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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: bits.h,v 1.4 1999/12/10 23:42:04 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 1.4 1999/12/10 23:42:04 mdw |
34 | * Change header file guard names. |
35 | * |
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36 | * Revision 1.3 1999/06/20 23:31:52 mdw |
37 | * More portability enhancements. |
38 | * |
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39 | * Revision 1.2 1999/06/17 00:12:46 mdw |
40 | * Improve portability for shift and rotate macros. |
41 | * |
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42 | * Revision 1.1 1999/06/01 09:46:19 mdw |
43 | * New addition: bit manipulation macros. |
44 | * |
45 | */ |
46 | |
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47 | #ifndef MLIB_BITS_H |
48 | #define MLIB_BITS_H |
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49 | |
50 | #ifdef __cplusplus |
51 | extern "C" { |
52 | #endif |
53 | |
54 | /*----- Header files ------------------------------------------------------*/ |
55 | |
56 | #include <limits.h> |
57 | #include <stddef.h> |
58 | |
59 | /*----- Decide on some types ----------------------------------------------*/ |
60 | |
61 | /* --- Decide on a 32-bit type --- * |
62 | * |
63 | * I want a type which is capable of expressing 32-bit numbers. Because some |
64 | * implementations have 64-bit @long@s (infinitely preferable to the abortion |
65 | * that is @long long@), using @unsigned long@ regardless is wasteful. So, |
66 | * if @int@ appears to be good enough, then I'll go with that. |
67 | */ |
68 | |
69 | #if UINT_MAX >= 0xffffffffu |
70 | typedef unsigned int uint32; |
71 | #else |
72 | typedef unsigned long uint32; |
73 | #endif |
74 | |
75 | /* --- Decide on 16-bit and 8-bit types --- * |
76 | * |
77 | * This is more for brevity than anything else. |
78 | */ |
79 | |
80 | typedef unsigned short uint16; |
81 | typedef unsigned char octet; |
82 | |
83 | /* --- WARNING! --- * |
84 | * |
85 | * Never lose sight of the fact that the above types may be wider than the |
86 | * names suggest. Some architectures have 32-bit @short@s for example. |
87 | */ |
88 | |
89 | /*----- Macros ------------------------------------------------------------*/ |
90 | |
91 | /* --- Useful masks --- */ |
92 | |
93 | #define MASK8 0xffu |
94 | #define MASK16 0xffffu |
95 | #define MASK32 0xffffffffu |
96 | |
97 | /* --- Type coercions --- */ |
98 | |
99 | #define U8(x) ((octet)((x) & MASK8)) |
100 | #define U16(x) ((uint16)((x) & MASK16)) |
101 | #define U32(x) ((uint32)((x) & MASK32)) |
102 | |
103 | /* --- Safe shifting macros --- */ |
104 | |
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105 | #define LSL8(v, s) U8(U8(v) << ((s) & 7u)) |
106 | #define LSR8(v, s) U8(U8(v) >> ((s) & 7u)) |
107 | #define LSL16(v, s) U16(U16(v) << ((s) & 15u)) |
108 | #define LSR16(v, s) U16(U16(v) >> ((s) & 15u)) |
109 | #define LSL32(v, s) U32(U32(v) << ((s) & 31u)) |
110 | #define LSR32(v, s) U32(U32(v) >> ((s) & 31u)) |
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111 | |
112 | /* --- Rotation macros --- */ |
113 | |
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114 | #define ROL8(v, s) (LSL8((v), (s)) | (LSR8((v), 8u - (s)))) |
115 | #define ROR8(v, s) (LSR8((v), (s)) | (LSL8((v), 8u - (s)))) |
116 | #define ROL16(v, s) (LSL16((v), (s)) | (LSR16((v), 16u - (s)))) |
117 | #define ROR16(v, s) (LSR16((v), (s)) | (LSL16((v), 16u - (s)))) |
118 | #define ROL32(v, s) (LSL32((v), (s)) | (LSR32((v), 32u - (s)))) |
119 | #define ROR32(v, s) (LSR32((v), (s)) | (LSL32((v), 32u - (s)))) |
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120 | |
121 | /* --- Storage and retrieval --- */ |
122 | |
123 | #define GETBYTE(p, o) (((octet *)(p))[o] & MASK8) |
124 | #define PUTBYTE(p, o, v) (((octet *)(p))[o] = U8((v))) |
125 | |
126 | #define LOAD8(p) (GETBYTE((p), 0)) |
127 | #define STORE8(p, v) (PUTBYTE((p), 0, (v))) |
128 | |
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129 | #define LOAD16_B(p) \ |
130 | (((uint16)GETBYTE((p), 0) << 8) | \ |
131 | ((uint16)GETBYTE((p), 1) << 0)) |
132 | #define LOAD16_L(p) \ |
133 | (((uint16)GETBYTE((p), 0) << 0) | \ |
134 | ((uint16)GETBYTE((p), 1) << 8)) |
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135 | #define LOAD16(p) LOAD16_B((p)) |
136 | |
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137 | #define STORE16_B(p, v) \ |
138 | (PUTBYTE((p), 0, (uint16)(v) >> 8), \ |
139 | PUTBYTE((p), 1, (uint16)(v) >> 0)) |
140 | #define STORE16_L(p, v) \ |
141 | (PUTBYTE((p), 0, (uint16)(v) >> 0), \ |
142 | PUTBYTE((p), 1, (uint16)(v) >> 8)) |
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143 | #define STORE16(p, v) STORE16_B((p), (v)) |
144 | |
145 | #define LOAD32_B(p) \ |
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146 | (((uint32)GETBYTE((p), 0) << 24) | \ |
147 | ((uint32)GETBYTE((p), 1) << 16) | \ |
148 | ((uint32)GETBYTE((p), 2) << 8) | \ |
149 | ((uint32)GETBYTE((p), 3) << 0)) |
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150 | #define LOAD32_L(p) \ |
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151 | (((uint32)GETBYTE((p), 0) << 0) | \ |
152 | ((uint32)GETBYTE((p), 1) << 8) | \ |
153 | ((uint32)GETBYTE((p), 2) << 16) | \ |
154 | ((uint32)GETBYTE((p), 3) << 24)) |
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155 | #define LOAD32(p) LOAD32_B((p)) |
156 | |
157 | #define STORE32_B(p, v) \ |
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158 | (PUTBYTE((p), 0, (uint32)(v) >> 24), \ |
159 | PUTBYTE((p), 1, (uint32)(v) >> 16), \ |
160 | PUTBYTE((p), 2, (uint32)(v) >> 8), \ |
161 | PUTBYTE((p), 3, (uint32)(v) >> 0)) |
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162 | #define STORE32_L(p, v) \ |
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163 | (PUTBYTE((p), 0, (uint32)(v) >> 0), \ |
164 | PUTBYTE((p), 1, (uint32)(v) >> 8), \ |
165 | PUTBYTE((p), 2, (uint32)(v) >> 16), \ |
166 | PUTBYTE((p), 3, (uint32)(v) >> 24)) |
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167 | #define STORE32(p, v) STORE32_B((p), (v)) |
168 | |
169 | /*----- That's all, folks -------------------------------------------------*/ |
170 | |
171 | #ifdef __cplusplus |
172 | } |
173 | #endif |
174 | |
175 | #endif |