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-rw-r--r--src/devices/machine/mc6854.cpp198
-rw-r--r--src/devices/machine/mc6854.h17
2 files changed, 132 insertions, 83 deletions
diff --git a/src/devices/machine/mc6854.cpp b/src/devices/machine/mc6854.cpp
index 488d3872745..f4a39617b02 100644
--- a/src/devices/machine/mc6854.cpp
+++ b/src/devices/machine/mc6854.cpp
@@ -22,7 +22,6 @@
TODO:
- CRC
- - DMA mode
- loop mode
- status prioritization
- NRZI vs. NRZ coding
@@ -34,9 +33,20 @@
#include "emu.h"
#include "mc6854.h"
-//#define VERBOSE 1
+#define LOG_SETUP (1U << 1)
+#define LOG_BITS (1U << 2)
+
+//#define VERBOSE (LOG_BITS|LOG_GENERAL | LOG_SETUP)
+//#define LOG_OUTPUT_STREAM std::cout
+
#include "logmacro.h"
+#define LOGSETUP(...) LOGMASKED(LOG_SETUP, __VA_ARGS__)
+#define LOGBITS(...) LOGMASKED(LOG_BITS, __VA_ARGS__)
+
+//#define VERBOSE 1
+//#include "logmacro.h"
+
/******************* parameters ******************/
@@ -66,6 +76,9 @@ constexpr unsigned mc6854_device::MAX_FRAME_LENGTH;
#define RIE ( m_cr1 & 2 ) /* interrupt enable */
#define TIE ( m_cr1 & 4 )
+#define RDSR ( m_cr1 & 8 ) /* DMA mode */
+#define TDSR ( m_cr1 & 0x10 )
+
#define DISCONTINUE ( m_cr1 & 0x20 ) /* discontinue received frame */
@@ -131,6 +144,8 @@ DEFINE_DEVICE_TYPE(MC6854, mc6854_device, "mc6854", "Motorola MC6854 ADLC")
mc6854_device::mc6854_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock) :
device_t(mconfig, MC6854, tag, owner, clock),
m_out_irq_cb(*this),
+ m_out_rdsr_cb(*this),
+ m_out_tdsr_cb(*this),
m_out_txd_cb(*this),
m_out_frame_cb(*this),
m_out_rts_cb(*this),
@@ -150,6 +165,8 @@ mc6854_device::mc6854_device(const machine_config &mconfig, const char *tag, dev
m_rreg(0),
m_rones(0),
m_rsize(0),
+ m_rxd(0),
+ m_rxc(0),
m_flen(0),
m_fpos(0)
{
@@ -172,6 +189,8 @@ mc6854_device::mc6854_device(const machine_config &mconfig, const char *tag, dev
void mc6854_device::device_start()
{
m_out_irq_cb.resolve_safe();
+ m_out_rdsr_cb.resolve_safe();
+ m_out_tdsr_cb.resolve_safe();
m_out_txd_cb.resolve();
m_out_frame_cb.resolve();
m_out_rts_cb.resolve_safe();
@@ -391,6 +410,7 @@ TIMER_CALLBACK_MEMBER(mc6854_device::tfifo_cb)
/* data underrun => abort */
logerror( "%f mc6854_tfifo_cb: FIFO underrun\n", machine().time().as_double() );
m_sr1 |= TU;
+ update_sr1();
m_tstate = 0;
send_bits( 0xffff, ABTEX ? 16 : 8, 0 );
m_flen = 0;
@@ -514,10 +534,10 @@ void mc6854_device::rfifo_push( uint8_t d )
}
m_rsize -= blen;
+ update_sr1( );
}
-
void mc6854_device::rfifo_terminate( )
{
/* mark most recently pushed byte as the last one of the frame */
@@ -537,7 +557,6 @@ void mc6854_device::rfifo_terminate( )
}
-
/* CPU pops the FIFO */
uint8_t mc6854_device::rfifo_pop( )
{
@@ -566,70 +585,9 @@ uint8_t mc6854_device::rfifo_pop( )
}
-/* MC6854 makes fields from bits */
WRITE_LINE_MEMBER( mc6854_device::set_rx )
{
- int fieldlen = ( m_rstate < 6 ) ? 8 : RWL;
-
- if ( RRESET || (m_sr2 & DCD) )
- return;
-
- if ( state )
- {
- m_rones++;
- m_rreg = (m_rreg >> 1) | 0x80000000;
- if ( m_rones >= 8 )
- {
- /* abort */
- m_rstate = 0;
- m_rsize = 0;
- if ( m_rstate > 1 )
- {
- /* only in-frame abort */
- m_sr2 |= RABT;
- LOG( "%f mc6854_receive_bit: abort\n", machine().time().as_double() );
