Sync/kernel/serial.c

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/************************
*** Team Kitty, 2019 ***
*** Sync ***
***********************/
/* This file provides an interface to the serial port.
* Most emulators allow the serial port to be saved into
* a text buffer, or a file, but this code should work on
* hardware with an actual serial port and monitor. */
/* After the development of Syncboot, this becomes a little bit harder.
* Some testing will be needed to know for certain whether this will work.
* Until then, this is to be put on hold. 21/07/19 - Curle */
#include <kernel.h>
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#define SERIAL_DATA(base) (base)
#define SERIAL_DLAB(base) (base + 1)
#define SERIAL_FIFO(base) (base + 2)
#define SERIAL_LINE(base) (base + 3)
#define SERIAL_MODEM(base) (base + 4)
#define SERIAL_LINE_STATUS(base) (base + 5)
#define COM1 0x3F8
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/** serialSetBaudrate:
* 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 divisor The new divisor for the baud rate.
*/
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void serialSetBaudrate() {
WritePort(SERIAL_LINE(COM1), 0x80, 1);
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WritePort(SERIAL_DATA(COM1), 0x03, 1);
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WritePort(SERIAL_DLAB(COM1), 0x00, 1);
}
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/** serialConfigure:
* Sets a specific data byteset in the Serial hardware.
* Required for expected operation.
*/
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void serialConfigure() {
/* 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
*/
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WritePort(SERIAL_LINE(COM1), 0x03, 1);
}
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/** serialConfigureBuffers:
* 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.
*
*/
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void serialConfigureBuffers() {
/* 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
*/
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WritePort(SERIAL_FIFO(COM1), 0xC7, 1);
}
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/** serialConfigureModem:
*/
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void serialConfigureModem() {
/* 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
*/
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WritePort(SERIAL_MODEM(COM1), 0x03, 1);
}
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/** serialCheck:
* Checks whether the Transmit FIFO Queue is empty on the given port.
*
* @return 0 If the queue is not empty.
* 1 If the queue is empty.
*/
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int serialCheck() {
return ReadPort(SERIAL_LINE_STATUS(COM1), 1) & 0x20;
}
/** serial_write:
* Prints a single character to the serial port.
* Does nothing fancy.
* @param data The character to write.
*/
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void serialWrite(const char chr) {
//Hang until we have access to the COM port.
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while(!serialCheck());
WritePort(COM1, chr, 1);
}
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/** serialPrint:
* Prints a string to the serial port.
* Does not support ANSI codes, or color.
*
* @param data The string to write.
*/
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void serialPrint(const char* data) {
for(size_t i = 0; i < strlen(data); i++) {
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serialWrite(data[i]);
}
}
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/** serialPrintf:
* A printf-style function for the serial port.
*
* @param format The base string - used to substitute the succeding values.
* @param ... The substitutions.
*/
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void serialPrintf(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);
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inttoa(storage, stringstore);
serialPrint(stringstore);
zeroString(stringstore);
i += 2;
} else if(format[i+1] == 'x') {
storage = va_arg(list, int);
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itoh(storage, stringstore);
serialPrint(stringstore);
zeroString(stringstore);
i += 2;
} else if(format[i+1] == 's') {
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serialPrint(va_arg(list, char*));
i += 2;
} else {
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serialPrint("ERROR: Attempting to parse unknown format string.");
return;
}
} else {
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serialWrite(format[i]);
i++;
}
}
va_end(list); //Free the list
}
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void serialInit() {
// Disable interrupts
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WritePort(SERIAL_DLAB(COM1), 0x00, 1);
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// Set baud rate divisor to 3
serialSetBaudrate();
// 8 bits, no parity, one stop bit.
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serialConfigure();
// Enable FIFO and clear buffers.
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serialConfigureBuffers();
// Enable IRQs, RTS/DSR set.
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serialConfigureModem();
}