From c26cd0e23863d42fbb2154e173ca3e3b119e4cd0 Mon Sep 17 00:00:00 2001
From: Paul Masurel <paul.masurel@gmail.com>
Date: Mon, 14 Mar 2016 10:03:21 +0900
Subject: [PATCH] blop

---
 src/core/fastfield.rs | 62 +++++++++++++++++++++++++++++++++++++++++++
 src/core/mod.rs       |  1 +
 2 files changed, 63 insertions(+)
 create mode 100644 src/core/fastfield.rs

diff --git a/src/core/fastfield.rs b/src/core/fastfield.rs
new file mode 100644
index 000000000..c612bcd3c
--- /dev/null
+++ b/src/core/fastfield.rs
@@ -0,0 +1,62 @@
+use std::io::Write;
+use std::io;
+use core::serialize::BinarySerializable;
+
+struct IntFastFieldWriter {
+    vals: Vec<u64>,
+}
+
+impl IntFastFieldWriter {
+
+    pub fn new() -> IntFastFieldWriter {
+        IntFastFieldWriter {
+            vals: Vec::new()
+        }
+    }
+
+    pub fn add(&mut self, val: u64) {
+        self.vals.push(val);
+    }
+
+    pub fn compute_num_bits(&self, amplitude: u64) -> u8 {
+        if amplitude == 0 {
+            0
+        }
+        else {
+            1 + self.compute_num_bits(amplitude / 2)
+        }
+    }
+
+    pub fn close(&self, write: &mut Write) -> io::Result<()> {
+        try!((self.vals.len() as u32).serialize(write));
+        if self.vals.is_empty() {
+            return Ok(())
+        }
+        let min = self.vals.iter().min().unwrap();
+        let max = self.vals.iter().max().unwrap();
+        let amplitude: u64 = max - min;
+        let num_bits = self.compute_num_bits(amplitude);
+        for val in self.vals.iter() {
+            try!(val.serialize(write));
+        }
+        Ok(())
+    }
+}
+
+
+#[cfg(test)]
+mod tests {
+
+    use super::IntFastFieldWriter;
+
+    #[test]
+    fn test_intfastfieldwriter() {
+        let mut write: Vec<u8> = Vec::new();
+        let mut int_fast_field_writer = IntFastFieldWriter::new();
+        int_fast_field_writer.add(4u64);
+        int_fast_field_writer.add(14u64);
+        int_fast_field_writer.add(2u64);
+        int_fast_field_writer.close(&mut write).unwrap();
+        assert_eq!(write.len(), 8 * 3 + 4);
+    }
+}
diff --git a/src/core/mod.rs b/src/core/mod.rs
index 77d2c9dfe..25ee0f666 100644
--- a/src/core/mod.rs
+++ b/src/core/mod.rs
@@ -13,6 +13,7 @@ pub mod store;
 pub mod simdcompression;
 pub mod fstmap;
 pub mod index;
+pub mod fastfield;
 
 
 use std::error;