From 4aca74566e861cef0f902602501bf274ba5c43f8 Mon Sep 17 00:00:00 2001
From: Louis Pilfold <louis@lpil.uk>
Date: Mon, 4 Sep 2023 13:01:40 +0100
Subject: Bitwise int functions

---
 src/gleam_stdlib.mjs | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

(limited to 'src/gleam_stdlib.mjs')

diff --git a/src/gleam_stdlib.mjs b/src/gleam_stdlib.mjs
index a2fbaa6..fb255d9 100644
--- a/src/gleam_stdlib.mjs
+++ b/src/gleam_stdlib.mjs
@@ -752,3 +752,32 @@ function try_get_field(value, field, or_else) {
 export function byte_size(string) {
   return new TextEncoder().encode(string).length;
 }
+
+// In Javascript bitwise operations convert numbers to a sequence of 32 bits
+// while Erlang uses arbitrary precision.
+// To get around this problem and get consistent results use BigInt and then
+// downcast the value back to a Number value.
+
+export function bitwise_and(x, y) {
+  return Number(BigInt(x) & BigInt(y));
+}
+
+export function bitwise_not(x) {
+  return Number(~BigInt(x));
+}
+
+export function bitwise_or(x, y) {
+  return Number(BigInt(x) | BigInt(y));
+}
+
+export function bitwise_exclusive_or(x, y) {
+  return Number(BigInt(x) ^ BigInt(y));
+}
+
+export function bitwise_shift_left(x, y) {
+  return Number(BigInt(x) << BigInt(y));
+}
+
+export function bitwise_shift_right(x, y) {
+  return Number(BigInt(x) >> BigInt(y));
+}
-- 
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