IEEE 754 floating point completion code, and implementation of the

FP_C (Floating Point Control Quadword).

From ross@NetBSD.  Added a way to disable it with option NO_IEEE,
which appears on the ramdisks to save space.  This affects only
programs compiled with -mieee, and what it essentially does is
enabling infinities and NaNs, instead of generating SIGFPE on
division by zero, overflow, etc.
ok art, deraadt

1 files changed, 495 insertions, 0 deletions

diff --git a/sys/lib/libkern/softfloat-specialize.h b/sys/lib/libkern/softfloat-specialize.h
new file mode 100644
index 00000000000..db9fb08b4ed
--- /dev/null
+++ b/sys/lib/libkern/softfloat-specialize.h
@@ -0,0 +1,495 @@
+/*	$OpenBSD: softfloat-specialize.h,v 1.1 2002/04/28 20:55:14 pvalchev Exp $	*/
+/*	$NetBSD: softfloat-specialize.h,v 1.1 2001/04/26 03:10:47 ross Exp $	*/
+
+/* This is a derivative work. */
+
+/*-
+ * Copyright (c) 2001 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Ross Harvey.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *        This product includes software developed by the NetBSD
+ *        Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+===============================================================================
+
+This C source fragment is part of the SoftFloat IEC/IEEE Floating-point
+Arithmetic Package, Release 2a.
+
+Written by John R. Hauser.  This work was made possible in part by the
+International Computer Science Institute, located at Suite 600, 1947 Center
+Street, Berkeley, California 94704.  Funding was partially provided by the
+National Science Foundation under grant MIP-9311980.  The original version
+of this code was written as part of a project to build a fixed-point vector
+processor in collaboration with the University of California at Berkeley,
+overseen by Profs. Nelson Morgan and John Wawrzynek.  More information
+is available through the Web page `http://HTTP.CS.Berkeley.EDU/~jhauser/
+arithmetic/SoftFloat.html'.
+
+THIS SOFTWARE IS DISTRIBUTED AS IS, FOR FREE.  Although reasonable
+effort has been made to avoid it, THIS SOFTWARE MAY CONTAIN FAULTS THAT
+WILL AT TIMES RESULT IN INCORRECT BEHAVIOR.  USE OF THIS SOFTWARE IS
+RESTRICTED TO PERSONS AND ORGANIZATIONS WHO CAN AND WILL TAKE FULL
+RESPONSIBILITY FOR ALL LOSSES, COSTS, OR OTHER PROBLEMS ARISING FROM
+THEIR OWN USE OF THE SOFTWARE, AND WHO ALSO EFFECTIVELY INDEMNIFY
+(possibly via similar legal warning) JOHN HAUSER AND THE INTERNATIONAL
+COMPUTER SCIENCE INSTITUTE AGAINST ALL LOSSES, COSTS, OR OTHER PROBLEMS
+ARISING FROM THE USE OF THE SOFTWARE BY THEIR CUSTOMERS AND CLIENTS.
+
+Derivative works are acceptable, even for commercial purposes, so long as
+(1) they include prominent notice that the work is derivative, and (2) they
+include prominent notice akin to these four paragraphs for those parts of
+this code that are retained.
+
+===============================================================================
+*/
+
+/*
+-------------------------------------------------------------------------------
+Underflow tininess-detection mode, statically initialized to default value.
+-------------------------------------------------------------------------------
+*/
+
+#ifndef NO_IEEE
+
+/* [ MP safe, does not change dynamically ] */
+int float_detect_tininess = float_tininess_after_rounding;
+
+/*
+-------------------------------------------------------------------------------
+Internal canonical NaN format.
+-------------------------------------------------------------------------------
+*/
+typedef struct {
+    flag sign;
+    bits64 high, low;
+} commonNaNT;
+
+/*
+-------------------------------------------------------------------------------
+The pattern for a default generated single-precision NaN.
+-------------------------------------------------------------------------------
+*/
+#define float32_default_nan 0xFFC00000
+
+/*
+-------------------------------------------------------------------------------
+Returns 1 if the single-precision floating-point value `a' is a NaN;
+otherwise returns 0.
+-------------------------------------------------------------------------------
+*/
+static flag float32_is_nan( float32 a )
+{
+
+    return ( 0xFF000000 < (bits32) ( a<<1 ) );
+
+}
+
+/*
+-------------------------------------------------------------------------------
+Returns 1 if the single-precision floating-point value `a' is a signaling
+NaN; otherwise returns 0.