- }
- }
- else
- {
- m_rsize++;
- if ( m_rstate && m_rsize >= fieldlen + 24 )
- rfifo_push( m_rreg );
- }
- }
- else if ( m_rones == 5 )
- {
- /* discards '0' inserted after 5 '1' */
- m_rones = 0;
- return;
- }
- else if ( m_rones == 6 )
- {
- /* flag */
- if ( FDSE )
- m_sr1 |= FD;
-
- if ( m_rstate > 1 )
- {
- /* end of frame */
- m_rreg >>= 1;
- m_rsize++;
- if ( m_rsize >= fieldlen + 24 ) /* last field */
- rfifo_push( m_rreg );
- rfifo_terminate( );
- LOG( "%f mc6854_receive_bit: end of frame\n", machine().time().as_double() );
- }
- m_rones = 0;
- m_rstate = 1;
- m_rsize = 0;
- } else
- {
- m_rones = 0;
- m_rreg >>= 1;
- m_rsize++;
- if ( m_rstate && m_rsize >= fieldlen + 24 )
- rfifo_push( m_rreg );
- }
+ m_rxd = state;
}
@@ -663,7 +621,10 @@ int mc6854_device::send_frame( uint8_t* data, int len )
}
memcpy( m_frame, data, len );
if ( FDSE )
+ {
m_sr1 |= FD;
+ update_sr1();
+ }
m_flen = len;
m_fpos = 0;
rfifo_push( m_frame[ m_fpos++ ] );
@@ -689,6 +650,7 @@ WRITE_LINE_MEMBER( mc6854_device::set_cts )
m_sr1 |= CTS;
else
m_sr1 &= ~CTS;
+ update_sr1();
}
@@ -737,7 +699,7 @@ void mc6854_device::update_sr1( )
else
m_sr1 &= ~S2RQ;
- /* update TRDA (always prioritized by CTS) */
+ /* update TDRA (always prioritized by CTS) */
if ( TRESET || ( m_sr1 & CTS ) )
m_sr1 &= ~TDRA;
else
@@ -757,9 +719,9 @@ void mc6854_device::update_sr1( )
/* update IRQ */
m_sr1 &= ~IRQ;
- if ( RIE && (m_sr1 & (TU | TDRA) ) )
+ if ( TIE && (m_sr1 & (TU | TDRA)) && !TDSR )
m_sr1 |= IRQ;
- if ( TIE )
+ if ( RIE && !RDSR )
{
if ( m_sr1 & (S2RQ | RDA | CTS) )
m_sr1 |= IRQ;
@@ -768,6 +730,8 @@ void mc6854_device::update_sr1( )
}
m_out_irq_cb((m_sr1 & IRQ) ? ASSERT_LINE : CLEAR_LINE);
+ m_out_rdsr_cb((m_sr1 & RDA) ? ASSERT_LINE : CLEAR_LINE);
+ m_out_tdsr_cb((m_sr1 & TDRA) ? ASSERT_LINE : CLEAR_LINE);
}
@@ -802,6 +766,7 @@ uint8_t mc6854_device::read(offs_t offset)
uint8_t data = rfifo_pop( );
LOG( "%f %s mc6854_r: get data $%02X\n",
machine().time().as_double(), machine().describe_context(), data );
+ m_out_rdsr_cb(CLEAR_LINE); // Deactive DMA request line regardless of mode
return data;
}
@@ -819,15 +784,13 @@ void mc6854_device::write(offs_t offset, uint8_t data)
{
case 0: /* control register 1 */
m_cr1 = data;
- LOG( "%f %s mc6854_w: set CR1=$%02X (ac=%i,irq=%c%c,%sreset=%c%c)\n",
+ LOGSETUP( "%f %s mc6854_w: set CR1=$%02X (ac=%i,irq=%c%c,%sreset=%c%c)\n",
machine().time().as_double(), machine().describe_context(), m_cr1,
AC ? 1 : 0,
RIE ? 'r' : '-', TIE ? 't' : '-',
DISCONTINUE ? "discontinue," : "",
RRESET ? 'r' : '-', TRESET ? 't' : '-' );
- if ( m_cr1 & 0xc )
- logerror( "%s mc6854 DMA not handled (CR1=$%02X)\n",
- machine().describe_context(), m_cr1 );
+
if ( DISCONTINUE )
{
/* abort receive FIFO but keeps shift register & synchro */
@@ -841,12 +804,14 @@ void mc6854_device::write(offs_t offset, uint8_t data)
m_sr1 &= ~FD;
m_sr2 &= ~(AP | FV | RIDLE | RABT | ERR | OVRN | DCD);
if ( m_dcd ) m_sr2 |= DCD;
+ update_sr1( );
}
if ( TRESET )
{
tfifo_clear( );
m_sr1 &= ~(TU | TDRA | CTS);
if ( m_cts ) m_sr1 |= CTS;
+ update_sr1( );
}
break;
@@ -855,7 +820,7 @@ void mc6854_device::write(offs_t offset, uint8_t data)
{
/* control register 3 */
m_cr3 = data;
