Speed things up quite a bit

1 files changed, 11 insertions, 11 deletions

diff --git a/riscv/decode.h b/riscv/decode.h
index 8e506e2..6c26a68 100644
--- a/riscv/decode.h
+++ b/riscv/decode.h
@@ -52,21 +52,22 @@ class insn_t
 {
 public:
   uint32_t bits() { return b; }
-  reg_t i_imm() { return int64_t(int32_t(b) >> 20); }
-  reg_t s_imm() { return x(7, 5) | (x(25, 7) << 5) | (imm_sign() << 12); }
-  reg_t sb_imm() { return (x(8, 4) << 1) | (x(25,6) << 5) | (x(7,1) << 11) | (imm_sign() << 12); }
-  reg_t u_imm() { return int64_t(int32_t(b) >> 12 << 12); }
-  reg_t uj_imm() { return (x(21, 10) << 1) | (x(20, 1) << 11) | (x(12, 8) << 12) | (imm_sign() << 20); }
+  int32_t i_imm() { return int32_t(b) >> 20; }
+  int32_t s_imm() { return x(7, 5) + (xs(25, 7) << 5); }
+  int32_t sb_imm() { return (x(8, 4) << 1) + (x(25,6) << 5) + (x(7,1) << 11) + (imm_sign() << 12); }
+  int32_t u_imm() { return int32_t(b) >> 12 << 12; }
+  int32_t uj_imm() { return (x(21, 10) << 1) + (x(20, 1) << 11) + (x(12, 8) << 12) + (imm_sign() << 20); }
   uint32_t rd() { return x(7, 5); }
   uint32_t rs1() { return x(15, 5); }
   uint32_t rs2() { return x(20, 5); }
   uint32_t rs3() { return x(27, 5); }
   uint32_t rm() { return x(12, 3); }
-  reg_t csr() { return x(20, 12); }
+  uint32_t csr() { return x(20, 12); }
 private:
   uint32_t b;
-  reg_t x(int lo, int len) { return b << (32-lo-len) >> (32-len); }
-  reg_t imm_sign() { return int64_t(int32_t(b) >> 31); }
+  uint32_t x(int lo, int len) { return b << (32-lo-len) >> (32-len); }
+  uint32_t xs(int lo, int len) { return int32_t(b) << (32-lo-len) >> (32-len); }
+  uint32_t imm_sign() { return xs(31, 1); }
 };
 
 template <class T, size_t N, bool zero_reg>
@@ -79,12 +80,11 @@ public:
   }
   void write(size_t i, T value)
   {
-    data[i] = value;
+    if (!(zero_reg && i == 0))
+      data[i] = value;
   }
   const T& operator [] (size_t i) const
   {
-    if (zero_reg)
-      const_cast<T&>(data[0]) = 0;
     return data[i];
   }
 private: