xref: /freebsd/contrib/xz/src/liblzma/lzma/fastpos_tablegen.c (revision f126890ac5386406dadf7c4cfa9566cbb56537c5)
1 // SPDX-License-Identifier: 0BSD
2 
3 ///////////////////////////////////////////////////////////////////////////////
4 //
5 /// \file       fastpos_tablegen.c
6 /// \brief      Generates the lzma_fastpos[] lookup table
7 ///
8 //  Authors:    Igor Pavlov
9 //              Lasse Collin
10 //
11 ///////////////////////////////////////////////////////////////////////////////
12 
13 #include <inttypes.h>
14 #include <stdio.h>
15 
16 #define lzma_attr_visibility_hidden
17 #include "fastpos.h"
18 
19 
20 int
21 main(void)
22 {
23 	uint8_t fastpos[1 << FASTPOS_BITS];
24 
25 	const uint8_t fast_slots = 2 * FASTPOS_BITS;
26 	uint32_t c = 2;
27 
28 	fastpos[0] = 0;
29 	fastpos[1] = 1;
30 
31 	for (uint8_t slot_fast = 2; slot_fast < fast_slots; ++slot_fast) {
32 		const uint32_t k = 1 << ((slot_fast >> 1) - 1);
33 		for (uint32_t j = 0; j < k; ++j, ++c)
34 			fastpos[c] = slot_fast;
35 	}
36 
37 	// Split the SPDX string so that it won't accidentally match
38 	// when tools search for the string.
39 	printf("// SPDX" "-License-Identifier" ": 0BSD\n\n"
40 		"// This file has been generated by fastpos_tablegen.c.\n\n"
41 		"#include \"common.h\"\n"
42 		"#include \"fastpos.h\"\n\n"
43 		"const uint8_t lzma_fastpos[1 << FASTPOS_BITS] = {");
44 
45 	for (size_t i = 0; i < (1 << FASTPOS_BITS); ++i) {
46 		if (i % 16 == 0)
47 			printf("\n\t");
48 
49 		printf("%3u", (unsigned int)(fastpos[i]));
50 
51 		if (i != (1 << FASTPOS_BITS) - 1)
52 			printf(",");
53 	}
54 
55 	printf("\n};\n");
56 
57 	return 0;
58 }
59