Call.cpp revision a8b91c52fd8a90b784835dfe1f8898035266c4dd 
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 */
29static 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/* We will call this generic function if there are no hints */
51#ifdef __mips__
52#define dvmPlatformInvoke dvmPlatformInvokeFFI
53
54extern "C" void dvmPlatformInvoke(void* pEnv, ClassObject* clazz, int argInfo,
55    int argc, const u4* argv, const char* signature, void* func, JValue* pResult);
56#endif
57
58/*
59 * Call "func" with the specified arguments.
60 *
61 * The second argument to JNI native functions is either the object (the
62 * "this" pointer) or, for static functions, a pointer to the class object.
63 * The Dalvik instructions will push "this" into argv[0], but it's up to
64 * us to insert the class object.
65 *
66 * Because there is no such thing in as a null "this" pointer, we use
67 * the non-NULL state of "clazz" to determine whether or not it's static.
68 *
69 * For maximum efficiency we should compute the CIF once and save it with
70 * the method.  However, this requires storing the data with every native
71 * method.  Since the goal is to have custom assembly versions of this
72 * on the platforms where performance matters, I'm recomputing the CIF on
73 * every call.
74 */
75void dvmPlatformInvoke(void* pEnv, ClassObject* clazz, int argInfo, int argc,
76    const u4* argv, const char* shorty, void* func, JValue* pReturn)
77{
78    const int kMaxArgs = argc+2;    /* +1 for env, maybe +1 for clazz */
79    ffi_cif cif;
80    ffi_type* types[kMaxArgs];
81    void* values[kMaxArgs];
82    ffi_type* retType;
83    char sigByte;
84    int srcArg, dstArg;
85
86    types[0] = &ffi_type_pointer;
87    values[0] = &pEnv;
88
89    types[1] = &ffi_type_pointer;
90    if (clazz != NULL) {
91        values[1] = &clazz;
92        srcArg = 0;
93    } else {
94        values[1] = (void*) argv++;
95        srcArg = 1;
96    }
97    dstArg = 2;
98
99    /*
100     * Scan the types out of the short signature.  Use them to fill out the
101     * "types" array.  Store the start address of the argument in "values".
102     */
103    retType = getFfiType(*shorty);
104    while ((sigByte = *++shorty) != '\0') {
105        types[dstArg] = getFfiType(sigByte);
106        values[dstArg++] = (void*) argv++;
107        if (sigByte == 'D' || sigByte == 'J')
108            argv++;
109    }
110
111    /*
112     * Prep the CIF (Call InterFace object).
113     */
114    if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, dstArg, retType, types) != FFI_OK) {
115        LOGE("ffi_prep_cif failed");
116        dvmAbort();
117    }
118
119    ffi_call(&cif, FFI_FN(func), pReturn, values);
120}
121