| /* |
| * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #ifndef SHARE_VM_CODE_COMPRESSEDSTREAM_HPP |
| #define SHARE_VM_CODE_COMPRESSEDSTREAM_HPP |
| |
| #include "memory/allocation.hpp" |
| |
| // Simple interface for filing out and filing in basic types |
| // Used for writing out and reading in debugging information. |
| |
| class CompressedStream : public ResourceObj { |
| friend class VMStructs; |
| protected: |
| u_char* _buffer; |
| int _position; |
| |
| enum { |
| // Constants for UNSIGNED5 coding of Pack200 |
| lg_H = 6, H = 1<<lg_H, // number of high codes (64) |
| L = (1<<BitsPerByte)-H, // number of low codes (192) |
| MAX_i = 4 // bytes are numbered in (0..4), max 5 bytes |
| }; |
| |
| // these inlines are defined only in compressedStream.cpp |
| static inline juint encode_sign(jint value); // for Pack200 SIGNED5 |
| static inline jint decode_sign(juint value); // for Pack200 SIGNED5 |
| static inline juint reverse_int(juint bits); // to trim trailing float 0's |
| |
| public: |
| CompressedStream(u_char* buffer, int position = 0) { |
| _buffer = buffer; |
| _position = position; |
| } |
| |
| u_char* buffer() const { return _buffer; } |
| |
| // Positioning |
| int position() const { return _position; } |
| void set_position(int position) { _position = position; } |
| }; |
| |
| |
| class CompressedReadStream : public CompressedStream { |
| private: |
| inline u_char read() { return _buffer[_position++]; } |
| |
| // This encoding, called UNSIGNED5, is taken from J2SE Pack200. |
| // It assumes that most values have lots of leading zeroes. |
| // Very small values, in the range [0..191], code in one byte. |
| // Any 32-bit value (including negatives) can be coded, in |
| // up to five bytes. The grammar is: |
| // low_byte = [0..191] |
| // high_byte = [192..255] |
| // any_byte = low_byte | high_byte |
| // coding = low_byte |
| // | high_byte low_byte |
| // | high_byte high_byte low_byte |
| // | high_byte high_byte high_byte low_byte |
| // | high_byte high_byte high_byte high_byte any_byte |
| // Each high_byte contributes six bits of payload. |
| // The encoding is one-to-one (except for integer overflow) |
| // and easy to parse and unparse. |
| |
| jint read_int_mb(jint b0) { |
| int pos = position() - 1; |
| u_char* buf = buffer() + pos; |
| assert(buf[0] == b0 && b0 >= L, "correctly called"); |
| jint sum = b0; |
| // must collect more bytes: b[1]...b[4] |
| int lg_H_i = lg_H; |
| for (int i = 0; ; ) { |
| jint b_i = buf[++i]; // b_i = read(); ++i; |
| sum += b_i << lg_H_i; // sum += b[i]*(64**i) |
| if (b_i < L || i == MAX_i) { |
| set_position(pos+i+1); |
| return sum; |
| } |
| lg_H_i += lg_H; |
| } |
| } |
| |
| public: |
| CompressedReadStream(u_char* buffer, int position = 0) |
| : CompressedStream(buffer, position) {} |
| |
| jboolean read_bool() { return (jboolean) read(); } |
| jbyte read_byte() { return (jbyte ) read(); } |
| jchar read_char() { return (jchar ) read_int(); } |
| jshort read_short() { return (jshort ) read_signed_int(); } |
| jint read_int() { jint b0 = read(); |
| if (b0 < L) return b0; |
| else return read_int_mb(b0); |
| } |
| jint read_signed_int(); |
| jfloat read_float(); // jfloat_cast(reverse_int(read_int())) |
| jdouble read_double(); // jdouble_cast(2*reverse_int(read_int)) |
| jlong read_long(); // jlong_from(2*read_signed_int()) |
| }; |
| |
| |
| class CompressedWriteStream : public CompressedStream { |
| private: |
| bool full() { |
| return _position >= _size; |
| } |
| void store(u_char b) { |
| _buffer[_position++] = b; |
| } |
| void write(u_char b) { |
| if (full()) grow(); |
| store(b); |
| } |
| void grow(); |
| |
| void write_int_mb(jint value); // UNSIGNED5 coding, 1-5 byte cases |
| |
| protected: |
| int _size; |
| |
| public: |
| CompressedWriteStream(int initial_size); |
| CompressedWriteStream(u_char* buffer, int initial_size, int position = 0) |
| : CompressedStream(buffer, position) { _size = initial_size; } |
| |
| void write_bool(jboolean value) { write(value); } |
| void write_byte(jbyte value) { write(value); } |
| void write_char(jchar value) { write_int(value); } |
| void write_short(jshort value) { write_signed_int(value); } |
| void write_int(jint value) { if ((juint)value < L && !full()) |
| store((u_char)value); |
| else write_int_mb(value); } |
| void write_signed_int(jint value); // write_int(encode_sign(value)) |
| void write_float(jfloat value); // write_int(reverse_int(jint_cast(v))) |
| void write_double(jdouble value); // write_int(reverse_int(<low,high>)) |
| void write_long(jlong value); // write_signed_int(<low,high>) |
| }; |
| |
| #endif // SHARE_VM_CODE_COMPRESSEDSTREAM_HPP |