* along with wimlib; if not, see http://www.gnu.org/licenses/.
*/
-#include "compress.h"
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include "wimlib/assert.h"
+#include "wimlib/compiler.h"
+#include "wimlib/compress.h"
+#include "wimlib/util.h"
+
#include <stdlib.h>
#include <string.h>
-static inline void
-flush_bits(struct output_bitstream *ostream)
-{
- *(u16*)ostream->bit_output = cpu_to_le16(ostream->bitbuf);
- ostream->bit_output = ostream->next_bit_output;
- ostream->next_bit_output = ostream->output;
- ostream->output += 2;
- ostream->num_bytes_remaining -= 2;
-}
-
/* Writes @num_bits bits, given by the @num_bits least significant bits of
* @bits, to the output @ostream. */
-int
-bitstream_put_bits(struct output_bitstream *ostream, output_bitbuf_t bits,
+void
+bitstream_put_bits(struct output_bitstream *ostream, u32 bits,
unsigned num_bits)
{
- unsigned rem_bits;
+ while (num_bits > ostream->free_bits) {
+ /* Buffer variable does not have space for the new bits. It
+ * needs to be flushed as a 16-bit integer. Bits in the second
+ * byte logically precede those in the first byte
+ * (little-endian), but within each byte the bits are ordered
+ * from high to low. This is true for both XPRESS and LZX
+ * compression. */
+
+ /* There must be at least 2 bytes of space remaining. */
+ if (unlikely(ostream->bytes_remaining < 2)) {
+ ostream->overrun = true;
+ return;
+ }
- wimlib_assert(num_bits <= 16);
- if (num_bits <= ostream->free_bits) {
- ostream->bitbuf = (ostream->bitbuf << num_bits) | bits;
- ostream->free_bits -= num_bits;
- } else {
+ /* Fill the buffer with as many bits that fit. */
+ unsigned fill_bits = ostream->free_bits;
- if (ostream->num_bytes_remaining + (ostream->output -
- ostream->bit_output) < 2)
- return 1;
-
- /* It is tricky to output the bits correctly. The correct way
- * is to output little-endian 2-byte words, such that the bits
- * in the SECOND byte logically precede those in the FIRST byte.
- * While the byte order is little-endian, the bit order is
- * big-endian; the first bit in a byte is the high-order one.
- * Any multi-bit numbers are in bit-big-endian form, so the
- * low-order bit of a multi-bit number is the LAST bit to be
- * output. */
- rem_bits = num_bits - ostream->free_bits;
- ostream->bitbuf <<= ostream->free_bits;
- ostream->bitbuf |= bits >> rem_bits;
- flush_bits(ostream);
- ostream->free_bits = 16 - rem_bits;
- ostream->bitbuf = bits;
+ ostream->bitbuf <<= fill_bits;
+ ostream->bitbuf |= bits >> (num_bits - fill_bits);
+ *(le16*)ostream->bit_output = cpu_to_le16(ostream->bitbuf);
+ ostream->bit_output = ostream->next_bit_output;
+ ostream->next_bit_output = ostream->output;
+ ostream->output += 2;
+ ostream->bytes_remaining -= 2;
+
+ ostream->free_bits = 16;
+ num_bits -= fill_bits;
+ bits &= (1U << num_bits) - 1;
}
- return 0;
+
+ /* Buffer variable has space for the new bits. */
+ ostream->bitbuf = (ostream->bitbuf << num_bits) | bits;
+ ostream->free_bits -= num_bits;
}
-/* Flushes any remaining bits in the output buffer to the output byte stream. */
-int
-flush_output_bitstream(struct output_bitstream *ostream)
+void
+bitstream_put_byte(struct output_bitstream *ostream, u8 n)
{
- if (ostream->num_bytes_remaining + (ostream->output -
- ostream->bit_output) < 2)
- return 1;
- if (ostream->free_bits != 16) {
- ostream->bitbuf <<= ostream->free_bits;
- flush_bits(ostream);
+ if (unlikely(ostream->bytes_remaining < 1)) {
+ ostream->overrun = true;
+ return;
}
- return 0;
+ *ostream->output++ = n;
+ ostream->bytes_remaining--;
+}
+
+/* Flushes any remaining bits to the output bitstream.
