diff --git a/CMakeLists.txt b/CMakeLists.txt
index c7f0c41..892a6cb 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -140,7 +140,8 @@ add_library("Aaru.Compression.Native" SHARED library.c apple_rle.c apple_rle.h a
zoo/lzh.h
zoo/ar.h
zoo/maketbl.c
- arc/pack.c)
+ arc/pack.c
+ arc/squeeze.c)
include(3rdparty/bzip2.cmake)
include(3rdparty/flac.cmake)
diff --git a/arc/squeeze.c b/arc/squeeze.c
new file mode 100644
index 0000000..1ab2d34
--- /dev/null
+++ b/arc/squeeze.c
@@ -0,0 +1,148 @@
+/*
+ * This file is part of the Aaru Data Preservation Suite.
+ * Copyright (c) 2019-2025 Natalia Portillo.
+ * Copyright © 2018-2019 David Ryskalczyk
+ *
+ * This library is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of the
+ * License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see .
+ */
+
+#include
+#include
+#include
+#include "../library.h"
+
+#define SPEOF 256 // Special end-of-file token.
+#define NUMVALS 257 // Number of values in the Huffman tree (256 chars + SPEOF).
+
+// Node structure for the Huffman decoding tree.
+struct nd
+{
+ int child[2]; // Children of the node.
+};
+
+// Static variables for the decompression state.
+static struct nd nodes[NUMVALS]; // The Huffman tree.
+static int numnodes; // Number of nodes in the tree.
+
+static int bpos; // Bit position in the current byte.
+static unsigned char curin; // Current byte being read.
+
+// Pointers for buffer management.
+static const unsigned char *in_buf_ptr;
+static size_t in_len_rem;
+static unsigned char *out_buf_ptr;
+static size_t out_len_rem;
+
+// Reads a byte from the input buffer.
+static int get_byte()
+{
+ if(in_len_rem == 0) { return EOF; }
+ in_len_rem--;
+ return *in_buf_ptr++;
+}
+
+static int arc_decompress_huffman(const unsigned char *in_buf, size_t in_len, unsigned char *out_buf, size_t *out_len)
+{
+ // Basic validation of pointers.
+ if(!in_buf || !out_buf || !out_len) { return -1; }
+
+ // Initialize buffer pointers and lengths.
+ in_buf_ptr = in_buf;
+ in_len_rem = in_len;
+ out_buf_ptr = out_buf;
+ out_len_rem = *out_len;
+
+ bpos = 99; // Force initial read.
+
+ // Read the number of nodes in the Huffman tree.
+ if(in_len_rem < 2) return -1;
+ numnodes = get_byte();
+ numnodes |= get_byte() << 8;
+
+ if(numnodes < 0 || numnodes >= NUMVALS)
+ {
+ return -1; // Invalid tree.
+ }
+
+ // ARC: initialize for possible empty tree (SPEOF only)
+ nodes[0].child[0] = -(SPEOF + 1);
+ nodes[0].child[1] = -(SPEOF + 1);
+
+ // Read the Huffman tree from the input buffer, sign-extend 16-bit values
+ for(int i = 0; i < numnodes; ++i)
+ {
+ if(in_len_rem < 4) return -1;
+ uint8_t b0 = get_byte();
+ uint8_t b1 = get_byte();
+ uint8_t b2 = get_byte();
+ uint8_t b3 = get_byte();
+ nodes[i].child[0] = (int16_t)((b0) | (b1 << 8));
+ nodes[i].child[1] = (int16_t)((b2) | (b3 << 8));
+ }
+
+ size_t written = 0;
+ // bpos is already 99 from init
+
+ while(written < *out_len)
+ {
+ int i = 0;
+ // follow bit stream in tree to a leaf
+ while(i >= 0)
+ {
+ if(++bpos > 7)
+ {
+ int c = get_byte();
+ if(c == EOF)
+ {
+ *out_len = written;
+ return 0; // End of input
+ }
+ curin = c;
+ bpos = 0;
+ // move a level deeper in tree
+ i = nodes[i].child[curin & 1];
+ }
+ else { i = nodes[i].child[1 & (curin >>= 1)]; }
+ }
+
+ // decode fake node index to original data value
+ int value = -(i + 1);
+
+ if(value == SPEOF)
+ {
+ break; // End of data
+ }
+
+ *out_buf_ptr++ = value;
+ written++;
+ }
+
+ *out_len = written;
+ return 0;
+}
+
+// Decompresses data using Huffman squeezing.
