xref: /freebsd/contrib/xz/src/liblzma/rangecoder/price_tablegen.c (revision f126890ac5386406dadf7c4cfa9566cbb56537c5)
1 // SPDX-License-Identifier: 0BSD
2 
3 ///////////////////////////////////////////////////////////////////////////////
4 //
5 /// \file       price_tablegen.c
6 /// \brief      Probability price table generator
7 ///
8 /// Compiling: gcc -std=c99 -o price_tablegen price_tablegen.c
9 ///
10 //  Authors:    Igor Pavlov
11 //              Lasse Collin
12 //
13 ///////////////////////////////////////////////////////////////////////////////
14 
15 #include <inttypes.h>
16 #include <stdio.h>
17 
18 // Make it compile without common.h.
19 #define BUILDING_PRICE_TABLEGEN
20 #define lzma_attr_visibility_hidden
21 
22 #include "range_common.h"
23 #include "price.h"
24 
25 
26 static uint32_t rc_prices[RC_PRICE_TABLE_SIZE];
27 
28 
29 static void
30 init_price_table(void)
31 {
32 	for (uint32_t i = (UINT32_C(1) << RC_MOVE_REDUCING_BITS) / 2;
33 			i < RC_BIT_MODEL_TOTAL;
34 			i += (UINT32_C(1) << RC_MOVE_REDUCING_BITS)) {
35 		const uint32_t cycles_bits = RC_BIT_PRICE_SHIFT_BITS;
36 		uint32_t w = i;
37 		uint32_t bit_count = 0;
38 
39 		for (uint32_t j = 0; j < cycles_bits; ++j) {
40 			w *= w;
41 			bit_count <<= 1;
42 
43 			while (w >= (UINT32_C(1) << 16)) {
44 				w >>= 1;
45 				++bit_count;
46 			}
47 		}
48 
49 		rc_prices[i >> RC_MOVE_REDUCING_BITS]
50 				= (RC_BIT_MODEL_TOTAL_BITS << cycles_bits)
51 				- 15 - bit_count;
52 	}
53 
54 	return;
55 }
56 
57 
58 static void
59 print_price_table(void)
60 {
61 	// Split the SPDX string so that it won't accidentally match
62 	// when tools search for the string.
63 	printf("// SPDX" "-License-Identifier" ": 0BSD\n\n"
64 		"// This file has been generated by price_tablegen.c.\n\n"
65 		"#include \"range_encoder.h\"\n\n"
66 		"const uint8_t lzma_rc_prices["
67 		"RC_PRICE_TABLE_SIZE] = {");
68 
69 	const size_t array_size = sizeof(lzma_rc_prices)
70 			/ sizeof(lzma_rc_prices[0]);
71 	for (size_t i = 0; i < array_size; ++i) {
72 		if (i % 8 == 0)
73 			printf("\n\t");
74 
75 		printf("%4" PRIu32, rc_prices[i]);
76 
77 		if (i != array_size - 1)
78 			printf(",");
79 	}
80 
81 	printf("\n};\n");
82 
83 	return;
84 }
85 
86 
87 int
88 main(void)
89 {
90 	init_price_table();
91 	print_price_table();
92 	return 0;
93 }
94