From e87001f07be069a07185837896d9e73ca08f3574 Mon Sep 17 00:00:00 2001
From: David Ellis <isv.damocles@gmail.com>
Date: Fri, 20 Sep 2024 17:11:57 -0500
Subject: [PATCH] Implement the js u16 arithmetic and bitwise operations (#905)

---
 alan_std.js      | 140 +++++++++++++++++++++++++++++++++++++++++++++++
 alan_std.test.js |  26 +++++++++
 2 files changed, 166 insertions(+)

diff --git a/alan_std.js b/alan_std.js
index 571a0f00..7010afb9 100644
--- a/alan_std.js
+++ b/alan_std.js
@@ -636,6 +636,17 @@ export function wrappingPowU8(a, b) {
   return v;
 }
 
+export function notU8(a) {
+  let v = ~a;
+  while (v > 255) {
+    v -= 256;
+  }
+  while (v < 0) {
+    v += 256;
+  }
+  return v;
+}
+
 export function wrappingShlU8(a, b) {
   let v = a << b;
   while (v > 255) {
@@ -687,3 +698,132 @@ export function rotateRightU8(a, b) {
   let p2 = a & rhs;
   return wrappingShrU8(p1, 8 - c) + wrappingShlU8(p2, c);
 }
+
+export function wrappingAddU16(a, b) {
+  let v = a + b;
+  while (v > 65_535) {
+    v -= 65_536;
+  }
+  while (v < 0) {
+    v += 65_536;
+  }
+  return v;
+}
+
+export function wrappingSubU16(a, b) {
+  let v = a - b;
+  while (v > 65_535) {
+    v -= 65_536;
+  }
+  while (v < 0) {
+    v += 65_536;
+  }
+  return v;
+}
+
+export function wrappingMulU16(a, b) {
+  let v = a * b;
+  while (v > 65_535) {
+    v -= 65_536;
+  }
+  while (v < 0) {
+    v += 65_536;
+  }
+  return v;
+}
+
+export function wrappingDivU16(a, b) {
+  let v = Math.floor(a / b);
+  while (v > 65_535) {
+    v -= 65_536;
+  }
+  while (v < 0) {
+    v += 65_536;
+  }
+  return v;
+}
+
+export function wrappingModU16(a, b) {
+  let v = a % b;
+  while (v > 65_535) {
+    v -= 65_536;
+  }
+  while (v < 0) {
+    v += 65_536;
+  }
+  return v;
+}
+
+export function wrappingPowU16(a, b) {
+  let v = Math.floor(a ** b);
+  while (v > 65_535) {
+    v -= 65_536;
+  }
+  while (v < 0) {
+    v += 65_536;
+  }
+  return v;
+}
+
+export function notU16(a) {
+  let v = ~a;
+  while (v > 65_535) {
+    v -= 65_536;
+  }
+  while (v < 0) {
+    v += 65_536;
+  }
+  return v;
+}
+
+export function wrappingShlU16(a, b) {
+  let v = a << b;
+  while (v > 65_535) {
+    v -= 65_536;
+  }
+  while (v < 0) {
+    v += 65_536;
+  }
+  return v;
+}
+
+export function wrappingShrU16(a, b) {
+  let v = a >> b;
+  while (v > 65_535) {
+    v -= 65_536;
+  }
+  while (v < 0) {
+    v += 65_536;
+  }
+  return v;
+}
+
+export function rotateLeftU16(a, b) {
+  let c = b;
+  while (c > 15) {
+    c -= 16;
+  }
+  if (c == 0) {
+    return a;
+  }
+  let lhs = clampU16(65_535 << c);
+  let rhs = clampU16(65_535 ^ lhs);
+  let p1 = a & lhs;
+  let p2 = a & rhs;
+  return wrappingShrU16(p1, 16 - c) + wrappingShlU16(p2, c);
+}
+
+export function rotateRightU16(a, b) {
+  let c = b;
+  while (c > 15) {
+    c -= 16;
+  }
+  if (c == 0) {
+    return a;
+  }
+  let rhs = clampU16(65_535 << c);
+  let lhs = clampU16(65_535 ^ rhs);
+  let p1 = a & lhs;
+  let p2 = a & rhs;
+  return wrappingShrU16(p1, 16 - c) + wrappingShlU16(p2, c);
+}
diff --git a/alan_std.test.js b/alan_std.test.js
index 62c269f4..6893c267 100644
--- a/alan_std.test.js
+++ b/alan_std.test.js
@@ -151,6 +151,8 @@ assert(alanStd.wrappingModU8(5, 2) == 1, "wrappingModU8 5 % 2 = 1");
 
 assert(alanStd.wrappingPowU8(2, 8) == 0, "wrappingPowU8 2 ^ 8 = 0");
 
+assert(alanStd.notU8(0) == 255, "notU8 0 = 255");
+
 assert(alanStd.wrappingShlU8(128, 1) == 0, "wrappingShlU8 128 << 1 = 0");
 
 assert(alanStd.wrappingShrU8(128, 1) == 64, "wrappingShrU8 128 >> 1 = 64");
@@ -158,3 +160,27 @@ assert(alanStd.wrappingShrU8(128, 1) == 64, "wrappingShrU8 128 >> 1 = 64");
 assert(alanStd.rotateLeftU8(128, 1) == 1, "rotateLeftU8 128 <<< 1 = 1");
 
 assert(alanStd.rotateRightU8(64, 1) == 128, "rotateRightU8 64 >>> 1 = 128");
+
+assert(alanStd.wrappingAddU16(1, 2) === 3, "wrappingAddU16 1 + 2 = 3");
+assert(alanStd.wrappingAddU16(65_535, 1) === 0, "wrappingAddU16 65_535 + 1 = 0");
+
+assert(alanStd.wrappingSubU16(1, 2) === 65_535, "wrappingSubU16 1 - 2 = 65_535");
+assert(alanStd.wrappingSubU16(65_535, 1) === 65_534, "wrappingSubU16 65_535 - 1 = 65_534");
+
+assert(alanStd.wrappingMulU16(256, 256) === 0, "wrappingMulU16 256 * 256 = 0");
+
+assert(alanStd.wrappingDivU16(128, 2) == 64, "wrappingDivU16 128 / 2 = 64");
+
+assert(alanStd.wrappingModU16(5, 2) == 1, "wrappingModU16 5 % 2 = 1");
+
+assert(alanStd.wrappingPowU16(2, 16) == 0, "wrappingPowU16 2 ^ 8 = 0");
+
+assert(alanStd.notU16(0) == 65_535, "notU16 0 = 65_535");
+
+assert(alanStd.wrappingShlU16(32_768, 1) == 0, "wrappingShlU16 32_768 << 1 = 0");
+
+assert(alanStd.wrappingShrU16(128, 1) == 64, "wrappingShrU16 128 >> 1 = 64");
+
+assert(alanStd.rotateLeftU16(32_768, 1) == 1, "rotateLeftU16 128 <<< 1 = 1");
+
+assert(alanStd.rotateRightU16(64, 1) == 128, "rotateRightU16 64 >>> 1 = 128");