# 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;
+
+ ostream->bitbuf <<= fill_bits;
+ ostream->bitbuf |= bits >> (num_bits - fill_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;
+ *(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
ostream->bitbuf = 0;
ostream->free_bits = 16;
+ ostream->output_start = data;
ostream->bit_output = data;
ostream->next_bit_output = data + 2;
ostream->output = data + 4;
- ostream->num_bytes_remaining = num_bytes - 4;
+ ostream->bytes_remaining = num_bytes;
+ ostream->overrun = false;
}
typedef struct {
void
make_canonical_huffman_code(unsigned num_syms,
unsigned max_codeword_len,
- const freq_t * restrict freq_tab,
- u8 * restrict lens,
- u16 * restrict codewords)
+ 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
git://wimlib.net / wimlib / blobdiff