Method drawFormatBits

src/third-party/qrcodegen/index.ts:262–286

(mask: int)

		// Draws two copies of the format bits (with its own error correction code)
		// based on the given mask and this object's error correction level field.
		private drawFormatBits(mask: int): void {
			// Calculate error correction code and pack bits
			const data: int = this.errorCorrectionLevel.formatBits << 3 | mask;  // errCorrLvl is uint2, mask is uint3
			let rem: int = data;
			for (let i = 0; i < 10; i++)
				rem = (rem << 1) ^ ((rem >>> 9) * 0x537);
			const bits = (data << 10 | rem) ^ 0x5412;  // uint15
			assert(bits >>> 15 == 0);

			// Draw first copy
			for (let i = 0; i <= 5; i++)
				this.setFunctionModule(8, i, getBit(bits, i));
			this.setFunctionModule(8, 7, getBit(bits, 6));
			this.setFunctionModule(8, 8, getBit(bits, 7));
			this.setFunctionModule(7, 8, getBit(bits, 8));
			for (let i = 9; i < 15; i++)
				this.setFunctionModule(14 - i, 8, getBit(bits, i));

			// Draw second copy
			for (let i = 0; i < 8; i++)
				this.setFunctionModule(this.size - 1 - i, 8, getBit(bits, i));
			for (let i = 8; i < 15; i++)
				this.setFunctionModule(8, this.size - 15 + i, getBit(bits, i));
			this.setFunctionModule(8, this.size - 8, true);  // Always dark
		}


		// Draws two copies of the version bits (with its own error correction code),