+ *
+ * Returns -1 if the stream has overrun; otherwise returns the total number of
+ * bytes in the output. */
+input_idx_t
+flush_output_bitstream(struct output_bitstream *ostream)
+{
+ if (unlikely(ostream->overrun))
+ return ~(input_idx_t)0;
+
+ *(le16*)ostream->bit_output =
+ cpu_to_le16((u16)((u32)ostream->bitbuf << ostream->free_bits));
+ *(le16*)ostream->next_bit_output =
+ cpu_to_le16(0);
+
+ return ostream->output - ostream->output_start;
}
/* Initializes an output bit buffer to write its output to the memory location
* pointer to by @data. */
void
-init_output_bitstream(struct output_bitstream *ostream, void *data,
- unsigned num_bytes)
+init_output_bitstream(struct output_bitstream *ostream,
+ void *data, unsigned num_bytes)
{
wimlib_assert(num_bytes >= 4);
ostream->bitbuf = 0;
ostream->free_bits = 16;
- ostream->bit_output = (u8*)data;
- ostream->next_bit_output = (u8*)data + 2;
- ostream->output = (u8*)data + 4;
- ostream->num_bytes_remaining = num_bytes - 4;
+ ostream->output_start = data;
+ ostream->bit_output = data;
+ ostream->next_bit_output = data + 2;
+ ostream->output = data + 4;
+ ostream->bytes_remaining = num_bytes;
+ ostream->overrun = false;
}
-/* Intermediate (non-leaf) node in a Huffman tree. */
-typedef struct HuffmanNode {
+typedef struct {
u32 freq;
u16 sym;
union {
u16 path_len;
u16 height;
};
- struct HuffmanNode *left_child;
- struct HuffmanNode *right_child;
} HuffmanNode;
-/* Leaf node in a Huffman tree. The fields are in the same order as the
- * HuffmanNode, so it can be cast to a HuffmanNode. There are no pointers to
- * the children in the leaf node. */
-typedef struct {
- u32 freq;
- u16 sym;
- union {
- u16 path_len;
- u16 height;
- };
-} HuffmanLeafNode;
+typedef struct HuffmanIntermediateNode {
+ HuffmanNode node_base;
+ HuffmanNode *left_child;
+ HuffmanNode *right_child;
+} HuffmanIntermediateNode;
+
-/* Comparator function for HuffmanLeafNodes. Sorts primarily by symbol
+/* Comparator function for HuffmanNodes. Sorts primarily by symbol
* frequency and secondarily by symbol value. */
static int
-cmp_leaves_by_freq(const void *__leaf1, const void *__leaf2)
+cmp_nodes_by_freq(const void *_leaf1, const void *_leaf2)
{
- const HuffmanLeafNode *leaf1 = __leaf1;
- const HuffmanLeafNode *leaf2 = __leaf2;
+ const HuffmanNode *leaf1 = _leaf1;
+ const HuffmanNode *leaf2 = _leaf2;
int freq_diff = (int)leaf1->freq - (int)leaf2->freq;
return freq_diff;
}
-/* Comparator function for HuffmanLeafNodes. Sorts primarily by code length and
+/* Comparator function for HuffmanNodes. Sorts primarily by code length and
* secondarily by symbol value. */
static int
-cmp_leaves_by_code_len(const void *__leaf1, const void *__leaf2)
+cmp_nodes_by_code_len(const void *_leaf1, const void *_leaf2)
{
- const HuffmanLeafNode *leaf1 = __leaf1;
- const HuffmanLeafNode *leaf2 = __leaf2;
+ const HuffmanNode *leaf1 = _leaf1;
+ const HuffmanNode *leaf2 = _leaf2;
int code_len_diff = (int)leaf1->path_len - (int)leaf2->path_len;
return code_len_diff;
}
+#define INVALID_SYMBOL 0xffff
+
/* Recursive function to calculate the depth of the leaves in a Huffman tree.
* */
static void
-huffman_tree_compute_path_lengths(HuffmanNode *node, u16 cur_len)
+huffman_tree_compute_path_lengths(HuffmanNode *base_node, u16 cur_len)
{
- if (node->sym == (u16)(-1)) {
+ if (base_node->sym == INVALID_SYMBOL) {
/* Intermediate node. */
+ HuffmanIntermediateNode *node = (HuffmanIntermediateNode*)base_node;
huffman_tree_compute_path_lengths(node->left_child, cur_len + 1);
huffman_tree_compute_path_lengths(node->right_child, cur_len + 1);
} else {
/* Leaf node. */
- node->path_len = cur_len;
+ base_node->path_len = cur_len;
}
}
* for symbol i.
