From 41d86c73b21191a3fa9ea5f476fc9f1fc5e4f8b3 Mon Sep 17 00:00:00 2001 From: Mark Adler Date: Sun, 4 Nov 2018 10:31:46 -0800 Subject: Add crc32_combine_gen() and crc32_combine_op() for fast combines. When the same len2 is used repeatedly, it is faster to use crc32_combine_gen() to generate an operator, that is then used to combine CRCs with crc32_combine_op(). --- zlib.h | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'zlib.h') diff --git a/zlib.h b/zlib.h index 0b74b25..14d87a2 100644 --- a/zlib.h +++ b/zlib.h @@ -1757,6 +1757,22 @@ ZEXTERN uLong ZEXPORT crc32_combine OF((uLong crc1, uLong crc2, z_off_t len2)); len2. */ +/* +ZEXTERN void ZEXPORT crc32_combine_gen OF((z_crc_t op[32], z_off_t len2)); + + Generate the operator op corresponding to length len2, to be used with + crc32_combine_op(). op must have room for 32 z_crc_t values. (32 is the + number of bits in the CRC.) +*/ + +ZEXTERN uLong ZEXPORT crc32_combine_op OF((uLong crc1, uLong crc2, + const z_crc_t *op)); +/* + Give the same result as crc32_combine(), using op in place of len2. op is + is generated from len2 by crc32_combine_gen(). This will be faster than + crc32_combine() if the generated op is used many times. +*/ + /* various hacks, don't look :) */ @@ -1844,6 +1860,7 @@ ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file)); /* backward compatibility */ ZEXTERN z_off64_t ZEXPORT gzoffset64 OF((gzFile)); ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off64_t)); ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off64_t)); + ZEXTERN void ZEXPORT crc32_combine_gen64 OF((z_crc_t *op, z_off64_t)); #endif #if !defined(ZLIB_INTERNAL) && defined(Z_WANT64) @@ -1854,6 +1871,7 @@ ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file)); /* backward compatibility */ # define z_gzoffset z_gzoffset64 # define z_adler32_combine z_adler32_combine64 # define z_crc32_combine z_crc32_combine64 +# define z_crc32_combine_gen z_crc32_combine64_gen # else # define gzopen gzopen64 # define gzseek gzseek64 @@ -1861,6 +1879,7 @@ ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file)); /* backward compatibility */ # define gzoffset gzoffset64 # define adler32_combine adler32_combine64 # define crc32_combine crc32_combine64 +# define crc32_combine_gen crc32_combine_gen64 # endif # ifndef Z_LARGE64 ZEXTERN gzFile ZEXPORT gzopen64 OF((const char *, const char *)); @@ -1869,6 +1888,7 @@ ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file)); /* backward compatibility */ ZEXTERN z_off_t ZEXPORT gzoffset64 OF((gzFile)); ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t)); ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t)); + ZEXTERN void ZEXPORT crc32_combine_gen64 OF((z_crc_t *op, z_off_t)); # endif #else ZEXTERN gzFile ZEXPORT gzopen OF((const char *, const char *)); @@ -1877,12 +1897,14 @@ ZEXTERN int ZEXPORT gzgetc_ OF((gzFile file)); /* backward compatibility */ ZEXTERN z_off_t ZEXPORT gzoffset OF((gzFile)); ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t)); ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t)); + ZEXTERN void ZEXPORT crc32_combine_gen OF((z_crc_t *op, z_off_t)); #endif #else /* Z_SOLO */ ZEXTERN uLong ZEXPORT adler32_combine OF((uLong, uLong, z_off_t)); ZEXTERN uLong ZEXPORT crc32_combine OF((uLong, uLong, z_off_t)); + ZEXTERN void ZEXPORT crc32_combine_gen OF((z_crc_t *op, z_off_t)); #endif /* !Z_SOLO */ -- cgit v1.2.3-55-g6feb