Introduce basic block

This commit introduces the basic block in emulator, meaning that
it makes emulator decode and execute numerous instructions at a
time.

Author: Risheng1128

src/decode.c

@@ -1663,9 +1663,9 @@ static inline bool op_unimp(struct rv_insn_t *rv_insn UNUSED,
 typedef bool (*decode_t)(struct rv_insn_t *rv_insn, uint32_t insn);
 
 /* decode RISC-V instruction */
-bool rv_decode(struct rv_insn_t *ir, uint32_t insn, uint8_t *insn_len)
+bool rv_decode(struct rv_insn_t *ir, uint32_t insn)
 {
-    assert(ir && insn_len);
+    assert(ir);
 
 #define OP_UNIMP op_unimp
 #define OP(insn) op_##insn
@@ -1704,7 +1704,7 @@ bool rv_decode(struct rv_insn_t *ir, uint32_t insn, uint8_t *insn_len)
     if ((insn & FC_OPCODE) != 3) {
         insn &= 0x0000FFFF;
         const uint16_t c_index = (insn & FC_FUNC3) >> 11 | (insn & FC_OPCODE);
-        *insn_len = INSN_16;
+        ir->insn_len = INSN_16;
 
         /* decode instruction (compressed instructions) */
         const decode_t op = rvc_jump_table[c_index];
@@ -1715,7 +1715,7 @@ bool rv_decode(struct rv_insn_t *ir, uint32_t insn, uint8_t *insn_len)
 
     /* standard uncompressed instruction */
     const uint32_t index = (insn & INSN_6_2) >> 2;
-    *insn_len = INSN_32;
+    ir->insn_len = INSN_32;
 
     /* decode instruction */
     const decode_t op = rv_jump_table[index];

src/decode.h

@@ -236,6 +236,19 @@ struct rv_insn_t {
 #if RV32_HAS(EXT_C)
     uint8_t shamt;
 #endif
+
+    /* instruction length */
+    uint8_t insn_len;
+};
+
+/* a translated basic block */
+struct block_t {
+    /* start of this blocks code */
+    struct rv_insn_t *ir;
+    /* index of instructions encompased */
+    uint32_t index;
+    /* maximum of instructions encompased */
+    uint32_t ir_capacity;
 };
 
 /* sign extend a 16 bit value */
@@ -251,6 +264,4 @@ static inline uint32_t sign_extend_b(const uint32_t x)
 }
 
 /* decode the RISC-V instruction */
-bool rv_decode(struct rv_insn_t *rv_insn,
-               const uint32_t insn,
-               uint8_t *insn_len);
+bool rv_decode(struct rv_insn_t *rv_insn, const uint32_t insn);