private final BigDecimal getDecimal0()

in dbsync/src/main/java/com/taobao/tddl/dbsync/binlog/LogBuffer.java [1404:1555]
136 lines of code
42 McCabe index (conditional complexity)

    private final BigDecimal getDecimal0(final int begin, final int intg, final int frac, final int intg0,
                                         final int frac0, final int intg0x, final int frac0x) {
        final int mask = ((buffer[begin] & 0x80) == 0x80) ? 0 : -1;
        int from = begin;

        /* max string length */
        final int len = ((mask != 0) ? 1 : 0) + ((intg != 0) ? intg : 1) // NL
                        + ((frac != 0) ? 1 : 0) + frac;
        char[] buf = new char[len];
        int pos = 0;

        if (mask != 0) /* decimal sign */
        buf[pos++] = ('-');

        final byte[] d_copy = buffer;
        d_copy[begin] ^= 0x80; /* clear sign */
        int mark = pos;

        if (intg0x != 0) {
            final int i = dig2bytes[intg0x];
            int x = 0;
            switch (i) {
                case 1:
                    x = d_copy[from] /* one byte */;
                    break;
                case 2:
                    x = getInt16BE(d_copy, from);
                    break;
                case 3:
                    x = getInt24BE(d_copy, from);
                    break;
                case 4:
                    x = getInt32BE(d_copy, from);
                    break;
            }
            from += i;
            x ^= mask;
            if (x < 0 || x >= powers10[intg0x + 1]) {
                throw new IllegalArgumentException("bad format, x exceed: " + x + ", " + powers10[intg0x + 1]);
            }
            if (x != 0 /* !digit || x != 0 */) {
                for (int j = intg0x; j > 0; j--) {
                    final int divisor = powers10[j - 1];
                    final int y = x / divisor;
                    if (mark < pos || y != 0) {
                        buf[pos++] = ((char) ('0' + y));
                    }
                    x -= y * divisor;
                }
            }
        }

        for (final int stop = from + intg0 * SIZE_OF_INT32; from < stop; from += SIZE_OF_INT32) {
            int x = getInt32BE(d_copy, from);
            x ^= mask;
            if (x < 0 || x > DIG_MAX) {
                throw new IllegalArgumentException("bad format, x exceed: " + x + ", " + DIG_MAX);
            }
            if (x != 0) {
                if (mark < pos) {
                    for (int i = DIG_PER_DEC1; i > 0; i--) {
                        final int divisor = powers10[i - 1];
                        final int y = x / divisor;
                        buf[pos++] = ((char) ('0' + y));
                        x -= y * divisor;
                    }
                } else {
                    for (int i = DIG_PER_DEC1; i > 0; i--) {
                        final int divisor = powers10[i - 1];
                        final int y = x / divisor;
                        if (mark < pos || y != 0) {
                            buf[pos++] = ((char) ('0' + y));
                        }
                        x -= y * divisor;
                    }
                }
            } else if (mark < pos) {
                for (int i = DIG_PER_DEC1; i > 0; i--)
                    buf[pos++] = ('0');
            }
        }

        if (mark == pos)
        /* fix 0.0 problem, only '.' may cause BigDecimal parsing exception. */
        buf[pos++] = ('0');

        if (frac > 0) {
            buf[pos++] = ('.');
            mark = pos;

            for (final int stop = from + frac0 * SIZE_OF_INT32; from < stop; from += SIZE_OF_INT32) {
                int x = getInt32BE(d_copy, from);
                x ^= mask;
                if (x < 0 || x > DIG_MAX) {
                    throw new IllegalArgumentException("bad format, x exceed: " + x + ", " + DIG_MAX);
                }
                if (x != 0) {
                    for (int i = DIG_PER_DEC1; i > 0; i--) {
                        final int divisor = powers10[i - 1];
                        final int y = x / divisor;
                        buf[pos++] = ((char) ('0' + y));
                        x -= y * divisor;
                    }
                } else {
                    for (int i = DIG_PER_DEC1; i > 0; i--)
                        buf[pos++] = ('0');
                }
            }

            if (frac0x != 0) {
                final int i = dig2bytes[frac0x];
                int x = 0;
                switch (i) {
                    case 1:
                        x = d_copy[from] /* one byte */;
                        break;
                    case 2:
                        x = getInt16BE(d_copy, from);
                        break;
                    case 3:
                        x = getInt24BE(d_copy, from);
                        break;
                    case 4:
                        x = getInt32BE(d_copy, from);
                        break;
                }
                x ^= mask;
                if (x != 0) {
                    final int dig = DIG_PER_DEC1 - frac0x;
                    x *= powers10[dig];
                    if (x < 0 || x > DIG_MAX) {
                        throw new IllegalArgumentException("bad format, x exceed: " + x + ", " + DIG_MAX);
                    }
                    for (int j = DIG_PER_DEC1; j > dig; j--) {
                        final int divisor = powers10[j - 1];
                        final int y = x / divisor;
                        buf[pos++] = ((char) ('0' + y));
                        x -= y * divisor;
                    }
                }
            }

            if (mark == pos)
            /* make number more friendly */
            buf[pos++] = ('0');
        }

        d_copy[begin] ^= 0x80; /* restore sign */
        // String decimal = String.valueOf(buf, 0, pos);
        // return new BigDecimal(decimal);
        return new BigDecimal(buf, 0, pos);
    }