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https://github.com/holub/mame
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z8: Preliminary UART emulation
This commit is contained in:
AJR
parent
b951f248c1
commit
7bd2bb2765
@ -11,8 +11,6 @@
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TODO:
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- strobed I/O
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- timer Tin/Tout modes
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- serial
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- instruction pipeline
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- internal diagnostic ROM in data space (requires high voltage reset)
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@ -37,8 +35,8 @@
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#define Z8_P3_IRQ1 0x08
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#define Z8_P3_IRQ2 0x02
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#define Z8_P3_IRQ3 0x01
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#define Z8_P3_DI 0x01 /* not supported */
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#define Z8_P3_DO 0x80 /* not supported */
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#define Z8_P3_SIN 0x01
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#define Z8_P3_SOUT 0x80
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#define Z8_P3_TIN 0x02
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#define Z8_P3_TOUT 0x40
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#define Z8_P3_DM 0x10 /* not supported */
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@ -437,6 +435,22 @@ void z8_device::p2_write(uint8_t data)
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m_output_cb[2](0, data & mask, mask);
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}
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void z8_device::p3_update_output()
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{
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uint8_t output = m_output[3] & 0xf0;
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if ((m_tmr & Z8_TMR_TOUT_MASK) != Z8_TMR_TOUT_OFF)
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output = (output & ~Z8_P3_TOUT) | (output ? Z8_P3_TOUT : 0);
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if ((m_p3m & Z8_P3M_P3_SERIAL) != 0)
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output = (output & ~Z8_P3_SOUT) | ((m_transmit_sr == 0 || BIT(m_transmit_sr, 0)) ? Z8_P3_SOUT : 0);
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if (m_p3_output != output)
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{
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m_output_cb[3](0, output, output ^ m_p3_output);
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m_p3_output = output;
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}
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}
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uint8_t z8_device::p3_read()
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{
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uint8_t mask = 0x0f;
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@ -447,45 +461,136 @@ uint8_t z8_device::p3_read()
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//{
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//}
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if ((m_tmr & Z8_TMR_TOUT_MASK) != Z8_TMR_TOUT_OFF)
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{
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mask |= Z8_P3_TOUT;
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if (m_tout)
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inputs |= Z8_P3_TOUT;
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}
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return (inputs & mask) | (m_output[3] & ~mask);
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return (inputs & mask) | (m_p3_output & ~mask);
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}
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void z8_device::p3_write(uint8_t data)
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{
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uint8_t mask = 0xf0;
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m_output[3] = data;
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m_output[3] = data & 0xf0;
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// TODO: special port 3 modes
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//if (!(m_p3m & 0x7c))
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//{
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//}
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if ((m_tmr & Z8_TMR_TOUT_MASK) != Z8_TMR_TOUT_OFF)
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data = (data & ~Z8_P3_TOUT) | (m_tout ? Z8_P3_TOUT : 0);
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p3_update_output();
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}
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if (mask)
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m_output_cb[3](0, data & mask, mask);
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bool z8_device::get_serial_in()
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{
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return (m_input[3] & Z8_P3_SIN) != 0;
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}
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void z8_device::sio_tick()
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{
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if (m_receive_started)
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{
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m_receive_count = (m_receive_count + 1) & 15;
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if (m_receive_count == 8)
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{
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if (m_receive_sr == 0)
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{
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if (!get_serial_in())
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{
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// start bit validated
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m_receive_sr |= 1 << 9;
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m_receive_parity = false;
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}
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else
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{
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// false start bit
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m_receive_started = false;
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m_receive_count = 0;
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}
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}
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else
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{
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// shift in data, parity or stop bit
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m_receive_sr >>= 1;
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if (get_serial_in())
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m_receive_sr |= 1 << 9;
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if (BIT(m_receive_sr, 0))
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{
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// received full character
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m_receive_buffer = (m_receive_sr & 0x1fe) >> 1;
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request_interrupt(3);
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m_receive_started = false;
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m_receive_count = 0;
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}
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else
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{
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if (BIT(m_receive_sr, 9))
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m_receive_parity = !m_receive_parity;
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// parity replaces received bit 7 if selected
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if (BIT(m_receive_sr, 1) && (m_p3m & Z8_P3M_PARITY) != 0)
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{
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if (m_receive_parity)
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m_receive_sr |= 1 << 9;
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else
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m_receive_sr &= ~(1 << 9);
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}
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}
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}
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}
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}
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else
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{
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// start bit is high-low transition
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m_receive_sr >>= 1;
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if (get_serial_in())
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m_receive_sr |= 1 << 9;
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else if (BIT(m_receive_sr, 8))
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{
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m_receive_started = true;
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m_receive_sr = 0;
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m_receive_count = 0;
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}
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}
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if (m_transmit_sr != 0)
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{
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m_transmit_count = (m_transmit_count + 1) & 15;
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if (m_transmit_count == 0)
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{
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m_transmit_sr >>= 1;
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if (m_transmit_sr == 0)
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request_interrupt(4);
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else
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{
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// parity replaces received bit 7 if selected
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if ((m_transmit_sr >> 1) == 3 && (m_p3m & Z8_P3M_PARITY) != 0)
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{
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if (m_transmit_parity)
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m_transmit_sr |= 1;
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else
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m_transmit_sr &= ~1;
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}
