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Add an input buffer (currently 32kB) to speed things up heaps, it still requires 25% longer to decompress as compared to upstream.

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This commit is contained in:
Glenn L McGrath
2002-11-24 06:01:20 +00:00
parent 7b1eca265a
commit eda4f53f2e
3 changed files with 77 additions and 28 deletions
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39
archival/libunarchive/decompress_unzip.c
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@ -88,8 +88,8 @@ static unsigned int gunzip_outbuf_count; /* bytes in output buffer */
/* This is used to sanify any unused bits from the bitbuffer
* so they arent skipped when reading trailers (trailing headers) */
unsigned char gunzip_in_buffer_count;
unsigned char *gunzip_in_buffer;
//unsigned char gunzip_in_buffer_count;
//unsigned char *gunzip_in_buffer;
/* gunzip_window size--must be a power of two, and
* at least 32K for zip's deflate method */
@ -142,13 +142,30 @@ static const unsigned char border[] = {
16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15
};
#define BYTEBUFFER_MAX 0x8000
unsigned char *bytebuffer = NULL;
unsigned int bytebuffer_offset = 0;
unsigned int bytebuffer_size = 0;
static void fill_bytebuffer()
{
if (bytebuffer_offset >= bytebuffer_size) {
/* Leave the first 4 bytes empty so we can always unwind the bitbuffer
* to the front of the bytebuffer, leave 4 bytes free at end of tail
* so we can easily top up buffer in check_trailer_gzip() */
bytebuffer_size = 4 + xread(gunzip_src_fd, &bytebuffer[4], BYTEBUFFER_MAX - 8);
bytebuffer_offset = 4;
}
}
static unsigned int fill_bitbuffer(unsigned int bitbuffer, unsigned int *current, const unsigned int required)
{
while (*current < required) {
bitbuffer |= ((unsigned int) xread_char(gunzip_src_fd)) << *current;
fill_bytebuffer();
bitbuffer |= ((unsigned int) bytebuffer[bytebuffer_offset]) << *current;
bytebuffer_offset++;
*current += 8;
}
return(bitbuffer);
}
@ -857,7 +874,10 @@ static int inflate_get_next_window(void)
int ret;
if (needAnotherBlock) {
if(e) { calculate_gunzip_crc(); return 0; } // Last block
if(e) {
calculate_gunzip_crc();
return 0;
} // Last block
method = inflate_block(&e);
needAnotherBlock = 0;
}
@ -875,6 +895,7 @@ static int inflate_get_next_window(void)
return 1; // More data left
} else needAnotherBlock = 1; // End of that block
}
/* Doesnt get here */
}
/*
@ -923,7 +944,8 @@ extern void GZ_gzReadOpen(int fd, void *unused, int nUnused)
gunzip_bytes_out = 0;
gunzip_src_fd = fd;
gunzip_in_buffer = malloc(8);
/* Input buffer */
bytebuffer = xmalloc(BYTEBUFFER_MAX);
/* initialize gunzip_window, bit buffer */
gunzip_bk = 0;
@ -940,12 +962,11 @@ extern void GZ_gzReadClose(void)
free(gunzip_crc_table);
/* Store unused bytes in a global buffer so calling applets can access it */
gunzip_in_buffer_count = 0;
if (gunzip_bk >= 8) {
/* Undo too much lookahead. The next read will be byte aligned
* so we can discard unused bits in the last meaningful byte. */
gunzip_in_buffer[gunzip_in_buffer_count] = gunzip_bb & 0xff;
gunzip_in_buffer_count++;
bytebuffer_offset--;
bytebuffer[bytebuffer_offset] = gunzip_bb & 0xff;
gunzip_bb >>= 8;
gunzip_bk -= 8;
}