elpatron
6c866dbad5
Enables importing .nmea logs into travel-day events with interval/change modes, optional GPS track, local encrypted archive, and a test fixture for the Kieler Förde route. Co-authored-by: Cursor <cursoragent@cursor.com>
31 lines
934 B
TypeScript
31 lines
934 B
TypeScript
/** Normalize NMEA text so identical content hashes the same across platforms. */
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export function normalizeNmeaTextForCrc(text: string): string {
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return text.replace(/\r\n/g, '\n').replace(/\r/g, '\n').trimEnd()
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}
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const CRC32_TABLE = (() => {
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const table = new Uint32Array(256)
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for (let i = 0; i < 256; i++) {
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let c = i
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for (let k = 0; k < 8; k++) {
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c = c & 1 ? 0xedb88320 ^ (c >>> 1) : c >>> 1
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}
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table[i] = c >>> 0
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}
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return table
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})()
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/** CRC-32 (IEEE / Ethernet polynomial), uppercase 8-char hex. */
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export function crc32Hex(text: string): string {
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const bytes = new TextEncoder().encode(text)
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let crc = 0xffffffff
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for (const byte of bytes) {
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crc = CRC32_TABLE[(crc ^ byte) & 0xff] ^ (crc >>> 8)
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}
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return ((crc ^ 0xffffffff) >>> 0).toString(16).toUpperCase().padStart(8, '0')
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}
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export function nmeaFileCrc32(text: string): string {
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return crc32Hex(normalizeNmeaTextForCrc(text))
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}
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