Make some fonctions const for static luts

Author: Coloquinte

src/lut.rs

@@ -61,16 +61,18 @@ impl Lut {
 
     /// Create a constant true Lut
     pub fn one(num_vars: usize) -> Lut {
-        let mut ret = Lut::new(num_vars);
-        fill_one(num_vars, ret.table.as_mut());
-        ret
+        Self {
+            num_vars,
+            table: vec![num_vars_mask(num_vars); table_size(num_vars)].into_boxed_slice(),
+        }
     }
 
     /// Create a constant false Lut
     pub fn zero(num_vars: usize) -> Lut {
-        let mut ret = Lut::new(num_vars);
-        fill_zero(num_vars, ret.table.as_mut());
-        ret
+        Self {
+            num_vars,
+            table: vec![0; table_size(num_vars)].into_boxed_slice(),
+        }
     }
 
     /// Create a Lut returning the value of one of its variables

src/operations.rs

@@ -83,8 +83,8 @@ pub const COUNT_MASKS: [u64; 7] = [
 ];
 
 /// u64 mask when the number of variables is smaller than 6
-pub fn num_vars_mask(num_vars: usize) -> u64 {
-    NUM_VARS_MASK[std::cmp::min(num_vars, 6)]
+pub const fn num_vars_mask(num_vars: usize) -> u64 {
+    NUM_VARS_MASK[if num_vars < 6 { num_vars } else { 6 }]
 }
 
 /// Size of the lookup table, in u64

src/static_lut.rs

@@ -22,25 +22,23 @@ pub struct StaticLut<const NUM_VARS: usize, const NUM_WORDS: usize> {
 
 impl<const NUM_VARS: usize, const NUM_WORDS: usize> Default for StaticLut<NUM_VARS, NUM_WORDS> {
     fn default() -> Self {
-        Self {
-            table: [0u64; NUM_WORDS],
-        }
+        Self::zero()
     }
 }
 
 impl<const NUM_VARS: usize, const NUM_WORDS: usize> StaticLut<NUM_VARS, NUM_WORDS> {
     /// Query the number of variables of the Lut
-    pub fn num_vars(&self) -> usize {
+    pub const fn num_vars(&self) -> usize {
         NUM_VARS
     }
 
     /// Query the number of bits in the Lut
-    pub fn num_bits(&self) -> usize {
+    pub const fn num_bits(&self) -> usize {
         1 << NUM_VARS
     }
 
     /// Query the number of 64-bit blocks in the Lut
-    pub fn num_blocks(&self) -> usize {
+    pub const fn num_blocks(&self) -> usize {
         table_size(NUM_VARS)
     }
 
@@ -60,15 +58,17 @@ impl<const NUM_VARS: usize, const NUM_WORDS: usize> StaticLut<NUM_VARS, NUM_WORD
     }
 
     /// Create a constant true Lut
-    pub fn one() -> Self {
-        let mut ret = Self::default();
-        fill_one(NUM_VARS, ret.table.as_mut());
-        ret
+    pub const fn one() -> Self {
+        Self {
+            table: [num_vars_mask(NUM_VARS); NUM_WORDS],
+        }
     }
 
     /// Create a constant false Lut
-    pub fn zero() -> Self {
-        Self::default()
+    pub const fn zero() -> Self {
+        Self {
+            table: [0; NUM_WORDS],
+        }
     }
 
     /// Create a Lut returning the value of one of its variables