1 files changed, 168 insertions, 0 deletions
diff --git a/devtools/client/debugger/src/utils/wasm.js b/devtools/client/debugger/src/utils/wasm.js
new file mode 100644
index 0000000000..78e667cf85
--- /dev/null
+++ b/devtools/client/debugger/src/utils/wasm.js
@@ -0,0 +1,168 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at <http://mozilla.org/MPL/2.0/>. */
+
+/* @flow */
+
+import { BinaryReader } from "wasmparser/dist/cjs/WasmParser";
+import {
+  WasmDisassembler,
+  NameSectionReader,
+} from "wasmparser/dist/cjs/WasmDis";
+
+import type { SourceId, WasmSourceContent } from "../types";
+type WasmState = {
+  lines: Array<number>,
+  offsets: Array<number>,
+};
+
+var wasmStates: { [string]: WasmState } = (Object.create(null): any);
+
+function maybeWasmSectionNameResolver(data: Uint8Array) {
+  try {
+    const parser = new BinaryReader();
+    parser.setData(data.buffer, 0, data.length);
+    const reader = new NameSectionReader();
+    reader.read(parser);
+    return reader.hasValidNames() ? reader.getNameResolver() : null;
+  } catch (ex) {
+    // Ignoring any errors during names section retrival.
+    return null;
+  }
+}
+
+/**
+ * @memberof utils/wasm
+ * @static
+ */
+export function getWasmText(sourceId: SourceId, data: Uint8Array) {
+  const nameResolver = maybeWasmSectionNameResolver(data);
+  const parser = new BinaryReader();
+  parser.setData(data.buffer, 0, data.length);
+  const dis = new WasmDisassembler();
+  if (nameResolver) {
+    dis.nameResolver = nameResolver;
+  }
+  dis.addOffsets = true;
+  const done = dis.disassembleChunk(parser);
+  let result = dis.getResult();
+  if (result.lines.length === 0) {
+    result = { lines: ["No luck with wast conversion"], offsets: [0], done };
+  }
+
+  const { offsets } = result;
+  const lines = [];
+  for (let i = 0; i < offsets.length; i++) {
+    lines[offsets[i]] = i;
+  }
+
+  wasmStates[sourceId] = { offsets, lines };
+
+  return { lines: result.lines, done: result.done };
+}
+
+/**
+ * @memberof utils/wasm
+ * @static
+ */
+export function getWasmLineNumberFormatter(sourceId: SourceId) {
+  const codeOf0 = 48,
+    codeOfA = 65;
+  const buffer = [
+    codeOf0,
+    codeOf0,
+    codeOf0,
+    codeOf0,
+    codeOf0,
+    codeOf0,
+    codeOf0,
+    codeOf0,
+  ];
+  let last0 = 7;
+  return function(number: number) {
+    const offset = lineToWasmOffset(sourceId, number - 1);
+    if (offset == undefined) {
+      return "";
+    }
+    let i = 7;
+    for (let n = offset; n !== 0 && i >= 0; n >>= 4, i--) {
+      const nibble = n & 15;
+      buffer[i] = nibble < 10 ? codeOf0 + nibble : codeOfA - 10 + nibble;
+    }
+    for (let j = i; j > last0; j--) {
+      buffer[j] = codeOf0;
+    }
+    last0 = i;
+    return String.fromCharCode.apply(null, buffer);
+  };
+}
+
+/**
+ * @memberof utils/wasm
+ * @static
+ */
+export function isWasm(sourceId: SourceId) {
+  return sourceId in wasmStates;
+}
+
+/**
+ * @memberof utils/wasm
+ * @static
+ */
+export function lineToWasmOffset(sourceId: SourceId, number: number): ?number {
+  const wasmState = wasmStates[sourceId];
+  if (!wasmState) {
+    return undefined;
+  }
+  let offset = wasmState.offsets[number];
+  while (offset === undefined && number > 0) {
+    offset = wasmState.offsets[--number];
+  }
+  return offset;
+}
+
+/**
+ * @memberof utils/wasm
+ * @static
+ */
+export function wasmOffsetToLine(sourceId: SourceId, offset: number): ?number {
+  const wasmState = wasmStates[sourceId];
+  if (!wasmState) {
+    return undefined;
+  }
+  return wasmState.lines[offset];
+}
+
+/**
+ * @memberof utils/wasm
+ * @static
+ */
+export function clearWasmStates() {
+  wasmStates = (Object.create(null): any);
+}
+
+const wasmLines: WeakMap<WasmSourceContent, string[]> = new WeakMap();
+export function renderWasmText(
+  sourceId: SourceId,
+  content: WasmSourceContent
+): string[] {
+  if (wasmLines.has(content)) {
+    return wasmLines.get(content) || [];
+  }
+
+  // binary does not survive as Uint8Array, converting from string
+  const { binary } = content.value;
+  const data = new Uint8Array(binary.length);
+  for (let i = 0; i < data.length; i++) {
+    data[i] = binary.charCodeAt(i);
+  }
+  const { lines } = getWasmText(sourceId, data);
+  const MAX_LINES = 1000000;
+  if (lines.length > MAX_LINES) {
+    lines.splice(MAX_LINES, lines.length - MAX_LINES);
+    lines.push(";; .... text is truncated due to the size");
+  }
+
+  wasmLines.set(content, lines);
+  return lines;
+}