Fix sbi_console_getchar return value if no UART is present

The UART drivers all return -1 if no character is present, and so that's
what we should do if there's no UART at all.

See discussion on https://github.com/riscv-non-isa/riscv-sbi-doc/issues/82

1 files changed, 1 insertions, 1 deletions

diff --git a/machine/mtrap.c b/machine/mtrap.c
index dcff050..3cea874 100644
--- a/machine/mtrap.c
+++ b/machine/mtrap.c
@@ -77,7 +77,7 @@ static uintptr_t mcall_console_getchar()
   } else if (htif) {
     return htif_console_getchar();
   } else {
-    return '\0';
+    return (uintptr_t)-1;
   }
 }