diff --git a/nemu/src/isa/riscv32/inst.c b/nemu/src/isa/riscv32/inst.c
index 81db1ee..a9f73f3 100644
--- a/nemu/src/isa/riscv32/inst.c
+++ b/nemu/src/isa/riscv32/inst.c
@@ -116,6 +116,16 @@ static int decode_exec(Decode *s) {
   INSTPAT("0000000 ????? ????? 001 ????? 00100 11", slli   , I, R(rd) = src1 << imm);
   INSTPAT("0000000 ????? ????? 101 ????? 00100 11", srli   , I, R(rd) = src1 >> imm);
   INSTPAT("0100000 ????? ????? 101 ????? 00100 11", srai   , I, R(rd) = (sword_t)src1 >> (imm & 0x01F));
+
+  INSTPAT("0000000 ????? ????? 000 ????? 01100 11", add    , R, R(rd) = src1 + src2);
+  INSTPAT("0100000 ????? ????? 000 ????? 01100 11", sub    , R, R(rd) = src1 - src2);
+  INSTPAT("0000000 ????? ????? 001 ????? 01100 11", sll    , R, R(rd) = src1 << src2);
+  INSTPAT("0000000 ????? ????? 010 ????? 01100 11", slt    , R, R(rd) = (sword_t)src1 < (sword_t)src2 ? 1 : 0);
+  INSTPAT("0000000 ????? ????? 011 ????? 01100 11", sltu   , R, R(rd) = src1 < src2 ? 1 : 0);
+  INSTPAT("0000000 ????? ????? 100 ????? 01100 11", xor    , R, R(rd) = src1 ^ src2);
+  INSTPAT("0000000 ????? ????? 101 ????? 01100 11", srl    , R, R(rd) = src1 >> src2);
+  INSTPAT("0100000 ????? ????? 101 ????? 01100 11", sra    , R, R(rd) = (sword_t)src1 >> (src2 & 0x01F));
+
   INSTPAT("0000000 00001 00000 000 00000 11100 11", ebreak , N, NEMUTRAP(s->pc, R(10))); // R(10) is $a0
   INSTPAT("??????? ????? ????? ??? ????? ????? ??", inv    , N, INV(s->pc));