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app_vue/node_modules/@webassemblyjs/leb128/lib/bits.js

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+// Copyright 2012 The Obvious Corporation.
+
+/*
+ * bits: Bitwise buffer utilities. The utilities here treat a buffer
+ * as a little-endian bigint, so the lowest-order bit is bit #0 of
+ * `buffer[0]`, and the highest-order bit is bit #7 of
+ * `buffer[buffer.length - 1]`.
+ */
+
+/*
+ * Modules used
+ */
+"use strict";
+/*
+ * Exported bindings
+ */
+
+/**
+ * Extracts the given number of bits from the buffer at the indicated
+ * index, returning a simple number as the result. If bits are requested
+ * that aren't covered by the buffer, the `defaultBit` is used as their
+ * value.
+ *
+ * The `bitLength` must be no more than 32. The `defaultBit` if not
+ * specified is taken to be `0`.
+ */
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.extract = extract;
+exports.inject = inject;
+exports.getSign = getSign;
+exports.highOrder = highOrder;
+
+function extract(buffer, bitIndex, bitLength, defaultBit) {
+  if (bitLength < 0 || bitLength > 32) {
+    throw new Error("Bad value for bitLength.");
+  }
+
+  if (defaultBit === undefined) {
+    defaultBit = 0;
+  } else if (defaultBit !== 0 && defaultBit !== 1) {
+    throw new Error("Bad value for defaultBit.");
+  }
+
+  var defaultByte = defaultBit * 0xff;
+  var result = 0; // All starts are inclusive. The {endByte, endBit} pair is exclusive, but
+  // if endBit !== 0, then endByte is inclusive.
+
+  var lastBit = bitIndex + bitLength;
+  var startByte = Math.floor(bitIndex / 8);
+  var startBit = bitIndex % 8;
+  var endByte = Math.floor(lastBit / 8);
+  var endBit = lastBit % 8;
+
+  if (endBit !== 0) {
+    // `(1 << endBit) - 1` is the mask of all bits up to but not including
+    // the endBit.
+    result = get(endByte) & (1 << endBit) - 1;
+  }
+
+  while (endByte > startByte) {
+    endByte--;
+    result = result << 8 | get(endByte);
+  }
+
+  result >>>= startBit;
+  return result;
+
+  function get(index) {
+    var result = buffer[index];
+    return result === undefined ? defaultByte : result;
+  }
+}
+/**
+ * Injects the given bits into the given buffer at the given index. Any
+ * bits in the value beyond the length to set are ignored.
+ */
+
+
+function inject(buffer, bitIndex, bitLength, value) {
+  if (bitLength < 0 || bitLength > 32) {
+    throw new Error("Bad value for bitLength.");
+  }
+
+  var lastByte = Math.floor((bitIndex + bitLength - 1) / 8);
+
+  if (bitIndex < 0 || lastByte >= buffer.length) {
+    throw new Error("Index out of range.");
+  } // Just keeping it simple, until / unless profiling shows that this
+  // is a problem.
+
+
+  var atByte = Math.floor(bitIndex / 8);
+  var atBit = bitIndex % 8;
+
+  while (bitLength > 0) {
+    if (value & 1) {
+      buffer[atByte] |= 1 << atBit;
+    } else {
+      buffer[atByte] &= ~(1 << atBit);
+    }
+
+    value >>= 1;
+    bitLength--;
+    atBit = (atBit + 1) % 8;
+
+    if (atBit === 0) {
+      atByte++;
+    }
+  }
+}
+/**
+ * Gets the sign bit of the given buffer.
+ */
+
+
+function getSign(buffer) {
+  return buffer[buffer.length - 1] >>> 7;
+}
+/**
+ * Gets the zero-based bit number of the highest-order bit with the
+ * given value in the given buffer.
+ *
+ * If the buffer consists entirely of the other bit value, then this returns
+ * `-1`.
+ */
+
+
+function highOrder(bit, buffer) {
+  var length = buffer.length;
+  var fullyWrongByte = (bit ^ 1) * 0xff; // the other-bit extended to a full byte
+
+  while (length > 0 && buffer[length - 1] === fullyWrongByte) {
+    length--;
+  }
+
+  if (length === 0) {
+    // Degenerate case. The buffer consists entirely of ~bit.
+    return -1;
+  }
+
+  var byteToCheck = buffer[length - 1];
+  var result = length * 8 - 1;
+
+  for (var i = 7; i > 0; i--) {
+    if ((byteToCheck >> i & 1) === bit) {
+      break;
+    }
+
+    result--;
+  }
+
+  return result;
+}