SH3_MMUAA
r = _reg_read_4(SH3_MMUAA | a);
_reg_write_4(SH3_MMUAA | a, 0);
if ((_reg_read_4(SH3_MMUAA | a) &
_reg_write_4(SH3_MMUAA | a, 0);
if ((_reg_read_4(SH3_MMUAA | a) &
_reg_write_4(SH3_MMUAA | a, 0);