1/*
2 * Copyright (c) 2002, 2008, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26struct unpacker;
27
28#define INT_MAX_VALUE ((int)0x7FFFFFFF)
29#define INT_MIN_VALUE ((int)0x80000000)
30
31#define CODING_SPEC(B, H, S, D) ((B)<<20|(H)<<8|(S)<<4|(D)<<0)
32#define CODING_B(x) ((x)>>20 & 0xF)
33#define CODING_H(x) ((x)>>8  & 0xFFF)
34#define CODING_S(x) ((x)>>4  & 0xF)
35#define CODING_D(x) ((x)>>0  & 0xF)
36
37#define CODING_INIT(B, H, S, D) \
38  { CODING_SPEC(B, H, S, D) , 0, 0, 0, 0, 0, 0, 0, 0}
39
40// For debugging purposes, some compilers do not like this and will complain.
41//    #define long do_not_use_C_long_types_use_jlong_or_int
42// Use of the type "long" is problematic, do not use it.
43
44struct coding {
45  int  spec;  // B,H,S,D
46
47  // Handy values derived from the spec:
48  int B() { return CODING_B(spec); }
49  int H() { return CODING_H(spec); }
50  int S() { return CODING_S(spec); }
51  int D() { return CODING_D(spec); }
52  int L() { return 256-CODING_H(spec); }
53  int  min, max;
54  int  umin, umax;
55  char isSigned, isSubrange, isFullRange, isMalloc;
56
57  coding* init();  // returns self or null if error
58  coding* initFrom(int spec_) {
59    assert(this->spec == 0);
60    this->spec = spec_;
61    return init();
62  }
63
64  static coding* findBySpec(int spec);
65  static coding* findBySpec(int B, int H, int S=0, int D=0);
66  static coding* findByIndex(int irregularCodingIndex);
67
68  static uint parse(byte* &rp, int B, int H);
69  static uint parse_lgH(byte* &rp, int B, int H, int lgH);
70  static void parseMultiple(byte* &rp, int N, byte* limit, int B, int H);
71
72  uint parse(byte* &rp) {
73    return parse(rp, CODING_B(spec), CODING_H(spec));
74  }
75  void parseMultiple(byte* &rp, int N, byte* limit) {
76    parseMultiple(rp, N, limit, CODING_B(spec), CODING_H(spec));
77  }
78
79  bool canRepresent(int x)         { return (x >= min  && x <= max);  }
80  bool canRepresentUnsigned(int x) { return (x >= umin && x <= umax); }
81
82  int sumInUnsignedRange(int x, int y);
83
84  int readFrom(byte* &rpVar, int* dbase);
85  void readArrayFrom(byte* &rpVar, int* dbase, int length, int* values);
86  void skipArrayFrom(byte* &rpVar, int length) {
87    readArrayFrom(rpVar, (int*)NULL, length, (int*)NULL);
88  }
89
90#ifndef PRODUCT
91  const char* string();
92#endif
93
94  void free();  // free self if isMalloc
95
96  // error handling
97  static void abort(const char* msg = null) { unpack_abort(msg); }
98};
99
100enum coding_method_kind {
101  cmk_ERROR,
102  cmk_BHS,
103  cmk_BHS0,
104  cmk_BHS1,
105  cmk_BHSD1,
106  cmk_BHS1D1full,  // isFullRange
107  cmk_BHS1D1sub,   // isSubRange
108
109  // special cases hand-optimized (~50% of all decoded values)
110  cmk_BYTE1,         //(1,256)      6%
111  cmk_CHAR3,         //(3,128)      7%
112  cmk_UNSIGNED5,     //(5,64)      13%
113  cmk_DELTA5,        //(5,64,1,1)   5%
114  cmk_BCI5,          //(5,4)       18%
115  cmk_BRANCH5,       //(5,4,2)      4%
116//cmk_UNSIGNED5H16,  //(5,16)       5%
117//cmk_UNSIGNED2H4,   //(2,4)        6%
118//cmk_DELTA4H8,      //(4,8,1,1)   10%
119//cmk_DELTA3H16,     //(3,16,1,1)   9%
120  cmk_BHS_LIMIT,
121
122  cmk_pop,
123  cmk_pop_BHS0,
124  cmk_pop_BYTE1,
125  cmk_pop_LIMIT,
126
127  cmk_LIMIT
128};
129
130enum {
131  BYTE1_spec       = CODING_SPEC(1, 256, 0, 0),
