Support 2/4/6/8-byte instructions

Most of the complexity is in instruction address translation, since
instructions may span page boundaries.

1 files changed, 21 insertions, 19 deletions

diff --git a/riscv/decode.h b/riscv/decode.h
index 543080d..b325c59 100644
--- a/riscv/decode.h
+++ b/riscv/decode.h
@@ -44,26 +44,29 @@ const int NFPR = 32;
 #define FSR_NXA  (FPEXC_NX << FSR_AEXC_SHIFT)
 #define FSR_AEXC (FSR_NVA | FSR_OFA | FSR_UFA | FSR_DZA | FSR_NXA)
 
+typedef uint64_t insn_bits_t;
 class insn_t
 {
 public:
-  uint32_t bits() { return b; }
-  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); }
-  uint32_t csr() { return x(20, 12); }
+  insn_t() = default;
+  insn_t(insn_bits_t bits) : b(bits) {}
+  insn_bits_t bits() { return b; }
+  int64_t i_imm() { return int64_t(b) >> 20; }
+  int64_t s_imm() { return x(7, 5) + (xs(25, 7) << 5); }
+  int64_t sb_imm() { return (x(8, 4) << 1) + (x(25,6) << 5) + (x(7,1) << 11) + (imm_sign() << 12); }
+  int64_t u_imm() { return int64_t(b) >> 12 << 12; }
+  int64_t uj_imm() { return (x(21, 10) << 1) + (x(20, 1) << 11) + (x(12, 8) << 12) + (imm_sign() << 20); }
+  uint64_t rd() { return x(7, 5); }
+  uint64_t rs1() { return x(15, 5); }
+  uint64_t rs2() { return x(20, 5); }
+  uint64_t rs3() { return x(27, 5); }
+  uint64_t rm() { return x(12, 3); }
+  uint64_t csr() { return x(20, 12); }
 private:
-  uint32_t b;
-  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); }
+  insn_bits_t b;
+  uint64_t x(int lo, int len) { return (b >> lo) & ((insn_bits_t(1) << len)-1); }
+  uint64_t xs(int lo, int len) { return int64_t(b) << (64-lo-len) >> (64-len); }
+  uint64_t imm_sign() { return xs(63, 1); }
 };
 
 template <class T, size_t N, bool zero_reg>
@@ -76,9 +79,8 @@ public:
   }
   void write(size_t i, T value)
   {
-    data[i] = value;
-    if (zero_reg)
-      data[0] = 0;
+    if (!zero_reg || i != 0)
+      data[i] = value;
   }
   const T& operator [] (size_t i) const
   {