void decode()

in src/main/java/org/apache/commons/net/util/Base64.java [655:704]
45 lines of code
15 McCabe index (conditional complexity)

    void decode(final byte[] in, int inPos, final int inAvail) {
        if (eof) {
            return;
        }
        if (inAvail < 0) {
            eof = true;
        }
        for (int i = 0; i < inAvail; i++) {
            if (buffer == null || buffer.length - pos < decodeSize) {
                resizeBuffer();
            }
            final byte b = in[inPos++];
            if (b == PAD) {
                // We're done.
                eof = true;
                break;
            }
            if (b >= 0 && b < DECODE_TABLE.length) {
                final int result = DECODE_TABLE[b];
                if (result >= 0) {
                    modulus = (++modulus) % 4;
                    x = (x << 6) + result;
                    if (modulus == 0) {
                        buffer[pos++] = (byte) ((x >> 16) & MASK_8BITS);
                        buffer[pos++] = (byte) ((x >> 8) & MASK_8BITS);
                        buffer[pos++] = (byte) (x & MASK_8BITS);
                    }
                }
            }
        }

        // Two forms of EOF as far as base64 decoder is concerned: actual
        // EOF (-1) and first time '=' character is encountered in stream.
        // This approach makes the '=' padding characters completely optional.
        if (eof && modulus != 0) {
            x = x << 6;
            switch (modulus) {
            case 2:
                x = x << 6;
                buffer[pos++] = (byte) ((x >> 16) & MASK_8BITS);
                break;
            case 3:
                buffer[pos++] = (byte) ((x >> 16) & MASK_8BITS);
                buffer[pos++] = (byte) ((x >> 8) & MASK_8BITS);
                break;
            default:
                break; // other values ignored
            }
        }
    }