--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/code/compressedStream.cpp Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,252 @@
+/*
+ * Copyright (c) 1997, 2017, 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.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "code/compressedStream.hpp"
+#include "utilities/ostream.hpp"
+
+// 32-bit one-to-one sign encoding taken from Pack200
+// converts leading sign bits into leading zeroes with trailing sign bit
+inline juint CompressedStream::encode_sign(jint value) {
+ return (value << 1) ^ (value >> 31);
+}
+inline jint CompressedStream::decode_sign(juint value) {
+ return (value >> 1) ^ -(jint)(value & 1);
+}
+
+// 32-bit self-inverse encoding of float bits
+// converts trailing zeroes (common in floats) to leading zeroes
+inline juint CompressedStream::reverse_int(juint i) {
+ // Hacker's Delight, Figure 7-1
+ i = (i & 0x55555555) << 1 | ((i >> 1) & 0x55555555);
+ i = (i & 0x33333333) << 2 | ((i >> 2) & 0x33333333);
+ i = (i & 0x0f0f0f0f) << 4 | ((i >> 4) & 0x0f0f0f0f);
+ i = (i << 24) | ((i & 0xff00) << 8) | ((i >> 8) & 0xff00) | (i >> 24);
+ return i;
+}
+
+
+jint CompressedReadStream::read_signed_int() {
+ return decode_sign(read_int());
+}
+
+// Compressing floats is simple, because the only common pattern
+// is trailing zeroes. (Compare leading sign bits on ints.)
+// Since floats are left-justified, as opposed to right-justified
+// ints, we can bit-reverse them in order to take advantage of int
+// compression.
+
+jfloat CompressedReadStream::read_float() {
+ int rf = read_int();
+ int f = reverse_int(rf);
+ return jfloat_cast(f);
+}
+
+jdouble CompressedReadStream::read_double() {
+ jint rh = read_int();
+ jint rl = read_int();
+ jint h = reverse_int(rh);
+ jint l = reverse_int(rl);
+ return jdouble_cast(jlong_from(h, l));
+}
+
+jlong CompressedReadStream::read_long() {
+ jint low = read_signed_int();
+ jint high = read_signed_int();
+ return jlong_from(high, low);
+}
+
+CompressedWriteStream::CompressedWriteStream(int initial_size) : CompressedStream(NULL, 0) {
+ _buffer = NEW_RESOURCE_ARRAY(u_char, initial_size);
+ _size = initial_size;
+ _position = 0;
+}
+
+void CompressedWriteStream::grow() {
+ u_char* _new_buffer = NEW_RESOURCE_ARRAY(u_char, _size * 2);
+ memcpy(_new_buffer, _buffer, _position);
+ _buffer = _new_buffer;
+ _size = _size * 2;
+}
+
+void CompressedWriteStream::write_signed_int(jint value) {
+ // this encoding, called SIGNED5, is taken from Pack200
+ write_int(encode_sign(value));
+}
+
+void CompressedWriteStream::write_float(jfloat value) {
+ juint f = jint_cast(value);
+ juint rf = reverse_int(f);
+ assert(f == reverse_int(rf), "can re-read same bits");
+ write_int(rf);
+}
+
+void CompressedWriteStream::write_double(jdouble value) {
+ juint h = high(jlong_cast(value));
+ juint l = low( jlong_cast(value));
+ juint rh = reverse_int(h);
+ juint rl = reverse_int(l);
+ assert(h == reverse_int(rh), "can re-read same bits");
+ assert(l == reverse_int(rl), "can re-read same bits");
+ write_int(rh);
+ write_int(rl);
+}
+
+void CompressedWriteStream::write_long(jlong value) {
+ write_signed_int(low(value));
+ write_signed_int(high(value));
+}
+
+
+/// The remaining details
+
+#ifndef PRODUCT
+// set this to trigger unit test
+void test_compressed_stream(int trace);
+bool test_compressed_stream_enabled = false;
+#endif
+
+void CompressedWriteStream::write_int_mb(jint value) {
+ debug_only(int pos1 = position());
+ juint sum = value;
+ for (int i = 0; ; ) {
+ if (sum < L || i == MAX_i) {
+ // remainder is either a "low code" or the 5th byte
+ assert(sum == (u_char)sum, "valid byte");
+ write((u_char)sum);
+ break;
+ }
+ sum -= L;
+ int b_i = L + (sum % H); // this is a "high code"
+ sum >>= lg_H; // extracted 6 bits
+ write(b_i); ++i;
+ }
+
+#ifndef PRODUCT
+ if (test_compressed_stream_enabled) { // hack to enable this stress test
+ test_compressed_stream_enabled = false;
+ test_compressed_stream(0);
+ }
+#endif
+}
+
+
+#ifndef PRODUCT
+/// a unit test (can be run by hand from a debugger)
+
+// Avoid a VS2005 compiler stack overflow w/ fastdebug build.
