Add support for decompressing Lempel-Ziv-Huffman, LH5 variant.

zoo/lh5.c

@@ -0,0 +1,94 @@
+/*
+ * 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 <http://www.gnu.org/licenses/>.
+ */
+
+/* lh5_mem.c
+ *
+ * In-memory I/O glue for LH5 decompression.
+ * Implements mem_getc(), mem_putc(), and the top-level
+ * lh5_decompress() entry point.
+ */
+
+#include "lh5.h"
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include "../library.h"
+
+/* Forward-declaration of the decompression driver in lzh.c */
+extern int lzh_decode(void);
+
+/* Buffer I/O state (see lh5_mem.h for externs) */
+const uint8_t *in_ptr;
+size_t         in_left;
+uint8_t       *out_ptr;
+size_t         out_left;
+int            mem_error;
+
+/*
+ * mem_getc(): return next compressed byte, or 0 when in_left==0.
+ * Never sets mem_error on input underflow.
+ */
+int mem_getc(void)
+{
+    if(in_left == 0) { return 0; /* mimic feof → subbitbuf = 0 */ }
+    int c = *in_ptr++;
+    in_left--;
+    return c;
+}
+
+/*
+ * mem_putc(): write one output byte, set mem_error on overflow.
+ */
+int mem_putc(int c)
+{
+    if(out_left == 0)
+    {
+        mem_error = 1;
+        return EOF;
+    }
+    *out_ptr++ = (uint8_t)c;
+    out_left--;
+    return c;
+}
+
+/*
+ * Top-level in-memory decompressor.
+ *
+ * in_buf  points to 'in_len' bytes of compressed data.
+ * out_buf must have at least *out_len bytes available.
+ * On return *out_len is set to the number of bytes written.
+ *
+ * Returns  0 on success
+ *         -1 on error (bad stream or output too small)
+ */
+AARU_EXPORT int AARU_CALL lh5_decompress(const uint8_t *in_buf, size_t in_len, uint8_t *out_buf, size_t *out_len)
+{
+    /* Initialize buffer pointers and error flag */
+    in_ptr    = in_buf;
+    in_left   = in_len;
+    out_ptr   = out_buf;
+    out_left  = *out_len;
+    mem_error = 0;
+
+    /* Invoke the core LH5 decode routine (now buffer-based) */
+    if(lzh_decode() != 0 || mem_error) { return -1; }
+
+    /* Compute actual output size */
+    *out_len = (size_t)(out_ptr - out_buf);
+    return 0;
+}