+-------------------------------------------------------------------------------
+*/
+flag float32_is_signaling_nan( float32 a )
+{
+
+    return ( ( ( a>>22 ) & 0x1FF ) == 0x1FE ) && ( a & 0x003FFFFF );
+
+}
+
+/*
+-------------------------------------------------------------------------------
+Returns the result of converting the single-precision floating-point NaN
+`a' to the canonical NaN format.  If `a' is a signaling NaN, the invalid
+exception is raised.
+-------------------------------------------------------------------------------
+*/
+static commonNaNT float32ToCommonNaN( float32 a )
+{
+    commonNaNT z;
+
+    if ( float32_is_signaling_nan( a ) ) float_raise( float_flag_invalid );
+    z.sign = a>>31;
+    z.low = 0;
+    z.high = ( (bits64) a )<<41;
+    return z;
+
+}
+
+/*
+-------------------------------------------------------------------------------
+Returns the result of converting the canonical NaN `a' to the single-
+precision floating-point format.
+-------------------------------------------------------------------------------
+*/
+static float32 commonNaNToFloat32( commonNaNT a )
+{
+
+    return ( ( (bits32) a.sign )<<31 ) | 0x7FC00000 | ( a.high>>41 );
+
+}
+
+/*
+-------------------------------------------------------------------------------
+Takes two single-precision floating-point values `a' and `b', one of which
+is a NaN, and returns the appropriate NaN result.  If either `a' or `b' is a
+signaling NaN, the invalid exception is raised.
+-------------------------------------------------------------------------------
+*/
+static float32 propagateFloat32NaN( float32 a, float32 b )
+{
+    flag aIsNaN, aIsSignalingNaN, bIsNaN, bIsSignalingNaN;
+
+    aIsNaN = float32_is_nan( a );
+    aIsSignalingNaN = float32_is_signaling_nan( a );
+    bIsNaN = float32_is_nan( b );
+    bIsSignalingNaN = float32_is_signaling_nan( b );
+    a |= 0x00400000;
+    b |= 0x00400000;
+    if ( aIsSignalingNaN | bIsSignalingNaN ) float_raise( float_flag_invalid );
+    if ( aIsSignalingNaN ) {
+        if ( bIsSignalingNaN ) goto returnLargerSignificand;
+        return bIsNaN ? b : a;
+    }
+    else if ( aIsNaN ) {
+        if ( bIsSignalingNaN | ! bIsNaN ) return a;
+ returnLargerSignificand:
+        if ( (bits32) ( a<<1 ) < (bits32) ( b<<1 ) ) return b;
+        if ( (bits32) ( b<<1 ) < (bits32) ( a<<1 ) ) return a;
+        return ( a < b ) ? a : b;
+    }
+    else {
+        return b;
+    }
+
+}
+
+
+/*
+-------------------------------------------------------------------------------
+Returns the result of converting the double-precision floating-point NaN
+`a' to the canonical NaN format.  If `a' is a signaling NaN, the invalid
+exception is raised.
+-------------------------------------------------------------------------------
+*/
+static commonNaNT float64ToCommonNaN( float64 a )
+{
+    commonNaNT z;
+
+    if ( float64_is_signaling_nan( a ) ) float_raise( float_flag_invalid );
+    z.sign = a>>63;
+    z.low = 0;
+    z.high = a<<12;
+    return z;
+
+}
+
+/*
+-------------------------------------------------------------------------------
+Returns the result of converting the canonical NaN `a' to the double-
+precision floating-point format.
+-------------------------------------------------------------------------------
+*/
+static float64 commonNaNToFloat64( commonNaNT a )
+{
+
+    return
+          ( ( (bits64) a.sign )<<63 )
+        | LIT64( 0x7FF8000000000000 )
+        | ( a.high>>12 );
+
+}
+
+/*
+-------------------------------------------------------------------------------
+Takes two double-precision floating-point values `a' and `b', one of which
+is a NaN, and returns the appropriate NaN result.  If either `a' or `b' is a
+signaling NaN, the invalid exception is raised.
