diff options
Diffstat (limited to 'src/devices/cpu/hmcs40/hmcs40op.cpp')
-rw-r--r-- | src/devices/cpu/hmcs40/hmcs40op.cpp | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/src/devices/cpu/hmcs40/hmcs40op.cpp b/src/devices/cpu/hmcs40/hmcs40op.cpp index a10629cf639..a0c6c6efb5c 100644 --- a/src/devices/cpu/hmcs40/hmcs40op.cpp +++ b/src/devices/cpu/hmcs40/hmcs40op.cpp @@ -21,18 +21,26 @@ inline void hmcs40_cpu_device::ram_w(u8 data) m_data->write_byte(address, data & 0xf); } +void hmcs40_cpu_device::exc_stack() +{ + // exchange stack/pc + u16 pc = m_stack[m_sp] & m_pcmask; + m_stack[m_sp] = m_pc; + m_pc = pc; +} + void hmcs40_cpu_device::pop_stack() { - m_pc = m_stack[0] & m_pcmask; - for (int i = 0; i < m_stack_levels-1; i++) - m_stack[i] = m_stack[i+1]; + if (++m_sp >= m_stack_levels) + m_sp = 0; + exc_stack(); } void hmcs40_cpu_device::push_stack() { - for (int i = m_stack_levels-1; i >= 1; i--) - m_stack[i] = m_stack[i-1]; - m_stack[0] = m_pc; + exc_stack(); + if (--m_sp < 0) + m_sp = m_stack_levels - 1; } |