qemu: signal correct exit code to QEMU

There were a few issues that were causing qemu-system-arm and
qemu-system-riscv to give the wrong exit codes. They are in fact capable
of exiting with 0 or 1 signalled from the running application, but this
functionality wasn't used. This commit changes this in the following
ways:

  * It fixes SemiHosting codes, which were incorrectly written in
    decimal while they should have been written in hexadecimal (oops!).
  * It modifies all the baremetal main functions (aka reset handlers) to
    exit with `exit(0)` instead of `abort()`.
  * It changes `syscall.Exit` to call `exit(code)` instead of `abort()`
    on baremetal targets.
  * It adds these new exit functions where necessary, implemented in a
    way that signals the correct exit status if running under QEMU.

All in all, this means that `tinygo test` doesn't have to look at the
output of a test to determine the outcome. It can simply look at the
exit code.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/runtime/runtime_mimxrt1062.go b/src/runtime/runtime_mimxrt1062.go
index a9cc063df..6c1212cba 100644
--- a/src/runtime/runtime_mimxrt1062.go
+++ b/src/runtime/runtime_mimxrt1062.go
@@ -43,7 +43,7 @@ func main() {
 	arm.EnableInterrupts(irq)
 
 	run()
-	abort()
+	exit(0)
 }
 
 func getRamSizeConfig(itcmKB, dtcmKB uint32) uint32 {
@@ -127,6 +127,10 @@ func putchar(c byte) {
 	machine.UART1.WriteByte(c)
 }
 
+func exit(code int) {
+	abort()
+}
+
 func abort() {
 	for {
 		arm.Asm("wfe")