added sampling

sampling/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "sampling"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+rand_chacha = "0.3.1"
+rand_core = "0.6.4"

sampling/src/lib.rs

@@ -0,0 +1 @@
+pub mod source;

sampling/src/source.rs

@@ -0,0 +1,45 @@
+use rand_chacha::rand_core::SeedableRng;
+use rand_core::RngCore;
+use rand_chacha::{ChaCha8Rng};
+
+const MAXF64: f64 = 9007199254740992.0;
+
+pub struct Source{
+    source:ChaCha8Rng,
+}
+
+impl Source{
+    pub fn new(seed: [u8;32]) -> Source{
+        Source{source:ChaCha8Rng::from_seed(seed)}
+    }
+
+    pub fn new_seed(&mut self) -> [u8;32]{
+        let mut seed: [u8; 32] = [0u8;32];
+        self.source.fill_bytes(&mut seed);
+        seed
+    }
+
+    #[inline(always)]
+    pub fn next_u64(&mut self) -> u64{
+        self.source.next_u64()
+    }
+
+    #[inline(always)]
+    pub fn next_u64n(&mut self, max: u64, mask: u64) -> u64{
+        let mut x: u64 = self.next_u64() & mask;
+        while x >= max{
+            x = self.next_u64() & mask;
+        }
+        x
+    }
+
+    #[inline(always)]
+    pub fn next_f64(&mut self, min: f64, max: f64) -> f64{
+        min + ((self.next_u64()<<11>>11) as f64)/MAXF64 * (max-min)
+    }
+
+    #[inline(always)]
+    pub fn fill_bytes(&mut self, bytes: &mut [u8]){
+        self.source.fill_bytes(bytes)
+    }
+}