perf: move CSI fast-path to top of main loop, add EXE fast-path, improve PRINT unrolling
Address reviewer feedback: - CSI fast-path is now a condition at the top of the codepoint loop instead of inside CLEAR, avoiding table lookups for the common case - EXE bytes < 0x18 get a fast-path before the CSI check so control bytes don't pay the penalty - PRINT loop unrolling replaced with while-based version that uses trueish eval and spares individual length checks in the unrolled case - Removed misplaced PRINT scan-ahead from CSI dispatch
This commit is contained in:
Ismail Pelaseyed
@@ -492,59 +492,6 @@ export class EscapeSequenceParser extends Disposable implements IEscapeSequenceP
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this._parseStack.chunkPos = chunkPos;
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}
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/**
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* CSI fast path: scan params and dispatch from position `start` (first byte after '[').
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* Returns new `i` position (>= 0) on success, -1 on failure/incomplete.
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* Stores a Promise in `_parseStack` and returns -2 for async handlers.
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*/
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private _csiFast(data: Uint32Array, start: number, length: number): number | Promise<boolean> {
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let k = start;
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let ch = data[k];
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if (ch >= 0x3c && ch <= 0x3f) {
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this._collect = ch;
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k++;
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}
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for (; k < length; k++) {
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ch = data[k];
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if (ch >= 0x30 && ch <= 0x39) {
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this._params.addDigit(ch - 48);
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} else if (ch === 0x3b) {
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this._params.addParam(0);
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} else if (ch === 0x3a) {
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this._params.addSubParam(-1);
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} else if (ch >= 0x40 && ch <= 0x7e) {
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const handlers = this._csiHandlers[this._collect << 8 | ch];
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let j = handlers ? handlers.length - 1 : -1;
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for (; j >= 0; j--) {
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const handlerResult = handlers[j](this._params);
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if (handlerResult === true) {
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break;
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} else if (handlerResult instanceof Promise) {
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const transition = ParserAction.CSI_DISPATCH << TableAccess.TRANSITION_ACTION_SHIFT | ParserState.GROUND;
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this._preserveStack(ParserStackType.CSI, handlers, j, transition, k);
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return handlerResult;
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}
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}
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if (j < 0) {
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this._csiHandlerFb(this._collect << 8 | ch, this._params);
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}
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this.precedingJoinState = 0;
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let pEnd = k + 1;
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if (pEnd < length && data[pEnd] >= 0x20 && data[pEnd] <= 0x7e) {
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for (++pEnd; pEnd < length; ++pEnd) {
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const pc = data[pEnd];
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if (pc < 0x20 || (pc > 0x7e && pc < NON_ASCII_PRINTABLE)) break;
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}
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this._printHandler(data, k + 1, pEnd);
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}
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return pEnd - 1;
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} else {
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break;
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}
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}
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return -1;
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}
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/**
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* Parse UTF32 codepoints in `data` up to `length`.
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*
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@@ -702,34 +649,96 @@ export class EscapeSequenceParser extends Disposable implements IEscapeSequenceP
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for (let i = start; i < length; ++i) {
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code = data[i];
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// EXE fast-path: common control bytes (0x00-0x17) in non-payload states
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if (code < 0x18 && this.currentState <= ParserState.CSI_IGNORE) {
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if (this._executeHandlers[code]) this._executeHandlers[code]();
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else this._executeHandlerFb(code);
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this.precedingJoinState = 0;
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continue;
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}
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// CSI fast-path: collapse ESC [ into a single entry, parse params+final in a tight loop
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if (code === 0x1b
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&& this.currentState !== ParserState.OSC_STRING
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&& this.currentState !== ParserState.DCS_PASSTHROUGH
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&& this.currentState !== ParserState.APC_STRING
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&& i + 1 < length && data[i + 1] === 0x5b
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) {
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this._params.reset();
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this._params.addParam(0); // ZDM
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this._collect = 0;
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let k = i + 2;
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if (k >= length) { i = k - 1; this.currentState = ParserState.CSI_ENTRY; continue; }
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let ch = data[k];
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if (ch >= 0x3c && ch <= 0x3f) {
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this._collect = ch;
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if (++k >= length) { i = k - 1; this.currentState = ParserState.CSI_PARAM; continue; }
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}
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let csiDone = false;
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for (; k < length; k++) {
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ch = data[k];
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if (ch >= 0x30 && ch <= 0x39) {
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this._params.addDigit(ch - 48);
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} else if (ch === 0x3b) {
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this._params.addParam(0);
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} else if (ch === 0x3a) {
