Create a file of functions for computing condition codes.

These haven't been very thuroughly tested, so use at your own risk.

--HG--
extra : convert_revision : 938885d36fea4a99f8228cdf195a0e0a38dd9031

src/base/condcodes.hh

@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2003-2005 The Regents of The University of Michigan
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * 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;
+ * neither the name of the copyright holders 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 COPYRIGHT HOLDERS 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 COPYRIGHT
+ * OWNER 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.
+ *
+ * Authors: Gabe Black
+ */
+
+#ifndef __BASE_CONDCODE_HH__
+#define __BASE_CONDCODE_HH__
+
+#include "base/bitfield.hh"
+
+/**
+ * Calculate the carry flag from an addition. This should work even when
+ * a carry value is also added in.
+ */
+inline
+bool
+findCarry(int width, uint64_t dest, uint64_t src1, uint64_t src2) {
+    int shift = width - 1;
+    return (~(dest >> shift) + (src1 >> shift) + (src2 >> shift)) & 0x2;
+}
+
+/**
+ * Calculate the overflow flag from an addition.
+ */
+inline
+bool
+findOverflow(int width, uint64_t dest, uint64_t src1, uint64_t src2) {
+    int shift = width - 1;
+    return ((src1 ^ ~src2) & (src1 ^ dest)) & (1 << shift);
+}
+
+/**
+ * Calculate the parity of a value. 1 is for odd parity and 0 is for even.
+ */
+inline
+bool
+findParity(int width, uint64_t dest) {
+    dest &= width;
+    dest ^= (dest >> 32);
+    dest ^= (dest >> 16);
+    dest ^= (dest >> 8);
+    dest ^= (dest >> 4);
+    dest ^= (dest >> 2);
+    dest ^= (dest >> 1);
+    return dest & 1;
+}
+
+/**
+ * Calculate the negative flag.
+ */
+inline
+bool
+findNegative(int width, uint64_t dest) {
+    return bits(dest, width - 1, width - 1);
+}
+
+/**
+ * Calculate the zero flag.
+ */
+inline
+bool
+findZero(int width, uint64_t dest) {
+    return !(dest & mask(width));
+}
+
+#endif // __BASE_CONDCODE_HH__