buffer: improve write(U)Int functions

This improves the performance of some write functions by around 5-15%.

PR-URL: #19289
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

benchmark/buffers/buffer-write.js

@@ -34,6 +34,7 @@ const INT32 = 0x7fffffff;
 const INT48 = 0x7fffffffffff;
 const UINT8 = 0xff;
 const UINT16 = 0xffff;
+const UINT32 = 0xffffffff;
 
 const mod = {
   writeInt8: INT8,
@@ -44,8 +45,8 @@ const mod = {
   writeUInt8: UINT8,
   writeUInt16BE: UINT16,
   writeUInt16LE: UINT16,
-  writeUInt32BE: INT32,
-  writeUInt32LE: INT32,
+  writeUInt32BE: UINT32,
+  writeUInt32LE: UINT32,
   writeUIntLE: INT8,
   writeUIntBE: INT16,
   writeIntLE: INT32,

lib/internal/buffer.js

@@ -481,9 +481,12 @@ function writeU_Int48LE(buf, value, offset, min, max) {
 
   const newVal = Math.floor(value * 2 ** -32);
   buf[offset++] = value;
-  buf[offset++] = (value >>> 8);
-  buf[offset++] = (value >>> 16);
-  buf[offset++] = (value >>> 24);
+  value = value >>> 8;
+  buf[offset++] = value;
+  value = value >>> 8;
+  buf[offset++] = value;
+  value = value >>> 8;
+  buf[offset++] = value;
   buf[offset++] = newVal;
   buf[offset++] = (newVal >>> 8);
   return offset;
@@ -495,9 +498,12 @@ function writeU_Int40LE(buf, value, offset, min, max) {
 
   const newVal = value;
   buf[offset++] = value;
-  buf[offset++] = (value >>> 8);
-  buf[offset++] = (value >>> 16);
-  buf[offset++] = (value >>> 24);
+  value = value >>> 8;
+  buf[offset++] = value;
+  value = value >>> 8;
+  buf[offset++] = value;
+  value = value >>> 8;
+  buf[offset++] = value;
   buf[offset++] = Math.floor(newVal * 2 ** -32);
   return offset;
 }
@@ -507,9 +513,12 @@ function writeU_Int32LE(buf, value, offset, min, max) {
   checkInt(value, min, max, buf, offset, 3);
 
   buf[offset++] = value;
-  buf[offset++] = (value >>> 8);
-  buf[offset++] = (value >>> 16);
-  buf[offset++] = (value >>> 24);
+  value = value >>> 8;
+  buf[offset++] = value;
+  value = value >>> 8;
+  buf[offset++] = value;
+  value = value >>> 8;
+  buf[offset++] = value;
   return offset;
 }
 
@@ -522,8 +531,10 @@ function writeU_Int24LE(buf, value, offset, min, max) {
   checkInt(value, min, max, buf, offset, 2);
 
   buf[offset++] = value;
-  buf[offset++] = (value >>> 8);
-  buf[offset++] = (value >>> 16);
+  value = value >>> 8;
+  buf[offset++] = value;
+  value = value >>> 8;
+  buf[offset++] = value;
   return offset;
 }
 
@@ -582,34 +593,43 @@ function writeU_Int48BE(buf, value, offset, min, max) {
   const newVal = Math.floor(value * 2 ** -32);
   buf[offset++] = (newVal >>> 8);
   buf[offset++] = newVal;
-  buf[offset++] = (value >>> 24);
-  buf[offset++] = (value >>> 16);
-  buf[offset++] = (value >>> 8);
-  buf[offset++] = value;
-  return offset;
+  buf[offset + 3] = value;
+  value = value >>> 8;
+  buf[offset + 2] = value;
+  value = value >>> 8;
+  buf[offset + 1] = value;
+  value = value >>> 8;
+  buf[offset] = value;
+  return offset + 4;
 }
 
 function writeU_Int40BE(buf, value, offset, min, max) {
   value = +value;
   checkInt(value, min, max, buf, offset, 4);
 
   buf[offset++] = Math.floor(value * 2 ** -32);
-  buf[offset++] = (value >>> 24);
-  buf[offset++] = (value >>> 16);
-  buf[offset++] = (value >>> 8);
-  buf[offset++] = value;
-  return offset;
+  buf[offset + 3] = value;
+  value = value >>> 8;
+  buf[offset + 2] = value;
+  value = value >>> 8;
+  buf[offset + 1] = value;
+  value = value >>> 8;
+  buf[offset] = value;
+  return offset + 4;
 }
 
 function writeU_Int32BE(buf, value, offset, min, max) {
   value = +value;
   checkInt(value, min, max, buf, offset, 3);
 
-  buf[offset++] = (value >>> 24);
-  buf[offset++] = (value >>> 16);
-  buf[offset++] = (value >>> 8);
-  buf[offset++] = value;
-  return offset;
+  buf[offset + 3] = value;
+  value = value >>> 8;
+  buf[offset + 2] = value;
+  value = value >>> 8;
+  buf[offset + 1] = value;
+  value = value >>> 8;
+  buf[offset] = value;
+  return offset + 4;
 }
 
 function writeUInt32BE(value, offset) {
@@ -620,10 +640,12 @@ function writeU_Int24BE(buf, value, offset, min, max) {
   value = +value;
   checkInt(value, min, max, buf, offset, 2);
 
-  buf[offset++] = (value >>> 16);
-  buf[offset++] = (value >>> 8);
-  buf[offset++] = value;
-  return offset;
+  buf[offset + 2] = value;
+  value = value >>> 8;
+  buf[offset + 1] = value;
+  value = value >>> 8;
+  buf[offset] = value;
+  return offset + 3;
 }
 
 function writeU_Int16BE(buf, value, offset, min, max) {