gem5/base/compression/lzss_compression.cc
Steve Reinhardt 25693e9e69 Make include paths explicit and update makefile accordingly.
arch/alpha/alpha_memory.cc:
arch/alpha/alpha_memory.hh:
arch/alpha/arguments.cc:
arch/alpha/arguments.hh:
arch/alpha/ev5.cc:
arch/alpha/ev5.hh:
arch/alpha/fake_syscall.cc:
arch/alpha/faults.cc:
arch/alpha/isa_desc:
arch/alpha/isa_traits.hh:
arch/alpha/osfpal.cc:
arch/alpha/vtophys.cc:
arch/alpha/vtophys.hh:
base/circlebuf.cc:
base/compression/lzss_compression.cc:
base/compression/lzss_compression.hh:
base/cprintf.cc:
base/cprintf.hh:
base/fast_alloc.cc:
base/fifo_buffer.cc:
base/fifo_buffer.hh:
base/hashmap.hh:
base/hostinfo.cc:
base/hostinfo.hh:
base/hybrid_pred.cc:
base/hybrid_pred.hh:
base/inet.cc:
base/inet.hh:
base/inifile.cc:
base/inifile.hh:
base/intmath.cc:
base/loader/aout_object.cc:
base/loader/aout_object.hh:
base/loader/ecoff_object.cc:
base/loader/ecoff_object.hh:
base/loader/elf_object.cc:
base/loader/elf_object.hh:
base/loader/exec_aout.h:
base/loader/exec_ecoff.h:
base/loader/object_file.cc:
base/loader/object_file.hh:
base/loader/symtab.cc:
base/loader/symtab.hh:
base/misc.cc:
base/misc.hh:
base/pollevent.cc:
base/pollevent.hh:
base/random.cc:
base/random.hh:
base/range.hh:
base/remote_gdb.cc:
base/remote_gdb.hh:
base/res_list.hh:
base/sat_counter.cc:
base/sat_counter.hh:
base/sched_list.hh:
base/socket.cc:
base/statistics.cc:
base/statistics.hh:
base/str.cc:
base/trace.cc:
base/trace.hh:
cpu/base_cpu.cc:
cpu/base_cpu.hh:
cpu/exec_context.cc:
cpu/exec_context.hh:
cpu/exetrace.cc:
cpu/exetrace.hh:
cpu/intr_control.cc:
cpu/intr_control.hh:
cpu/memtest/memtest.cc:
cpu/memtest/memtest.hh:
cpu/pc_event.cc:
cpu/pc_event.hh:
cpu/simple_cpu/simple_cpu.cc:
cpu/simple_cpu/simple_cpu.hh:
cpu/static_inst.cc:
cpu/static_inst.hh:
dev/alpha_console.cc:
dev/alpha_console.hh:
dev/console.cc:
dev/console.hh:
dev/disk_image.cc:
dev/disk_image.hh:
dev/etherbus.cc:
dev/etherbus.hh:
dev/etherdump.cc:
dev/etherdump.hh:
dev/etherint.cc:
dev/etherint.hh:
dev/etherlink.cc:
dev/etherlink.hh:
dev/etherpkt.hh:
dev/ethertap.cc:
dev/ethertap.hh:
dev/simple_disk.cc:
dev/simple_disk.hh:
kern/tru64/tru64_syscalls.cc:
kern/tru64/tru64_syscalls.hh:
sim/debug.cc:
sim/eventq.cc:
sim/eventq.hh:
sim/main.cc:
sim/param.cc:
sim/param.hh:
sim/prog.cc:
sim/prog.hh:
sim/serialize.cc:
sim/serialize.hh:
sim/sim_events.cc:
sim/sim_events.hh:
sim/sim_object.cc:
sim/sim_object.hh:
sim/sim_time.cc:
sim/system.cc:
sim/system.hh:
sim/universe.cc:
test/circletest.cc:
test/cprintftest.cc:
test/initest.cc:
test/nmtest.cc:
test/offtest.cc:
test/paramtest.cc:
test/rangetest.cc:
test/stattest.cc:
test/strnumtest.cc:
test/symtest.cc:
test/tokentest.cc:
test/tracetest.cc:
util/tap/tap.cc:
    Make include paths explicit.