- LOG( "%f %s mc6854_w: set CR3=$%02X (lcf=%i,aex=%i,idl=%i,fdse=%i,loop=%i,tst=%i,dtr=%i)\n",
+ LOGSETUP( "%f %s mc6854_w: set CR3=$%02X (lcf=%i,aex=%i,idl=%i,fdse=%i,loop=%i,tst=%i,dtr=%i)\n",
machine().time().as_double(), machine().describe_context(), m_cr3,
LCF ? (CEX ? 16 : 8) : 0, AEX ? 1 : 0,
IDL0 ? 0 : 1, FDSE ? 1 : 0, LOOP ? 1 : 0,
@@ -872,7 +837,7 @@ void mc6854_device::write(offs_t offset, uint8_t data)
{
/* control register 2 */
m_cr2 = data;
- LOG( "%f %s mc6854_w: set CR2=$%02X (pse=%i,bytes=%i,fmidle=%i,%s,tlast=%i,clr=%c%c,rts=%i)\n",
+ LOGSETUP( "%f %s mc6854_w: set CR2=$%02X (pse=%i,bytes=%i,fmidle=%i,%s,tlast=%i,clr=%c%c,rts=%i)\n",
machine().time().as_double(), machine().describe_context(), m_cr2,
PSE ? 1 : 0, TWOBYTES ? 2 : 1, FMIDLE ? 1 : 0,
FCTDRA ? "fc" : "tdra", TLAST ? 1 : 0,
@@ -889,6 +854,7 @@ void mc6854_device::write(offs_t offset, uint8_t data)
m_sr2 &= ~(AP | FV | RIDLE | RABT | ERR | OVRN | DCD);
if ( m_dcd )
m_sr2 |= DCD;
+ update_sr1( );
}
if ( data & 0x40 )
{
@@ -896,6 +862,7 @@ void mc6854_device::write(offs_t offset, uint8_t data)
m_sr1 &= ~(TU | TDRA | CTS);
if ( m_cts )
m_sr1 |= CTS;
+ update_sr1( );
}
m_out_rts_cb( RTS ? 1 : 0 );
@@ -903,7 +870,7 @@ void mc6854_device::write(offs_t offset, uint8_t data)
break;
case 2: /* transmitter data: continue data */
- LOG( "%f %smc6854_w: push data=$%02X\n", machine().time().as_double(), machine().describe_context(), data );
+ LOGSETUP( "%f %smc6854_w: push data=$%02X\n", machine().time().as_double(), machine().describe_context(), data );
tfifo_push( data );
break;
@@ -912,7 +879,7 @@ void mc6854_device::write(offs_t offset, uint8_t data)
{
/* control register 4 */
m_cr4 = data;
- LOG( "%f %s mc6854_w: set CR4=$%02X (interframe=%i,tlen=%i,rlen=%i,%s%s)\n", machine().time().as_double(), machine().describe_context(), m_cr4,
+ LOGSETUP( "%f %s mc6854_w: set CR4=$%02X (interframe=%i,tlen=%i,rlen=%i,%s%s)\n", machine().time().as_double(), machine().describe_context(), m_cr4,
TWOINTER ? 2 : 1,
TWL, RWL,
ABT ? ( ABTEX ? "abort-ext," : "abort,") : "",
@@ -927,7 +894,7 @@ void mc6854_device::write(offs_t offset, uint8_t data)
else
{
/* transmitter data: last data */
- LOG( "%f %s mc6854_w: push last-data=$%02X\n", machine().time().as_double(), machine().describe_context(), data );
+ LOGSETUP( "%f %s mc6854_w: push last-data=$%02X\n", machine().time().as_double(), machine().describe_context(), data );
tfifo_push( data );
tfifo_terminate( );
}
@@ -938,9 +905,82 @@ void mc6854_device::write(offs_t offset, uint8_t data)
}
}
+inline bool mc6854_device::receive_allowed() const
+{
+ return (!RRESET && !(m_sr2 & DCD));
+}
+
+/* MC6854 makes fields from bits */
WRITE_LINE_MEMBER( mc6854_device::rxc_w )
{
- // TODO
+ if (receive_allowed() && state && !m_rxc)
+ {
+ int fieldlen = ( m_rstate < 6 ) ? 8 : RWL;
+
+ if ( m_rxd )
+ {
+ LOGBITS("I ");
+ m_rones++;
+ m_rreg = (m_rreg >> 1) | 0x80000000;
+ if ( m_rones >= 8 )
+ {
+ /* abort */
+ m_rstate = 0;
+ m_rsize = 0;
+ if ( m_rstate > 1 )
+ {
+ /* only in-frame abort */
+ m_sr2 |= RABT;
+ LOG( "%f mc6854_receive_bit: abort\n", machine().time().as_double() );
+ }
+ }
+ else
+ {
+ m_rsize++;
+ if ( m_rstate && m_rsize >= fieldlen + 24 )
+ rfifo_push( m_rreg );
