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Use fastpos.h when encoding LZMA dictionary size in

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Filter Flags encoder.
This commit is contained in:
Lasse Collin 2008-01-15 14:23:35 +02:00
parent e5728142a2
commit f10fc6a69d
1 changed files with 18 additions and 20 deletions
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38
src/liblzma/common/filter_flags_encoder.c
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@ -19,6 +19,7 @@
#include "common.h" #include "common.h"
#include "lzma_encoder.h" #include "lzma_encoder.h"
#include "fastpos.h"
/// \brief Calculates the size of the Filter Properties field /// \brief Calculates the size of the Filter Properties field
@ -204,35 +205,32 @@ properties_lzma(uint8_t *out, size_t *out_pos, size_t out_size,
// Dictionary flags // Dictionary flags
// //
// Dictionary size is encoded using six bits of // Dictionary size is encoded using similar encoding that is used
// which one is mantissa and five are exponent. // internally by LZMA.
// //
// There are some limits that must hold to keep // This won't work if dictionary size can be zero:
// this coding working.
# if LZMA_DICTIONARY_SIZE_MAX > UINT32_MAX / 2
# error LZMA_DICTIONARY_SIZE_MAX is too big.
# endif
# if LZMA_DICTIONARY_SIZE_MIN < 1 # if LZMA_DICTIONARY_SIZE_MIN < 1
# error LZMA_DICTIONARY_SIZE_MIN cannot be zero. # error LZMA_DICTIONARY_SIZE_MIN cannot be zero.
# endif # endif
uint32_t d = options->dictionary_size;
// Validate it: // Validate it:
if (options->dictionary_size < LZMA_DICTIONARY_SIZE_MIN if (d < LZMA_DICTIONARY_SIZE_MIN || d > LZMA_DICTIONARY_SIZE_MAX)
|| options->dictionary_size > LZMA_DICTIONARY_SIZE_MAX)
return LZMA_HEADER_ERROR; return LZMA_HEADER_ERROR;
if (options->dictionary_size == 1) { // Round up to to the next 2^n or 2^n + 2^(n - 1) depending on which
// Special case // one is the next:
out[*out_pos] = 0x00; --d;
} else { d |= d >> 2;
// TODO This could be more elegant. d |= d >> 3;
uint32_t i = 1; d |= d >> 4;
while (((2 | ((i + 1) & 1)) << ((i - 1) / 2)) d |= d >> 8;
< options->dictionary_size) d |= d >> 16;
++i; ++d;
out[*out_pos] = i;
}
// Get the highest two bits using the proper encoding:
out[*out_pos] = get_pos_slot(d) - 1;
++*out_pos; ++*out_pos;
return LZMA_OK; return LZMA_OK;