Provide optimised bn_addw() for riscv64.

1 files changed, 18 insertions, 1 deletions

diff --git a/src/lib/libcrypto/bn/arch/riscv64/bn_arch.h b/src/lib/libcrypto/bn/arch/riscv64/bn_arch.h
index 66256acad0..a8c50eb06d 100644
--- a/src/lib/libcrypto/bn/arch/riscv64/bn_arch.h
+++ b/src/lib/libcrypto/bn/arch/riscv64/bn_arch.h
@@ -1,4 +1,4 @@
-/*      $OpenBSD: bn_arch.h,v 1.5 2023/07/07 16:10:32 jsing Exp $ */
+/*      $OpenBSD: bn_arch.h,v 1.6 2023/07/09 10:36:53 jsing Exp $ */
 /*
  * Copyright (c) 2023 Joel Sing <jsing@openbsd.org>
  *
@@ -24,6 +24,23 @@
 
 #if defined(__GNUC__)
 
+#define HAVE_BN_ADDW
+
+static inline void
+bn_addw(BN_ULONG a, BN_ULONG b, BN_ULONG *out_r1, BN_ULONG *out_r0)
+{
+        BN_ULONG carry, r0;
+
+        __asm__ (
+            "add   %[r0], %[a], %[b] \n"
+            "sltu  %[carry], %[r0], %[a] \n"
+            : [carry]"=r"(carry), [r0]"=&r"(r0)
+            : [a]"r"(a), [b]"r"(b));
+
+        *out_r1 = carry;
+        *out_r0 = r0;
+}
+
 #define HAVE_BN_MULW
  
 static inline void