1 /*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 /*
18 * This uses the FFI (Foreign Function Interface) library to abstract away
19 * the system-dependent stuff. The FFI code is slower than a custom
20 * assembly version, but has the distinct advantage of having been
21 * written already for several platforms.
22 */
23 #include "Dalvik.h"
24 #include "ffi.h"
25
26 /*
27 * Convert a signature type character to an FFI type.
28 */
getFfiType(char sigType)29 static ffi_type* getFfiType(char sigType)
30 {
31 switch (sigType) {
32 case 'V': return &ffi_type_void;
33 case 'Z': return &ffi_type_uint8;
34 case 'B': return &ffi_type_sint8;
35 case 'C': return &ffi_type_uint16;
36 case 'S': return &ffi_type_sint16;
37 case 'I': return &ffi_type_sint32;
38 case 'F': return &ffi_type_float;
39 case 'J': return &ffi_type_sint64;
40 case 'D': return &ffi_type_double;
41 case '[':
42 case 'L': return &ffi_type_pointer;
43 default:
44 LOGE("bad ffitype 0x%02x", sigType);
45 dvmAbort();
46 return NULL;
47 }
48 }
49
50 /*
51 * Call "func" with the specified arguments.
52 *
53 * The second argument to JNI native functions is either the object (the
54 * "this" pointer) or, for static functions, a pointer to the class object.
55 * The Dalvik instructions will push "this" into argv[0], but it's up to
56 * us to insert the class object.
57 *
58 * Because there is no such thing in as a null "this" pointer, we use
59 * the non-NULL state of "clazz" to determine whether or not it's static.
60 *
61 * For maximum efficiency we should compute the CIF once and save it with
62 * the method. However, this requires storing the data with every native
63 * method. Since the goal is to have custom assembly versions of this
64 * on the platforms where performance matters, I'm recomputing the CIF on
65 * every call.
66 */
dvmPlatformInvoke(void * pEnv,ClassObject * clazz,int argInfo,int argc,const u4 * argv,const char * shorty,void * func,JValue * pReturn)67 void dvmPlatformInvoke(void* pEnv, ClassObject* clazz, int argInfo, int argc,
68 const u4* argv, const char* shorty, void* func, JValue* pReturn)
69 {
70 const int kMaxArgs = argc+2; /* +1 for env, maybe +1 for clazz */
71 ffi_cif cif;
72 ffi_type* types[kMaxArgs];
73 void* values[kMaxArgs];
74 ffi_type* retType;
75 char sigByte;
76 int srcArg, dstArg;
77
78 types[0] = &ffi_type_pointer;
79 values[0] = &pEnv;
80
81 types[1] = &ffi_type_pointer;
82 if (clazz != NULL) {
83 values[1] = &clazz;
84 srcArg = 0;
85 } else {
86 values[1] = (void*) argv++;
87 srcArg = 1;
88 }
89 dstArg = 2;
90
91 /*
92 * Scan the types out of the short signature. Use them to fill out the
93 * "types" array. Store the start address of the argument in "values".
94 */
95 retType = getFfiType(*shorty);
96 while ((sigByte = *++shorty) != '\0') {
97 types[dstArg] = getFfiType(sigByte);
98 values[dstArg++] = (void*) argv++;
99 if (sigByte == 'D' || sigByte == 'J')
100 argv++;
101 }
102
103 /*
104 * Prep the CIF (Call InterFace object).
105 */
106 if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, dstArg, retType, types) != FFI_OK) {
107 LOGE("ffi_prep_cif failed");
108 dvmAbort();
109 }
110
111 ffi_call(&cif, FFI_FN(func), pReturn, values);
112 }
113