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// See LICENSE for license details.
#ifdef __riscv
#include "femto.h"
#include "spinlock.h"
struct { uint32_t arr[2]; } volatile tohost __attribute__((section(".htif")));
struct { uint32_t arr[2]; } volatile fromhost __attribute__((section(".htif")));
static spinlock_t htif_lock = SPINLOCK_INIT;
static inline void htif_send(uint8_t dev, uint8_t cmd, int64_t data)
{
/* endian neutral encoding with ordered 32-bit writes */
union { uint32_t arr[2]; uint64_t val; } encode = {
.val = (uint64_t)dev << 56 | (uint64_t)cmd << 48 | data
};
tohost.arr[0] = encode.arr[0];
tohost.arr[1] = encode.arr[1];
}
static inline void htif_recv(uint8_t *dev, uint8_t *cmd, int64_t *data)
{
/* endian neutral decoding with ordered 32-bit reads */
union { uint32_t arr[2]; uint64_t val; } decode;
decode.arr[0] = fromhost.arr[0];
decode.arr[1] = fromhost.arr[1];
*dev = decode.val >> 56;
*cmd = (decode.val >> 48) & 0xff;
*data = decode.val << 16 >> 16;
}
static int64_t htif_get_fromhost(uint8_t dev, uint8_t cmd)
{
/* receive data for specified device and command */
uint8_t rdev, rcmd;
int64_t data;
htif_recv(&rdev, &rcmd, &data);
return rdev == dev && rcmd == cmd ? data : -1;
}
static void htif_set_tohost(uint8_t dev, uint8_t cmd, int64_t data)
{
/* send data with specified device and command */
while (tohost.arr[0]) {
asm volatile ("" : : "r" (fromhost.arr[0]));
asm volatile ("" : : "r" (fromhost.arr[1]));
}
htif_send(dev, cmd, data);
}
static int htif_getchar()
{
int ch;
spinlock_lock(&htif_lock);
if ((ch = htif_get_fromhost(1, 0) & 0xff)) {
htif_set_tohost(1, 0, 0);
}
spinlock_unlock(&htif_lock);
return ch;
}
static int htif_putchar(int ch)
{
spinlock_lock(&htif_lock);
htif_set_tohost(1, 1, ch & 0xff);
spinlock_unlock(&htif_lock);
return ch & 0xff;
}
static void htif_poweroff(int status)
{
for (;;) {
htif_set_tohost(0, 0, 1);
}
}
console_device_t console_htif = {
NULL,
htif_getchar,
htif_putchar
};
poweroff_device_t poweroff_htif = {
NULL,
htif_poweroff
};
#endif
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