cregit-Linux how code gets into the kernel

Release 4.9 lib/zlib_deflate/defutil.h

Directory: lib/zlib_deflate

#define Assert(err, str) 

#define Trace(dummy) 

#define Tracev(dummy) 

#define Tracecv(err, dummy) 

#define Tracevv(dummy) 

#define LENGTH_CODES 29
/* number of length codes, not counting the special END_BLOCK code */

#define LITERALS  256
/* number of literal bytes 0..255 */

/* number of Literal or Length codes, including the END_BLOCK code */

#define D_CODES   30
/* number of distance codes */

#define BL_CODES  19
/* number of codes used to transfer the bit lengths */

#define HEAP_SIZE (2*L_CODES+1)
/* maximum heap size */

#define MAX_BITS 15
/* All codes must not exceed MAX_BITS bits */

#define INIT_STATE    42

#define BUSY_STATE   113

#define FINISH_STATE 666
/* Stream status */

/* Data structure describing a single value and its code string. */

typedef struct ct_data_s {
    union {
ush  freq;       /* frequency count */
ush  code;       /* bit string */
    union {
ush  dad;        /* father node in Huffman tree */
ush  len;        /* length of bit string */

#define Freq fc.freq

#define Code fc.code

#define Dad

#define Len  dl.len

typedef struct static_tree_desc_s  static_tree_desc;

typedef struct tree_desc_s {
ct_data *dyn_tree;           /* the dynamic tree */
int     max_code;            /* largest code with non zero frequency */
static_tree_desc *stat_desc; /* the corresponding static tree */

typedef ush Pos;

typedef unsigned IPos;

/* A Pos is an index in the character window. We use short instead of int to
 * save space in the various tables. IPos is used only for parameter passing.

typedef struct deflate_state {
z_streamp strm;      /* pointer back to this zlib stream */
int   status;        /* as the name implies */
Byte *pending_buf;   /* output still pending */
ulg   pending_buf_size; /* size of pending_buf */
Byte *pending_out;   /* next pending byte to output to the stream */
int   pending;       /* nb of bytes in the pending buffer */
int   noheader;      /* suppress zlib header and adler32 */
Byte  data_type;     /* UNKNOWN, BINARY or ASCII */
Byte  method;        /* STORED (for zip only) or DEFLATED */
int   last_flush;    /* value of flush param for previous deflate call */

                /* used by deflate.c: */

uInt  w_size;        /* LZ77 window size (32K by default) */
uInt  w_bits;        /* log2(w_size)  (8..16) */
uInt  w_mask;        /* w_size - 1 */

Byte *window;
    /* Sliding window. Input bytes are read into the second half of the window,
     * and move to the first half later to keep a dictionary of at least wSize
     * bytes. With this organization, matches are limited to a distance of
     * wSize-MAX_MATCH bytes, but this ensures that IO is always
     * performed with a length multiple of the block size. Also, it limits
     * the window size to 64K, which is quite useful on MSDOS.
     * To do: use the user input buffer as sliding window.

ulg window_size;
    /* Actual size of window: 2*wSize, except when the user input buffer
     * is directly used as sliding window.

Pos *prev;
    /* Link to older string with same hash index. To limit the size of this
     * array to 64K, this link is maintained only for the last 32K strings.
     * An index in this array is thus a window index modulo 32K.

Pos *head; /* Heads of the hash chains or NIL. */

uInt  ins_h;          /* hash index of string to be inserted */
uInt  hash_size;      /* number of elements in hash table */
uInt  hash_bits;      /* log2(hash_size) */
uInt  hash_mask;      /* hash_size-1 */

uInt  hash_shift;
    /* Number of bits by which ins_h must be shifted at each input
     * step. It must be such that after MIN_MATCH steps, the oldest
     * byte no longer takes part in the hash key, that is:
     *   hash_shift * MIN_MATCH >= hash_bits

long block_start;
    /* Window position at the beginning of the current output block. Gets
     * negative when the window is moved backwards.

uInt match_length;           /* length of best match */
IPos prev_match;             /* previous match */
int match_available;         /* set if previous match exists */
uInt strstart;               /* start of string to insert */
uInt match_start;            /* start of matching string */
uInt lookahead;              /* number of valid bytes ahead in window */

uInt prev_length;
    /* Length of the best match at previous step. Matches not greater than this
     * are discarded. This is used in the lazy match evaluation.

uInt max_chain_length;
    /* To speed up deflation, hash chains are never searched beyond this
     * length.  A higher limit improves compression ratio but degrades the
     * speed.

uInt max_lazy_match;
    /* Attempt to find a better match only when the current match is strictly
     * smaller than this value. This mechanism is used only for compression
     * levels >= 4.

#   define max_insert_length  max_lazy_match
    /* Insert new strings in the hash table only if the match length is not
     * greater than this length. This saves time but degrades compression.
     * max_insert_length is used only for compression levels <= 3.

int level;    /* compression level (1..9) */
int strategy; /* favor or force Huffman coding*/

uInt good_match;
    /* Use a faster search when the previous match is longer than this */

int nice_match; /* Stop searching when current match exceeds this */

                /* used by trees.c: */
    /* Didn't use ct_data typedef below to suppress compiler warning */
struct ct_data_s dyn_ltree[HEAP_SIZE];   /* literal and length tree */
struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */
struct ct_data_s bl_tree[2*BL_CODES+1];  /* Huffman tree for bit lengths */

struct tree_desc_s l_desc;               /* desc. for literal tree */
struct tree_desc_s d_desc;               /* desc. for distance tree */
struct tree_desc_s bl_desc;              /* desc. for bit length tree */

ush bl_count[MAX_BITS+1];
    /* number of codes at each bit length for an optimal tree */

int heap[2*L_CODES+1];      /* heap used to build the Huffman trees */
int heap_len;               /* number of elements in the heap */
int heap_max;               /* element of largest frequency */
    /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
     * The same heap array is used to build all trees.

