Initial release of Web Tools 0.0.5

src/lib/crc.ts

@@ -0,0 +1,152 @@
+export interface CrcParameters {
+  width: number
+  polynomial: bigint
+  initialValue: bigint
+  inputReflected: boolean
+  outputReflected: boolean
+  xorOut: bigint
+}
+
+export interface CrcPreset extends CrcParameters {
+  id: string
+  name: string
+  check: bigint
+}
+
+export const CRC_PRESETS: CrcPreset[] = [
+  { id: 'crc-32-iso-hdlc', name: 'CRC-32 / ISO-HDLC', width: 32, polynomial: 0x04c11db7n, initialValue: 0xffffffffn, inputReflected: true, outputReflected: true, xorOut: 0xffffffffn, check: 0xcbf43926n },
+  { id: 'crc-16-ccitt-false', name: 'CRC-16 / CCITT-FALSE', width: 16, polynomial: 0x1021n, initialValue: 0xffffn, inputReflected: false, outputReflected: false, xorOut: 0n, check: 0x29b1n },
+  { id: 'crc-16-modbus', name: 'CRC-16 / MODBUS', width: 16, polynomial: 0x8005n, initialValue: 0xffffn, inputReflected: true, outputReflected: true, xorOut: 0n, check: 0x4b37n },
+  { id: 'crc-16-arc', name: 'CRC-16 / ARC', width: 16, polynomial: 0x8005n, initialValue: 0n, inputReflected: true, outputReflected: true, xorOut: 0n, check: 0xbb3dn },
+  { id: 'crc-16-xmodem', name: 'CRC-16 / XMODEM', width: 16, polynomial: 0x1021n, initialValue: 0n, inputReflected: false, outputReflected: false, xorOut: 0n, check: 0x31c3n },
+  { id: 'crc-8', name: 'CRC-8', width: 8, polynomial: 0x07n, initialValue: 0n, inputReflected: false, outputReflected: false, xorOut: 0n, check: 0xf4n },
+]
+
+function reflectBigInt(value: bigint, width: number): bigint {
+  let reflected = 0n
+  for (let bit = 0; bit < width; bit += 1) {
+    if (value & (1n << BigInt(bit))) reflected |= 1n << BigInt(width - 1 - bit)
+  }
+  return reflected
+}
+
+function validateParameters(parameters: CrcParameters) {
+  if (!Number.isInteger(parameters.width) || parameters.width < 8 || parameters.width > 64) {
+    throw new Error('CRC 位宽必须是 8 至 64 的整数')
+  }
+  const mask = (1n << BigInt(parameters.width)) - 1n
+  if (parameters.polynomial <= 0n || parameters.polynomial > mask) throw new Error('CRC 多项式超出当前位宽')
+  if (parameters.initialValue < 0n || parameters.initialValue > mask) throw new Error('CRC 初始值超出当前位宽')
+  if (parameters.xorOut < 0n || parameters.xorOut > mask) throw new Error('CRC 异或输出值超出当前位宽')
+}
+
+function reflectNumber(value: number, width: number): number {
+  let current = value >>> 0
+  let reflected = 0
+  for (let bit = 0; bit < width; bit += 1) {
+    reflected = ((reflected * 2) + (current & 1)) >>> 0
+    current >>>= 1
+  }
+  return reflected
+}
+
+function calculateNumberCrc(chunks: Iterable<Uint8Array>, parameters: CrcParameters): bigint {
+  const width = parameters.width
+  const mask = width === 32 ? 0xffffffff : (2 ** width) - 1
+  const trim = (value: number) => width === 32 ? value >>> 0 : (value & mask) >>> 0
+  const polynomial = Number(parameters.polynomial) >>> 0
+  const table = new Uint32Array(256)
+  let remainder = trim(Number(parameters.initialValue))
+
+  if (parameters.inputReflected) {
+    const reflectedPolynomial = reflectNumber(polynomial, width)
+    for (let index = 0; index < 256; index += 1) {
+      let entry = index
+      for (let bit = 0; bit < 8; bit += 1) {
+        entry = entry & 1 ? (entry >>> 1) ^ reflectedPolynomial : entry >>> 1
+      }
+      table[index] = trim(entry)
+    }
+    for (const data of chunks) {
+      for (const byte of data) {
+        remainder = trim((remainder >>> 8) ^ table[(remainder ^ byte) & 0xff])
+      }
+    }
+  } else {
+    const topBit = 2 ** (width - 1)
+    for (let index = 0; index < 256; index += 1) {
+      let entry = trim(index << (width - 8))
+      for (let bit = 0; bit < 8; bit += 1) {
+        entry = trim(entry & topBit ? (entry << 1) ^ polynomial : entry << 1)
+      }
+      table[index] = entry
+    }
+    for (const data of chunks) {
+      for (const byte of data) {
+        const tableIndex = ((remainder >>> (width - 8)) ^ byte) & 0xff
+        remainder = trim((remainder << 8) ^ table[tableIndex])
+      }
+    }
+  }
+
+  if (parameters.inputReflected !== parameters.outputReflected) remainder = reflectNumber(remainder, width)
+  return BigInt(trim(remainder ^ Number(parameters.xorOut)))
+}
+
+function calculateBigIntCrc(chunks: Iterable<Uint8Array>, parameters: CrcParameters): bigint {
+  const width = parameters.width
+  const shift = BigInt(width - 8)
+  const mask = (1n << BigInt(width)) - 1n
+  const table: bigint[] = []
+  let remainder = parameters.initialValue & mask
+
+  if (parameters.inputReflected) {
+    const reflectedPolynomial = reflectBigInt(parameters.polynomial, width)
+    for (let index = 0; index < 256; index += 1) {
+      let entry = BigInt(index)
+      for (let bit = 0; bit < 8; bit += 1) {
+        entry = entry & 1n ? (entry >> 1n) ^ reflectedPolynomial : entry >> 1n
+      }
+      table[index] = entry & mask
+    }
+    for (const data of chunks) {
+      for (const byte of data) {
+        remainder = ((remainder >> 8n) ^ table[Number((remainder ^ BigInt(byte)) & 0xffn)]) & mask
+      }
+    }
+  } else {
+    const topBit = 1n << BigInt(width - 1)
+    for (let index = 0; index < 256; index += 1) {
+      let entry = BigInt(index) << shift
+      for (let bit = 0; bit < 8; bit += 1) {
+        entry = entry & topBit ? (entry << 1n) ^ parameters.polynomial : entry << 1n
+        entry &= mask
+      }
+      table[index] = entry
+    }
+    for (const data of chunks) {
+      for (const byte of data) {
+        const tableIndex = Number(((remainder >> shift) ^ BigInt(byte)) & 0xffn)
+        remainder = ((remainder << 8n) ^ table[tableIndex]) & mask
+      }
+    }
+  }
+
+  if (parameters.inputReflected !== parameters.outputReflected) remainder = reflectBigInt(remainder, width)
+  return (remainder ^ parameters.xorOut) & mask
+}
+
+export function calculateCrcChunks(chunks: Iterable<Uint8Array>, parameters: CrcParameters): bigint {
+  validateParameters(parameters)
+  return parameters.width <= 32
+    ? calculateNumberCrc(chunks, parameters)
+    : calculateBigIntCrc(chunks, parameters)
+}
+
+export function calculateCrc(data: Uint8Array, parameters: CrcParameters): bigint {
+  return calculateCrcChunks([data], parameters)
+}
+
+export function formatCrc(value: bigint, width: number): string {
+  return value.toString(16).toUpperCase().padStart(Math.ceil(width / 4), '0')
+}