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Diffstat (limited to 'src/devices/cpu/hmcs40/hmcs40op.cpp')
-rw-r--r--src/devices/cpu/hmcs40/hmcs40op.cpp20
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;
}