Initial drop

Add some riscv code

Signed-off-by: Carlos Maiolino <[email protected]>

1 files changed, 60 insertions, 0 deletions

diff --git a/riscv/riscv-probe/libfemto/drivers/semihost.c b/riscv/riscv-probe/libfemto/drivers/semihost.c
new file mode 100644
index 0000000..9f47834
--- /dev/null
+++ b/riscv/riscv-probe/libfemto/drivers/semihost.c
@@ -0,0 +1,60 @@
+// See LICENSE for license details.
+
+#ifdef __riscv
+
+#include "femto.h"
+
+enum {
+    SBI_CONSOLE_PUTCHAR = 1,
+    SBI_CONSOLE_GETCHAR = 2,
+    SBI_SHUTDOWN = 8
+};
+
+#define __syscall(...) \
+    asm volatile ("ecall\n\t" : "+r"(a0) : __VA_ARGS__ : "memory")
+
+static inline long semihost_call0(long n)
+{
+    register long a7 __asm__("a7") = n;
+    register long a0 __asm__("a0");
+    __syscall("r"(a7));
+    return a0;
+}
+
+static inline long semihost_call1(long n, long a)
+{
+    register long a7 __asm__("a7") = n;
+    register long a0 __asm__("a0") = a;
+    __syscall("r"(a7), "0"(a0));
+    return a0;
+}
+
+static int semihost_getchar()
+{
+    semihost_call0(SBI_CONSOLE_GETCHAR);
+}
+
+static int semihost_putchar(int ch)
+{
+    semihost_call1(SBI_CONSOLE_PUTCHAR, ch);
+}
+
+static void semihost_poweroff(int status)
+{
+    semihost_call0(SBI_SHUTDOWN);
+    __builtin_unreachable();
+}
+
+console_device_t console_semihost = {
+    NULL,
+    semihost_getchar,
+    semihost_putchar
+};
+
+
+poweroff_device_t poweroff_semihost = {
+	NULL,
+	semihost_poweroff
+};
+
+#endif
\ No newline at end of file