
+
+      printf_unfiltered ("%%st(%d) %s ", st_regno, fpreg == top ? "=>" : "  ");
 
       switch ((ep->tag >> (fpreg * 2)) & 3) 
 	{
@@ -240,10 +276,9 @@ print_387_status (status, ep)
 	case 3: printf_unfiltered ("empty "); break;
 	}
       for (i = 9; i >= 0; i--)
-	printf_unfiltered ("%02x", ep->regs[fpreg][i]);
+	printf_unfiltered ("%02x", ep->regs[st_regno][i]);
       
-      floatformat_to_double(&floatformat_i387_ext, (char *) ep->regs[fpreg], 
-			      &val);
+      i387_to_double((char *) ep->regs[st_regno], (char *) &val);
       printf_unfiltered ("  %g\n", val);
     }
 }
-- 
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