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i8244: simplify pos strobe hold

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This commit is contained in:
hap 2020-08-21 23:33:07 +02:00
parent d87a23d9b6
commit fad6c07331
1 changed files with 6 additions and 6 deletions
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12
src/devices/video/i8244.cpp
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@ -304,13 +304,13 @@ uint8_t i8244_device::read(offs_t offset)
{ {
data = m_control_status; data = m_control_status;
// position strobe status
data |= m_vdc.s.control & 0x02;
// hstatus (not same as hblank), goes high at falling edge of X=0x70 // hstatus (not same as hblank), goes high at falling edge of X=0x70
int h = screen().hpos(); int h = screen().hpos();
data |= (h >= 225 && h < m_bgate_start && get_y_beam() <= m_vblank_start) ? 1 : 0; data |= (h >= 225 && h < m_bgate_start && get_y_beam() <= m_vblank_start) ? 1 : 0;
// position strobe status
data |= m_pos_hold ? 2 : 0;
m_irq_func(CLEAR_LINE); m_irq_func(CLEAR_LINE);
m_control_status &= ~0xcc; m_control_status &= ~0xcc;
@ -328,7 +328,7 @@ uint8_t i8244_device::read(offs_t offset)
data = m_y_latch; data = m_y_latch;
m_y_hold = false; m_y_hold = false;
} }
else if (m_pos_hold || !(m_vdc.s.control & 0x02)) else if (m_pos_hold)
data = m_y_beam_pos; data = m_y_beam_pos;
else else
data = get_y_beam(); data = get_y_beam();
@ -337,7 +337,7 @@ uint8_t i8244_device::read(offs_t offset)
case 0xa5: case 0xa5:
{ {
if (m_pos_hold || !(m_vdc.s.control & 0x02)) if (m_pos_hold)
{ {
data = m_x_beam_pos; data = m_x_beam_pos;
m_pos_hold = false; m_pos_hold = false;
@ -347,7 +347,7 @@ uint8_t i8244_device::read(offs_t offset)
// Y is latched when reading X // Y is latched when reading X
m_y_hold = true; m_y_hold = true;
m_y_latch = (m_vdc.s.control & 0x02) ? get_y_beam() : m_y_beam_pos; m_y_latch = get_y_beam();
break; break;
} }