24 lines
606 B
JavaScript
24 lines
606 B
JavaScript
const fsp = require('fs').promises;
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async function merge(file1, file2, out)
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{
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if (!out)
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{
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console.error('USAGE: nodejs merge.js layer1 layer2 output');
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process.exit();
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}
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const layer1 = await fsp.readFile(file1);
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const layer2 = await fsp.readFile(file2);
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const zero = Buffer.alloc(4096);
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for (let i = 0; i < layer2.length; i += 4096)
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{
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if (zero.compare(layer2, i, i+4096) != 0)
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{
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layer2.copy(layer1, i, i, i+4096);
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}
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}
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await fsp.writeFile(out, layer1);
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}
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merge(process.argv[2], process.argv[3], process.argv[4]);
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