Implement Serial Console messaging.

Intended to be used for debugging, but it's useful.
This commit is contained in:
Jenny Curle 2019-04-07 15:34:15 +01:00
parent 245d09b056
commit e4fcbb20b4
8 changed files with 295 additions and 14 deletions

19
include/kernel/serial.h Executable file
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@ -0,0 +1,19 @@
#pragma once
extern void init_serial();
extern void serial_set_baud_rate(uint16_t, uint16_t);
extern void serial_configure_line(uint16_t);
extern void serial_configure_buffers(uint16_t);
extern void serial_write(uint16_t, const char);
extern void serial_configure_modem(uint16_t);
extern int serial_check_tqueue(uint16_t);
extern void serial_print(uint16_t, const char*);
extern void serial_printf(const char*, ...);

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@ -25,8 +25,5 @@ void puts(const char*);
void handleControlSequence(struct csi_sequence);
void set_cursor(int, int);
void term_scroll(bool);
void int_to_ascii(int, char*);
void int_to_hex(int, char*);
void empty_string(char*);
bool isDigit(char c);

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@ -13,3 +13,9 @@ void outb(unsigned short, unsigned char);
void memcpy(void*, void*, size_t);
void memset(void*, int, size_t);
void int_to_ascii(int, char*);
void int_to_hex(int, char*);
void empty_string(char*);

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@ -30,13 +30,13 @@ void gdt_set_gate(int num, unsigned long base,
gdt[num].low_limit = (limit & 0xFFFF);
gdt[num].granular = ((limit >> 16) & 0x0F);
gdt[num].granular != (gran & 0xF0);
gdt[num].granular = (gran & 0xF0);
gdt[num].access = access;
}
void gdt_install() {
gp.limit = (sizeof(struct gdt_item) * 3) - 1;
gp.base = &gdt;
gp.base = (unsigned int)&gdt;
gdt_set_gate(0, 0, 0, 0, 0); //NULL item

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@ -3,15 +3,20 @@
#include <kernel/tty.h>
#include <kernel/gdt.h>
#include <kernel/serial.h>
int kernel_main(void) {
//Prepare the GDT
gdt_install();
//Prepare interrupts
//idt_install();
//Prepare the screen, and blank it out.
// Prepare the screen, and blank it out.
screen_initialize();
// Prepare the serial console.
init_serial();
serial_print(0x3F8, "[INFO] Serial ready.");
// Prepare the GDT
//gdt_install();
// Prepare interrupts
//idt_install();
//Print a copyright message.
term_writes("(c)");
term_setcolor(GREEN);

