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machine/ins8250.cpp: Implement transmit Break functionality. (#11665)

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Mark Garlanger 2023-10-29 11:20:52 -05:00 committed by GitHub
parent 48ea29cf12
commit 2d318f541a
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2 changed files with 32 additions and 6 deletions
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36
src/devices/machine/ins8250.cpp
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@ -179,7 +179,7 @@ static constexpr u8 INS8250_LCR_2STOP_BITS = 0x04;
//static constexpr u8 INS8250_LCR_PEN = 0x08;
//static constexpr u8 INS8250_LCR_EVEN_PAR = 0x10;
//static constexpr u8 INS8250_LCR_PARITY = 0x20;
//static constexpr u8 INS8250_LCR_BREAK = 0x40;
static constexpr u8 INS8250_LCR_BREAK = 0x40;
static constexpr u8 INS8250_LCR_DLAB = 0x80;
/* ints will continue to be set for as long as there are ints pending */
@ -299,9 +299,11 @@ void ins8250_uart_device::ins8250_w(offs_t offset, u8 data)
set_fcr(data);
break;
case 3:
{
bool break_state_changed = bool((m_regs.lcr ^ data) & INS8250_LCR_BREAK);
m_regs.lcr = data;
{
int data_bit_count = (m_regs.lcr & INS8250_LCR_BITCOUNT_MASK) + 5;
parity_t parity;
stop_bits_t stop_bits;
@ -336,6 +338,19 @@ void ins8250_uart_device::ins8250_w(offs_t offset, u8 data)
else
stop_bits = STOP_BITS_2;
if (break_state_changed)
{
int new_out_val = (m_regs.lcr & INS8250_LCR_BREAK) ? 0 : m_txd;
if (m_regs.mcr & INS8250_MCR_LOOPBACK)
{
device_serial_interface::rx_w(new_out_val);
}
else
{
m_out_tx_cb(new_out_val);
}
}
set_data_frame(1, data_bit_count, parity, stop_bits);
}
break;
@ -349,7 +364,10 @@ void ins8250_uart_device::ins8250_w(offs_t offset, u8 data)
if (m_regs.mcr & INS8250_MCR_LOOPBACK)
{
m_out_tx_cb(1);
device_serial_interface::rx_w(m_txd);
if ((m_regs.lcr & INS8250_LCR_BREAK) == 0)
{
device_serial_interface::rx_w(m_txd);
}
m_out_dtr_cb(1);
m_out_rts_cb(1);
m_out_out1_cb(1);
@ -357,7 +375,10 @@ void ins8250_uart_device::ins8250_w(offs_t offset, u8 data)
}
else
{
m_out_tx_cb(m_txd);
if ((m_regs.lcr & INS8250_LCR_BREAK) == 0)
{
m_out_tx_cb(m_txd);
}
device_serial_interface::rx_w(m_rxd);
m_out_dtr_cb((m_regs.mcr & INS8250_MCR_DTR) ? 0 : 1);
m_out_rts_cb((m_regs.mcr & INS8250_MCR_RTS) ? 0 : 1);
@ -568,6 +589,13 @@ void ins8250_uart_device::tra_complete()
void ins8250_uart_device::tra_callback()
{
m_txd = transmit_register_get_data_bit();
if (m_regs.lcr & INS8250_LCR_BREAK)
{
// in break mode, don't change transmitted bit
return;
}
if (m_regs.mcr & INS8250_MCR_LOOPBACK)
{
device_serial_interface::rx_w(m_txd);

2
src/mame/heathkit/tlb.cpp
View File

@ -15,8 +15,6 @@
Input can also come from the serial port.
TODO:
- INS8250 needs to implement "Set Break" (LCR, bit 6) before Break key
will function as expected.
- 49/50 row mode does not work when DOT clocks are programmed as documented
in the manual. It does work when DOT clock is fixed at the 20.282 MHz
rate.