1 files changed, 36 insertions, 0 deletions
diff --git a/old/dhwt-codec/src/trim.rs b/old/dhwt-codec/src/trim.rs
new file mode 100644
index 0000000..85a920a
--- /dev/null
+++ b/old/dhwt-codec/src/trim.rs
@@ -0,0 +1,36 @@
+use crate::io::{Value, TWO, ZERO};
+use std::ops::{Index, IndexMut};
+
+pub fn trim<X: Index<usize, Output = Value> + IndexMut<usize, Output = Value>>(
+    size: usize,
+    a: &mut X,
+) {
+    let half = size / 2;
+    let quarter = size / 4;
+    for i in 0..(size / 2 / 4) {
+        let hi = half + i * 4;
+        let qi = quarter + i * 2;
+        a[qi] = (a[qi + 0] + a[qi + 1]) / TWO;
+        a[qi + 1] = (a[hi + 0] + a[hi + 1] + a[hi + 2] + a[hi + 3]) / (TWO * TWO);
+    }
+    for i in half..size {
+        a[i] = ZERO;
+    }
+}
+
+pub fn untrim<X: Index<usize, Output = Value> + IndexMut<usize, Output = Value>>(
+    size: usize,
+    a: &mut X,
+) {
+    let half = size / 2;
+    let quarter = size / 4;
+    for i in 0..(size / 2 / 4) {
+        let hi = half + i * 4;
+        let qi = quarter + i * 2;
+        a[hi + 0] = a[qi + 1];
+        a[hi + 1] = a[qi + 1];
+        a[hi + 2] = a[qi + 1];
+        a[hi + 3] = a[qi + 1];
+        a[qi + 1] = a[qi];
+    }
+}