acpi: add aml_decrement() and aml_subtract()

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>

hw/acpi/aml-build.c

@@ -502,6 +502,12 @@ Aml *aml_add(Aml *arg1, Aml *arg2, Aml *dst)
     return build_opcode_2arg_dst(0x72 /* AddOp */, arg1, arg2, dst);
 }
 
+/* ACPI 1.0b: 16.2.5.4 Type 2 Opcodes Encoding: DefSubtract */
+Aml *aml_subtract(Aml *arg1, Aml *arg2, Aml *dst)
+{
+    return build_opcode_2arg_dst(0x74 /* SubtractOp */, arg1, arg2, dst);
+}
+
 /* ACPI 1.0b: 16.2.5.4 Type 2 Opcodes Encoding: DefIncrement */
 Aml *aml_increment(Aml *arg)
 {
@@ -510,6 +516,14 @@ Aml *aml_increment(Aml *arg)
     return var;
 }
 
+/* ACPI 1.0b: 16.2.5.4 Type 2 Opcodes Encoding: DefDecrement */
+Aml *aml_decrement(Aml *arg)
+{
+    Aml *var = aml_opcode(0x76 /* DecrementOp */);
+    aml_append(var, arg);
+    return var;
+}
+
 /* ACPI 1.0b: 16.2.5.4 Type 2 Opcodes Encoding: DefIndex */
 Aml *aml_index(Aml *arg1, Aml *idx)
 {

include/hw/acpi/aml-build.h

@@ -231,7 +231,9 @@ Aml *aml_shiftleft(Aml *arg1, Aml *count);
 Aml *aml_shiftright(Aml *arg1, Aml *count);
 Aml *aml_lless(Aml *arg1, Aml *arg2);
 Aml *aml_add(Aml *arg1, Aml *arg2, Aml *dst);
+Aml *aml_subtract(Aml *arg1, Aml *arg2, Aml *dst);
 Aml *aml_increment(Aml *arg);
+Aml *aml_decrement(Aml *arg);
 Aml *aml_index(Aml *arg1, Aml *idx);
 Aml *aml_notify(Aml *arg1, Aml *arg2);
 Aml *aml_call1(const char *method, Aml *arg1);