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this._params.addSubParam(-1);
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} else if (ch >= 0x40 && ch <= 0x7e) {
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const handlers = this._csiHandlers[this._collect << 8 | ch];
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let j = handlers ? handlers.length - 1 : -1;
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for (; j >= 0; j--) {
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handlerResult = handlers[j](this._params);
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if (handlerResult === true) {
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break;
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} else if (handlerResult instanceof Promise) {
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transition = ParserAction.CSI_DISPATCH << TableAccess.TRANSITION_ACTION_SHIFT | ParserState.GROUND;
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this._preserveStack(ParserStackType.CSI, handlers, j, transition, k);
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return handlerResult;
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}
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}
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if (j < 0) {
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this._csiHandlerFb(this._collect << 8 | ch, this._params);
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}
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this.precedingJoinState = 0;
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i = k;
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this.currentState = ParserState.GROUND;
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csiDone = true;
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break;
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} else if (ch >= 0x20 && ch <= 0x2f) {
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this._collect <<= 8;
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this._collect |= ch;
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i = k;
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this.currentState = ParserState.CSI_INTERMEDIATE;
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csiDone = true;
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break;
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} else {
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break;
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}
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}
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if (!csiDone) {
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i = k - 1;
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this.currentState = ParserState.CSI_PARAM;
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}
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continue;
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}
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// normal transition & action lookup
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transition = this._transitions.table[this.currentState << TableAccess.INDEX_STATE_SHIFT | (code < 0xa0 ? code : NON_ASCII_PRINTABLE)];
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switch (transition >> TableAccess.TRANSITION_ACTION_SHIFT) {
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case ParserAction.PRINT:
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// read ahead with loop unrolling
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// Note: 0x20 (SP) is included, 0x7F (DEL) is excluded
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for (let j = i + 1; ; ++j) {
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if (j >= length || (code = data[j]) < 0x20 || (code > 0x7e && code < NON_ASCII_PRINTABLE)) {
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this._printHandler(data, i, j);
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i = j - 1;
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break;
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}
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if (++j >= length || (code = data[j]) < 0x20 || (code > 0x7e && code < NON_ASCII_PRINTABLE)) {
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this._printHandler(data, i, j);
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i = j - 1;
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break;
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}
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if (++j >= length || (code = data[j]) < 0x20 || (code > 0x7e && code < NON_ASCII_PRINTABLE)) {
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this._printHandler(data, i, j);
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i = j - 1;
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break;
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}
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if (++j >= length || (code = data[j]) < 0x20 || (code > 0x7e && code < NON_ASCII_PRINTABLE)) {
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this._printHandler(data, i, j);
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i = j - 1;
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break;
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}
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}
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let c = i;
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const l4 = length - 4;
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while (c < l4
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&& data[++c] >= 0x20 && (data[c] <= 0x7e || data[c] >= NON_ASCII_PRINTABLE)
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&& data[++c] >= 0x20 && (data[c] <= 0x7e || data[c] >= NON_ASCII_PRINTABLE)
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&& data[++c] >= 0x20 && (data[c] <= 0x7e || data[c] >= NON_ASCII_PRINTABLE)
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&& data[++c] >= 0x20 && (data[c] <= 0x7e || data[c] >= NON_ASCII_PRINTABLE)
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) {}
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if (c >= l4)
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while (c < length && data[c] >= 0x20 && (data[c] <= 0x7e || data[c] >= NON_ASCII_PRINTABLE)) c++;
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this._printHandler(data, i, c);
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i = c - 1;
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break;
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case ParserAction.EXECUTE:
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if (this._executeHandlers[code]) this._executeHandlers[code]();
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@@ -814,18 +823,6 @@ export class EscapeSequenceParser extends Disposable implements IEscapeSequenceP
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this._params.reset();
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this._params.addParam(0); // ZDM
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this._collect = 0;
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if ((transition & TableAccess.TRANSITION_STATE_MASK) === ParserState.ESCAPE
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&& i + 2 < length && data[i + 1] === 0x5b) {
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const csiFastResult = this._csiFast(data, i + 2, length);
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if (csiFastResult instanceof Promise) {
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return csiFastResult;
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}
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if (csiFastResult >= 0) {
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i = csiFastResult as number;
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this.currentState = ParserState.GROUND;
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continue;
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}
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}
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break;
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case ParserAction.DCS_HOOK:
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this._dcsParser.hook(this._collect << 8 | code, this._params);
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