132  CHAR3_spec       = CODING_SPEC(3, 128, 0, 0),
133  UNSIGNED4_spec   = CODING_SPEC(4, 256, 0, 0),
134  UNSIGNED5_spec   = CODING_SPEC(5, 64, 0, 0),
135  SIGNED5_spec     = CODING_SPEC(5, 64, 1, 0),
136  DELTA5_spec      = CODING_SPEC(5, 64, 1, 1),
137  UDELTA5_spec     = CODING_SPEC(5, 64, 0, 1),
138  MDELTA5_spec     = CODING_SPEC(5, 64, 2, 1),
139  BCI5_spec        = CODING_SPEC(5, 4, 0, 0),
140  BRANCH5_spec     = CODING_SPEC(5, 4, 2, 0)
141};
142
143enum {
144  B_MAX = 5,
145  C_SLOP = B_MAX*10
146};
147
148struct coding_method;
149
150// iterator under the control of a meta-coding
151struct value_stream {
152  // current coding of values or values
153  coding c;               // B,H,S,D,etc.
154  coding_method_kind cmk; // type of decoding needed
155  byte* rp;               // read pointer
156  byte* rplimit;          // final value of read pointer
157  int sum;                // partial sum of all values so far (D=1 only)
158  coding_method* cm;      // coding method that defines this stream
159
160  void init(byte* band_rp, byte* band_limit, coding* defc);
161  void init(byte* band_rp, byte* band_limit, int spec)
162    { init(band_rp, band_limit, coding::findBySpec(spec)); }
163
164  void setCoding(coding* c);
165  void setCoding(int spec) { setCoding(coding::findBySpec(spec)); }
166
167  // Parse and decode a single value.
168  int getInt();
169
170  // Parse and decode a single byte, with no error checks.
171  int getByte() {
172    assert(cmk == cmk_BYTE1);
173    assert(rp < rplimit);
174    return *rp++ & 0xFF;
175  }
176
177  // Used only for asserts.
178  bool hasValue();
179
180  void done() { assert(!hasValue()); }
181
182  // Sometimes a value stream has an auxiliary (but there are never two).
183  value_stream* helper() {
184    assert(hasHelper());
185    return this+1;
186  }
187  bool hasHelper();
188
189  // error handling
190  //  inline void abort(const char* msg);
191  //  inline void aborting();
192};
193
194struct coding_method {
195  value_stream vs0;       // initial state snapshot (vs.meta==this)
196
197  coding_method* next;    // what to do when we run out of bytes
198
199  // these fields are used for pop codes only:
200  int* fValues;           // favored value array
201  int  fVlength;          // maximum favored value token
202  coding_method* uValues; // unfavored value stream
203
204  // pointer to outer unpacker, for error checks etc.
205  unpacker* u;
206
207  // Initialize a value stream.
208  void reset(value_stream* state);
209
210  // Parse a band header, size a band, and initialize for further action.
211  // band_rp advances (but not past band_limit), and meta_rp advances.
212  // The mode gives context, such as "inside a pop".
213  // The defc and N are the incoming parameters to a meta-coding.
214  // The value sink is used to collect output values, when desired.
215  void init(byte* &band_rp, byte* band_limit,
216            byte* &meta_rp, int mode,
217            coding* defc, int N,
218            intlist* valueSink);
219
220  // error handling
221  void abort(const char* msg) { unpack_abort(msg, u); }
222  bool aborting()             { return unpack_aborting(u); }
223};
224
225//inline void value_stream::abort(const char* msg) { cm->abort(msg); }
226//inline void value_stream::aborting()             { cm->aborting(); }
227