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#include <reg52.h> /* special function register 8052 */
#include <rtx51tny.h> /* RTX-51 tiny functions & defines */
#define OLEN 8 /* size of serial transmission buffer */
unsigned char ostart; /* transmission buffer start index */
unsigned char oend; /* transmission buffer end index */
idata char outbuf[OLEN]; /* storage for transmission buffer */
unsigned char otask = 0xff; /* task number of output task */
#define ILEN 8 /* size of serial receiving buffer */
unsigned char istart; /* receiving buffer start index */
unsigned char iend; /* receiving buffer end index */
idata char inbuf[ILEN]; /* storage for receiving buffer */
unsigned char itask = 0xff; /* task number of output task */
#define CTRL_Q 0x11 /* Control+Q character code */
#define CTRL_S 0x13 /* Control+S character code */
bit sendfull; /* flag: marks transmit buffer full */
bit sendactive; /* flag: marks transmitter active */
bit sendstop; /* flag: marks XOFF character */
/******************************************************************************/
/* putbuf: write a character to SBUF or transmission buffer */
/******************************************************************************/
void putbuf (char c) {
if (!sendfull) { /* transmit only if buffer not full */
if (!sendactive && !sendstop) { /* if transmitter not active: */
sendactive = 1; /* transfer the first character direct */
SBUF = c; /* to SBUF to start transmission */
}
else { /* otherwize: */
outbuf[oend++ & (OLEN-1)] = c; /* transfer char to transmission buffer */
if (((oend ^ ostart) & (OLEN-1)) == 0) sendfull = 1;
} /* set flag if buffer is full */
}
}
/******************************************************************************/
/* putchar: interrupt controlled putchar function */
/******************************************************************************/
char putchar (char c) {
if (c == '\n') { /* expand new line character: */
while (sendfull) { /* wait for transmission buffer empty */
otask = os_running_task_id (); /* set output task number */
os_wait (K_SIG, 0, 0); /* RTX-51 call: wait for signal */
otask = 0xff; /* clear output task number */
}
putbuf (0x0D); /* send CR before LF for <new line> */
}
while (sendfull) { /* wait for transmission buffer empty */
otask = os_running_task_id (); /* set output task number */
os_wait (K_SIG, 0, 0); /* RTX-51 call: wait for signal */
otask = 0xff; /* clear output task number */
}
putbuf (c); /* send character */
return (c); /* return character: ANSI requirement */
}
/******************************************************************************/
/* _getkey: interrupt controlled _getkey */
/******************************************************************************/
char _getkey (void) {
while (iend == istart) {
itask = os_running_task_id (); /* set input task number */
os_wait (K_SIG, 0, 0); /* RTX-51 call: wait for signal */
itask = 0xff; /* clear input task number */
}
return (inbuf[istart++ & (ILEN-1)]);
}
/******************************************************************************/
/* serial: serial receiver / transmitter interrupt */
/******************************************************************************/
void serial (void) interrupt 4 using 2 { /* use registerbank 2 for interrupt */
unsigned char c;
bit start_trans = 0;
if (RI) { /* if receiver interrupt */
c = SBUF; /* read character */
RI = 0; /* clear interrupt request flag */
switch (c) { /* process character */
case CTRL_S:
sendstop = 1; /* if Control+S stop transmission */
break;
case CTRL_Q:
start_trans = sendstop; /* if Control+Q start transmission */
sendstop = 0;
break;
default: /* read all other characters into inbuf */
if (istart + ILEN != iend) {
inbuf[iend++ & (ILEN-1)] = c;
}
/* if task waiting: signal ready */
if (itask != 0xFF) isr_send_signal (itask);
break;
}
}
if (TI || start_trans) { /* if transmitter interrupt */
TI = 0; /* clear interrupt request flag */
if (ostart != oend) { /* if characters in buffer and */
if (!sendstop) { /* if not Control+S received */
SBUF = outbuf[ostart++ & (OLEN-1)]; /* transmit character */
sendfull = 0; /* clear 'sendfull' flag */
/* if task waiting: signal ready */
if (otask != 0xFF) isr_send_signal (otask);
}
}
else sendactive = 0; /* if all transmitted clear 'sendactive' */
}
}
/******************************************************************************/
/* serial_init: initialize serial interface */
/******************************************************************************/
void serial_init (void) {
SCON = 0x50; /* mode 1: 8-bit UART, enable receiver */
TMOD |= 0x20; /* timer 1 mode 2: 8-Bit reload */
TH1 = 0xf3; /* reload value 2400 baud */
TR1 = 1; /* timer 1 run */
ES = 1; /* enable serial port interrupt */
}