--HG--
extra : convert_revision : 941cbdc591fd4d3d1d9f095cd58fc23dd2d73840
2003-10-10 11:09:00 -07:00

166 lines
4.9 KiB
C++

/*
* Copyright (c) 2003 The Regents of The University of Michigan
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met: redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer;
* redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution;
* neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** @file
* LZSSCompression definitions.
*/
#include <assert.h>
#include "base/compression/lzss_compression.hh"
#include "base/misc.hh" //for fatal
int
LZSSCompression::findSubString(uint8_t *src, int front, int back, int size)
{
int subSize = 0;
int max_length = 2048;
if (size - back < max_length) {
max_length = size - back;
}
for (int i = 0; i < max_length; ++i) {
if (src[front+i] != src[back+i]) {
return subSize;
}
++subSize;
}
return subSize;
}
int
LZSSCompression::emitByte(uint8_t *dest, uint8_t byte)
{
if ((byte >> 5 & 0x7) == 0 || (byte >> 5 & 0x7) == 7) {
// If the top 3 bits are the same, emit 00<6bits>
dest[0] = byte & 0x3f;
return 1;
} else {
// emit 01XXXXXX <8 bits>
dest[0] = 0x40;
dest[1] = byte;
return 2;
}
}
void
LZSSCompression::emitString(uint8_t *dest, uint16_t P, uint16_t L)
{
// Emit 1<7P> <5P><3L> <8L>
dest[0] = 1<<7 | (P >> 5 & 0x7f);
dest[1] = ((P & 0x1f) << 3) | (L>>8 & 0x3);
dest[2] = L & 0xFF;
}
int
LZSSCompression::compress(uint8_t *dest, uint8_t *src, int size)
{
if (size > 4096) {
fatal("Compression can only handle block sizes of 4096 bytes or less");
}
// Encode the first byte.
int dest_index = emitByte(dest, src[0]);
int i = 1;
// A 11 bit field
uint16_t L;
// A 12 bit field
uint16_t P = 0;
while (i < size && dest_index < size) {
L = 0;
if (dest_index+3 >= size) {
dest_index = size;
continue;
}
if (i == size - 1) {
// Output the character
dest_index += emitByte(&dest[dest_index], src[i]);
++i;
continue;
}
for (int j = 0; j < i; ++j) {
int sub_size = findSubString(src, j, i, size);
if (sub_size >= L) {
L = sub_size;
P = j;
}
}
if (L > 1) {
// Output the string reference
emitString(&dest[dest_index], P, L);
dest_index += 3;
i = i+L;
} else {
// Output the character
dest_index += emitByte(&dest[dest_index], src[i]);
++i;
}
}
if (dest_index >= size) {
// Have expansion instead of compression, just copy.
memcpy(dest,src,size);
return size;
}
return dest_index;
}
int
LZSSCompression::uncompress(uint8_t *dest, uint8_t *src, int size)
{
int index = 0;
int i = 0;
while (i < size) {
if (src[i] & 1<<7 ) {
// We have a string
// Extract P
int start = (src[i] & 0x3f)<<5 | ((src[i+1] >> 3) & 0x1f);
// Extract L
int len = (src[i+1] & 0x07)<<8 | src[i+2];
i += 3;
for (int j = start; j < start+len; ++j) {
dest[index++] = dest[j];
}
} else {
// We have a character
if (src[i] & 1<<6) {
// Value is in the next byte
dest[index++] = src[i+1];
i += 2;
} else {
// just extend the lower 6 bits
dest[index++] = (src[i] & 0x3f) | ((src[i] & 1<<5) ? 0xC0 : 0);
++i;
}
}
}
return index;
}