v5: add disassembler support for ALLOCATE_EXT_OPCODE

Test: TH
Change-Id: I99c39900b5567232704b325e169860ca0df10e22
diff --git a/disassembler.c b/disassembler.c
index 57843bc..fb9d042 100644
--- a/disassembler.c
+++ b/disassembler.c
@@ -247,8 +247,14 @@
                     bprintf("r%d, r%d", reg_num, reg_num ^ 1);
                     break;
                 case ALLOCATE_EXT_OPCODE:
-                    print_opcode("alloc");
-                    bprintf("r%d", reg_num);
+                    print_opcode("allocate");
+                    if (reg_num == 0) {
+                        bprintf("r%d", reg_num);
+                    } else {
+                        uint32_t alloc_len = 0;
+                        DECODE_IMM(alloc_len, 2);
+                        bprintf("%d", alloc_len);
+                    }
                     break;
                 case TRANSMITDISCARD_EXT_OPCODE:
                     print_opcode("trans");