feat(binary): add interleave4_12_24/4_16_32()

thi-ng · Jan 25, 2021 · 89044d2 · 89044d2
1 parent d54d943
commit 89044d2
Showing 1 changed file with 20 additions and 0 deletions.
diff --git a/packages/binary/src/splat.ts b/packages/binary/src/splat.ts
@@ -48,3 +48,23 @@ export const same4 = (x: number) => ((x >> 4) & 0xf) === (x & 0xf);
  * @param x -
  */
 export const same8 = (x: number) => ((x >> 8) & 0xff) === (x & 0xff);
+
+/**
+ * Expands 3x4bit value like `0xabc` to 24bits: `0xaabbcc`
+ *
+ * @param x
+ */
+export const interleave4_12_24 = (x: number) =>
+    ((x & 0xf00) * 0x1100) | ((x & 0xf0) * 0x110) | ((x & 0xf) * 0x11);
+
+/**
+ * Expands 4x4bit value like `0xabcd` to 32bits: `0xaabbccdd`
+ *
+ * @param x
+ */
+export const interleave4_16_32 = (x: number) =>
+    (((x & 0xf000) * 0x11000) |
+        ((x & 0xf00) * 0x1100) |
+        ((x & 0xf0) * 0x110) |
+        ((x & 0xf) * 0x11)) >>>
+    0;