HP 34401A, User Manual

Page: 195 / 236

void interrupt int_char_in(void)
{
enable(); /* Enable hardware interrupts */
if(int_buf_count < INT_BUF_size) {
*int+ = inportb(RDR); /* Read byte from UART */
int_bu+;
if(int_buf_in >= i INT_BUF_size) int_buf_in = int_buf;
int_buf_ovfl = 0;
}
else {
inportb(RDR); /* Clear UART interrupt */
int_buf_ovfl = 1;
}
outportb(INT_controller,End_of_interrupt); /* Non-specific EOI */
}
void send_ctlc(void)
{
outportb(MCR,0x8); /* De-assert DTR */
delay(10); /* Wait 10 mS for stray characters */
while(!(inportb(LSR) & 0x20)) ; /* Wait on transmitter register */
outportb(THR,0x3); /* Send ^C */
while(!(inportb(LSR) & 0x40)) ; /* Wait for ^C to be sent */
int_buf_in = int_buf_out = int_buf; /* Clear int_char_in buffer */
int_buf_count = int_buf_ovfl = 0;
delay(20); /* 20mS for HP 34401 to clean up */
outportb(MCR,0x9); /* Assert DTR */
}
RS-232 Operation Using Turbo C (continued)
Chapter 6 Application Programs
RS-232 Operation Using Turbo C
196