+-------------------------------------------------------------------------------
+*/
+static float64 propagateFloat64NaN( float64 a, float64 b )
+{
+    flag aIsNaN, aIsSignalingNaN, bIsNaN, bIsSignalingNaN;
+
+    aIsNaN = float64_is_nan( a );
+    aIsSignalingNaN = float64_is_signaling_nan( a );
+    bIsNaN = float64_is_nan( b );
+    bIsSignalingNaN = float64_is_signaling_nan( b );
+    a |= LIT64( 0x0008000000000000 );
+    b |= LIT64( 0x0008000000000000 );
+    if ( aIsSignalingNaN | bIsSignalingNaN ) float_raise( float_flag_invalid );
+    if ( aIsSignalingNaN ) {
+        if ( bIsSignalingNaN ) goto returnLargerSignificand;
+        return bIsNaN ? b : a;
+    }
+    else if ( aIsNaN ) {
+        if ( bIsSignalingNaN | ! bIsNaN ) return a;
+ returnLargerSignificand:
+        if ( (bits64) ( a<<1 ) < (bits64) ( b<<1 ) ) return b;
+        if ( (bits64) ( b<<1 ) < (bits64) ( a<<1 ) ) return a;
+        return ( a < b ) ? a : b;
+    }
+    else {
+        return b;
+    }
+
+}
+
+#ifdef FLOATX80
+
+/*
+-------------------------------------------------------------------------------
+The pattern for a default generated extended double-precision NaN.  The
+`high' and `low' values hold the most- and least-significant bits,
+respectively.
+-------------------------------------------------------------------------------
+*/
+#define floatx80_default_nan_high 0xFFFF
+#define floatx80_default_nan_low  LIT64( 0xC000000000000000 )
+
+/*
+-------------------------------------------------------------------------------
+Returns 1 if the extended double-precision floating-point value `a' is a
+NaN; otherwise returns 0.
+-------------------------------------------------------------------------------
+*/
+static flag floatx80_is_nan( floatx80 a )
+{
+
+    return ( ( a.high & 0x7FFF ) == 0x7FFF ) && (bits64) ( a.low<<1 );
+
+}
+
+/*
+-------------------------------------------------------------------------------
+Returns 1 if the extended double-precision floating-point value `a' is a
+signaling NaN; otherwise returns 0.
+-------------------------------------------------------------------------------
+*/
+flag floatx80_is_signaling_nan( floatx80 a )
+{
+    bits64 aLow;
+
+    aLow = a.low & ~ LIT64( 0x4000000000000000 );
+    return
+           ( ( a.high & 0x7FFF ) == 0x7FFF )
+        && (bits64) ( aLow<<1 )
+        && ( a.low == aLow );
+
+}
+
+/*
+-------------------------------------------------------------------------------
+Returns the result of converting the extended double-precision floating-
+point NaN `a' to the canonical NaN format.  If `a' is a signaling NaN, the
+invalid exception is raised.
+-------------------------------------------------------------------------------
+*/
+static commonNaNT floatx80ToCommonNaN( floatx80 a )
+{
+    commonNaNT z;
+
+    if ( floatx80_is_signaling_nan( a ) ) float_raise( float_flag_invalid );
+    z.sign = a.high>>15;
+    z.low = 0;
+    z.high = a.low<<1;
+    return z;
+
+}
+
+/*
+-------------------------------------------------------------------------------
+Returns the result of converting the canonical NaN `a' to the extended
+double-precision floating-point format.
+-------------------------------------------------------------------------------
+*/
+static floatx80 commonNaNToFloatx80( commonNaNT a )
+{
+    floatx80 z;
+
+    z.low = LIT64( 0xC000000000000000 ) | ( a.high>>1 );
+    z.high = ( ( (bits16) a.sign )<<15 ) | 0x7FFF;
+    return z;
+
+}
+
+/*
+-------------------------------------------------------------------------------
+Takes two extended double-precision floating-point values `a' and `b', one
+of which is a NaN, and returns the appropriate NaN result.  If either `a' or
+`b' is a signaling NaN, the invalid exception is raised.
+-------------------------------------------------------------------------------
+*/
+static floatx80 propagateFloatx80NaN( floatx80 a, floatx80 b )
+{
+    flag aIsNaN, aIsSignalingNaN, bIsNaN, bIsSignalingNaN;
+
+    aIsNaN = floatx80_is_nan( a );
+    aIsSignalingNaN = floatx80_is_signaling_nan( a );
+    bIsNaN = floatx80_is_nan( b );
+    bIsSignalingNaN = floatx80_is_signaling_nan( b );
+    a.low |= LIT64( 0xC000000000000000 );
+    b.low |= LIT64( 0xC000000000000000 );
+    if ( aIsSignalingNaN | bIsSignalingNaN ) float_raise( float_flag_invalid );
+    if ( aIsSignalingNaN ) {
+        if ( bIsSignalingNaN ) goto returnLargerSignificand;
+        return bIsNaN ? b : a;
+    }
+    else if ( aIsNaN ) {
+        if ( bIsSignalingNaN | ! bIsNaN ) return a;
+ returnLargerSignificand:
+        if ( a.low < b.low ) return b;
+        if ( b.low < a.low ) return a;
+        return ( a.high < b.high ) ? a : b;
+    }
+    else {
+        return b;
+    }
+
+}
+
+#endif
+
+#ifdef FLOAT128
+
+/*
+-------------------------------------------------------------------------------
+The pattern for a default generated quadruple-precision NaN.  The `high' and
+`low' values hold the most- and least-significant bits, respectively.
