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#include "uart.hpp"
#include <sys/io.hpp>
template <UART port> struct Uart16550 : public kIoDevice, private Port<unsigned short, port> {
using Base = Port<unsigned short, port>;
using Ports = UART;
using PortOffset = UARTPortOffset;
// Line Control
// | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
// |dla| | parity | s | data |
enum LineControl : unsigned char {
d5bit = 0x00, // 0000 0000 data bits
d6bit = 0x01, // 0000 0001
d7bit = 0x02, // 0000 0010
d8bit = 0x03, // 0000 0011
none = 0x00, // 0000 0000 parity bits
odd = 0x08, // 0000 1000
even = 0x18, // 0001 1000
mark = 0x28, // 0010 1000
space = 0x38, // 0011 1000
s1bit = 0x00, // 0000 0000 stop bits
s2bit = 0x04, // 0000 0100 1.5 for 5bit data; 2 otherwise
dlab = 0x80 // 1000 0000 divisor latch access bit
};
// Line Status Register
enum LineStatus : unsigned char {
DR = (1 << 0), // data ready: see if there is data to read
OE = (1 << 1), // overrun error: see if there has been data lost
PE = (1 << 2), // parity error: see if there was error in transmission
FE = (1 << 3), // framing error: see if a stop bit was missing
BI = (1 << 4), // break indicator: see if there is a break in data input
THRE = (1 << 5), // transmitter holding register empty: see if transmission buffer is empty
TEMT = (1 << 6), // transmitter empty: see if transmitter is not doing anything
ERRO = (1 << 7), // impending error: see if there is an error with a word in the input buffer
};
[[nodiscard]] static bool
test()
{
Base::out(0x00, 1); // Disable all interrupts
Base::out(0x80, 3); // Enable DLAB (set baud rate divisor)
Base::out(0x03, 0); // Set divisor to 3 (lo byte) 38400 baud
Base::out(0x00, 1); // (hi byte)
Base::out(0x03, 3); // 8 bits, no parity, one stop bit
Base::out(0xc7, 2); // Enable FIFO, clear them, with 14-byte threshold
Base::out(0x0b, 4); // IRQs enabled, RTS/DSR set
Base::out(0x1e, 4); // Set in loopback mode, test the serial chip
Base::out(0xae, 0); // Test serial chip (send byte 0xAE and check if serial
// returns same byte)
// Check if serial is faulty (i.e: not same byte as sent)
if (Base::in() != 0xae) { return false; }
// If serial is not faulty set it in normal operation mode
// (not-loopback with IRQs enabled and OUT#1 and OUT#2 bits enabled)
Base::out(0x0f, 4);
return true;
}
[[nodiscard]] static bool
thre()
{
return Base::in(PortOffset::LineStatus)&THRE;
}
void
putc(char a) override
{
while (!thre()) {}
Base::out(a);
if (a == '\n') putc('\r');
}
int
puts(const char *string, int length) override
{
int written = 0;
if (length == -1)
while (*string != '\0') {
putc(*string);
++string;
++written;
}
else {
for (int i = 0; i < length; ++i) putc(string[i]);
written += length;
}
return written;
}
void
flush() override
{
}
};
static_assert(sizeof(Uart16550<COM1>) == sizeof(void *));
template <>
FILE *
uart_init<COM1>()
{
static Uart16550<COM1> device;
return &device;
}
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