fastpos.h File Reference

Kind of two-bit version of bit scan reverse. More...

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Macros
#define	FASTPOS_BITS   13
#define	fastpos_shift(extra, n)    ((extra) + (n) * (FASTPOS_BITS - 1))
#define	fastpos_limit(extra, n)    (UINT32_C(1) << (FASTPOS_BITS + fastpos_shift(extra, n)))
#define	fastpos_result(dist, extra, n)

Functions
static uint32_t	get_dist_slot (uint32_t dist)

Variables
const uint8_t	lzma_fastpos [1<< FASTPOS_BITS]

Detailed Description

Kind of two-bit version of bit scan reverse.

Definition in file fastpos.h.

Macro Definition Documentation

FASTPOS_BITS

#define FASTPOS_BITS   13

Definition at line 92 of file fastpos.h.

fastpos_limit

#define fastpos_limit	(		extra,
			n
	)		(UINT32_C(1) << (FASTPOS_BITS + fastpos_shift(extra, n)))

Definition at line 100 of file fastpos.h.

fastpos_result

#define fastpos_result	(		dist,
			extra,
			n
	)

Value:

    (uint32_t)(lzma_fastpos[(dist) >> fastpos_shift(extra, n)]) \
            + 2 * fastpos_shift(extra, n)

Definition at line 103 of file fastpos.h.

fastpos_shift

#define fastpos_shift	(		extra,
			n
	)		((extra) + (n) * (FASTPOS_BITS - 1))

Definition at line 97 of file fastpos.h.

Function Documentation

get_dist_slot()

static uint32_t get_dist_slot ( uint32_t  dist )

inlinestatic

Definition at line 109 of file fastpos.h.

{
    // If it is small enough, we can pick the result directly from
    // the precalculated table.
    if (dist < fastpos_limit(0, 0))
        return lzma_fastpos[dist];
 
    if (dist < fastpos_limit(0, 1))
        return fastpos_result(dist, 0, 1);
 
    return fastpos_result(dist, 0, 2);
}

References fastpos_limit, fastpos_result, and lzma_fastpos.

Referenced by fill_dist_prices(), lzma_lzma2_props_encode(), and match().

Variable Documentation

lzma_fastpos

const uint8_t lzma_fastpos[1<< FASTPOS_BITS]

extern

Definition at line 6 of file fastpos_table.c.

Referenced by get_dist_slot().