uch depth[2*L_CODES+1];
    /* Depth of each subtree used as tie breaker for trees of equal frequency

uch *l_buf;          /* buffer for literals or lengths */

uInt  lit_bufsize;
    /* Size of match buffer for literals/lengths.  There are 4 reasons for
     * limiting lit_bufsize to 64K:
     *   - frequencies can be kept in 16 bit counters
     *   - if compression is not successful for the first block, all input
     *     data is still in the window so we can still emit a stored block even
     *     when input comes from standard input.  (This can also be done for
     *     all blocks if lit_bufsize is not greater than 32K.)
     *   - if compression is not successful for a file smaller than 64K, we can
     *     even emit a stored file instead of a stored block (saving 5 bytes).
     *     This is applicable only for zip (not gzip or zlib).
     *   - creating new Huffman trees less frequently may not provide fast
     *     adaptation to changes in the input data statistics. (Take for
     *     example a binary file with poorly compressible code followed by
     *     a highly compressible string table.) Smaller buffer sizes give
     *     fast adaptation but have of course the overhead of transmitting
     *     trees more frequently.
     *   - I can't count above 4

uInt last_lit;      /* running index in l_buf */

ush *d_buf;
    /* Buffer for distances. To simplify the code, d_buf and l_buf have
     * the same number of elements. To use different lengths, an extra flag
     * array would be necessary.

ulg opt_len;        /* bit length of current block with optimal trees */
ulg static_len;     /* bit length of current block with static trees */
ulg compressed_len; /* total bit length of compressed file */
uInt matches;       /* number of string matches in current block */
int last_eob_len;   /* bit length of EOB code for last block */

ulg bits_sent;      /* bit length of the compressed data */

ush bi_buf;
    /* Output buffer. bits are inserted starting at the bottom (least
     * significant bits).
int bi_valid;
    /* Number of valid bits in bi_buf.  All bits above the last valid bit
     * are always zero.


typedef struct deflate_workspace {
    /* State memory for the deflator */
deflate_state deflate_memory;
Byte *window_memory;
Pos *prev_memory;
Pos *head_memory;
char *overlay_memory;

#define zlib_deflate_window_memsize(windowBits) \
	(2 * (1 << (windowBits)) * sizeof(Byte))

#define zlib_deflate_prev_memsize(windowBits) \
	((1 << (windowBits)) * sizeof(Pos))

#define zlib_deflate_head_memsize(memLevel) \
	((1 << ((memLevel)+7)) * sizeof(Pos))

#define zlib_deflate_overlay_memsize(memLevel) \
	((1 << ((memLevel)+6)) * (sizeof(ush)+2))

/* Output a byte on the stream.
 * IN assertion: there is enough room in pending_buf.

#define put_byte(s, c) {s->pending_buf[s->pending++] = (c);}

/* Minimum amount of lookahead, except at the end of the input file.
 * See deflate.c for comments about the MIN_MATCH+1.

#define MAX_DIST(s)  ((s)->w_size-MIN_LOOKAHEAD)
/* In order to simplify the code, particularly on 16 bit machines, match
 * distances are limited to MAX_DIST instead of WSIZE.

        /* in trees.c */
void zlib_tr_init         (deflate_state *s);
int  zlib_tr_tally        (deflate_state *s, unsigned dist, unsigned lc);
ulg  zlib_tr_flush_block  (deflate_state *s, char *buf, ulg stored_len,
			   int eof);
void zlib_tr_align        (deflate_state *s);
void zlib_tr_stored_block (deflate_state *s, char *buf, ulg stored_len,
			   int eof);
void zlib_tr_stored_type_only (deflate_state *);

/* ===========================================================================
 * Output a short LSB first on the stream.
 * IN assertion: there is enough room in pendingBuf.

#define put_short(s, w) { \
    put_byte(s, (uch)((w) & 0xff)); \
    put_byte(s, (uch)((ush)(w) >> 8)); \

/* ===========================================================================
 * Flush the bit buffer, keeping at most 7 bits in it.

static inline void bi_flush(deflate_state *s) { if (s->bi_valid == 16) { put_short(s, s->bi_buf); s->bi_buf = 0; s->bi_valid = 0; } else if (s->bi_valid >= 8) { put_byte(s, (Byte)s->bi_buf); s->bi_buf >>= 8; s->bi_valid -= 8; } }


linus torvaldslinus torvalds77100.00%1100.00%

/* =========================================================================== * Flush the bit buffer and align the output on a byte boundary */
static inline void bi_windup(deflate_state *s) { if (s->bi_valid > 8) { put_short(s, s->bi_buf); } else if (s->bi_valid > 0) { put_byte(s, (Byte)s->bi_buf); } s->bi_buf = 0; s->bi_valid = 0; #ifdef DEBUG_ZLIB s->bits_sent = (s->bits_sent+7) & ~7; #endif }


linus torvaldslinus torvalds85100.00%1100.00%

Overall Contributors

linus torvaldslinus torvalds72390.04%120.00%
joern engeljoern engel435.35%240.00%
james kenistonjames keniston364.48%120.00%
joe perchesjoe perches10.12%120.00%
Directory: lib/zlib_deflate