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#include "htif.h"
#include "atomic.h"
#include "mtrap.h"
volatile uint64_t tohost __attribute__((section(".htif")));
volatile uint64_t fromhost __attribute__((section(".htif")));
volatile int htif_console_buf;
static spinlock_t htif_lock = SPINLOCK_INIT;
static void __check_fromhost()
{
uint64_t fh = fromhost;
if (!fh)
return;
fromhost = 0;
// this should be from the console
assert(FROMHOST_DEV(fh) == 1);
switch (FROMHOST_CMD(fh)) {
case 0:
htif_console_buf = 1 + (uint8_t)FROMHOST_DATA(fh);
break;
case 1:
break;
default:
assert(0);
}
}
static void __set_tohost(uintptr_t dev, uintptr_t cmd, uintptr_t data)
{
while (tohost)
__check_fromhost();
tohost = TOHOST_CMD(dev, cmd, data);
}
int htif_console_getchar()
{
spinlock_lock(&htif_lock);
__check_fromhost();
int ch = htif_console_buf;
if (ch >= 0) {
htif_console_buf = -1;
__set_tohost(1, 0, 0);
}
spinlock_unlock(&htif_lock);
return ch - 1;
}
static void do_tohost_fromhost(uintptr_t dev, uintptr_t cmd, uintptr_t data)
{
spinlock_lock(&htif_lock);
__set_tohost(dev, cmd, data);
while (1) {
uint64_t fh = fromhost;
if (fh) {
if (FROMHOST_DEV(fh) == dev && FROMHOST_CMD(fh) == cmd) {
fromhost = 0;
break;
}
__check_fromhost();
}
}
spinlock_unlock(&htif_lock);
}
void htif_syscall(uintptr_t arg)
{
do_tohost_fromhost(0, 0, arg);
}
void htif_console_putchar(uint8_t ch)
{
spinlock_lock(&htif_lock);
__set_tohost(1, 1, ch);
spinlock_unlock(&htif_lock);
}
void htif_poweroff()
{
while (1) {
fromhost = 0;
tohost = 1;
}
}
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