From 67d567b5c3713441951740f41b030b7df276f153 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Tue, 15 Jul 2014 19:50:08 +1000
Subject: [PATCH] stream: add stream bit printing object

Allows one to print a given number of bits from an integral value easily
using streams.
---
 stream.cpp | 49 ++++++++++++++++++++++++++++++++++++++++++++-----
 stream.hpp | 42 ++++++++++++++++++++++++++++--------------
 2 files changed, 72 insertions(+), 19 deletions(-)

diff --git a/stream.cpp b/stream.cpp
index cbe71261..c2f4bf7a 100644
--- a/stream.cpp
+++ b/stream.cpp
@@ -19,18 +19,57 @@
 
 #include "stream.hpp"
 
+#include "debug.hpp"
+
+using util::stream::null;
+using util::stream::bits;
+
+//-----------------------------------------------------------------------------
 std::ostream&
-nullstream::put (char)
+null::put (char)
     { return *this; }
 
 
+//-----------------------------------------------------------------------------
 bool
-nullstream::good (void) const
+null::good (void) const
     { return !bad () && !eof () && !fail (); }
 
 
-bool nullstream::bad  (void) const { return false; }
-bool nullstream::eof  (void) const { return false; }
-bool nullstream::fail (void) const { return false; }
+//-----------------------------------------------------------------------------
+bool null::bad  (void) const { return false; }
+bool null::eof  (void) const { return false; }
+bool null::fail (void) const { return false; }
 
 
+//-----------------------------------------------------------------------------
+bits::bits (uintmax_t _value, unsigned _count):
+    value (_value),
+    count (_count)
+{
+    CHECK_LE (count, sizeof(value) * 8);
+}
+
+
+//-----------------------------------------------------------------------------
+std::ostream&
+operator<< (std::ostream &os, util::stream::bits b) {
+    char digits[sizeof (b.value) * 8 + 1] = { 0 };
+    char *cursor = std::end (digits) - 1;
+
+    uintmax_t bits  = b.value;
+    unsigned  count = b.count;
+
+    while (count) {
+        CHECK_GE (cursor, digits);
+
+        --cursor;
+        *cursor = (bits & 0x01) ? '1' : '0';
+
+        bits >>= 1;
+        count -= 1;
+    }
+
+    os << cursor << "/" << b.count;
+    return os;
+}
diff --git a/stream.hpp b/stream.hpp
index e0570913..45400fb8 100644
--- a/stream.hpp
+++ b/stream.hpp
@@ -22,25 +22,39 @@
 
 #include <iostream>
 
+namespace util {
+    namespace stream {
+        //---------------------------------------------------------------------
+        class null : public std::ostream {
+            public:
+                std::ostream & put   (char c);
+                std::ostream & write (const char *s, std::streamsize n);
 
-class nullstream : public std::ostream {
-    public:
-        std::ostream & put   (char c);
-        std::ostream & write (const char *s, std::streamsize n);
+                std::streampos tellp (void);
+                std::ostream & seekp (std::streampos pos);
+                std::ostream & seekp (std::streamoff off,
+                                      std::ios_base::seekdir dir);
 
-        std::streampos tellp (void);
-        std::ostream & seekp (std::streampos pos);
-        std::ostream & seekp (std::streamoff off,
-                              std::ios_base::seekdir dir);
+                std::ostream & flush (void);
 
-        std::ostream & flush (void);
+                bool good (void) const;
+                bool bad  (void) const;
+                bool eof  (void) const;
+                bool fail (void) const;
 
-        bool good (void) const;
-        bool bad  (void) const;
-        bool eof  (void) const;
-        bool fail (void) const;
+        };
 
-};
 
+        //---------------------------------------------------------------------
+        struct bits {
+            bits (uintmax_t value, unsigned count);
+
+            uintmax_t value;
+            unsigned  count;
+        };
+    }
+}
+
+std::ostream& operator<< (std::ostream&, util::stream::bits);
 
 #endif