+-------------------------------------------------------------------------------
+*/
+#define float128_default_nan_high LIT64( 0xFFFF800000000000 )
+#define float128_default_nan_low  LIT64( 0x0000000000000000 )
+
+/*
+-------------------------------------------------------------------------------
+Returns 1 if the quadruple-precision floating-point value `a' is a NaN;
+otherwise returns 0.
+-------------------------------------------------------------------------------
+*/
+flag float128_is_nan( float128 a )
+{
+
+    return
+           ( LIT64( 0xFFFE000000000000 ) <= (bits64) ( a.high<<1 ) )
+        && ( a.low || ( a.high & LIT64( 0x0000FFFFFFFFFFFF ) ) );
+
+}
+
+/*
+-------------------------------------------------------------------------------
+Returns 1 if the quadruple-precision floating-point value `a' is a
+signaling NaN; otherwise returns 0.
+-------------------------------------------------------------------------------
+*/
+flag float128_is_signaling_nan( float128 a )
+{
+
+    return
+           ( ( ( a.high>>47 ) & 0xFFFF ) == 0xFFFE )
+        && ( a.low || ( a.high & LIT64( 0x00007FFFFFFFFFFF ) ) );
+
+}
+
+/*
+-------------------------------------------------------------------------------
+Returns the result of converting the quadruple-precision floating-point NaN
+`a' to the canonical NaN format.  If `a' is a signaling NaN, the invalid
+exception is raised.
+-------------------------------------------------------------------------------
+*/
+static commonNaNT float128ToCommonNaN( float128 a )
+{
+    commonNaNT z;
+
+    if ( float128_is_signaling_nan( a ) ) float_raise( float_flag_invalid );
+    z.sign = a.high>>63;
+    shortShift128Left( a.high, a.low, 16, &z.high, &z.low );
+    return z;
+
+}
+
+/*
+-------------------------------------------------------------------------------
+Returns the result of converting the canonical NaN `a' to the quadruple-
+precision floating-point format.
+-------------------------------------------------------------------------------
+*/
+static float128 commonNaNToFloat128( commonNaNT a )
+{
+    float128 z;
+
+    shift128Right( a.high, a.low, 16, &z.high, &z.low );
+    z.high |= ( ( (bits64) a.sign )<<63 ) | LIT64( 0x7FFF800000000000 );
+    return z;
+
+}
+
+/*
+-------------------------------------------------------------------------------
+Takes two quadruple-precision floating-point values `a' and `b', one of
+which is a NaN, and returns the appropriate NaN result.  If either `a' or
+`b' is a signaling NaN, the invalid exception is raised.
+-------------------------------------------------------------------------------
+*/
+static float128 propagateFloat128NaN( float128 a, float128 b )
+{
+    flag aIsNaN, aIsSignalingNaN, bIsNaN, bIsSignalingNaN;
+
+    aIsNaN = float128_is_nan( a );
+    aIsSignalingNaN = float128_is_signaling_nan( a );
+    bIsNaN = float128_is_nan( b );
+    bIsSignalingNaN = float128_is_signaling_nan( b );
+    a.high |= LIT64( 0x0000800000000000 );
+    b.high |= LIT64( 0x0000800000000000 );
+    if ( aIsSignalingNaN | bIsSignalingNaN ) float_raise( float_flag_invalid );
+    if ( aIsSignalingNaN ) {
+        if ( bIsSignalingNaN ) goto returnLargerSignificand;
+        return bIsNaN ? b : a;
+    }
+    else if ( aIsNaN ) {
+        if ( bIsSignalingNaN | ! bIsNaN ) return a;
+ returnLargerSignificand:
+        if ( lt128( a.high<<1, a.low, b.high<<1, b.low ) ) return b;
+        if ( lt128( b.high<<1, b.low, a.high<<1, a.low ) ) return a;
+        return ( a.high < b.high ) ? a : b;
+    }
+    else {
+        return b;
+    }
+
+}
+
+#endif
+
+#endif /* !NO_IEEE */