X-Git-Url: https://wimlib.net/git/?p=wimlib;a=blobdiff_plain;f=src%2Fdecompress.c;h=bed7b5a486876c3d056f4888f20cd9e0cb031823;hp=e97aab5c5c2f72cbf407ccacc65f8a750fb62f01;hb=a2993f836221de10e3f3e220d38aa4b72d367a61;hpb=908adfc82c98c531ca847f183489ccf57e190e16

diff --git a/src/decompress.c b/src/decompress.c
index e97aab5c..bed7b5a4 100644
--- a/src/decompress.c
+++ b/src/decompress.c
@@ -27,11 +27,11 @@
 #include <string.h>
 
 /*
- * Builds a fast huffman decoding table from an array that gives the length of
- * the codeword for each symbol in the alphabet.  Originally based on code
- * written by David Tritscher (taken the original LZX decompression code); also
- * heavily modified to add some optimizations used in the zlib code, as well as
- * more comments.
+ * make_huffman_decode_table: - Builds a fast huffman decoding table from an
+ * array that gives the length of the codeword for each symbol in the alphabet.
+ * Originally based on code written by David Tritscher (taken the original LZX
+ * decompression code); also heavily modified to add some optimizations used in
+ * the zlib code, as well as more comments.
  *
  * @decode_table:	The array in which to create the fast huffman decoding
  * 			table.  It must have a length of at least
@@ -167,6 +167,10 @@ int make_huffman_decode_table(u16 decode_table[],  unsigned num_syms,
 		const unsigned entries_per_long = sizeof(unsigned long) /
 						  sizeof(decode_table[0]);
 		if (num_entries >= entries_per_long) {
+			/* Fill in the Huffman decode table entries one unsigned
+			 * long at a time.  On 32-bit systems this is 2 entries
+			 * per store, while on 64-bit systems this is 4 entries
+			 * per store. */
 			wimlib_assert2(decode_table_pos % entries_per_long == 0);
 			BUILD_BUG_ON(sizeof(unsigned long) != 4 &&
 				     sizeof(unsigned long) != 8);
@@ -176,14 +180,21 @@ int make_huffman_decode_table(u16 decode_table[],  unsigned num_syms,
 			unsigned long v = sym;
 			if (sizeof(unsigned long) >= 4)
 				v |= v << 16;
-			if (sizeof(unsigned long) >= 8)
+			if (sizeof(unsigned long) >= 8) {
+				/* This may produce a compiler warning if an
+				 * unsigned long is 32 bits, but this won't be
+				 * executed unless an unsigned long is at least
+				 * 64 bits anyway. */
 				v |= v << 32;
+			}
 			do {
 				*p++ = v;
 			} while (--n);
 
 			decode_table_pos += num_entries;
 		} else {
+			/* Fill in the Huffman decode table entries one 16-bit
+			 * integer at a time. */
 			do {
 				decode_table[decode_table_pos++] = sym;
 			} while (--num_entries);
@@ -234,7 +245,6 @@ int make_huffman_decode_table(u16 decode_table[],  unsigned num_syms,
 		unsigned sym = sorted_syms[i];
 		unsigned codeword_len = lens[sym];
 		unsigned extra_bits = codeword_len - table_bits;
-		unsigned extra_mask;
 
 		cur_codeword <<= (codeword_len - prev_codeword_len);
 		prev_codeword_len = codeword_len;
@@ -282,8 +292,8 @@ int make_huffman_decode_table(u16 decode_table[],  unsigned num_syms,
 	return 0;
 }
 
-/* Reads a Huffman-encoded symbol when it is known there are less than
- * MAX_CODE_LEN bits remaining in the bitstream. */
+/* Reads a Huffman-encoded symbol from the bistream when the number of remaining
+ * bits is less than the maximum codeword length. */
 int read_huffsym_near_end_of_input(struct input_bitstream *istream,
 				   const u16 decode_table[],
 				   const u8 lens[],