+AARU_EXPORT int AARU_CALL arc_decompress_squeeze(const unsigned char *in_buf, size_t in_len, unsigned char *out_buf,
+ size_t *out_len)
+{
+ size_t temp_len = *out_len * 2;
+ unsigned char *temp_buf = malloc(temp_len);
+ if(!temp_buf) return -1;
+
+ int result = arc_decompress_huffman(in_buf, in_len, temp_buf, &temp_len);
+ if(result == 0) { result = arc_decompress_pack(temp_buf, temp_len, out_buf, out_len); }
+
+ free(temp_buf);
+ return result;
+}
diff --git a/library.h b/library.h
index e05e0cf..1949018 100644
--- a/library.h
+++ b/library.h
@@ -120,5 +120,7 @@ AARU_EXPORT uint64_t AARU_CALL AARU_get_acn_version();
// ARC method 3: Stored with non-repeat packing
AARU_EXPORT int AARU_CALL arc_decompress_pack(const unsigned char *in_buf, size_t in_len, unsigned char *out_buf, size_t *out_len);
+// ARC method 4: Huffman squeezing
+AARU_EXPORT int AARU_CALL arc_decompress_squeeze(const unsigned char *in_buf, size_t in_len, unsigned char *out_buf, size_t *out_len);
#endif // AARU_COMPRESSION_NATIVE_LIBRARY_H
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index a61ec8b..af9b4d0 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -48,10 +48,11 @@ file(COPY ${CMAKE_CURRENT_SOURCE_DIR}/data/alice29.lh5
file(COPY ${CMAKE_CURRENT_SOURCE_DIR}/data/arcpack.bin
DESTINATION ${CMAKE_CURRENT_BINARY_DIR}/data/)
+file(COPY ${CMAKE_CURRENT_SOURCE_DIR}/data/arcsqueeze.bin
+ DESTINATION ${CMAKE_CURRENT_BINARY_DIR}/data/)
+
# 'Google_Tests_run' is the target name
# 'test1.cpp tests2.cpp' are source files with tests
add_executable(tests_run apple_rle.cpp crc32.c crc32.h adc.cpp bzip2.cpp lzip.cpp lzfse.cpp zstd.cpp lzma.cpp flac.cpp
- zoo/lzd.cpp arc/pack.cpp
- lh5.cpp
- arc/pack.cpp)
+ zoo/lzd.cpp arc/pack.cpp lh5.cpp arc/squeeze.cpp)
target_link_libraries(tests_run gtest gtest_main "Aaru.Compression.Native")
diff --git a/tests/arc/squeeze.cpp b/tests/arc/squeeze.cpp
new file mode 100644
index 0000000..aee5d58
--- /dev/null
+++ b/tests/arc/squeeze.cpp
@@ -0,0 +1,81 @@
+/*
+ * This file is part of the Aaru Data Preservation Suite.
+ * Copyright (c) 2019-2025 Natalia Portillo.
+ *
+ * This library is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of the
+ * License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see .
+ */
+
+#include
+#include
+#include
+
+#include "../../library.h"
+#include "../crc32.h"
+#include "gtest/gtest.h"
+
+#define EXPECTED_CRC32 0x66007dba
+
+static const uint8_t *buffer;
+
+class squeezeFixture : public ::testing::Test
+{
+public:
+ squeezeFixture()
+ {
+ // initialization;
+ // can also be done in SetUp()
+ }
+
+protected:
+ void SetUp()
+ {
+ char path[PATH_MAX];
+ char filename[PATH_MAX];
+
+ getcwd(path, PATH_MAX);
+ snprintf(filename, PATH_MAX, "%s/data/arcsqueeze.bin", path);
+
+ FILE *file = fopen(filename, "rb");
+ buffer = (const uint8_t *)malloc(88044);
+ fread((void *)buffer, 1, 88044, file);
+ fclose(file);
+ }
+
+ void TearDown() { free((void *)buffer); }
+
+ ~squeezeFixture()
+ {
+ // resources cleanup, no exceptions allowed
+ }
+
+ // shared user data
+};
+
+TEST_F(squeezeFixture, squeeze)
+{
+ size_t destLen = 152089;
+ size_t srcLen = 88044;
+ auto *outBuf = (uint8_t *)malloc(152089);
+
+ auto err = arc_decompress_squeeze(buffer, srcLen, outBuf, &destLen);
+
+ EXPECT_EQ(err, 0);
+ EXPECT_EQ(destLen, 152089);
+
+ auto crc = crc32_data(outBuf, 152089);
+
+ free(outBuf);
+
+ EXPECT_EQ(crc, EXPECTED_CRC32);
+}
\ No newline at end of file
diff --git a/tests/data/arcsqueeze.bin b/tests/data/arcsqueeze.bin
new file mode 100755
index 0000000..23c9fe0
Binary files /dev/null and b/tests/data/arcsqueeze.bin differ
diff --git a/tests/zoo/lzd.cpp b/tests/zoo/lzd.cpp
index d1ec820..d8d8a1d 100644
--- a/tests/zoo/lzd.cpp
+++ b/tests/zoo/lzd.cpp
@@ -25,7 +25,7 @@
#include
#include
-#include "../library.h"
+#include "../../library.h"
#include "../crc32.h"
#include "gtest/gtest.h"