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sed1520: don't write to ram when column address out of range

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This commit is contained in:
hap 2022-09-16 20:08:53 +02:00
parent 5027ed2bc3
commit 3a6ab235cb
2 changed files with 28 additions and 12 deletions
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34
src/devices/video/sed1520.cpp
View File

@ -2,12 +2,12 @@
// copyright-holders:Sandro Ronco
/***************************************************************************
SED1520 LCD controller
SED1560 LCD controller
EPL43102 LCD controller
SED1520 LCD controller
SED1560 LCD controller
EPL43102 LCD controller
TODO:
- busy flag
TODO:
- busy flag
***************************************************************************/
@ -225,17 +225,33 @@ uint8_t sed15xx_device_base::status_read()
void sed15xx_device_base::data_write(uint8_t data)
{
m_ddr[(m_page * m_page_size + m_column) % m_ddr_size] = data;
m_data = data;
// no RAM write when column address is invalid
if (m_column < m_page_size)
{
m_ddr[(m_page * m_page_size + m_column) % m_ddr_size] = data;
m_column++;
}
}
uint8_t sed15xx_device_base::data_read()
{
uint8_t data = m_data;
m_data = m_ddr[(m_page * m_page_size + m_column) % m_ddr_size];
if (!machine().side_effects_disabled() && !m_modify_write && m_column < m_page_size)
m_column++;
if (machine().side_effects_disabled())
return data;
if (m_column < m_page_size)
{
m_data = m_ddr[(m_page * m_page_size + m_column) % m_ddr_size];
if (!m_modify_write)
m_column++;
}
else
{
// invalid column, not sure what happens with data latch
m_data = 0;
}
return data;
}

6
src/devices/video/sed1520.h
View File

@ -2,9 +2,9 @@
// copyright-holders:Sandro Ronco
/***************************************************************************
SED1520 LCD controller
SED1560 LCD controller
EPL43102 LCD controller
SED1520 LCD controller
SED1560 LCD controller
EPL43102 LCD controller
***************************************************************************/