Variable LZX window sizes

[wimlib] / src / compress.c

diff --git a/src/compress.c b/src/compress.c
index f98a5a524854c112eb35906d22cc3f0b779cdf70..86c3c2bcd7bb28cd7e7614b191f112b95b252bc0 100644 (file)
--- a/src/compress.c
+++ b/src/compress.c
@@ -38,45 +38,43 @@
 /* Writes @num_bits bits, given by the @num_bits least significant bits of
  * @bits, to the output @ostream. */
 void
-bitstream_put_bits(struct output_bitstream *ostream, output_bitbuf_t bits,
+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;
+               }
 
-       if (num_bits <= ostream->free_bits) {
-               /* Buffer variable had space for the new bits.  */
-               ostream->bitbuf = (ostream->bitbuf << num_bits) | bits;
-               ostream->free_bits -= num_bits;
-               return;
-       }
+               /* Fill the buffer with as many bits that fit.  */
+               unsigned fill_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.  */
+               ostream->bitbuf <<= fill_bits;
+               ostream->bitbuf |= bits >> (num_bits - fill_bits);
 
-       wimlib_assert(num_bits <= 16);
+               *(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;
 
-       /* There must be at least 2 bytes of space remaining.  */
-       if (unlikely(ostream->bytes_remaining < 2)) {
-               ostream->overrun = true;
-               return;
+               ostream->free_bits = 16;
+               num_bits -= fill_bits;
+               bits &= (1U << num_bits) - 1;
        }
 
-       /* Fill the buffer with as many bits that fit.  */
-       rem_bits = num_bits - ostream->free_bits;
-       ostream->bitbuf <<= ostream->free_bits;
-       ostream->bitbuf |= bits >> rem_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 - rem_bits;
-       ostream->bitbuf = bits;
+       /* Buffer variable has space for the new bits.  */
+       ostream->bitbuf = (ostream->bitbuf << num_bits) | bits;
+       ostream->free_bits -= num_bits;
 }
 
 void