*/
void
-make_canonical_huffman_code(unsigned num_syms, unsigned max_codeword_len,
- const freq_t freq_tab[], u8 lens[],
- u16 codewords[])
+make_canonical_huffman_code(unsigned num_syms,
+ unsigned max_codeword_len,
+ const freq_t freq_tab[restrict],
+ u8 lens[restrict],
+ u16 codewords[restrict])
{
/* We require at least 2 possible symbols in the alphabet to produce a
* valid Huffman decoding table. It is allowed that fewer than 2 symbols
/* Initialize the array of leaf nodes with the symbols and their
* frequencies. */
- HuffmanLeafNode leaves[num_used_symbols];
+ HuffmanNode leaves[num_used_symbols];
unsigned leaf_idx = 0;
for (unsigned i = 0; i < num_syms; i++) {
if (freq_tab[i] != 0) {
* format constrains codes to 16 bits or less each. However, it is
* still possible for there to be more than 16 intermediate nodes, as
* long as no leaf has a depth of more than 16. */
- HuffmanNode inodes[num_used_symbols - 1];
+ HuffmanIntermediateNode inodes[num_used_symbols - 1];
/* Pointer to the leaf node of lowest frequency that hasn't already been
* added as the child of some intermediate note. */
- HuffmanLeafNode *cur_leaf;
+ HuffmanNode *cur_leaf;
/* Pointer past the end of the array of leaves. */
- HuffmanLeafNode *end_leaf = &leaves[num_used_symbols];
+ HuffmanNode *end_leaf = &leaves[num_used_symbols];
/* Pointer to the intermediate node of lowest frequency. */
- HuffmanNode *cur_inode;
+ HuffmanIntermediateNode *cur_inode;
/* Pointer to the next unallocated intermediate node. */
- HuffmanNode *next_inode;
+ HuffmanIntermediateNode *next_inode;
/* Only jump back to here if the maximum length of the codewords allowed
* by the LZX format (16 bits) is exceeded. */
/* Sort the leaves from those that correspond to the least frequent
* symbol, to those that correspond to the most frequent symbol. If two
* leaves have the same frequency, they are sorted by symbol. */
- qsort(leaves, num_used_symbols, sizeof(leaves[0]), cmp_leaves_by_freq);
+ qsort(leaves, num_used_symbols, sizeof(leaves[0]), cmp_nodes_by_freq);
cur_leaf = &leaves[0];
cur_inode = &inodes[0];
* remaining leaves or from the intermediate nodes. */
if (cur_leaf != end_leaf && (cur_inode == next_inode ||
- cur_leaf->freq <= cur_inode->freq)) {
- f1 = (HuffmanNode*)cur_leaf++;
+ cur_leaf->freq <= cur_inode->node_base.freq)) {
+ f1 = cur_leaf++;
} else if (cur_inode != next_inode) {
- f1 = cur_inode++;
+ f1 = (HuffmanNode*)cur_inode++;
}
if (cur_leaf != end_leaf && (cur_inode == next_inode ||
- cur_leaf->freq <= cur_inode->freq)) {
- f2 = (HuffmanNode*)cur_leaf++;
+ cur_leaf->freq <= cur_inode->node_base.freq)) {
+ f2 = cur_leaf++;
} else if (cur_inode != next_inode) {
- f2 = cur_inode++;
+ f2 = (HuffmanNode*)cur_inode++;
} else {
/* All nodes used up! */
break;
/* next_inode becomes the parent of f1 and f2. */
- next_inode->freq = f1->freq + f2->freq;
- next_inode->sym = (u16)(-1); /* Invalid symbol. */
- next_inode->left_child = f1;
- next_inode->right_child = f2;
+ next_inode->node_base.freq = f1->freq + f2->freq;
+ next_inode->node_base.sym = INVALID_SYMBOL;
+ next_inode->left_child = f1;
+ next_inode->right_child = f2;
/* We need to keep track of the height so that we can detect if
* the length of a codeword has execeed max_codeword_len. The
* parent node has a height one higher than the maximum height
* of its children. */
- next_inode->height = max(f1->height, f2->height) + 1;
+ next_inode->node_base.height = max(f1->height, f2->height) + 1;
/* Check to see if the code length of the leaf farthest away
* from next_inode has exceeded the maximum code length. */
- if (next_inode->height > max_codeword_len) {
+ if (next_inode->node_base.height > max_codeword_len) {
/* The code lengths can be made more uniform by making
* the frequencies more uniform. Divide all the
* frequencies by 2, leaving 1 as the minimum frequency.
/* The Huffman tree is now complete, and its height is no more than
* max_codeword_len. */
- HuffmanNode *root = next_inode - 1;
- wimlib_assert(root->height <= max_codeword_len);
+ HuffmanIntermediateNode *root = next_inode - 1;
+ wimlib_assert(root->node_base.height <= max_codeword_len);
/* Compute the path lengths for the leaf nodes. */
- huffman_tree_compute_path_lengths(root, 0);
+ huffman_tree_compute_path_lengths(&root->node_base, 0);
/* Sort the leaf nodes primarily by code length and secondarily by
* symbol. */
- qsort(leaves, num_used_symbols, sizeof(leaves[0]), cmp_leaves_by_code_len);
+ qsort(leaves, num_used_symbols, sizeof(leaves[0]), cmp_nodes_by_code_len);
u16 cur_codeword = 0;
unsigned cur_codeword_len = 0;
git://wimlib.net / wimlib / blobdiff