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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: bits.h,v 1.3 1999/06/20 23:31:52 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 1.3 1999/06/20 23:31:52 mdw |
34 | * More portability enhancements. |
35 | * |
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36 | * Revision 1.2 1999/06/17 00:12:46 mdw |
37 | * Improve portability for shift and rotate macros. |
38 | * |
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39 | * Revision 1.1 1999/06/01 09:46:19 mdw |
40 | * New addition: bit manipulation macros. |
41 | * |
42 | */ |
43 | |
44 | #ifndef BITS_H |
45 | #define BITS_H |
46 | |
47 | #ifdef __cplusplus |
48 | extern "C" { |
49 | #endif |
50 | |
51 | /*----- Header files ------------------------------------------------------*/ |
52 | |
53 | #include <limits.h> |
54 | #include <stddef.h> |
55 | |
56 | /*----- Decide on some types ----------------------------------------------*/ |
57 | |
58 | /* --- Decide on a 32-bit type --- * |
59 | * |
60 | * I want a type which is capable of expressing 32-bit numbers. Because some |
61 | * implementations have 64-bit @long@s (infinitely preferable to the abortion |
62 | * that is @long long@), using @unsigned long@ regardless is wasteful. So, |
63 | * if @int@ appears to be good enough, then I'll go with that. |
64 | */ |
65 | |
66 | #if UINT_MAX >= 0xffffffffu |
67 | typedef unsigned int uint32; |
68 | #else |
69 | typedef unsigned long uint32; |
70 | #endif |
71 | |
72 | /* --- Decide on 16-bit and 8-bit types --- * |
73 | * |
74 | * This is more for brevity than anything else. |
75 | */ |
76 | |
77 | typedef unsigned short uint16; |
78 | typedef unsigned char octet; |
79 | |
80 | /* --- WARNING! --- * |
81 | * |
82 | * Never lose sight of the fact that the above types may be wider than the |
83 | * names suggest. Some architectures have 32-bit @short@s for example. |
84 | */ |
85 | |
86 | /*----- Macros ------------------------------------------------------------*/ |
87 | |
88 | /* --- Useful masks --- */ |
89 | |
90 | #define MASK8 0xffu |
91 | #define MASK16 0xffffu |
92 | #define MASK32 0xffffffffu |
93 | |
94 | /* --- Type coercions --- */ |
95 | |
96 | #define U8(x) ((octet)((x) & MASK8)) |
97 | #define U16(x) ((uint16)((x) & MASK16)) |
98 | #define U32(x) ((uint32)((x) & MASK32)) |
99 | |
100 | /* --- Safe shifting macros --- */ |
101 | |
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102 | #define LSL8(v, s) U8(U8(v) << ((s) & 7u)) |
103 | #define LSR8(v, s) U8(U8(v) >> ((s) & 7u)) |
104 | #define LSL16(v, s) U16(U16(v) << ((s) & 15u)) |
105 | #define LSR16(v, s) U16(U16(v) >> ((s) & 15u)) |
106 | #define LSL32(v, s) U32(U32(v) << ((s) & 31u)) |
107 | #define LSR32(v, s) U32(U32(v) >> ((s) & 31u)) |
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108 | |
109 | /* --- Rotation macros --- */ |
110 | |
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111 | #define ROL8(v, s) (LSL8((v), (s)) | (LSR8((v), 8u - (s)))) |
112 | #define ROR8(v, s) (LSR8((v), (s)) | (LSL8((v), 8u - (s)))) |
113 | #define ROL16(v, s) (LSL16((v), (s)) | (LSR16((v), 16u - (s)))) |
114 | #define ROR16(v, s) (LSR16((v), (s)) | (LSL16((v), 16u - (s)))) |
115 | #define ROL32(v, s) (LSL32((v), (s)) | (LSR32((v), 32u - (s)))) |
116 | #define ROR32(v, s) (LSR32((v), (s)) | (LSL32((v), 32u - (s)))) |
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117 | |
118 | /* --- Storage and retrieval --- */ |
119 | |
120 | #define GETBYTE(p, o) (((octet *)(p))[o] & MASK8) |
121 | #define PUTBYTE(p, o, v) (((octet *)(p))[o] = U8((v))) |
122 | |
123 | #define LOAD8(p) (GETBYTE((p), 0)) |
124 | #define STORE8(p, v) (PUTBYTE((p), 0, (v))) |
125 | |
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126 | #define LOAD16_B(p) \ |
127 | (((uint16)GETBYTE((p), 0) << 8) | \ |
128 | ((uint16)GETBYTE((p), 1) << 0)) |
129 | #define LOAD16_L(p) \ |
130 | (((uint16)GETBYTE((p), 0) << 0) | \ |
131 | ((uint16)GETBYTE((p), 1) << 8)) |
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132 | #define LOAD16(p) LOAD16_B((p)) |
133 | |
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134 | #define STORE16_B(p, v) \ |
135 | (PUTBYTE((p), 0, (uint16)(v) >> 8), \ |
136 | PUTBYTE((p), 1, (uint16)(v) >> 0)) |
137 | #define STORE16_L(p, v) \ |
138 | (PUTBYTE((p), 0, (uint16)(v) >> 0), \ |
139 | PUTBYTE((p), 1, (uint16)(v) >> 8)) |
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140 | #define STORE16(p, v) STORE16_B((p), (v)) |
141 | |
142 | #define LOAD32_B(p) \ |
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143 | (((uint32)GETBYTE((p), 0) << 24) | \ |
144 | ((uint32)GETBYTE((p), 1) << 16) | \ |
145 | ((uint32)GETBYTE((p), 2) << 8) | \ |
146 | ((uint32)GETBYTE((p), 3) << 0)) |
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147 | #define LOAD32_L(p) \ |
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148 | (((uint32)GETBYTE((p), 0) << 0) | \ |
149 | ((uint32)GETBYTE((p), 1) << 8) | \ |
150 | ((uint32)GETBYTE((p), 2) << 16) | \ |
151 | ((uint32)GETBYTE((p), 3) << 24)) |
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152 | #define LOAD32(p) LOAD32_B((p)) |
153 | |
154 | #define STORE32_B(p, v) \ |
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155 | (PUTBYTE((p), 0, (uint32)(v) >> 24), \ |
156 | PUTBYTE((p), 1, (uint32)(v) >> 16), \ |
157 | PUTBYTE((p), 2, (uint32)(v) >> 8), \ |
158 | PUTBYTE((p), 3, (uint32)(v) >> 0)) |
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159 | #define STORE32_L(p, v) \ |
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160 | (PUTBYTE((p), 0, (uint32)(v) >> 0), \ |
161 | PUTBYTE((p), 1, (uint32)(v) >> 8), \ |
162 | PUTBYTE((p), 2, (uint32)(v) >> 16), \ |
163 | PUTBYTE((p), 3, (uint32)(v) >> 24)) |
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164 | #define STORE32(p, v) STORE32_B((p), (v)) |
165 | |
166 | /*----- That's all, folks -------------------------------------------------*/ |
167 | |
168 | #ifdef __cplusplus |
169 | } |
170 | #endif |
171 | |
172 | #endif |