buffer: improve write(U)Int functions

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

PR-URL: https://github.com/nodejs/node/pull/19289
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

1 files changed, 52 insertions, 30 deletions

diff --git a/lib/internal/buffer.js b/lib/internal/buffer.js
index fe10b20c805..2c65194bfa0 100644
--- a/lib/internal/buffer.js
+++ b/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;
 }
 
@@ -582,11 +593,14 @@ 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) {
@@ -594,22 +608,28 @@ function writeU_Int40BE(buf, value, offset, min, max) {
   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) {