syscall_emul: [patch 2/22] move SyscallDesc into its own .hh and .cc

The class was crammed into syscall_emul.hh which has tons of forward
declarations and template definitions. To clean it up a bit, moved the
class into separate files and commented the class with doxygen style
comments. Also, provided some encapsulation by adding some accessors and
a mutator.

The syscallreturn.hh file was renamed syscall_return.hh to make it consistent
with other similarly named files in the src/sim directory.

The DPRINTF_SYSCALL macro was moved into its own header file with the
include the Base and Verbose flags as well.

--HG--
rename : src/sim/syscallreturn.hh => src/sim/syscall_return.hh

1 files changed, 116 insertions, 0 deletions

diff --git a/src/sim/syscall_return.hh b/src/sim/syscall_return.hh
new file mode 100644
index 000000000..fdd740775
--- /dev/null
+++ b/src/sim/syscall_return.hh
@@ -0,0 +1,116 @@
+/*
+ * 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 __SIM_SYSCALLRETURN_HH__
+#define __SIM_SYSCALLRETURN_HH__
+
+#include "base/types.hh"
+
+/**
+ * This class represents the return value from an emulated system call,
+ * including any errno setting.
+ *
+ * On some platforms, the return value and errno are encoded in a
+ * single signed integer.  A value less than zero but greater than
+ * -4096 indicates an error, and the value is the negation of the
+ * errno value.  Otherwise, the call was successful and the integer is
+ * the return value.  (Large negative numbers are considered
+ * successful to allow syscalls to return pointers to high memory,
+ * e.g., stack addresses.)  See, for example, Appendix A of the AMD64
+ * ABI spec at http://www.x86-64.org/documentation/abi.pdf.
+ *
+ * Other platforms use a more complex interface, returning a value and
+ * an error code in separate registers.
+ *
+ * This class is designed to support both types of interfaces.
+ */
+class SyscallReturn
+{
+  public:
+
+    /// For simplicity, allow the object to be initialized with a
+    /// single signed integer using the same positive=success,
+    /// negative=-errno convention described above.
+    ///
+    /// Typically this constructor is used as a default type
+    /// conversion, so a bare integer is used where a SyscallReturn
+    /// value is expected, e.g., as the return value from a system
+    /// call emulation function ('return 0;' or 'return -EFAULT;').
+    SyscallReturn(int64_t v)
+        : value(v), retryFlag(false)
+    {}
+
+    /// Pseudo-constructor to create an instance with the retry flag set.
+    static SyscallReturn retry()
+    {
+        SyscallReturn s(0);
+        s.retryFlag = true;
+        return s;
+    }
+
+    ~SyscallReturn() {}
+
+    /// Was the system call successful?
+    bool successful() const
+    {
+        return (value >= 0 || value <= -4096);
+    }
+
+    /// Does the syscall need to be retried?
+    bool needsRetry() const { return retryFlag; }
+
+    /// The return value
+    int64_t returnValue() const
+    {
+        assert(successful());
+        return value;
+    }
+
+    /// The errno value
+    int errnoValue() const
+    {
+        assert(!successful());
+        return -value;
+    }
+
+    /// The encoded value (as described above)
+    int64_t encodedValue() const
+    {
+        return value;
+    }
+
+  private:
+
+    int64_t value;
+
+    bool retryFlag;
+};
+
+#endif