buffer: add {read|write}Big[U]Int64{BE|LE} methods

PR-URL: https://github.com/nodejs/node/pull/19691
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

1 files changed, 147 insertions, 0 deletions

diff --git a/lib/internal/buffer.js b/lib/internal/buffer.js
index 64c026002cc..9a70dd4c89e 100644
--- a/lib/internal/buffer.js
+++ b/lib/internal/buffer.js
@@ -63,6 +63,82 @@ function boundsError(value, length, type) {
 }
 
 // Read integers.
+function readBigUInt64LE(offset = 0) {
+  validateNumber(offset, 'offset');
+  const first = this[offset];
+  const last = this[offset + 7];
+  if (first === undefined || last === undefined)
+    boundsError(offset, this.length - 8);
+
+  const lo = first +
+    this[++offset] * 2 ** 8 +
+    this[++offset] * 2 ** 16 +
+    this[++offset] * 2 ** 24;
+
+  const hi = this[++offset] +
+    this[++offset] * 2 ** 8 +
+    this[++offset] * 2 ** 16 +
+    last * 2 ** 24;
+
+  return BigInt(lo) + (BigInt(hi) << 32n);
+}
+
+function readBigUInt64BE(offset = 0) {
+  validateNumber(offset, 'offset');
+  const first = this[offset];
+  const last = this[offset + 7];
+  if (first === undefined || last === undefined)
+    boundsError(offset, this.length - 8);
+
+  const hi = first * 2 ** 24 +
+    this[++offset] * 2 ** 16 +
+    this[++offset] * 2 ** 8 +
+    this[++offset];
+
+  const lo = this[++offset] * 2 ** 24 +
+    this[++offset] * 2 ** 16 +
+    this[++offset] * 2 ** 8 +
+    last;
+
+  return (BigInt(hi) << 32n) + BigInt(lo);
+}
+
+function readBigInt64LE(offset = 0) {
+  validateNumber(offset, 'offset');
+  const first = this[offset];
+  const last = this[offset + 7];
+  if (first === undefined || last === undefined)
+    boundsError(offset, this.length - 8);
+
+  const val = this[offset + 4] +
+    this[offset + 5] * 2 ** 8 +
+    this[offset + 6] * 2 ** 16 +
+    (last << 24); // Overflow
+  return (BigInt(val) << 32n) +
+    BigInt(first +
+    this[++offset] * 2 ** 8 +
+    this[++offset] * 2 ** 16 +
+    this[++offset] * 2 ** 24);
+}
+
+function readBigInt64BE(offset = 0) {
+  validateNumber(offset, 'offset');
+  const first = this[offset];
+  const last = this[offset + 7];
+  if (first === undefined || last === undefined)
+    boundsError(offset, this.length - 8);
+
+  const val = (first << 24) + // Overflow
+    this[++offset] * 2 ** 16 +
+    this[++offset] * 2 ** 8 +
+    this[++offset];
+  return (BigInt(val) << 32n) +
+    BigInt(this[++offset] * 2 ** 24 +
+    this[++offset] * 2 ** 16 +
+    this[++offset] * 2 ** 8 +
+    last);
+}
+
 function readUIntLE(offset, byteLength) {
   if (offset === undefined)
     throw new ERR_INVALID_ARG_TYPE('offset', 'number', offset);
@@ -473,6 +549,68 @@ function readDoubleForwards(offset = 0) {
 }
 
 // Write integers.
+function writeBigU_Int64LE(buf, value, offset, min, max) {
+  checkInt(value, min, max, buf, offset, 7);
+
+  let lo = Number(value & 0xffffffffn);
+  buf[offset++] = lo;
+  lo = lo >> 8;
+  buf[offset++] = lo;
+  lo = lo >> 8;
+  buf[offset++] = lo;
+  lo = lo >> 8;
+  buf[offset++] = lo;
+  let hi = Number(value >> 32n & 0xffffffffn);
+  buf[offset++] = hi;
+  hi = hi >> 8;
+  buf[offset++] = hi;
+  hi = hi >> 8;
+  buf[offset++] = hi;
+  hi = hi >> 8;
+  buf[offset++] = hi;
+  return offset;
+}
+
+function writeBigUInt64LE(value, offset = 0) {
+  return writeBigU_Int64LE(this, value, offset, 0n, 0xffffffffffffffffn);
+}
+
+function writeBigU_Int64BE(buf, value, offset, min, max) {
+  checkInt(value, min, max, buf, offset, 7);
+
+  let lo = Number(value & 0xffffffffn);
+  buf[offset + 7] = lo;
+  lo = lo >> 8;
+  buf[offset + 6] = lo;
+  lo = lo >> 8;
+  buf[offset + 5] = lo;
+  lo = lo >> 8;
+  buf[offset + 4] = lo;
+  let hi = Number(value >> 32n & 0xffffffffn);
+  buf[offset + 3] = hi;
+  hi = hi >> 8;
+  buf[offset + 2] = hi;
+  hi = hi >> 8;
+  buf[offset + 1] = hi;
+  hi = hi >> 8;
+  buf[offset] = hi;
+  return offset + 8;
+}
+
+function writeBigUInt64BE(value, offset = 0) {
+  return writeBigU_Int64BE(this, value, offset, 0n, 0xffffffffffffffffn);
+}
+
+function writeBigInt64LE(value, offset = 0) {
+  return writeBigU_Int64LE(
+    this, value, offset, -0x8000000000000000n, 0x7fffffffffffffffn);
+}
+
+function writeBigInt64BE(value, offset = 0) {
+  return writeBigU_Int64BE(
+    this, value, offset, -0x8000000000000000n, 0x7fffffffffffffffn);
+}
+
 function writeUIntLE(value, offset, byteLength) {
   if (byteLength === 6)
     return writeU_Int48LE(this, value, offset, 0, 0xffffffffffff);
@@ -790,6 +928,15 @@ function writeFloatBackwards(val, offset = 0) {
 class FastBuffer extends Uint8Array {}
 
 function addBufferPrototypeMethods(proto) {
+  proto.readBigUInt64LE = readBigUInt64LE,
+  proto.readBigUInt64BE = readBigUInt64BE,
+  proto.readBigInt64LE = readBigInt64LE,
+  proto.readBigInt64BE = readBigInt64BE,
+  proto.writeBigUInt64LE = writeBigUInt64LE,
+  proto.writeBigUInt64BE = writeBigUInt64BE,
+  proto.writeBigInt64LE = writeBigInt64LE,
+  proto.writeBigInt64BE = writeBigInt64BE,
+
   proto.readUIntLE = readUIntLE;
   proto.readUInt32LE = readUInt32LE;
   proto.readUInt16LE = readUInt16LE;