automate P256 integration

2 files changed, 12 insertions, 0 deletions

diff --git a/liblow/cmovznz.c b/liblow/cmovznz.c
new file mode 100644
index 000000000..8533ade99
--- /dev/null
+++ b/liblow/cmovznz.c
@@ -0,0 +1,10 @@
+#include <stdint.h>
+#include "liblow.h"
+uint64_t cmovznz(uint64_t t, uint64_t z, uint64_t nz) {
+  asm ("testq %1, %1;" "\n"
+  "\t" "cmovnzq %3, %0;"
+      :"=r"(z)
+      :"r"(t), "0"(z), "r"(nz)
+      );
+  return z;
+}
diff --git a/liblow/liblow.h b/liblow/liblow.h
new file mode 100644
index 000000000..a8af0f52f
--- /dev/null
+++ b/liblow/liblow.h
@@ -0,0 +1,2 @@
+#include <stdint.h>
+uint64_t cmovznz(uint64_t t, uint64_t z, uint64_t nz);