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else if (BIT(m_transmit_sr, 0))
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m_transmit_parity = !m_transmit_parity;
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// serial output
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logerror("Transmitting %d bit (time = %.2f usec)\n", BIT(m_transmit_sr, 0), machine().time().as_double() * 1.0E6);
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p3_update_output();
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}
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}
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}
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}
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uint8_t z8_device::sio_read()
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{
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return 0xff;
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return m_receive_buffer;
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}
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void z8_device::sio_write(uint8_t data)
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{
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// overwrite shift register with data + 1 start bit + 2 stop bits
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m_transmit_sr = (m_transmit_sr & 1) | (uint16_t(data) << 2) | (3 << 10);
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m_transmit_parity = false;
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// synchronize the shift clock
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m_transmit_count = 15;
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}
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template <int T>
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@ -569,13 +674,13 @@ void z8_device::t1_trigger()
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void z8_device::tout_init()
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{
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m_tout = true;
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m_output_cb[3](0, (m_output[3] & ~Z8_P3_TOUT) | (m_tout ? Z8_P3_TOUT : 0), Z8_P3_TOUT);
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p3_update_output();
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}
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void z8_device::tout_toggle()
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{
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m_tout = !m_tout;
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m_output_cb[3](0, (m_output[3] & ~Z8_P3_TOUT) | (m_tout ? Z8_P3_TOUT : 0), Z8_P3_TOUT);
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p3_update_output();
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}
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uint8_t z8_device::tmr_read()
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@ -720,7 +825,16 @@ void z8_device::p2m_write(uint8_t data)
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void z8_device::p3m_write(uint8_t data)
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{
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if ((data & Z8_P3M_P3_SERIAL) == 0)
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{
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m_transmit_sr = 0;
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m_transmit_count = 0;
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m_receive_started = false;
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m_receive_count = 0;
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}
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m_p3m = data;
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p3_update_output();
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}
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void z8_device::ipr_write(uint8_t data)
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@ -1115,8 +1229,17 @@ void z8_device::device_start()
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m_p01m = 0;
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m_p2m = 0;
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m_p3m = 0;
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m_p3_output = 0;
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m_tmr = 0;
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m_tout = true;
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m_transmit_sr = 0;
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m_transmit_count = 0;
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m_transmit_parity = false;
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m_receive_buffer = 0;
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m_receive_sr = 0;
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m_receive_count = 0;
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m_receive_parity = false;
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m_receive_started = false;
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m_irq_taken = false;
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m_irq_initialized = false;
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@ -1131,9 +1254,18 @@ void z8_device::device_start()
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save_item(NAME(m_p01m));
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save_item(NAME(m_p2m));
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save_item(NAME(m_p3m));
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save_item(NAME(m_p3_output));
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save_item(NAME(m_tmr));
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save_item(NAME(m_t));
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save_item(NAME(m_tout));
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save_item(NAME(m_transmit_sr));
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save_item(NAME(m_transmit_count));
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save_item(NAME(m_transmit_parity));
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save_item(NAME(m_receive_buffer));
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save_item(NAME(m_receive_sr));
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save_item(NAME(m_receive_count));
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save_item(NAME(m_receive_parity));
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save_item(NAME(m_receive_started));
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save_item(NAME(m_count));
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save_item(NAME(m_pre));
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save_item(NAME(m_pre_count));
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@ -1336,16 +1468,16 @@ void z8_device::device_reset()
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m_imr &= ~Z8_IMR_ENABLE;
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m_irq_initialized = false;
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p01m_write(0x4d);
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p2m_write(0xff);
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p3m_write(0x00);
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p3_write(m_output[3] | 0xf0);
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m_pre[0] &= ~Z8_PRE0_COUNT_MODULO_N;
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m_pre[1] &= ~(Z8_PRE1_COUNT_MODULO_N | Z8_PRE1_INTERNAL_CLOCK);
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m_tmr = 0x00;
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timer_stop<0>();
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timer_stop<1>();
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m_output[3] = 0xf0;
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p01m_write(0x4d);
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p2m_write(0xff);
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p3m_write(0x00);
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}
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@ -101,6 +101,7 @@ private:
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uint8_t m_p01m; // port 0/1 mode
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uint8_t m_p2m; // port 2 mode
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uint8_t m_p3m; // port 3 mode
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uint8_t m_p3_output; // port 3 output (alternate functions included)
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// timer registers
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uint8_t m_tmr; // timer mode
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@ -110,6 +111,18 @@ private:
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uint8_t m_pre_count[2]; // prescaler counts
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bool m_tout; // toggle output
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// serial transmitter registers
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uint16_t m_transmit_sr; // transmitter shift register
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uint8_t m_transmit_count; // counter for transmitter timing
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bool m_transmit_parity; // transmitter parity calculation
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// serial receiver registers
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uint8_t m_receive_buffer; // received character
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uint16_t m_receive_sr; // receiver shift register
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uint8_t m_receive_count; // counter for receiver timing
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bool m_receive_parity; // receiver parity calculation
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bool m_receive_started; // true if receiver has seen start bit
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// fake registers
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uint8_t m_fake_r[16]; // fake working registers
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@ -124,6 +137,7 @@ private:
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// timers
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emu_timer *m_internal_timer[2];
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bool get_serial_in();
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void sio_tick();
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template <int T> void timer_start();
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@ -147,6 +161,7 @@ private:
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void p2_write(uint8_t data);
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uint8_t p3_read();
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void p3_write(uint8_t data);
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void p3_update_output();
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uint8_t sio_read();
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void sio_write(uint8_t data);
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uint8_t tmr_read();
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