+ }
+ }
+ else if ( m_rones == 5 )
+ {
+ /* discards '0' inserted after 5 '1' */
+ LOGBITS("A zero is discarded\n");
+ m_rones = 0;
+ return;
+ }
+ else if ( m_rones == 6 )
+ {
+ /* flag */
+ if ( FDSE )
+ {
+ m_sr1 |= FD;
+ update_sr1( );
+ }
+
+ if ( m_rstate > 1 )
+ {
+ /* end of frame */
+ m_rreg >>= 1;
+ m_rsize++;
+ if ( m_rsize >= fieldlen + 24 ) /* last field */
+ rfifo_push( m_rreg );
+ rfifo_terminate( );
+ LOG( "%f mc6854_receive_bit: end of frame\n", machine().time().as_double() );
+ }
+ m_rones = 0;
+ m_rstate = 1;
+ m_rsize = 0;
+ } else
+ {
+ LOGBITS("O ");
+ m_rones = 0;
+ m_rreg >>= 1;
+ m_rsize++;
+ if ( m_rstate && m_rsize >= fieldlen + 24 )
+ rfifo_push( m_rreg );
+ }
+ }
+ m_rxc = state;
}
WRITE_LINE_MEMBER( mc6854_device::txc_w )
diff --git a/src/devices/machine/mc6854.h b/src/devices/machine/mc6854.h
index defd3aa76c1..2e2fe6fa663 100644
--- a/src/devices/machine/mc6854.h
+++ b/src/devices/machine/mc6854.h
@@ -23,16 +23,19 @@ public:
mc6854_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock = 0);
- auto out_irq_cb() { return m_out_irq_cb.bind(); }
- auto out_txd_cb() { return m_out_txd_cb.bind(); }
- auto out_rts_cb() { return m_out_rts_cb.bind(); }
- auto out_dtr_cb() { return m_out_dtr_cb.bind(); }
+ auto out_irq_cb() { return m_out_irq_cb.bind(); }
+ auto out_rdsr_cb() { return m_out_rdsr_cb.bind(); }
+ auto out_tdsr_cb() { return m_out_tdsr_cb.bind(); }
+ auto out_txd_cb() { return m_out_txd_cb.bind(); }
+ auto out_rts_cb() { return m_out_rts_cb.bind(); }
+ auto out_dtr_cb() { return m_out_dtr_cb.bind(); }
template <typename... T> void set_out_frame_callback(T &&... args) { m_out_frame_cb.set(std::forward<T>(args)...); }
/* interface to CPU via address/data bus*/
uint8_t read(offs_t offset);
void write(offs_t offset, uint8_t data);
+ uint8_t dma_r(){ return read(2); }
/* low-level, bit-based interface */
DECLARE_WRITE_LINE_MEMBER( set_rx );
@@ -52,12 +55,15 @@ protected:
// device-level overrides
virtual void device_start() override;
virtual void device_reset() override;
+ bool receive_allowed() const;
private:
static constexpr unsigned FIFO_SIZE = 3; // hardcoded size of the 6854 FIFO (this is a hardware limit)
// internal state
devcb_write_line m_out_irq_cb; /* interrupt request */
+ devcb_write_line m_out_rdsr_cb; /* Rx fifo DMA request */
+ devcb_write_line m_out_tdsr_cb; /* Tx fifo DMA request */
/* low-level, bit-based interface */
devcb_write_line m_out_txd_cb; /* transmit bit */
@@ -87,6 +93,8 @@ private:
uint8_t m_rones; /* count '1 bits */
uint8_t m_rsize; /* bits in the shift register */
uint16_t m_rfifo[FIFO_SIZE]; /* X x 8-bit FIFO + full & addr marker bits */
+ bool m_rxd;
+ bool m_rxc;
/* frame-based interface*/
uint8_t m_frame[MAX_FRAME_LENGTH];
@@ -132,6 +140,7 @@ DECLARE_DEVICE_TYPE(MC6854, mc6854_device)
The frame-based interface is higher-level and faster.
It passes bytes directly from one end to the other without bothering with
the actual bit-encoding, synchronization, and CRC.
+
Once completed, a frame is sent through out_frame. Aborted frames are not
transmitted at all. No start flag, stop flag, or crc bits are transmitted.
send_frame makes a frame available to the CPU through the 6854 (it may