Add ARC method 4 Huffman squeezing decompression implementation and tests

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 <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#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;
+}