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#include "uart_16550.h"
#include <stddef.h>
int
uart_thre(enum UART port)
{
return inb(port + LineStatus) & THRE;
}
void
uart_putc(const FILE *self, char a)
{
while (uart_thre((enum UART)self->id) == 0) {}
outb(a, self->id);
if (a == '\n') {
while (uart_thre((enum UART)self->id) == 0) {}
outb('\r', self->id);
}
}
int
uart_puts(const FILE *self, const char *string, int length)
{
int written = 0;
if (length == -1)
while (*string != '\0') {
uart_putc(self, *string);
++string;
++written;
}
else
for (int i = 0; i < length; ++i) {
uart_putc(self, string[i]);
++written;
}
return written;
}
void
uart_flush(__attribute__((unused)) const FILE *self)
{
}
FILE uart_stream;
FILE *
uart_init(enum UART port)
{
outb(0x00, port + 1); // Disable all interrupts
outb(0x80, port + 3); // Enable DLAB (set baud rate divisor)
outb(0x03, port + 0); // Set divisor to 3 (lo byte) 38400 baud
outb(0x00, port + 1); // (hi byte)
outb(0x03, port + 3); // 8 bits, no parity, one stop bit
outb(0xc7, port + 2); // Enable FIFO, clear them, with 14-byte threshold
outb(0x0b, port + 4); // IRQs enabled, RTS/DSR set
outb(0x1e, port + 4); // Set in loopback mode, test the serial chip
outb(0xae, port + 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 (inb(port + 0) != 0xae) { return NULL; }
// If serial is not faulty set it in normal operation mode
// (not-loopback with IRQs enabled and OUT#1 and OUT#2 bits enabled)
outb(0x0f, port + 4);
uart_stream.id = port;
uart_stream.putc = &uart_putc;
uart_stream.puts = &uart_puts;
uart_stream.flush = &uart_flush;
return &uart_stream;
}
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