libthread: use consistent stack calculation code in makecontext

Also reduce duplication: makecontext is per-arch not per-os-arch.

May fix #353.

1 files changed, 24 insertions, 0 deletions

diff --git a/src/libthread/arm-ucontext.c b/src/libthread/arm-ucontext.c
new file mode 100644
index 00000000..512ca973
--- /dev/null
+++ b/src/libthread/arm-ucontext.c
@@ -0,0 +1,24 @@
+#include "threadimpl.h"
+
+void
+makecontext(ucontext_t *uc, void (*fn)(void), int argc, ...)
+{
+	int i, *sp;
+	va_list arg;
+
+	sp = USPALIGN(uc, 4);
+	va_start(arg, argc);
+	for(i=0; i<4 && i<argc; i++)
+		(&uc->uc_mcontext.arm_r0)[i] = va_arg(arg, uint);
+	va_end(arg);
+	uc->uc_mcontext.arm_sp = (uint)sp;
+	uc->uc_mcontext.arm_lr = (uint)fn;
+}
+
+int
+swapcontext(ucontext_t *oucp, const ucontext_t *ucp)
+{
+	if(getcontext(oucp) == 0)
+		setcontext(ucp);
+	return 0;
+}