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Fix STPC serial unlocking behavior, add some more comments to the code

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This commit is contained in:
RichardG867
2020-07-20 15:24:51 -03:00
parent 31ca983604
commit a4cf2c7859
1 changed files with 11 additions and 9 deletions
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20
src/chipset/stpc.c
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@@ -719,8 +719,9 @@ stpc_reg_read(uint16_t addr, void *priv)
if (addr == 0x22)
ret = dev->reg_offset;
else if (dev->reg_offset >= 0xc0)
return 0xff; /* Cyrix CPU registers: let the CPU code handle those */
return 0xff; /* Cyrix CPU registers: let the CPU code handle these */
else if ((dev->reg_offset == 0x56) || (dev->reg_offset == 0x57)) {
/* ELCR is in here, not in port 4D0h. */
ret = elcr_read(dev->reg_offset, NULL);
if (dev->reg_offset == 0x57)
ret |= (dev->regs[dev->reg_offset] & 0x01);
@@ -743,7 +744,7 @@ stpc_reset(void *priv)
dev->regs[0x7b] = 0xff;
if (device_get_priv(&stpc_lpt_device))
dev->regs[0x4c] |= 0x80; /* LPT strap */
if (stpc_serial_handlers(0))
if (stpc_serial_handlers(0x00))
dev->regs[0x4c] |= 0x03; /* UART straps */
}
@@ -977,7 +978,7 @@ stpc_serial_init(const device_t *info)
dev->uart[0] = device_add_inst(&ns16550_device, 1);
dev->uart[1] = device_add_inst(&ns16550_device, 2);
/* Initialization is performed by stpc_reset. */
/* Initialization is performed by stpc_reset */
return dev;
}
@@ -1035,18 +1036,19 @@ stpc_lpt_write(uint16_t addr, uint8_t val, void *priv)
stpc_lpt_t *dev = (stpc_lpt_t *) priv;
if (dev->unlocked < 2) {
if (addr == 0x3f0) {
if (val == 0x55)
dev->unlocked++;
else
dev->unlocked = 0;
}
/* Cheat a little bit: in reality, any write to any
I/O port is supposed to reset the unlock counter. */
if ((addr == 0x3f0) && (val == 0x55))
dev->unlocked++;
else
dev->unlocked = 0;
} else if (addr == 0x3f0) {
if (val == 0xaa)
dev->unlocked = 0;
else
dev->offset = val;
} else if (dev->offset == 1) {
/* dev->reg1 is set by stpc_lpt_handlers */
stpc_lpt_handlers(dev, val);
} else if (dev->offset == 4) {
dev->reg4 = (val & 0x03);