rvv: merge mulhu.h and arith.h

Signed-off-by: Chih-Min Chao <chihmin.chao@sifive.com>

1 files changed, 38 insertions, 2 deletions

diff --git a/riscv/arith.h b/riscv/arith.h
index d909a11..b4370cb 100644
--- a/riscv/arith.h
+++ b/riscv/arith.h
@@ -2,8 +2,44 @@
 
 #ifndef _RISCV_ARITH_H
 #define _RISCV_ARITH_H
-#include <limits.h>
-#include <stdint.h>
+
+#include <cstdint>
+#include <climits>
+
+inline uint64_t mulhu(uint64_t a, uint64_t b)
+{
+  uint64_t t;
+  uint32_t y1, y2, y3;
+  uint64_t a0 = (uint32_t)a, a1 = a >> 32;
+  uint64_t b0 = (uint32_t)b, b1 = b >> 32;
+
+  t = a1*b0 + ((a0*b0) >> 32);
+  y1 = t;
+  y2 = t >> 32;
+
+  t = a0*b1 + y1;
+  y1 = t;
+
+  t = a1*b1 + y2 + (t >> 32);
+  y2 = t;
+  y3 = t >> 32;
+
+  return ((uint64_t)y3 << 32) | y2;
+}
+
+inline int64_t mulh(int64_t a, int64_t b)
+{
+  int negate = (a < 0) != (b < 0);
+  uint64_t res = mulhu(a < 0 ? -a : a, b < 0 ? -b : b);
+  return negate ? ~res + (a * b == 0) : res;
+}
+
+inline int64_t mulhsu(int64_t a, uint64_t b)
+{
+  int negate = a < 0;
+  uint64_t res = mulhu(a < 0 ? -a : a, b);
+  return negate ? ~res + (a * b == 0) : res;
+}
 
 //ref:  https://locklessinc.com/articles/sat_arithmetic/
 template<typename T, typename UT>