Implement bit array class.

1 files changed, 76 insertions, 0 deletions

diff --git a/crawl-ref/source/bitary.cc b/crawl-ref/source/bitary.cc
new file mode 100644
index 0000000000..d822dcd327
--- /dev/null
+++ b/crawl-ref/source/bitary.cc
@@ -0,0 +1,76 @@
+/*
+ *  File:         bitary.cc
+ *  Summary:      Bit array data type.
+ *  Created by:   Robert Vollmert
+ */
+
+#include "AppHdr.h"
+
+#include "bitary.h"
+
+#include "debug.h"
+
+#define LONGSIZE (sizeof(unsigned long)*8)
+
+bit_array::bit_array(unsigned long s)
+    : size(s)
+{
+    nwords = (int) ((size + LONGSIZE - 1) / LONGSIZE);
+    data = new unsigned long[nwords];
+    reset();
+}
+
+bit_array::~bit_array()
+{
+    delete[] data;
+}
+
+void bit_array::reset()
+{
+    for (int w = 0; w < nwords; ++w)
+        data[w] = 0;
+}
+
+bool bit_array::get(unsigned long index) const
+{
+    ASSERT(index < size);
+    int w = index / LONGSIZE;
+    int b = index % LONGSIZE;
+    return (data[w] & (1UL << b));
+}
+
+void bit_array::set(unsigned long index, bool value)
+{
+    ASSERT(index < size);
+    int w = index / LONGSIZE;
+    int b = index % LONGSIZE;
+    if (value)
+        data[w] |= (1UL << b);
+    else
+        data[w] &= ~(1UL << b);
+}
+
+bit_array& bit_array::operator |= (const bit_array& other)
+{
+    ASSERT(size == other.size);
+    for (int w = 0; w < nwords; ++w)
+        data[w] |= other.data[w];
+    return (*this);
+}
+
+bit_array& bit_array::operator &= (const bit_array& other)
+{
+    ASSERT(size == other.size);
+    for (int w = 0; w < nwords; ++w)
+        data[w] &= other.data[w];
+    return (*this);
+}
+
+bit_array bit_array::operator & (const bit_array& other) const
+{
+    ASSERT(size == other.size);
+    bit_array res = bit_array(size);
+    for (int w = 0; w < nwords; ++w)
+        res.data[w] = data[w] & other.data[w];
+    return (res);
+}