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#include <asm/interrupt.h>
#include <errno.h>
#include <kernel/sched.h>
#include <kernel/serial.h>
#include <kernel/tty.h>
#include <limits.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>
#define NRTTY \
(sizeof(ttys) / sizeof(struct tty_struct*))
static struct tty_struct *ttys[] = {
NULL,
&tty_rs
};
/* check if a buffer's empty and if so, go to sleep */
static int sleep_while_empty(struct tty_queue *q) {
cli();
while(1) {
if(q->pread == q->pwrite)
interruptible_sleep_on(&q->waiting);
/* check again to see if anything was read, or we were interrupted */
if(q->pread == q->pwrite) {
sti();
return -1;
}
sti();
return 0;
}
}
/* check if a buffer's full and if so, go to sleep */
static int sleep_while_full(struct tty_queue *q, struct tty_struct *tty) {
cli();
while(1) {
/*
* if the buffer is full, first notify the
* driver so it can try to remove some
* data then, check again and if it's
* still full, go to sleep.
*/
if(q->pwrite == ((q->pread - 1) % sizeof(q->buf)))
if(tty->write)
tty->write();
if(q->pwrite == ((q->pread - 1) % sizeof(q->buf)))
interruptible_sleep_on(&q->waiting);
/* check again to see if anything was removed, or we were interrupted */
if(q->pwrite == ((q->pread - 1) % sizeof(q->buf))) {
sti();
return -1;
}
sti();
return 0;
}
}
ssize_t tty_read(unsigned tty, void *buf, size_t len) {
size_t i;
char *b = buf;
struct tty_queue *q = &ttys[tty]->rqueue;
if(tty > NRTTY || ttys[tty] == NULL)
return -1;
if(len == 0)
return 0;
if(len > SSIZE_MAX)
len = SSIZE_MAX;
for(i = 0; i < len; i++) {
/* check if the buffer's empty and if so, go to sleep */
if(sleep_while_empty(q) < 0) {
if(i == 0)
return -EINTR;
return i;
}
*b++ = q->buf[q->pread];
q->pread = (q->pread + 1) % TTY_BUF_SIZE;
}
return len;
}
ssize_t tty_write(unsigned tty, void *buf, size_t len) {
size_t i;
char *b = buf;
struct tty_queue *q = &ttys[tty]->wqueue;
if(tty > NRTTY || ttys[tty] == NULL)
return -1;
if(len == 0)
return 0;
if(len > SSIZE_MAX)
len = SSIZE_MAX;
for(i = 0; i < len; i++) {
/* check if the buffer's full and if so, go to sleep */
if(sleep_while_full(q, ttys[tty]) < 0) {
if(i == 0)
return -EINTR;
return i;
}
q->buf[q->pwrite] = *b++;
q->pwrite = (q->pwrite + 1) % TTY_BUF_SIZE;
}
/* tell the driver that new data is available */
cli();
if(ttys[tty]->write)
ttys[tty]->write();
sti();
return len;
}
void tty_init(void) {
int i;
for(i = 0; i < NRTTY; i++) {
if(!ttys[i])
continue;
memset(&ttys[i]->rqueue, 0, sizeof(struct tty_queue));
memset(&ttys[i]->wqueue, 0, sizeof(struct tty_queue));
if(ttys[i]->init)
ttys[i]->init();
}
}
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