From aaf2f8bc394961083457c6d66f38cdbab8f4c225 Mon Sep 17 00:00:00 2001
From: Sears Russell <sears@cs.berkeley.edu>
Date: Sun, 8 Jun 2008 20:45:04 +0000
Subject: [PATCH] Binary search implementations

---
 stasis/page/compression/binary_search.h | 68 +++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 stasis/page/compression/binary_search.h

diff --git a/stasis/page/compression/binary_search.h b/stasis/page/compression/binary_search.h
new file mode 100644
index 0000000..4ab2de0
--- /dev/null
+++ b/stasis/page/compression/binary_search.h
@@ -0,0 +1,68 @@
+#ifndef _ROSE_COMPRESSION_BINARY_SEARCH_H__
+#define _ROSE_COMPRESSION_BINARY_SEARCH_H__
+
+// From wikipedia
+
+int binary_search(int * A, int value, intptr_t high, intptr_t low) {
+  int N = high;
+  //  low = 0;
+  //  high = N;
+  while (low < high) {
+    intptr_t mid = low + ((high - low) / 2);
+    if (A[mid] < value)
+      low = mid + 1; 
+    else
+      //can't be high = mid-1: here A[mid] >= value,
+      //so high can't be < mid if A[mid] == value
+      high = mid; 
+  }
+  // high == low, using high or low depends on taste 
+  if ((low < N) && (A[low] == value))
+    return low; // found
+  else
+    return -1; // not found        
+}
+
+
+#define rose_binary_search(accessor) do{				\
+    int64_t bs_N = bs_high;						\
+    int64_t bs_mid;							\
+    while (bs_low < bs_high) {						\
+      bs_mid = bs_low + ((bs_high - bs_low) / 2);			\
+      if (*accessor(bs_mid) /*A[mid]*/ < bs_value)			\
+	bs_low = bs_mid + 1;						\
+      else								\
+	/*can't be high = mid-1: here A[mid] >= value,*/		\
+	/*so high can't be < mid if A[mid] == value*/			\
+	bs_high = bs_mid;						\
+    }									\
+    /* high == low, using high or low depends on taste */		\
+    if ((bs_low < bs_N) && (*accessor(bs_low)/*A[low]*/ == bs_value))	\
+      bs_ret = bs_low; /* found */					\
+    else								\
+      bs_ret = -1; /* not found */					\
+  } while(0)
+
+/** Find the insertion point for a value in the array.  Assumes that items stored in the array are unique. */
+
+#define rose_binary_search_greatest_lower(accessor) do{				\
+    int64_t bs_N = bs_high;						\
+    int64_t bs_mid;							\
+    while (bs_low < bs_high) {						\
+      bs_mid = bs_low + ((bs_high - bs_low) / 2);			\
+      if (accessor(bs_mid) /*A[mid]*/ < bs_value)			\
+	bs_low = bs_mid + 1;						\
+      else								\
+	/*can't be high = mid-1: here A[mid] >= value,*/		\
+	/*so high can't be < mid if A[mid] == value*/			\
+	bs_high = bs_mid;						\
+    }									\
+    /* high == low, using high or low depends on taste */		\
+    if ((bs_low < bs_N))						\
+      bs_ret = bs_low; /* found */					\
+    else								\
+      bs_ret = -1; /* not found */					\
+  } while(0)
+
+
+#endif // _ROSE_COMPRESSION_BINARY_SEARCH_H__