void main() {
void interrupt ( * old_dos9h ) () ; /* points at DOS keyboard
interrupt service routine */
void interrupt ( * old_dos62 ) () ; /* previous int 62h handler */
void interrupt ( * old_dos63 ) () ; /* previous int 63h handler */
int id , /* ID of init process */
dosint , /* Interrupt flag upon entry */
count ; /* init process's argc */
char * argument[10] ; /* pointer to a maximum of 10 arguments */
Init_malloc (); /* Activate the safe memory management routines */
/* Init_malloc() uses malloc() which requires */
/* interrupts to be enabled */
/* Initialization */
dosint = Mod_int ( INT_DISABLE ) ; /* Disable all interrupts */
readyq = Q_create () ; /* Create a queue for ready processes */
keyboard_buff_ptr = Q_create () ; /* Create a queue for the keyboard */
old_dos9h = getvect ( 0x9 ) ; /* Preserve dos ISR's */
old_dos62 = getvect ( 0x62 ) ;
old_dos63 = getvect ( 0x63 ) ;
setvect ( 0x9 , Key_handler ); /* redirect Keyboard ISR from DOS to keyhand */
setvect ( 0x62, System_service ) ; /* Set kernel ISR */
setvect ( 0x63 , Yield_process ) ; /* Set defer ISR */
Init_screen () ;
/* main loop */
Cprintf ("\nThis is the main procedure\n");
Cprintf ("Now I will init as a child processes\n") ;
count = 3 ;
argument [0] = "Init" ;
argument [1] = "init 1st parameter" ;
argument [2] = "init 2nd parameter" ;
id = Proc_start ( Init , count , argument ) ;
Cprintf ("Process init has been created with ID = %2d\n" , id ) ;
Cprintf ("Now, main() is going to call scheduler() \n") ;
Scheduler() ;
/* Clean-up */
Cprintf("\nNo more processes , I will finish up and exit OS\n");
Q_destroy ( readyq ) ;
Q_destroy ( keyboard_buff_ptr ) ;
Free_malloc () ; /* dactivate the safe memory management routines */
setvect ( 0x9 , old_dos9h ) ; /* Return to DOS keyboard driver */
setvect ( 0x62, old_dos62 ) ;
setvect ( 0x63, old_dos63 ) ;
Mod_int ( dosint ) ; /* restore interrupt flag */
_AX = 0x100 ; /* restore hardware cursor */
_CX = 0xD0E ;
geninterrupt ( 0x10 ) ;
} /* end of main() */
/*
* Serial_open
*
* Serial_open configures the specified serial port (USART) for operation according the specified baud rate and configuration.
* It uses Queue functions to allocate a QCB to manage transmit and receive buffers. It initializes the interface between the
* ISRs (RXC and UDRE) and the queues for the port by initializing the QCB "handles" to be used by the ISRs. The RXCx interrupt is enabled.
* Serial_open returns 0 for success and -1 if an error occurs (e.g., bad port ID, baud rate, frame parameters or invalid buffer sizes).
*
* @param int port - specifies USART 0, 1, 2 or 3. For right now, 0 is the only one active.
* @param long speed - baud rate
* @param constant that specifies framing parameters (data bits, parity, stop bits)
* @return returns 0 for success and -1 if an error occurs
*/
int Serial_open(int port, long speed, int config)
{
if (port < 0 || port > 3)
{
return -1;
}
//Creates a Rqueue forRX and TX
ports[port].rx_qid = Q_create(ports[port].rx_bufsize, ports[port].rx_buffer);
ports[port].tx_qid = Q_create(ports[port].tx_bufsize, ports[port].tx_buffer);
//Sets U2X0 to 1 for lowest error rate
regs[port]->ucsra |= (1<<U2X0); //Changed made here
long reg_set = -1;
switch(speed)
{
case 2400:
reg_set = 832;
break;
case 4800:
reg_set = 416;
break;
case 9600:
reg_set = 207;
break;
case 14400:
reg_set = 138;
break;
case 19200:
reg_set = 103;
break;
case 28800:
reg_set = 68;
break;
case 38400L:
reg_set = 51;
break;
case 57600L:
reg_set = 34;
break;
case 76800L:
reg_set = 25;
break;
case 115200L:
reg_set = 16;
break;
case 230400L:
reg_set = 8;
break;
case 250000L:
reg_set = 7;
break;
}
//Protects from interrupts
ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
{
regs[port]->ubrr = reg_set; //Sets the baud rate
regs[port]->ucsrc = config; //Sets the data frame structure
regs[port]->ucsrb = (1<<RXEN0) | (1<<TXEN0) | (1<<RXCIE0); //Enables RX, TX, and RX interrupt
}
sei(); //Enables global interrupts
return 0;
}
