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mc68340: correct MC68340 baud rate calculation [R. Belmont]

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This commit is contained in:
arbee 2019-05-26 21:17:35 -04:00
parent 8c401055b8
commit c9bf74de4e
2 changed files with 74 additions and 0 deletions
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71
src/devices/machine/mc68681.cpp
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@ -70,6 +70,9 @@ static const int baud_rate_ACR_0_X_1[] = { 75, 110, 134, 150, 3600, 14400, 28800
static const int baud_rate_ACR_1[] = { 75, 110, 134, 150, 300, 600, 1200, 2000, 2400, 4800, 1800, 9600, 19200, 0, 0, 0 }; /* xr68c681 X=0 */
static const int baud_rate_ACR_1_X_1[] = { 50, 110, 134, 200, 3600, 14400, 28800, 57600, 115200, 4800, 7200, 9600, 38400, 0, 0, 0 };
static const int baud_rate_ACR_0_340[] = { 50, 110, 134, 200, 300, 600, 1200, 1050, 2400, 4800, 7200, 9600, 38400, 76800, 0, 0 }; /* xr68c681 ACR:7=0 */
static const int baud_rate_ACR_1_340[] = { 75, 110, 134, 150, 300, 600, 1200, 2000, 2400, 4800, 1800, 9600, 19200, 38400, 0, 0 }; /* xr68c681 ACR:7=1 */
#define INT_INPUT_PORT_CHANGE 0x80
#define INT_DELTA_BREAK_B 0x40
#define INT_RXRDY_FFULLB 0x20
@ -1007,6 +1010,74 @@ int duart_base_device::calc_baud(int ch, bool rx, uint8_t data)
return baud_rate;
}
int mc68340_duart_device::calc_baud(int ch, bool rx, uint8_t data)
{
int baud_rate;
if (BIT(ACR, 7) == 0)
{
baud_rate = baud_rate_ACR_0_340[data & 0x0f];
if (ch == 0)
{
if ((data & 0xf) == 0xe)
{
baud_rate = ip3clk/16;
}
else if ((data & 0xf) == 0xf)
{
baud_rate = ip3clk;
}
}
else if (ch == 1)
{
if ((data & 0xf) == 0xe)
{
baud_rate = ip5clk/16;
}
else if ((data & 0xf) == 0xf)
{
baud_rate = ip5clk;
}
}
}
else
{
baud_rate = baud_rate_ACR_1_340[data & 0x0f];
if (ch == 0)
{
if ((data & 0xf) == 0xe)
{
baud_rate = ip3clk/16;
}
else if ((data & 0xf) == 0xf)
{
baud_rate = ip3clk;
}
}
else if (ch == 1)
{
if ((data & 0xf) == 0xe)
{
baud_rate = ip5clk/16;
}
else if ((data & 0xf) == 0xf)
{
baud_rate = ip5clk;
}
}
}
if ((baud_rate == 0) && ((data & 0xf) != 0xd))
{
LOG("Unsupported transmitter clock: channel %d, clock select = %02x\n", ch, data);
}
//printf("%s ch %d setting baud to %d\n", tag(), ch, baud_rate);
return baud_rate;
}
int xr68c681_device::calc_baud(int ch, bool rx, uint8_t data)
{
int baud_rate;

3
src/devices/machine/mc68681.h
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@ -242,6 +242,9 @@ public:
protected:
virtual void device_add_mconfig(machine_config &config) override;
mc68340_duart_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, uint32_t clock);
private:
virtual int calc_baud(int ch, bool rx, uint8_t data) override;
};
class xr68c681_device : public mc68681_device