disas/riscv: Add decode for Zawrs extension

Add disassembly support for these instructions from Zawrs:

* wrs.sto
* wrs.nto

Signed-off-by: Balaji Ravikumar <bravikumar@rivosinc.com>
Signed-off-by: Rob Bradford <rbradford@rivosinc.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20240705165316.127494-1-rbradford@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

disas/riscv.c

@@ -974,6 +974,8 @@ typedef enum {
     rv_op_amomaxu_h = 943,
     rv_op_amocas_b  = 944,
     rv_op_amocas_h  = 945,
+    rv_op_wrs_sto = 946,
+    rv_op_wrs_nto = 947,
 } rv_op;
 
 /* register names */
@@ -2232,6 +2234,8 @@ const rv_opcode_data rvi_opcode_data[] = {
     { "amomaxu.h", rv_codec_r_a, rv_fmt_aqrl_rd_rs2_rs1, NULL, 0, 0, 0 },
     { "amocas.b", rv_codec_r_a, rv_fmt_aqrl_rd_rs2_rs1, NULL, 0, 0, 0 },
     { "amocas.h", rv_codec_r_a, rv_fmt_aqrl_rd_rs2_rs1, NULL, 0, 0, 0 },
+    { "wrs.sto", rv_codec_none, rv_fmt_none, NULL, 0, 0, 0 },
+    { "wrs.nto", rv_codec_none, rv_fmt_none, NULL, 0, 0, 0 },
 };
 
 /* CSR names */
@@ -3980,6 +3984,8 @@ static void decode_inst_opcode(rv_decode *dec, rv_isa isa)
                     case 0: op = rv_op_ecall; break;
                     case 32: op = rv_op_ebreak; break;
                     case 64: op = rv_op_uret; break;
+                    case 416: op = rv_op_wrs_nto; break;
+                    case 928: op = rv_op_wrs_sto; break;
                     }
                     break;
                 case 256: