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#include <kernel/arch/i386/tty/serial.h>
#include <stdint.h>
const int COM1 = 0x3f8;
// TODO move to some header file
inline void port_outb(uint16_t port, uint8_t val) {
asm volatile("outb %0, %1" : : "a" (val), "Nd" (port));
}
inline uint8_t port_inb(uint16_t port) {
uint8_t val;
asm volatile("inb %1, %0" : "=a" (val) : "Nd" (port));
return val;
}
void serial_init() {
// see https://www.sci.muni.cz/docs/pc/serport.txt
port_outb(COM1 + 1, 0x00); // disable interrupts, we won't be using them
// set baud rate divisor
port_outb(COM1 + 3, 0b10000000); // enable DLAB
port_outb(COM1 + 0, 0x01); // divisor = 1 (low byte)
port_outb(COM1 + 1, 0x00); // (high byte)
port_outb(COM1 + 3, 0b00000011); // 8 bits, no parity, one stop bit
port_outb(COM1 + 2, 0b11000111); // enable FIFO with 14-bit trigger level (???)
port_outb(COM1 + 4, 0b00001111); // enable everything in the MCR
/* the example on the OSDEV wiki does a selftest of the serial connection
* i don't really see the point as long as i'm not using it for input?
* if i start using serial for input, TODO selftest */
}
void serial_putchar(char c) {
while ((port_inb(COM1 + 5) & 0x20) == 0); // wait for THRE
port_outb(COM1, c);
}
void serial_write(const char *buf, size_t len) {
for (size_t i = 0; i < len; i++)
serial_putchar(buf[i]);
}
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