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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: bits.h,v 1.2 1999/06/17 00:12:46 mdw Exp $ |
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4 | * |
5 | * Portable bit-level manipulation macros |
6 | * |
7 | * (c) 1998 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of the mLib utilities library. |
13 | * |
14 | * mLib is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
18 | * |
19 | * mLib is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with mLib; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: bits.h,v $ |
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33 | * Revision 1.2 1999/06/17 00:12:46 mdw |
34 | * Improve portability for shift and rotate macros. |
35 | * |
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36 | * Revision 1.1 1999/06/01 09:46:19 mdw |
37 | * New addition: bit manipulation macros. |
38 | * |
39 | */ |
40 | |
41 | #ifndef BITS_H |
42 | #define BITS_H |
43 | |
44 | #ifdef __cplusplus |
45 | extern "C" { |
46 | #endif |
47 | |
48 | /*----- Header files ------------------------------------------------------*/ |
49 | |
50 | #include <limits.h> |
51 | #include <stddef.h> |
52 | |
53 | /*----- Decide on some types ----------------------------------------------*/ |
54 | |
55 | /* --- Decide on a 32-bit type --- * |
56 | * |
57 | * I want a type which is capable of expressing 32-bit numbers. Because some |
58 | * implementations have 64-bit @long@s (infinitely preferable to the abortion |
59 | * that is @long long@), using @unsigned long@ regardless is wasteful. So, |
60 | * if @int@ appears to be good enough, then I'll go with that. |
61 | */ |
62 | |
63 | #if UINT_MAX >= 0xffffffffu |
64 | typedef unsigned int uint32; |
65 | #else |
66 | typedef unsigned long uint32; |
67 | #endif |
68 | |
69 | /* --- Decide on 16-bit and 8-bit types --- * |
70 | * |
71 | * This is more for brevity than anything else. |
72 | */ |
73 | |
74 | typedef unsigned short uint16; |
75 | typedef unsigned char octet; |
76 | |
77 | /* --- WARNING! --- * |
78 | * |
79 | * Never lose sight of the fact that the above types may be wider than the |
80 | * names suggest. Some architectures have 32-bit @short@s for example. |
81 | */ |
82 | |
83 | /*----- Macros ------------------------------------------------------------*/ |
84 | |
85 | /* --- Useful masks --- */ |
86 | |
87 | #define MASK8 0xffu |
88 | #define MASK16 0xffffu |
89 | #define MASK32 0xffffffffu |
90 | |
91 | /* --- Type coercions --- */ |
92 | |
93 | #define U8(x) ((octet)((x) & MASK8)) |
94 | #define U16(x) ((uint16)((x) & MASK16)) |
95 | #define U32(x) ((uint32)((x) & MASK32)) |
96 | |
97 | /* --- Safe shifting macros --- */ |
98 | |
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99 | #define LSL8(v, s) U8(U8(v) << ((s) & 7u)) |
100 | #define LSR8(v, s) U8(U8(v) >> ((s) & 7u)) |
101 | #define LSL16(v, s) U16(U16(v) << ((s) & 15u)) |
102 | #define LSR16(v, s) U16(U16(v) >> ((s) & 15u)) |
103 | #define LSL32(v, s) U32(U32(v) << ((s) & 31u)) |
104 | #define LSR32(v, s) U32(U32(v) >> ((s) & 31u)) |
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105 | |
106 | /* --- Rotation macros --- */ |
107 | |
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108 | #define ROL8(v, s) (LSL8((v), (s)) | (LSR8((v), 8u - (s)))) |
109 | #define ROR8(v, s) (LSR8((v), (s)) | (LSL8((v), 8u - (s)))) |
110 | #define ROL16(v, s) (LSL16((v), (s)) | (LSR16((v), 16u - (s)))) |
111 | #define ROR16(v, s) (LSR16((v), (s)) | (LSL16((v), 16u - (s)))) |
112 | #define ROL32(v, s) (LSL32((v), (s)) | (LSR32((v), 32u - (s)))) |
113 | #define ROR32(v, s) (LSR32((v), (s)) | (LSL32((v), 32u - (s)))) |
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114 | |
115 | /* --- Storage and retrieval --- */ |
116 | |
117 | #define GETBYTE(p, o) (((octet *)(p))[o] & MASK8) |
118 | #define PUTBYTE(p, o, v) (((octet *)(p))[o] = U8((v))) |
119 | |
120 | #define LOAD8(p) (GETBYTE((p), 0)) |
121 | #define STORE8(p, v) (PUTBYTE((p), 0, (v))) |
122 | |
123 | #define LOAD16_B(p) ((GETBYTE((p), 0) << 8) | GETBYTE((p), 1)) |
124 | #define LOAD16_L(p) (GETBYTE((p), 0) | (GETBYTE((p), 1) << 8)) |
125 | #define LOAD16(p) LOAD16_B((p)) |
126 | |
127 | #define STORE16_B(p, v) (PUTBYTE((p), 0, (v) >> 8), PUTBYTE((p), 1, (v))) |
128 | #define STORE16_L(p, v) (PUTBYTE((p), 0, (v)), PUTBYTE((p), 1, (v) >> 8)) |
129 | #define STORE16(p, v) STORE16_B((p), (v)) |
130 | |
131 | #define LOAD32_B(p) \ |
132 | ((GETBYTE((p), 0) << 24) | (GETBYTE((p), 1) << 16) | \ |
133 | (GETBYTE((p), 2) << 8) | (GETBYTE((p), 3) << 0)) |
134 | #define LOAD32_L(p) \ |
135 | ((GETBYTE((p), 0) << 0) | (GETBYTE((p), 1) << 8) | \ |
136 | (GETBYTE((p), 2) << 16) | (GETBYTE((p), 3) << 24)) |
137 | #define LOAD32(p) LOAD32_B((p)) |
138 | |
139 | #define STORE32_B(p, v) \ |
140 | (PUTBYTE((p), 0, (v) >> 24), PUTBYTE((p), 1, (v) >> 16), \ |
141 | PUTBYTE((p), 2, (v) >> 8), PUTBYTE((p), 3, (v) >> 0)) |
142 | #define STORE32_L(p, v) \ |
143 | (PUTBYTE((p), 0, (v) >> 0), PUTBYTE((p), 1, (v) >> 8), \ |
144 | PUTBYTE((p), 2, (v) >> 16), PUTBYTE((p), 3, (v) >> 24)) |
145 | #define STORE32(p, v) STORE32_B((p), (v)) |
146 | |
147 | /*----- That's all, folks -------------------------------------------------*/ |
148 | |
149 | #ifdef __cplusplus |
150 | } |
151 | #endif |
152 | |
153 | #endif |