s2-tools/dist/readers/grib2/sections/index.js

A collection of geospatial tools primarily designed for WGS84, Web Mercator, and S2.

import { BufferReader } from '../../';
import { parseGrib2Section0 } from './0';
import { parseGrib2Section1 } from './1';
import { parseGrib2Section2 } from './2';
import { parseGrib2Section3 } from './3';
import { parseGrib2Section4 } from './4';
import { parseGrib2Section5 } from './5';
import { parseGrib2Section6 } from './6';
import { parseGrib2Section7 } from './7';
import { parseGrib2Section8 } from './8';
export * from './0';
export * from './1';
export * from './2';
export * from './3';
export * from './4';
export * from './5';
export * from './6';
export * from './7';
export * from './8';
export * from './other';
/**
 * @param gribChunk Buffer containing individual GRIB definition
 * @returns Array of Section Buffers where the index of the item corresponds to the section number. If a section is missing, it will be represented as null
 */
export function splitSectionChunks(gribChunk) {
    const sections = {};
    let currentSection = gribChunk;
    // Split sections in file
    while (currentSection.byteLength !== 0) {
        const sectionNumber = getSectionNumber(currentSection);
        // First section length is always 16 bytes long and is identified by the first 4 bytes being 'GRIB'
        // const length = sectionNumber === 0 ? 16 : currentSection.getUint32(0);
        const length = sectionNumber === 0 ? 16 : currentSection.getUint32(0);
        const section = new BufferReader(currentSection.slice(0, length).buffer);
        currentSection = new BufferReader(currentSection.slice(length).buffer);
        parseGrib2Section(section, sections);
    }
    return sections;
}
/**
 * Parse the given section
 * @param reader - The section to parse
 * @param sections - The result to write to
 */
function parseGrib2Section(reader, sections) {
    const sectionNumber = getSectionNumber(reader);
    switch (sectionNumber) {
        case 0:
            sections.indicator = parseGrib2Section0(reader);
            break;
        case 1:
            sections.identification = parseGrib2Section1(reader);
            break;
        case 2:
            sections.local = parseGrib2Section2(reader);
            break;
        case 3:
            sections.gridDefinition = parseGrib2Section3(reader);
            break;
        case 4:
            sections.productDefinition = parseGrib2Section4(reader, sections);
            break;
        case 5:
            sections.dataRepresentation = parseGrib2Section5(reader);
            break;
        case 6:
            sections.bitMap = parseGrib2Section6(reader);
            break;
        case 7:
            sections.data = parseGrib2Section7(reader, sections);
            break;
        case 8:
            sections.end = parseGrib2Section8(reader);
            break;
        default:
            throw new Error(`Unknown section number: ${sectionNumber}`);
    }
}
/**
 * @param section Buffer containing GRIB Section data
 * @returns Section number of the input GRIB Section data
 */
export function getSectionNumber(section) {
    const first4ByteString = section.parseString(0, 4);
    if (first4ByteString === 'GRIB')
        return 0;
    if (first4ByteString === '7777')
        return 8;
    const sectionNumber = section.getUint8(4);
    return sectionNumber;
}
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