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Simplify and fix lz4 compresses function.

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Con Kolivas 2021-03-06 09:32:42 +11:00
parent 467fd92605
commit 042eb57e03
1 changed files with 15 additions and 21 deletions
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36
stream.c
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@ -1882,11 +1882,8 @@ int close_stream_in(rzip_control *control, void *ss)
so do not compress any block that is incompressible by lz4. */ so do not compress any block that is incompressible by lz4. */
static int lz4_compresses(rzip_control *control, uchar *s_buf, i64 s_len) static int lz4_compresses(rzip_control *control, uchar *s_buf, i64 s_len)
{ {
int in_len, test_len = s_len, save_len = s_len; int dlen, test_len;
int dlen;
char *c_buf = NULL, *test_buf = (char *)s_buf; char *c_buf = NULL, *test_buf = (char *)s_buf;
/* set minimum buffer test size based on the length of the test stream */
int buftest_size = (test_len > 5 * STREAM_BUFSIZE ? STREAM_BUFSIZE : STREAM_BUFSIZE / 4096);
int ret = 0; int ret = 0;
int workcounter = 0; /* count # of passes */ int workcounter = 0; /* count # of passes */
int best_dlen = INT_MAX; /* save best compression estimate */ int best_dlen = INT_MAX; /* save best compression estimate */
@ -1894,40 +1891,37 @@ static int lz4_compresses(rzip_control *control, uchar *s_buf, i64 s_len)
if (!LZ4_TEST) if (!LZ4_TEST)
return 1; return 1;
in_len = MIN(test_len, buftest_size); dlen = MIN(s_len, STREAM_BUFSIZE);
dlen = STREAM_BUFSIZE + STREAM_BUFSIZE / 16 + 64 + 3; test_len = MIN(dlen, STREAM_BUFSIZE >> 8);
c_buf = malloc(dlen); c_buf = malloc(dlen);
if (unlikely(!c_buf)) if (unlikely(!c_buf))
fatal_return(("Unable to allocate c_buf in lz4_compresses\n"), 0); fatal_return(("Unable to allocate c_buf in lz4_compresses\n"), 0);
/* Test progressively larger blocks at a time and as soon as anything /* Test progressively larger blocks at a time and as soon as anything
compressible is found, jump out as a success */ compressible is found, jump out as a success */
while (test_len > 0) { do {
int lz4_ret; int lz4_ret;
workcounter++; workcounter++;
lz4_ret = LZ4_compress_default((const char *)test_buf, c_buf, test_len, dlen); lz4_ret = LZ4_compress_default((const char *)test_buf, c_buf, test_len, dlen);
if (!lz4_ret) // Bigger than dlen, no point going further if (!lz4_ret) // Bigger than dlen
break; lz4_ret = test_len;
if (lz4_ret < best_dlen) if (lz4_ret < best_dlen)
best_dlen = lz4_ret; best_dlen = lz4_ret;
if (lz4_ret < test_len) { if (lz4_ret < test_len) {
ret = 1; ret = 1;
break; break;
} }
/* expand and move buffer */ /* expand test length */
test_len -= in_len; test_len <<= 1;
if (test_len) { } while (test_len <= dlen);
test_buf += (ptrdiff_t)in_len;
if (buftest_size < STREAM_BUFSIZE) if (!ret)
buftest_size <<= 1; print_maxverbose("lz4 testing FAILED for chunk %ld. %d Passes\n", workcounter);
in_len = MIN(test_len, buftest_size); else {
print_maxverbose("lz4 testing OK for chunk %ld. Compressed size = %5.2F%% of chunk, %d Passes\n",
s_len, 100 * ((double) best_dlen / (double) test_len), workcounter);
} }
}
print_maxverbose("lz4 testing %s for chunk %ld. Compressed size = %5.2F%% of chunk, %d Passes\n",
(ret == 0? "FAILED" : "OK"), save_len,
100 * ((double) best_dlen / (double) in_len), workcounter);
dealloc(c_buf); dealloc(c_buf);