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1 | /* |
2 | * ========== Copyright Header Begin ========================================== | |
3 | * | |
4 | * OpenSPARC T2 Processor File: BL_Utils.h | |
5 | * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved. | |
6 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES. | |
7 | * | |
8 | * The above named program is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU General Public | |
10 | * License version 2 as published by the Free Software Foundation. | |
11 | * | |
12 | * The above named program is distributed in the hope that it will be | |
13 | * useful, but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
15 | * General Public License for more details. | |
16 | * | |
17 | * You should have received a copy of the GNU General Public | |
18 | * License along with this work; if not, write to the Free Software | |
19 | * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. | |
20 | * | |
21 | * ========== Copyright Header End ============================================ | |
22 | */ | |
23 | ||
24 | #ifndef __BL_Utils_h__ | |
25 | #define __BL_Utils_h__ | |
26 | ||
27 | #include "BL_Types.h" | |
28 | ||
29 | //Extract a range of bits from a 64-bit word. | |
30 | inline uint64_t bit_selection(uint64_t v,uint8_t e,uint8_t s) | |
31 | { | |
32 | assert((e-s) <= 63); | |
33 | if((e-s) == 63) | |
34 | return v; | |
35 | else | |
36 | return ((v) & (((1ULL << ((e)-(s)+1))-1)<<(s))); | |
37 | } | |
38 | ||
39 | //Extract and downshift a bitfield indexed by (s)tarting | |
40 | //offset and (len)gth from a (v)alue | |
41 | ||
42 | inline uint64_t bit_shift(uint64_t v,uint8_t s,uint8_t len) | |
43 | { | |
44 | return (bit_selection(v,((s)+(len-1)),s)>>(s)); | |
45 | } | |
46 | ||
47 | // get_lsb() isolated the least significat bit in v. This | |
48 | // works through the carry generated by twos complement | |
49 | // negate operation. | |
50 | ||
51 | inline uint64_t get_lsb( uint64_t v ) | |
52 | { | |
53 | return v & -v; | |
54 | } | |
55 | ||
56 | // clr_lsb() clears the least significant of v. Note this | |
57 | // works through the borrow logic generated by - 1 | |
58 | ||
59 | inline uint64_t clr_lsb( uint64_t v ) | |
60 | { | |
61 | return v & (v - 1); | |
62 | } | |
63 | ||
64 | // is_power_two() returns true when value v is a power of two. | |
65 | // The routines fails for v == 0 ... you'll have to add that | |
66 | // zero test explicitely. | |
67 | ||
68 | inline bool is_power_of_two( uint64_t v ) | |
69 | { | |
70 | return clr_lsb(v) == 0; | |
71 | } | |
72 | ||
73 | // bit2idx() returns the index of the set bit in v. It uses a | |
74 | // De Bruijn sequence, which is a cyclic sequence of n bits in | |
75 | // which no sequence of n bits appears more then once. | |
76 | // http://en.wikipedia.org/wiki/De_Bruijn_sequence. The magic | |
77 | // sequence in the constant multiplier in the function below. | |
78 | // The value v has to be a power of two. | |
79 | ||
80 | static inline uint_t bit2idx( uint32_t v ) | |
81 | { | |
82 | assert(is_power_of_two(v)); | |
83 | ||
84 | static uint_t bit2tbl[32] = | |
85 | { | |
86 | 0, 1, 28, 2, 29, 14, 24, 3, 30, 22, 20, 15, 25, 17, 4, 8, | |
87 | 31, 27, 13, 23, 21, 19, 16, 7, 26, 12, 18, 6, 11, 5, 10, 9 | |
88 | }; | |
89 | ||
90 | // Note that we ignore bit 32 and above of the multiply result | |
91 | // as the type is uint32_t. | |
92 | ||
93 | return bit2tbl[(v * 0x077CB531) >> 27]; | |
94 | } | |
95 | ||
96 | // rounds a value down to a power_of_two. | |
97 | inline uint64_t round_down_to_power_of_two(uint64_t value, uint64_t power_of_two) | |
98 | { | |
99 | assert(is_power_of_two(power_of_two)); | |
100 | ||
101 | return value & ~(power_of_two - 1); | |
102 | } | |
103 | ||
104 | ||
105 | #endif | |
106 |