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[PPI8255] Fixed handshaking signals for modes 1/2.

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This commit is contained in:
Curt Coder 2009-06-08 13:30:09 +00:00
parent 31d3633838
commit 7f060d3bca
1 changed files with 65 additions and 10 deletions
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75
src/emu/machine/8255ppi.c
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@ -117,12 +117,15 @@ struct _ppi8255
UINT8 ibf_b;
UINT8 inte_a;
UINT8 inte_b;
UINT8 inte_1;
UINT8 inte_2;
UINT8 in_mask[3]; /* input mask */
UINT8 in_mask[3]; /* input mask */
UINT8 out_mask[3]; /* output mask */
UINT8 read[3]; /* data read from ports */
UINT8 latch[3]; /* data written to ports */
UINT8 output[3]; /* actual output data */
UINT8 control; /* mode control word */
};
@ -161,16 +164,16 @@ INLINE void ppi8255_get_handshake_signals(ppi8255_t *ppi8255, int is_read, UINT8
}
else if (ppi8255->group_a_mode == 2)
{
handshake |= ppi8255->inte_a ? 0x08 : 0x00;
handshake |= ppi8255->obf_a ? 0x00 : 0x80;
handshake |= ppi8255->ibf_a ? 0x20 : 0x00;
handshake |= ((ppi8255->obf_a && ppi8255->inte_1) || (ppi8255->ibf_a && ppi8255->inte_2)) ? 0x08 : 0x00;
mask |= 0xA8;
}
/* group B */
if (ppi8255->group_b_mode == 1)
{
if (ppi8255->port_a_dir)
if (ppi8255->port_b_dir)
{
handshake |= ppi8255->ibf_b ? 0x02 : 0x00;
handshake |= (ppi8255->ibf_b && ppi8255->inte_b) ? 0x01 : 0x00;
@ -210,6 +213,16 @@ static void ppi8255_input(const device_config *device, int port, UINT8 data)
}
}
if (((ppi8255->group_a_mode == 1) && (ppi8255->port_a_dir == 1)) || (ppi8255->group_a_mode == 2))
{
/* is !STBA asserted? */
if (!ppi8255->ibf_a && !(data & 0x10))
{
ppi8255->ibf_a = 1;
changed = 1;
}
}
if ((ppi8255->group_b_mode == 1) && (ppi8255->port_b_dir == 0))
{
/* is !ACKB asserted? */
@ -220,6 +233,16 @@ static void ppi8255_input(const device_config *device, int port, UINT8 data)
}
}
if ((ppi8255->group_b_mode == 1) && (ppi8255->port_b_dir == 1))
{
/* is !STBB asserted? */
if (!ppi8255->ibf_b && !(data & 0x04))
{
ppi8255->ibf_b = 1;
changed = 1;
}
}
if (changed)
ppi8255_write_port(device, 2);
}
@ -241,9 +264,23 @@ static UINT8 ppi8255_read_port(const device_config *device, int port)
}
result |= ppi8255->latch[port] & ppi8255->out_mask[port];
/* read special port 2 signals */
if (port == 2)
switch (port)
{
case 0:
/* clear input buffer full flag */
ppi8255->ibf_a = 0;
break;
case 1:
/* clear input buffer full flag */
ppi8255->ibf_b = 0;
break;
case 2:
/* read special port 2 signals */
ppi8255_get_handshake_signals(ppi8255, 1, &result);
break;
}
return result;
}
@ -252,6 +289,7 @@ static UINT8 ppi8255_read_port(const device_config *device, int port)
READ8_DEVICE_HANDLER( ppi8255_r )
{
ppi8255_t *ppi8255 = get_safe_token(device);
UINT8 result = 0;
offset %= 4;
@ -265,7 +303,7 @@ READ8_DEVICE_HANDLER( ppi8255_r )
break;
case 3: /* Control word */
result = 0xFF;
result = ppi8255->control;
break;
}
@ -340,10 +378,16 @@ WRITE8_DEVICE_HANDLER( ppi8255_w )
bit = (data >> 1) & 0x07;
if (data & 1)
ppi8255->latch[2] |= (1<<bit); /* set bit */
ppi8255->latch[2] |= (1<<bit); /* set bit */
else
ppi8255->latch[2] &= ~(1<<bit); /* reset bit */
if (bit == 2 && ppi8255->group_b_mode == 1) ppi8255->inte_b = data & 1;
if (bit == 4 && ppi8255->group_a_mode == 1 && ppi8255->port_a_dir) ppi8255->inte_a = data & 1;
if (bit == 6 && ppi8255->group_a_mode == 1 && !ppi8255->port_a_dir) ppi8255->inte_a = data & 1;
if (bit == 4 && ppi8255->group_a_mode == 2) ppi8255->inte_2 = data & 1;
if (bit == 6 && ppi8255->group_a_mode == 2) ppi8255->inte_1 = data & 1;
ppi8255_write_port(device, 2);
}
break;
@ -472,6 +516,14 @@ static void set_mode(const device_config *device, int data, int call_handlers)
for (i = 0; i < 3; i++)
ppi8255_write_port(device, i);
}
/* reset flip-flops */
ppi8255->obf_a = ppi8255->ibf_a = 0;
ppi8255->obf_b = ppi8255->ibf_b = 0;
ppi8255->inte_a = ppi8255->inte_b = ppi8255->inte_1 = ppi8255->inte_2 = 0;
/* store control word */
ppi8255->control = data;
}
@ -524,6 +576,8 @@ static DEVICE_START( ppi8255 ) {
state_save_register_device_item(device, 0, ppi8255->ibf_b);
state_save_register_device_item(device, 0, ppi8255->inte_a);
state_save_register_device_item(device, 0, ppi8255->inte_b);
state_save_register_device_item(device, 0, ppi8255->inte_1);
state_save_register_device_item(device, 0, ppi8255->inte_2);
state_save_register_device_item_array(device, 0, ppi8255->in_mask);
state_save_register_device_item_array(device, 0, ppi8255->out_mask);
state_save_register_device_item_array(device, 0, ppi8255->read);
@ -541,14 +595,15 @@ static DEVICE_RESET( ppi8255 ) {
ppi8255->port_b_dir = 0;
ppi8255->port_ch_dir = 0;
ppi8255->port_cl_dir = 0;
ppi8255->obf_a = ppi8255->ibf_a = ppi8255->inte_a = 0;
ppi8255->obf_b = ppi8255->ibf_b = ppi8255->inte_b = 0;
ppi8255->obf_a = ppi8255->ibf_a = 0;
ppi8255->obf_b = ppi8255->ibf_b = 0;
ppi8255->inte_a = ppi8255->inte_b = ppi8255->inte_1 = ppi8255->inte_2 = 0;
for ( i = 0; i < 3; i++ ) {
ppi8255->in_mask[i] = ppi8255->out_mask[i] = ppi8255->read[i] = ppi8255->latch[i] = ppi8255->output[i] = 0;
}
set_mode(device, 0x1b, 0); /* Mode 0, all ports set to input */
set_mode(device, 0x9b, 0); /* Mode 0, all ports set to input */
}