// SPDX-License-Identifier: GPL-2.0-or-later /* * 842 Software Compression * * Copyright (C) 2015 Dan Streetman, IBM Corp * * See 842.h for details of the 842 compressed format. */ #define pr_fmt(fmt) … #define MODULE_NAME … #include <linux/hashtable.h> #include "842.h" #include "842_debugfs.h" #define SW842_HASHTABLE8_BITS … #define SW842_HASHTABLE4_BITS … #define SW842_HASHTABLE2_BITS … /* By default, we allow compressing input buffers of any length, but we must * use the non-standard "short data" template so the decompressor can correctly * reproduce the uncompressed data buffer at the right length. However the * hardware 842 compressor will not recognize the "short data" template, and * will fail to decompress any compressed buffer containing it (I have no idea * why anyone would want to use software to compress and hardware to decompress * but that's beside the point). This parameter forces the compression * function to simply reject any input buffer that isn't a multiple of 8 bytes * long, instead of using the "short data" template, so that all compressed * buffers produced by this function will be decompressable by the 842 hardware * decompressor. Unless you have a specific need for that, leave this disabled * so that any length buffer can be compressed. */ static bool sw842_strict; module_param_named(strict, sw842_strict, bool, 0644); static u8 comp_ops[OPS_MAX][5] = …; struct sw842_hlist_node8 { … }; struct sw842_hlist_node4 { … }; struct sw842_hlist_node2 { … }; #define INDEX_NOT_FOUND … #define INDEX_NOT_CHECKED … struct sw842_param { … }; #define get_input_data(p, o, b) … #define init_hashtable_nodes(p, b) … #define find_index(p, b, n) … #define check_index(p, b, n) … #define replace_hash(p, b, i, d) … static u8 bmask[8] = …; static int add_bits(struct sw842_param *p, u64 d, u8 n); static int __split_add_bits(struct sw842_param *p, u64 d, u8 n, u8 s) { … } static int add_bits(struct sw842_param *p, u64 d, u8 n) { … } static int add_template(struct sw842_param *p, u8 c) { … } static int add_repeat_template(struct sw842_param *p, u8 r) { … } static int add_short_data_template(struct sw842_param *p, u8 b) { … } static int add_zeros_template(struct sw842_param *p) { … } static int add_end_template(struct sw842_param *p) { … } static bool check_template(struct sw842_param *p, u8 c) { … } static void get_next_data(struct sw842_param *p) { … } /* update the hashtable entries. * only call this after finding/adding the current template * the dataN fields for the current 8 byte block must be already updated */ static void update_hashtables(struct sw842_param *p) { … } /* find the next template to use, and add it * the p->dataN fields must already be set for the current 8 byte block */ static int process_next(struct sw842_param *p) { … } /** * sw842_compress * * Compress the uncompressed buffer of length @ilen at @in to the output buffer * @out, using no more than @olen bytes, using the 842 compression format. * * Returns: 0 on success, error on failure. The @olen parameter * will contain the number of output bytes written on success, or * 0 on error. */ int sw842_compress(const u8 *in, unsigned int ilen, u8 *out, unsigned int *olen, void *wmem) { … } EXPORT_SYMBOL_GPL(…); static int __init sw842_init(void) { … } module_init(…) …; static void __exit sw842_exit(void) { … } module_exit(sw842_exit); MODULE_LICENSE(…) …; MODULE_DESCRIPTION(…) …; MODULE_AUTHOR(…) …;
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