+// The following pragma optimize turns off optimization ONLY
+// for this block (a matching directive turns it back on later).
+// These directives can be removed once the MS VS.NET 2005
+// compiler stack overflow is fixed.
+#if defined(_MSC_VER) && _MSC_VER >=1400 && !defined(_WIN64)
+#pragma optimize("", off)
+#pragma warning(disable: 4748)
+#endif
+
+// generator for an "interesting" set of critical values
+enum { stretch_limit = (1<<16) * (64-16+1) };
+static jlong stretch(jint x, int bits) {
+ // put x[high 4] into place
+ jlong h = (jlong)((x >> (16-4))) << (bits - 4);
+ // put x[low 12] into place, sign extended
+ jlong l = ((jlong)x << (64-12)) >> (64-12);
+ // move l upwards, maybe
+ l <<= (x >> 16);
+ return h ^ l;
+}
+
+PRAGMA_DIAG_PUSH
+PRAGMA_FORMAT_IGNORED // Someone needs to deal with this.
+void test_compressed_stream(int trace) {
+ CompressedWriteStream bytes(stretch_limit * 100);
+ jint n;
+ int step = 0, fails = 0;
+#define CHECKXY(x, y, fmt) { \
+ ++step; \
+ int xlen = (pos = decode.position()) - lastpos; lastpos = pos; \
+ if (trace > 0 && (step % trace) == 0) { \
+ tty->print_cr("step %d, n=%08x: value=" fmt " (len=%d)", \
+ step, n, x, xlen); } \
+ if (x != y) { \
+ tty->print_cr("step %d, n=%d: " fmt " != " fmt, step, n, x, y); \
+ fails++; \
+ } }
+ for (n = 0; n < (1<<8); n++) {
+ jbyte x = (jbyte)n;
+ bytes.write_byte(x); ++step;
+ }
+ for (n = 0; n < stretch_limit; n++) {
+ jint x = (jint)stretch(n, 32);
+ bytes.write_int(x); ++step;
+ bytes.write_signed_int(x); ++step;
+ bytes.write_float(jfloat_cast(x)); ++step;
+ }
+ for (n = 0; n < stretch_limit; n++) {
+ jlong x = stretch(n, 64);
+ bytes.write_long(x); ++step;
+ bytes.write_double(jdouble_cast(x)); ++step;
+ }
+ int length = bytes.position();
+ if (trace != 0)
+ tty->print_cr("set up test of %d stream values, size %d", step, length);
+ step = 0;
+ // now decode it all
+ CompressedReadStream decode(bytes.buffer());
+ int pos, lastpos = decode.position();
+ for (n = 0; n < (1<<8); n++) {
+ jbyte x = (jbyte)n;
+ jbyte y = decode.read_byte();
+ CHECKXY(x, y, "%db");
+ }
+ for (n = 0; n < stretch_limit; n++) {
+ jint x = (jint)stretch(n, 32);
+ jint y1 = decode.read_int();
+ CHECKXY(x, y1, "%du");
+ jint y2 = decode.read_signed_int();
+ CHECKXY(x, y2, "%di");
+ jint y3 = jint_cast(decode.read_float());
+ CHECKXY(x, y3, "%df");
+ }
+ for (n = 0; n < stretch_limit; n++) {
+ jlong x = stretch(n, 64);
+ jlong y1 = decode.read_long();
+ CHECKXY(x, y1, INT64_FORMAT "l");
+ jlong y2 = jlong_cast(decode.read_double());
+ CHECKXY(x, y2, INT64_FORMAT "d");
+ }
+ int length2 = decode.position();
+ if (trace != 0)
+ tty->print_cr("finished test of %d stream values, size %d", step, length2);
+ guarantee(length == length2, "bad length");
+ guarantee(fails == 0, "test failures");
+}
+PRAGMA_DIAG_POP
+
+#if defined(_MSC_VER) &&_MSC_VER >=1400 && !defined(_WIN64)
+#pragma warning(default: 4748)
+#pragma optimize("", on)
+#endif
+
+#endif // PRODUCT