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//------------------------------------------------------------------------------
// GB_serialize_method: parse the compression method
//------------------------------------------------------------------------------
// SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2022, All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
//------------------------------------------------------------------------------
#include "GB.h"
#include "GB_serialize.h"
void GB_serialize_method
(
// output
int32_t *algo, // algorithm to use
int32_t *level, // compression level
// input
int32_t method
)
{
if (method < 0)
{
// no compression if method is negative
(*algo) = GxB_COMPRESSION_NONE ;
(*level) = 0 ;
return ;
}
// Determine the algorithm and level. Lower levels give faster compression
// time but not as good of compression. Higher levels give more compact
// compressions, at the cost of higher run times. For all methods: a level
// of zero, or a level setting outside the range permitted for a method,
// means that default level for that method is used.
(*algo) = 1000 * (method / 1000) ;
(*level) = method % 1000 ;
switch (*algo)
{
default :
(*algo) = GxB_COMPRESSION_LZ4 ;
(*level) = 0 ; // level is ignored
break ;
case GxB_COMPRESSION_LZ4 :
(*level) = 0 ; // level is ignored
break ;
case GxB_COMPRESSION_LZ4HC :
// level 1 to 9, with a default of 9. Note that LZ4HC supports
// levels 10, 11, and 12, but these are very slow and do not
// provide much benefit over level 9. Level 10 often results in
// a larger blob than level 9. Level 12 is typically just a tiny
// bit more compact than level 9, but can be 10x slower, or worse,
// as compared to level 9.
if ((*level) <= 0 || (*level) > 9) (*level) = 9 ;
break ;
// These cases will be uncommented when the methods are implemented:
// case GxB_COMPRESSION_ZLIB:
// // level 1 to 9, with a default of 6
// if ((*level) <= 0 || (*level) > 9) (*level) = 6 ;
// break ;
// case GxB_COMPRESSION_LZO:
// // level 1 (X1ST) to 2 (XST), with a default of 2
// if ((*level) <= 0 || (*level) > 2) (*level) = 2 ;
// break ;
// case GxB_COMPRESSION_BZIP2:
// // level 1 to 9, with a default of 9
// if ((*level) <= 0 || (*level) > 9) (*level) = 9 ;
// break ;
// case GxB_COMPRESSION_LZSS:
// (*level) = 0 ; // level is ignored
// break ;
}
}
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