/* Pointer to the compress() implementation chosen at allocation time */
void (*impl)(struct lzx_compressor *, struct lzx_output_bitstream *);
+ /* If true, the compressor need not preserve the input buffer if it
+ * compresses the data successfully. */
+ bool destructive;
+
/* The Huffman symbol frequency counters for the current block. */
struct lzx_freqs freqs;
}
static u64
-lzx_get_needed_memory(size_t max_bufsize, unsigned compression_level)
+lzx_get_needed_memory(size_t max_bufsize, unsigned compression_level,
+ bool destructive)
{
u64 size = 0;
return 0;
size += lzx_get_compressor_size(max_bufsize, compression_level);
- size += max_bufsize; /* in_buffer */
+ if (!destructive)
+ size += max_bufsize; /* in_buffer */
return size;
}
static int
lzx_create_compressor(size_t max_bufsize, unsigned compression_level,
- void **c_ret)
+ bool destructive, void **c_ret)
{
unsigned window_order;
struct lzx_compressor *c;
if (!c)
goto oom0;
+ c->destructive = destructive;
+
c->num_main_syms = lzx_get_num_main_syms(window_order);
c->window_order = window_order;
- c->in_buffer = MALLOC(max_bufsize);
- if (!c->in_buffer)
- goto oom1;
+ if (!c->destructive) {
+ c->in_buffer = MALLOC(max_bufsize);
+ if (!c->in_buffer)
+ goto oom1;
+ }
if (compression_level <= LZX_MAX_FAST_LEVEL) {
{
struct lzx_compressor *c = _c;
struct lzx_output_bitstream os;
+ size_t result;
/* Don't bother trying to compress very small inputs. */
if (in_nbytes < 100)
return 0;
/* Copy the input data into the internal buffer and preprocess it. */
- memcpy(c->in_buffer, in, in_nbytes);
+ if (c->destructive)
+ c->in_buffer = (void *)in;
+ else
+ memcpy(c->in_buffer, in, in_nbytes);
c->in_nbytes = in_nbytes;
lzx_do_e8_preprocessing(c->in_buffer, in_nbytes);
(*c->impl)(c, &os);
/* Flush the output bitstream and return the compressed size or 0. */
- return lzx_flush_output(&os);
+ result = lzx_flush_output(&os);
+ if (!result && c->destructive)
+ lzx_undo_e8_preprocessing(c->in_buffer, c->in_nbytes);
+ return result;
}
static void
{
struct lzx_compressor *c = _c;
- FREE(c->in_buffer);
+ if (!c->destructive)
+ FREE(c->in_buffer);
ALIGNED_FREE(c);
}