184
kernel/serial.c Executable file
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@ -0,0 +1,184 @@
#include <kernel/utils.h>
#include <stdarg.h>
#include <stdint.h>
#include <stddef.h>
#define SERIAL_DATA_PORT(base) (base)
#define SERIAL_FIFO_COMMAND_PORT(base) (base + 2)
#define SERIAL_LINE_COMMAND_PORT(base) (base + 3)
#define SERIAL_MODEM_COMMAND_PORT(base) (base + 4)
#define SERIAL_LINE_STATUS_PORT(base) (base + 5)
#define SERIAL_COM1_BASE 0x3F8
#define SERIAL_LINE_ENABLE_DLAB 0x80
/** serial_set_baud_rate:
* Sets the speed that data is sent via the serial port.
* The default speed is 115200 bits/s.
* The argument given is the divisor of the number.
* Hence, the new speed becomes (115200/divisor) bits/s.
*
* @param com The COM port to configure.
* @param divisor The new divisor for the baud rate.
*/
void serial_set_baud_rate(uint16_t com, uint16_t divisor) {
outb(SERIAL_LINE_COMMAND_PORT(com),
SERIAL_LINE_ENABLE_DLAB);
outb(SERIAL_DATA_PORT(com),
(divisor >> 8) & 0x00FF);
outb(SERIAL_DATA_PORT(com),
divisor & 0x00FF);
}
/** serial_configure_line:
* Sets a specific data byteset in the Serial hardware.
* Required for expected operation.
*
* @param com The COM port to configure.
*/
void serial_configure_line(uint16_t com) {
/* Bit: | 7 | 6 | 5 4 3 | 2 | 1 0 |
* Content: | d | b | parity| s | dl |
* Value: | 0 | 0 | 0 0 0 | 0 | 1 1 | = 0x03
*/
outb(SERIAL_LINE_COMMAND_PORT(com), 0x0B);
}
/** serial_configure_buffers:
* Enables FIFO (First In First Out) on the Serial line.
* It clears both the receive and transmit queues.
* It uses a 14 byte wide queue.
*
* @param com The COM port to configure.
*/
void serial_configure_buffers(uint16_t com) {
/* Bit: | 7 6 | 5 | 4 | 3 | 2 | 1 | 0 |
* Content: | 1v1 | bs | r | dma | clt | clr | e |
* Value: | 1 1 | 0 | 0 | 0 | 1 | 1 | 1 | = 0xC7
*/
outb(SERIAL_FIFO_COMMAND_PORT(com), 0xC7);
}
/** serial_configure_modem
* @param com The COM port to configure.
*/
void serial_configure_modem(uint16_t com) {
/* Bit: | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
* Content: | r | r | af | lb | ao2 | ao1 | rts | dtr |
* Value: | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | = 0x03
*/
outb(SERIAL_MODEM_COMMAND_PORT(com), 0x3);
}
/** serial_check_tqueue:
* Checks whether the Transmit FIFO Queue is empty on the given port.
*
* @param com The COM port to check.
* @return 0 If the queue is not empty.
* 1 If the queue is empty.
*/
int serial_check_tqueue(uint16_t com) {
return inb(SERIAL_LINE_STATUS_PORT(com)) & 0x20;
}
/** serial_write:
* Prints a single character to the serial port.
* Does nothing fancy.
* @param com The COM port to write to.
* @param data The character to write.
*/
void serial_write(uint16_t com, const char chr) {
//Hang until we have access to the COM port.
while(serial_check_tqueue(com) == 0);
outb(com, chr);
}
/** serial_print:
* Prints a string to the serial port.
* Does not support ANSI codes, or color.
*
* @param com The COM port to write to.
* @param data The string to write.
*/
void serial_print(uint16_t com, const char* data) {
for(size_t i = 0; i < strlen(data); i++) {
serial_write(com, data[i]);
}
}
/** serial_printf:
* A printf-style function for the serial port.
*
* @param format The base string - used to substitute the succeding values.
* @param ... The substitutions.
*/
void serial_printf(uint16_t com, const char* format, ...) {
uint32_t storage; //To hold temporary variables
char stringstore[10] = {0}; //To convert ints to strings.
va_list list;
va_start(list, format);
for(size_t i = 0; i < strlen(format); i++) {
//Check for the format specifier
if(format[i] == '%') {
//Check for the other specs
if(format[i+1] == 'd') {
storage = va_arg(list, int);
int_to_ascii(storage, stringstore);
serial_print(com, stringstore);
empty_string(stringstore);
i += 2;
} else if(format[i+1] == 'x') {
storage = va_arg(list, int);
int_to_hex(storage, stringstore);
serial_print(com, stringstore);
empty_string(stringstore);
i += 2;
} else if(format[i+1] == 's') {
serial_print(com, va_arg(list, char*));
i += 2;
} else {
serial_print(com, "ERROR: Attempting to parse unknown format string.");
return;
}
} else {
serial_write(com, format[i]);
i++;
}
}
va_end(list); //Free the list
}
void init_serial() {
// Disable interrupts
outb(SERIAL_COM1_BASE + 1, 0x00);
// Set baud rate divisor.
serial_set_baud_rate(SERIAL_COM1_BASE, 3);
// 8 bits, no parity, one stop bit.
serial_configure_line(SERIAL_COM1_BASE);
// Enable FIFO and clear buffers.
serial_configure_buffers(SERIAL_COM1_BASE);
// Enable IRQs, RTS/DSR set.
serial_configure_modem(SERIAL_COM1_BASE);
}

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@ -1,4 +1,7 @@
#include <kernel/utils.h>
#include <stddef.h>
#include <stdint.h>
#include <stdbool.h>
#include <stddef.h>
size_t strlen(const char* string) {
@ -33,3 +36,69 @@ void memset(void* src, int chr, size_t n) {
*ptr++ = (unsigned char) chr;
}
}
void int_to_ascii(int num, char* string) {
size_t i = 0; //Counter.
//TODO: Convert this to a for-loop?
int32_t calc = 0;
bool negative = false;
if(num == 0) {
string[0] = '0';
string[1] = '\0';
return;
}
if(num < 0) {
negative = true;
num = -num;
}
while(num != 0) {
calc = num % 10;
num = num / 10;
calc += 48;
string[i] = calc;
i++;
}
if(negative) {
string[i] = '-';
i++;
}
for(size_t j = 0; j < i/2; j++) {
calc = string[j];
string[j] = string[i-j-1];
string[j-i-1] = calc;
}
}
void int_to_hex(int num, char* string) {
empty_string(string);
uint8_t i = 8;
uint8_t temp = 0;
while(i != 0) {
i--;
temp = num & 0xF;
num = num >> 4;
if(temp >= 10) {
temp += 7;
}
temp += 48;
string[i] = temp;
}
}
void empty_string(char* string) {
size_t len = strlen(string);
for(size_t i = 0; i < len + 1; i++) {
string[i] = '\0';
}
}

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@ -30,6 +30,7 @@ LIBS:=$(LIBS) $(KERNEL_ARCH_LIBS)
KERNEL_OBJS= \
$(KERNEL_ARCH_OBJS) \
kernel/utils.o \
kernel/serial.o \
kernel/gdt.o \
kernel/idt.o \
kernel/kernel.o