1 files changed, 32 insertions, 0 deletions
diff --git a/src/lib/base.ts b/src/lib/base.ts
new file mode 100644
index 0000000..59c91cc
--- /dev/null
+++ b/src/lib/base.ts
@@ -0,0 +1,32 @@
+export const b2: string[] = 
+  '01'.split('')
+
+export const b16: string[] = 
+  '0123456789abcdef'.split('')
+
+export const b62: string[] = 
+  '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'.split('')
+
+export function encode(n: bigint, charset: string[]): string {
+  const base = BigInt(charset.length)
+
+  if (n == BigInt(0)) {
+    return '0'
+  } else {
+    var xs = []
+    while (n > BigInt(0)) {
+      xs.push(charset[Number(n % base)])
+      n = n / base
+    }
+    return xs.reverse().join('')
+  }
+}
+
+export function decode(xs: string, charset: string[]): bigint {
+  const base = BigInt(charset.length)
+
+  return xs
+    .split('')
+    .reverse()
+    .reduce((acc, x, i) => acc + (BigInt(charset.indexOf(x)) * (base ** BigInt(i))), BigInt(0))
+}