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io: Handle big-endian in ByteStream

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This commit is contained in:
Jeff Schiller 2023-12-25 14:17:10 -08:00
parent 6d1d33e970
commit cb95ddc3ef
2 changed files with 44 additions and 1 deletions
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20
io/bytestream.js
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@ -13,6 +13,8 @@
* This object allows you to peek and consume bytes as numbers and strings out
* of a stream. More bytes can be pushed into the back of the stream via the
* push() method.
* By default, the stream is Little Endian (that is the least significant byte
* is first). To change to Big Endian, use setBigEndian().
*/
export class ByteStream {
/**
@ -55,6 +57,21 @@ export class ByteStream {
* @private
*/
this.bytesRead_ = 0;
/**
* Whether the stream is little-endian (true) or big-endian (false).
* @type {boolean}
* @private
*/
this.littleEndian_ = true;
}
setBigEndian() {
this.littleEndian_ = false;
}
setLittleEndian() {
this.littleEndian_ = true;
}
/**
@ -117,7 +134,8 @@ export class ByteStream {
let pageIndex = 0;
let ptr = this.ptr;
for (let i = 0; i < num; ++i) {
result |= (curPage[ptr++] << (i * 8));
const exp = (this.littleEndian_ ? i : (num - 1 - i)) * 8;
result |= (curPage[ptr++] << exp);
if (ptr >= curPage.length) {
curPage = this.pages_[pageIndex++];