CVS commit: src/sys/arch/m68k/fpe

[Tetsuya Isaki]

Module Name:    src
Committed By:   isaki
Date:           Mon Jun 25 04:52:23 UTC 2012

Modified Files:
        src/sys/arch/m68k/fpe: fpu_int.c

Log Message:
Rewrite fpu_int().
Especially, remove the special treatment when |x| < 1
because it forgets to consider FPCR round mode.
See PR/46627 for the detail.  Thanks Y.Sugahara for advice.


To generate a diff of this commit:
cvs rdiff -u -r1.10 -r1.11 src/sys/arch/m68k/fpe/fpu_int.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.


Modified files:

Index: src/sys/arch/m68k/fpe/fpu_int.c
diff -u src/sys/arch/m68k/fpe/fpu_int.c:1.10 src/sys/arch/m68k/fpe/fpu_int.c:1.11
--- src/sys/arch/m68k/fpe/fpu_int.c:1.10	Mon Jul 18 14:11:27 2011
+++ src/sys/arch/m68k/fpe/fpu_int.c	Mon Jun 25 04:52:23 2012
@@ -1,4 +1,4 @@
-/*	$NetBSD: fpu_int.c,v 1.10 2011/07/18 14:11:27 isaki Exp $	*/
+/*	$NetBSD: fpu_int.c,v 1.11 2012/06/25 04:52:23 isaki Exp $	*/
 
 /*
  * Copyright (c) 1995 Ken Nakata
@@ -29,7 +29,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: fpu_int.c,v 1.10 2011/07/18 14:11:27 isaki Exp $");
+__KERNEL_RCSID(0, "$NetBSD: fpu_int.c,v 1.11 2012/06/25 04:52:23 isaki Exp $");
 
 #include <sys/types.h>
 
@@ -78,50 +78,28 @@ struct fpn *
 fpu_int(struct fpemu *fe)
 {
 	register struct fpn *x = &fe->fe_f2;
-	register int rsh, lsh, wsh, i;
+	register int rsh;
 
 	/* special cases first */
 	if (x->fp_class != FPC_NUM) {
 		return x;
 	}
-	/*
-	 * even if we have exponent == -1, we still have possiblity
-	 * that the result >= 1.0 when mantissa ~= 1.0 and rounded up
-	 */
-	if (x->fp_exp < -1) {
-		x->fp_class = FPC_ZERO;
-		x->fp_mant[0] = x->fp_mant[1] = x->fp_mant[2] = 0;
-		return x;
-	}
 
-	/* real work */
 	rsh = FP_NMANT - 1 - x->fp_exp;
-	if (rsh - FP_NG <= 0) {
+	if (rsh <= FP_NG) {
 		return x;
 	}
 
-	fpu_shr(x, rsh - FP_NG);	/* shift to the right */
+	/* shift to the right */
+	x->fp_exp = 0;
+	fpu_shr(x, rsh - FP_NG);
 
-	if (fpu_round(fe, x) == 1 /* rounded up */ &&
-	    x->fp_mant[2 - (FP_NMANT-rsh)/32] & (1 << ((FP_NMANT-rsh)%32))
-	    /* x >= 2.0 */) {
-		rsh--;			/* reduce shift count by 1 */
-		x->fp_exp++;		/* adjust exponent */
-	}
+	/* round according to FPCR round mode */
+	fpu_round(fe, x);
 
 	/* shift it back to the left */
-	wsh = rsh / 32;
-	lsh = rsh % 32;
-	rsh = 32 - lsh;
-	for (i = 0; i + wsh < 2; i++) {
-		x->fp_mant[i] = (x->fp_mant[i+wsh] << lsh) |
-		    (x->fp_mant[i+wsh+1] >> rsh);
-	}
-	x->fp_mant[i] = (x->fp_mant[i+wsh] << lsh);
-	i++;
-	for (; i < 3; i++) {
-		x->fp_mant[i] = 0;
-	}
+	x->fp_exp = FP_NMANT - 1;
+	fpu_norm(x);
 
 	return x;
 }