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@amoghmargoor
Last active Nov 9, 2019
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Rust program for checking performance of Iterators
extern crate rand;
use rand::Rng;
use std::io::BufWriter;
use std::io::Write;
use std::fs::OpenOptions;
use std::fs::File;
use std::str::FromStr;
use std::io::BufReader;
use std::io::BufRead;
use std::string::String;
use std::str::from_utf8;
use std::time::Instant;
fn main() {
let filename : String = String::from_str("/tmp/rand.txt")
.expect("unable to create string");
let mut buffer : [i32; 10000] = read_from_file(filename);
let coefficients: [i64; 12] = [34, 45, 56, 78, 90, 32, 12, 13, 45, 56, 89, 67];
let qlp_shift: i16 = 0;
/**
* **********************************************
* Only measuring the performance of below loop.
* **********************************************
*/
let now = Instant::now();
for i in 12..buffer.len() {
let prediction = coefficients.iter()
.zip(&buffer[i - 12..i])
.map(|(&c, &s)| c * s as i64)
.sum::<i64>() >> 32;
let delta = buffer[i];
buffer[i] = prediction as i32 + delta;
}
println!("Elapsed time: {}", now.elapsed().as_nanos())
}
fn read_from_file(fname : String) -> [i32; 10000] {
let file = File::open(fname)
.expect("Could not open file");
let mut array= [0; 10000];
let mut reader = BufReader::new(file);
let mut buf = vec![];
let mut num_bytes = reader.read_until(b' ', &mut buf)
.expect("Cursor read should not fail");
let mut i = 0;
while num_bytes != 0 {
let int_str: &str = from_utf8(buf.as_slice())
.expect("unable to create string")
.trim();
if !int_str.is_empty() {
array[i] = int_str.parse::<i32>().expect(&format!("int_str cannot be parsed into digit {} ", int_str));
i = i+1;
}
buf.clear();
num_bytes = reader.read_until(b' ', &mut buf)
.expect("Cursor read should not fail");
}
assert_eq!(array.len(), 10000);
array
}
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