void pcw16_state::pcw16_keyboard_init()
{
int i;
int b;
/* if sum of all bits in the byte is even, then the data
has even parity, otherwise it has odd parity */
for (i=0; i<256; i++)
{
int data;
int sum;
sum = 0;
data = i;
for (b=0; b<8; b++)
{
sum+=data & 0x01;
data = data>>1;
}
m_keyboard_parity_table[i] = sum & 0x01;
}
/* clear int */
pcw16_keyboard_int(0);
/* reset state */
m_keyboard_state = 0;
/* reset ready for transmit */
pcw16_keyboard_reset();
}
/* interfaces to a pc-at keyboard */
static READ8_HANDLER(pcw16_keyboard_data_shift_r)
{
//logerror("keyboard data shift r: %02x\n", pcw16_keyboard_data_shift);
pcw16_keyboard_state &= ~(PCW16_KEYBOARD_BUSY_STATUS);
pcw16_keyboard_int(0);
/* reset for reception */
pcw16_keyboard_reset();
/* read byte */
return pcw16_keyboard_data_shift;
}
static WRITE8_HANDLER(pcw16_keyboard_control_w)
{
//logerror("Keyboard control w: %02x\n",data);
pcw16_keyboard_previous_state = pcw16_keyboard_state;
/* if set, set parity */
if (data & 0x080)
{
pcw16_keyboard_state |= PCW16_KEYBOARD_PARITY_MASK;
}
/* clear read/write bits */
pcw16_keyboard_state &=
~(PCW16_KEYBOARD_FORCE_KEYBOARD_CLOCK |
PCW16_KEYBOARD_TRANSMIT_MODE);
/* set read/write bits from data */
pcw16_keyboard_state |= (data & 0x03);
if (data & PCW16_KEYBOARD_RESET_INTERFACE)
{
pcw16_keyboard_reset();
}
if (data & PCW16_KEYBOARD_TRANSMIT_MODE)
{
/* force clock changed */
if (((pcw16_keyboard_state^pcw16_keyboard_previous_state) & PCW16_KEYBOARD_FORCE_KEYBOARD_CLOCK)!=0)
{
/* just cleared? */
if ((pcw16_keyboard_state & PCW16_KEYBOARD_FORCE_KEYBOARD_CLOCK)==0)
{
/* write */
/* busy */
pcw16_keyboard_state |= PCW16_KEYBOARD_BUSY_STATUS;
/* keyboard takes data */
at_keyboard_write(pcw16_keyboard_data_shift);
/* set clock low - no furthur transmissions */
pcw16_keyboard_set_clock_state(0);
/* set int */
pcw16_keyboard_int(1);
}
}
}
if (((pcw16_keyboard_state^pcw16_keyboard_previous_state) & PCW16_KEYBOARD_TRANSMIT_MODE)!=0)
{
if ((pcw16_keyboard_state & PCW16_KEYBOARD_TRANSMIT_MODE)==0)
{
if ((pcw16_system_status & (1<<1))!=0)
{
pcw16_keyboard_int(0);
}
}
}
pcw16_keyboard_refresh_outputs();
}
