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smsplus/pio.c
Ryan Danbrook e7f2dc54e0 Initial commit
2016-09-21 19:54:51 -04:00

257 lines
7.5 KiB
C
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/*
pio.c --
I/O chip and peripheral emulation.
*/
#include "shared.h"
io_state io_lut[2][256];
io_state *io_current;
void pio_init(void)
{
int i, j;
/* Make pin state LUT */
for(j = 0; j < 2; j++)
{
for(i = 0; i < 0x100; i++)
{
/* Common control: pin direction */
io_lut[j][i].tr_dir[0] = (i & 0x01) ? PIN_DIR_IN : PIN_DIR_OUT;
io_lut[j][i].th_dir[0] = (i & 0x02) ? PIN_DIR_IN : PIN_DIR_OUT;
io_lut[j][i].tr_dir[1] = (i & 0x04) ? PIN_DIR_IN : PIN_DIR_OUT;
io_lut[j][i].th_dir[1] = (i & 0x08) ? PIN_DIR_IN : PIN_DIR_OUT;
if(j == 1)
{
/* Programmable output state (Export machines only) */
io_lut[j][i].tr_level[0] = (i & 0x01) ? PIN_LVL_HI : (i & 0x10) ? PIN_LVL_HI : PIN_LVL_LO;
io_lut[j][i].th_level[0] = (i & 0x02) ? PIN_LVL_HI : (i & 0x20) ? PIN_LVL_HI : PIN_LVL_LO;
io_lut[j][i].tr_level[1] = (i & 0x04) ? PIN_LVL_HI : (i & 0x40) ? PIN_LVL_HI : PIN_LVL_LO;
io_lut[j][i].th_level[1] = (i & 0x08) ? PIN_LVL_HI : (i & 0x80) ? PIN_LVL_HI : PIN_LVL_LO;
}
else
{
/* Fixed output state (Domestic machines only) */
io_lut[j][i].tr_level[0] = (i & 0x01) ? PIN_LVL_HI : PIN_LVL_LO;
io_lut[j][i].th_level[0] = (i & 0x02) ? PIN_LVL_HI : PIN_LVL_LO;
io_lut[j][i].tr_level[1] = (i & 0x04) ? PIN_LVL_HI : PIN_LVL_LO;
io_lut[j][i].th_level[1] = (i & 0x08) ? PIN_LVL_HI : PIN_LVL_LO;
}
}
}
// hack dos code doesn't call system_reset
pio_reset();
}
void pio_reset(void)
{
/* GG SIO power-on defaults */
sms.sio.pdr = 0x7F;
sms.sio.ddr = 0xFF;
sms.sio.txdata = 0x00;
sms.sio.rxdata = 0xFF;
sms.sio.sctrl = 0x00;
/* SMS I/O power-on defaults */
ioctrl_w(0xFF);
}
void pio_shutdown(void)
{
/* Nothing to do */
}
void system_assign_device(int port, int type)
{
sms.device[port].type = type;
}
void ioctrl_w(uint8 data)
{
sms.ioctrl = data;
io_current = &io_lut[sms.territory][data];
}
uint8 device_r(int offset)
{
uint8 temp = 0x7F;
switch(sms.device[offset].type)
{
case DEVICE_NONE:
break;
case DEVICE_PAD2B:
break;
case DEVICE_PADDLE:
break;
}
return temp;
}
uint8 input_r(int offset)
{
uint8 temp = 0xFF;
/*
If I/O chip is disabled, reads return last byte of instruction that
read the I/O port.
