mirror of
https://github.com/cc65/cc65.git
synced 2024-12-30 05:30:41 +00:00
37 lines
1.1 KiB
C
37 lines
1.1 KiB
C
|
/*
|
||
|
|
* uncompress.c
|
||
|
|
*
|
||
|
|
* Piotr Fusik, 18.11.2001
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <zlib.h>
|
||
|
|
|
||
|
|
int uncompress (char* dest, unsigned* destLen,
|
||
|
|
const char* source, unsigned sourceLen)
|
||
|
|
{
|
||
|
|
unsigned len;
|
||
|
|
unsigned char* ptr;
|
||
|
|
unsigned long csum;
|
||
|
|
/* source[0]: Compression method and flags
|
||
|
|
bits 0 to 3: Compression method (must be Z_DEFLATED)
|
||
|
|
bits 4 to 7: Compression info (must be <= 7)
|
||
|
|
source[1]: Flags
|
||
|
|
bits 0 to 4: Check bits
|
||
|
|
bit 5: Preset dictionary (not supported, sorry)
|
||
|
|
bits 6 to 7: Compression level
|
||
|
|
*/
|
||
|
|
if ((source[0] & 0x8f) != Z_DEFLATED || source[1] & 0x20)
|
||
|
|
return Z_DATA_ERROR;
|
||
|
|
if ((((unsigned) source[0] << 8) | (unsigned char) source[1]) % 31)
|
||
|
|
return Z_DATA_ERROR;
|
||
|
|
*destLen = len = inflatemem(dest, source + 2);
|
||
|
|
ptr = (unsigned char*) source + sourceLen - 4;
|
||
|
|
csum = adler32(adler32(0L, Z_NULL, 0), dest, len);
|
||
|
|
if ((unsigned char) csum != ptr[3]
|
||
|
|
|| (unsigned char) (csum >> 8) != ptr[2]
|
||
|
|
|| (unsigned char) (csum >> 16) != ptr[1]
|
||
|
|
|| (unsigned char) (csum >> 24) != ptr[0])
|
||
|
|
return Z_DATA_ERROR;
|
||
|
|
return Z_OK;
|
||
|
|
}
|