*/
if(sms.memctrl & 0x04)
return z80_read_unmapped();
offset &= 1;
if(offset == 0)
{
/* Input port #0 */
if(input.pad[0] & INPUT_UP) temp &= ~0x01; /* D0 */
if(input.pad[0] & INPUT_DOWN) temp &= ~0x02; /* D1 */
if(input.pad[0] & INPUT_LEFT) temp &= ~0x04; /* D2 */
if(input.pad[0] & INPUT_RIGHT) temp &= ~0x08; /* D3 */
if(input.pad[0] & INPUT_BUTTON2) temp &= ~0x10; /* TL */
if(input.pad[0] & INPUT_BUTTON1) temp &= ~0x20; /* TR */
if(sms.console == CONSOLE_GG)
{
uint8 state = sio_r(0x01);
temp = (temp & 0x3F) | (state & 0x03) << 6; /* Insert D1,D0 */
}
else
{
if(input.pad[1] & INPUT_UP) temp &= ~0x40; /* D0 */
if(input.pad[1] & INPUT_DOWN) temp &= ~0x80; /* D1 */
}
/* Adjust TR state if it is an output */
if(io_current->tr_dir[0] == PIN_DIR_OUT) {
temp &= ~0x20;
temp |= (io_current->tr_level[0] == PIN_LVL_HI) ? 0x20 : 0x00;
}
}
else
{
/* Input port #1 */
if(sms.console == CONSOLE_GG)
{
uint8 state = sio_r(0x01);
temp = (temp & 0xF0) | ((state & 0x3C) >> 2); /* Insert TR,TL,D3,D2 */
temp = (temp & 0x7F) | ((state & 0x40) << 1); /* Insert TH */
}
else
{
if(input.pad[1] & INPUT_LEFT) temp &= ~0x01; /* D2 */
if(input.pad[1] & INPUT_RIGHT) temp &= ~0x02; /* D3 */
if(input.pad[1] & INPUT_BUTTON2) temp &= ~0x04; /* TL */
if(input.pad[1] & INPUT_BUTTON1) temp &= ~0x08; /* TR */
/* Adjust TR state if it is an output */
if(io_current->tr_dir[1] == PIN_DIR_OUT) {
temp &= ~0x08;
temp |= (io_current->tr_level[1] == PIN_LVL_HI) ? 0x08 : 0x00;
}
/* Adjust TH state if it is an output */
if(io_current->th_dir[1] == PIN_DIR_OUT) {
temp &= ~0x80;
temp |= (io_current->th_level[1] == PIN_LVL_HI) ? 0x80 : 0x00;
}
if(input.system & INPUT_RESET) temp &= ~0x10;
}
/* /CONT fixed at '1' for SMS/SMS2/GG */
/* /CONT fixed at '0' for GEN/MD */
if(IS_MD) temp &= ~0x20;
/* Adjust TH state if it is an output */
if(io_current->th_dir[0] == PIN_DIR_OUT) {
temp &= ~0x40;
temp |= (io_current->th_level[0] == PIN_LVL_HI) ? 0x40 : 0x00;
}
}
return temp;
}
uint8 sio_r(int offset)
{
uint8 temp;
switch(offset & 0xFF)
{
case 0: /* Input port #2 */
temp = 0xE0;
if(input.system & INPUT_START) temp &= ~0x80;
if(sms.territory == TERRITORY_DOMESTIC) temp &= ~0x40;
if(sms.display == DISPLAY_NTSC) temp &= ~0x20;
return temp;
case 1: /* Parallel data register */
temp = 0x00;
temp |= (sms.sio.ddr & 0x01) ? 0x01 : (sms.sio.pdr & 0x01);
temp |= (sms.sio.ddr & 0x02) ? 0x02 : (sms.sio.pdr & 0x02);
temp |= (sms.sio.ddr & 0x04) ? 0x04 : (sms.sio.pdr & 0x04);
temp |= (sms.sio.ddr & 0x08) ? 0x08 : (sms.sio.pdr & 0x08);
temp |= (sms.sio.ddr & 0x10) ? 0x10 : (sms.sio.pdr & 0x10);
temp |= (sms.sio.ddr & 0x20) ? 0x20 : (sms.sio.pdr & 0x20);
temp |= (sms.sio.ddr & 0x40) ? 0x40 : (sms.sio.pdr & 0x40);
temp |= (sms.sio.pdr & 0x80);
return temp;
case 2: /* Data direction register and NMI enable */
return sms.sio.ddr;
case 3: /* Transmit data buffer */
return sms.sio.txdata;
case 4: /* Receive data buffer */
return sms.sio.rxdata;
case 5: /* Serial control */
return sms.sio.sctrl;
case 6: /* Stereo sound control */
return 0xFF;
}
/* Just to please compiler */
return -1;
}
void sio_w(int offset, int data)
{
switch(offset & 0xFF)
{
case 0: /* Input port #2 (read-only) */
return;
case 1: /* Parallel data register */
sms.sio.pdr = data;
return;
case 2: /* Data direction register and NMI enable */
sms.sio.ddr = data;
return;
case 3: /* Transmit data buffer */
sms.sio.txdata = data;
return;
case 4: /* Receive data buffer */
return;
case 5: /* Serial control */
sms.sio.sctrl = data & 0xF8;
return;
case 6: /* Stereo output control */
psg_stereo_w(data);
return;
}
}
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